System and method for slice advance inversion for magnetic resonance imaging

Abstract

Systems and methods are provided for jointly acquiring non-inverted contrast and inverted contrast slice advance inversion sequences. In one example, a method for a magnetic resonance imaging (MRI) system includes acquiring (1102) k-space data with the MRI system according to a slice advance inversion sequence that jointly generates an inversion-free prepared contrast and one or more inversion contrasts for a plurality of slices in a scan volume of a subject, wherein the k-space data comprises first k-space data (1104) of the contrast acquired during one or more non-inversion repetitions without inversion preparation and second k-space data (1108) of the one or more inverted contrasts acquired during one or more inversion repetitions, wherein a repetition time of each of the one or more non-inversion repetitions and the one or more inversion repetitions is constant; and reconstructing (1112) one or more images from the k-space data.

Description

Technical Field

[0001] This specification generally relates to medical imaging. More specifically, the present disclosure relates to magnetic resonance imaging. Background Art

[0002] Magnetic resonance imaging (MRI) is a medical imaging modality that creates images of the inside of the human body without using X-rays or other ionizing radiation. An MRI scan typically includes a series of radiofrequency (RF) excitation pulses and magnetic field gradient pulses that are emitted in a specific sequence at a specific timing to prepare for contrast and encode spatial information as signals to generate an image. Summary of the Invention

[0003] In one example, a method for a magnetic resonance imaging (MRI) system includes: acquiring k-space data using the MRI system according to a slice presaturation sequence that jointly generates non-inversion prepared contrast for multiple slices in a scan volume of a subject and one or more inversion contrasts, wherein the k-space data includes first k-space data of the non-inversion prepared contrast acquired during one or more non-inversion repetitions and second k-space data of the one or more inversion contrasts acquired during one or more inversion repetitions, wherein the repetition time of each of the one or more non-inversion repetitions and the one or more inversion repetitions is constant; and reconstructing one or more images from the k-space data for each of the multiple slices.

[0004] It should be understood that the above Summary of the Invention is provided to introduce in a simplified form a series of concepts that are further described in the Detailed Description. This does not mean identifying the key features or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the Detailed Description. Moreover, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Brief Description of the Drawings

[0005] The present disclosure will be better understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0006] Figure 1 is a block diagram of an MRI apparatus according to an embodiment of the present disclosure;

[0007] Figure 2 and Figure 3 shows example slice plots of a first repetition, a second repetition, and a final repetition of a first example slice presaturation sequence;

[0008] Figure 4 shows an example inversion pulse sequence that can be performed as part of the first example slice presaturation sequence;

[0009] Figure 5 Illustrates an example imaging sequence that can be performed as part of a first example slice presaturation sequence;

[0010] Figure 6 Illustrates Figure 5 An enlarged view of a portion of an example imaging sequence of

[0011] Figure 7 Illustrates an example saturation band sequence that can be performed as part of a first example slice presaturation sequence;

[0012] Figure 8 Illustrates example slice plots of the first and second repetitions of a second example slice presaturation sequence;

[0013] Figure 9 And Figure 10 Illustrates example slice plots of the first, second, third, and fifth repetitions of a third example slice presaturation sequence;

[0014] Figure 11 Is a flowchart illustrating an example high-level method for performing an MRI scan according to a slice presaturation sequence;

[0015] Figure 12 Is a flowchart illustrating an example method for performing a first example slice presaturation sequence;

[0016] Figure 13 Is a flowchart illustrating an example method for performing a second example slice presaturation sequence;

[0017] Figure 14 Is a flowchart illustrating an example method for performing a third example slice presaturation sequence;

[0018] Figure 15 Illustrates an example image reconstructed from k-space data acquired using a second example slice presaturation sequence; and

[0019] Figure 16 Illustrates an example image reconstructed from k-space data acquired using a third example slice presaturation sequence. Detailed Description

[0020] The following description relates to magnetic resonance imaging (MRI), and more particularly to a slice presaturation inversion sequence for obtaining inversion contrast images of a subject. Inversion preparation is a key means for T1 contrast acquisition in MRI. An inversion sequence (also known as an inversion recovery sequence) is used to prepare the inversion contrast, which typically includes a 180° inversion radiofrequency (RF) pulse that precedes a conventional spin echo sequence with a 90°-180° echo sequence. The time between the inversion pulse and the 90° pulse of the spin echo sequence is referred to as the inversion time (TI). The inversion pulse flips the initial longitudinal magnetization (M0) of all tissues in the imaged slice to a point opposite the direction of the main magnetic field (B0). During the TI interval, these inverted tissues undergo T1 relaxation. When the spin echo sequence begins (at the 90° pulse), the initial longitudinal magnetization of different tissues is separated based on their different intrinsic T1 relaxation times. Thus, the degree of image contrast can be controlled by changing the TI. Using an inversion sequence to prepare the inversion contrast can have various benefits, including increased T1 sensitivity, additive T1 and T2 contrast, and the ability to suppress signals from selected tissues.

[0021] To achieve uniform inversion contrast across the acquisition volume for 2D acquisitions, dummy repetitions (TRs) or inversion blocks are used, resulting in a significant amount of non-acquisition time. Dummy TRs can include one or more TRs during which the inversion pulse is applied but no signal acquisition occurs. If a second TI is needed (e.g., one for T2 FLAIR and one for phase-sensitive inversion recovery T1w), new dummy TRs are required. Thus, the inversion sequence can be time-consuming.

[0022] Accordingly, in accordance with the embodiments disclosed herein, the inversion contrast can be prepared according to a new 2D slice presaturation inversion sequence in which a first acquisition volume (e.g., a T2-weighted volume) is acquired without an inversion pulse to prepare for the acquisition of one or several inversion contrasts (with different TIs). The inversion pulse and the imaging sequence (e.g., readout) are interleaved such that k-space data is constantly acquired only with a minimal non-acquisition time (e.g., during the inversion pulse), thereby shortening the scan time by eliminating the need for dummy TRs. In some examples, the slice presaturation inversion sequence can include additional slice-selective saturation bands for improving inversion uniformity.

[0023] The slice presaturation inversion sequence disclosed herein can be used to generate flexible contrast mechanisms, such as fast spin echo (FSE) or single-shot FSE (SSFSE) imaging with T2, T2 fluid attenuated inversion recovery (FLAIR), or phase-sensitive T1, and can acquire additional TIs for white matter (WM)-null or gray matter (GM)-null contrast (e.g., for a single fast sequence that includes acquisition of multiple image contrasts, such as NeuroMix). In contrast to, for example, fingerprinting, the entire inversion curve, which can be crucial for identifying early pathology, including WM and GM null points, can be sampled. By sampling the inversion curve at any number of TIs, the slice presaturation inversion sequence can also be used for rapid T1 mapping. If adiabatic inversion pulses are used, the slice presaturation inversion sequence is very robust against B1 inhomogeneities. The slice presaturation inversion sequence can also be used to rapidly acquire diffusion-weighted imaging (DWI) data at different TIs, thereby adding T1 as another dimension for tissue modeling.

[0024] Figure 1 An example MRI apparatus that can be used to obtain an MR signal of an imaging subject is shown. The MRI apparatus can include: a set of gradient coils configured to provide magnetic gradients along respective orthogonal directions; a radio frequency (RF) system configured to transmit RF pulses and receive the MR signal of the imaging subject; and a controller that can control the set of gradient coils and the RF system to perform the slice presaturation inversion sequence disclosed herein. Figures 2 to 10 An example slice presaturation inversion sequence is illustrated, including: Figure 2 and Figure 3 a slice plot of a first example slice presaturation inversion sequence as shown; Figure 8 a slice plot of a second example slice presaturation inversion sequence as shown; Figure 9 and Figure 10 a slice plot of a third example slice presaturation inversion sequence as shown; and example pulse sequences, imaging sequences, and saturation band sequences that can be performed as part of the slice presaturation inversion sequence disclosed herein as shown. Figures 4 to 7 An example high-level method for performing the slice presaturation inversion sequence is shown, the high-level method having example methods for performing the first example slice presaturation inversion sequence, the second example slice presaturation inversion sequence, and the third example slice presaturation inversion sequence as shown respectively. Figure 11 Example images that can be reconstructed from the slice presaturation inversion sequence disclosed herein are shown. Figure 12 、 Figure 13 and Figure 14 respectively. Figure 15 and Figure 16

[0025] Figure 1 ​An MRI apparatus 10 (e.g., an MRI system) is illustrated, which includes a static magnetic field magnet unit 12, a gradient coil unit 13, an RF coil unit 14, an RF body coil unit 15 (e.g., a volume coil unit), a transmit / receive (T / R) switch 20, an RF driver unit 22, a gradient coil driver unit 23, a data acquisition unit 24, a controller unit 25, a patient bed or examination table 26, a data processing unit 31, a scan control device 32, and a display unit 33. In some embodiments, the RF coil unit 14 is a surface coil, which is a local coil that is typically placed near the anatomical structure of interest of the subject 16. Here, the RF body coil unit 15 is a transmit coil that transmits RF signals, and the local surface of the RF coil unit 14 receives MR signals. Thus, the transmit body coil (e.g., the RF body coil unit 15) and the surface receive coil (e.g., the RF coil unit 14) are independent but electromagnetically coupled components. The MRI apparatus 10 transmits electromagnetic pulse signals to the subject 16 placed in the imaging space 18 where a static magnetic field is formed, to perform a scan to obtain magnetic resonance signals from the subject 16. One or more images of the subject 16 can be reconstructed based on the magnetic resonance signals thus obtained by scanning.

[0026] The static magnetic field magnet unit 12 includes, for example, a toroidal superconducting magnet installed in a toroidal vacuum vessel. The magnet defines a cylindrical space around the subject 16 and generates a constant main static magnetic field B0.

[0027] The MRI apparatus 10 also includes a gradient coil unit 13, which forms a gradient magnetic field in the imaging space 18 to provide three-dimensional position information for the magnetic resonance signals received by the RF coil array. The gradient coil unit 13 includes three gradient coil systems, and each of the three gradient coil systems generates a gradient magnetic field along one of three spatial axes perpendicular to each other, and generates a gradient field in each of the frequency encoding direction, the phase encoding direction, and the slice selection direction according to the imaging conditions. More specifically, the gradient coil unit 13 applies a gradient field in the slice selection direction (or scan direction) of the subject 16 to select a slice; and the RF body coil unit 15 or the local RF coil array can transmit RF pulses to the selected slice of the subject 16. The gradient coil unit 13 also applies a gradient field in the phase encoding direction of the subject 16 to phase-encode the magnetic resonance signals from the slice excited by the RF pulses. Then the gradient coil unit 13 applies a gradient field in the frequency encoding direction of the subject 16 to frequency-encode the magnetic resonance signals from the slice excited by the RF pulses.

[0028] The RF coil unit 14 is arranged to surround, for example, the region of the subject 16 to be imaged. In some examples, the RF coil unit 14 may be referred to as a surface coil or a receive coil. In a static magnetic field space or imaging space 18 in which a static magnetic field B0 is formed by the static magnetic field magnet unit 12, the RF body coil unit 15 transmits an RF pulse, which is an electromagnetic wave, to the subject 16 based on a control signal from the controller unit 25, and thereby generates a high-frequency magnetic field B1. This excites the proton spins in the slice of the subject 16 to be imaged. The RF coil unit 14 receives an electromagnetic wave generated when the proton spins excited in this way in the slice of the subject 16 to be imaged return to alignment with the initial magnetization vector as a magnetic resonance signal. In some embodiments, the RF coil unit 14 may transmit RF pulses and receive MR signals. In other embodiments, the RF coil unit 14 may be used only for receiving MR signals and not for transmitting RF pulses.

[0029] The RF body coil unit 15 is arranged to surround, for example, the imaging space 18 and generate an RF magnetic field pulse orthogonal to the main magnetic field B0 generated by the static magnetic field magnet unit 12 within the imaging space 18 to excite nuclei. The RF body coil unit 15 is fixedly attached and connected to the MRI apparatus 10 as compared with the RF coil unit 14 that can be disconnected from the MRI apparatus 10 and replaced with another RF coil unit. In addition, although local coils (such as the RF coil unit 14) may transmit signals to or receive signals from only a local region of the subject 16, the RF body coil unit 15 generally has a larger coverage area. For example, the RF body coil unit 15 can be used to transmit or receive signals to or from the whole body of the subject 16. Using only a receive local coil and a transmit body coil provides uniform RF excitation and good image uniformity at the cost of higher RF power deposited in the subject. For a transmit-receive local coil, the local coil provides RF excitation to the region of interest and receives MR signals, thereby reducing the RF power deposited in the subject. It should be understood that the specific use of the RF coil unit 14 and / or the RF body coil unit 15 depends on the imaging application.

[0030] When operating in the receive mode, the T / R switch 20 can selectively electrically connect the RF body coil unit 15 to the data acquisition unit 24, and when operating in the transmit mode, the T / R switch can selectively electrically connect the RF body coil unit to the RF driver unit 22. Similarly, when the RF coil unit 14 operates in the receive mode, the T / R switch 20 can selectively electrically connect the RF coil unit 14 to the data acquisition unit 24, and when the RF coil unit operates in the transmit mode, the T / R switch can selectively electrically connect the RF coil unit to the RF driver unit 22. When both the RF coil unit 14 and the RF body coil unit 15 are used for a single scan, for example, if the RF coil unit 14 is configured to receive MR signals and the RF body coil unit 15 is configured to transmit RF signals, the T / R switch 20 can direct the control signal from the RF driver unit 22 to the RF body coil unit 15 while directing the received MR signals from the RF coil unit 14 to the data acquisition unit 24. The coils of the RF body coil unit 15 can be configured to operate in a transmit-only mode or a transmit-receive mode. The coils of the RF coil unit 14 can be configured to operate in a transmit-receive mode or a receive-only mode.

[0031] The RF driver unit 22 includes a gate modulator (not shown), an RF power amplifier (not shown), and an RF oscillator (not shown), which are used to drive an RF coil (e.g., the RF body coil unit 15) and form a high-frequency magnetic field in the imaging space 18. The RF driver unit 22 modulates the RF signal received from the RF oscillator into a signal with a predetermined envelope and a predetermined timing based on the control signal from the controller unit 25 and using the gate modulator. The RF signal modulated by the gate modulator is amplified by the RF power amplifier and then output to the RF body coil unit 15.

[0032] The gradient coil driver unit 23 drives the gradient coil unit 13 based on the control signal from the controller unit 25, and thereby generates a gradient magnetic field in the imaging space 18. The gradient coil driver unit 23 includes three driver circuits (not shown) corresponding to the three gradient coil systems included in the gradient coil unit 13.

[0033] The data acquisition unit 24 includes a preamplifier (not shown), a phase detector (not shown), and an analog / digital converter (not shown) for acquiring the magnetic resonance signals received by the RF coil unit 14. In the data acquisition unit 24, the phase detector uses the output of the RF oscillator from the RF driver unit 22 as a reference signal to perform phase detection on the magnetic resonance signals received from the RF coil unit 14 and amplified by the preamplifier, and outputs the phase-detected analog magnetic resonance signals to the analog / digital converter to be converted into digital signals. The digital signals thus obtained are output to the data processing unit 31.

[0034] The MRI apparatus 10 includes an examination table 26 on which the subject 16 is placed. By moving the examination table 26 based on a control signal from the controller unit 25, the subject 16 can be moved inside and outside the imaging space 18.

[0035] The controller unit 25 includes a computer and a recording medium on which a program to be executed by the computer is recorded. When the program is executed by the computer, it causes the respective parts of the apparatus to perform operations corresponding to a predetermined scan. The recording medium may include, for example, a ROM, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a non-volatile memory card. The controller unit 25 is connected to the scan control device 32 and processes the operation signals input to the scan control device 32, and also controls the examination table 26, the RF driver unit 22, the gradient coil driver unit 23, and the data acquisition unit 24 by outputting control signals to them. The controller unit 25 also controls the data processing unit 31 and the display unit 33 based on the operation signals received from the scan control device 32 to obtain a desired image.

[0036] The scan control device 32 includes user input devices such as a touch screen, a keyboard, and a mouse. The operator uses the scan control device 32, for example, to input such data as an imaging protocol and to set the region where the imaging sequence is to be executed. The data regarding the imaging protocol and the imaging sequence execution region are output to the controller unit 25.

[0037] The data processing unit 31 includes a computer and a recording medium on which a program to be executed by the computer to perform predetermined data processing is recorded. The data processing unit 31 is connected to the controller unit 25 and performs data processing based on the control signals received from the controller unit 25. The data processing unit 31 is also connected to the data acquisition unit 24 and generates spectral data by applying various image processing operations to the magnetic resonance signals output from the data acquisition unit 24.

[0038] The display unit 33 includes a display device and displays an image on the display screen of the display device based on a control signal received from the controller unit 25. The display unit 33 displays, for example, an image of an input item for which the operator inputs operation data from the scan control device 32. The display unit 33 also displays a two-dimensional (2D) slice image or a three-dimensional (3D) image of the subject 16 generated by the data processing unit 31.

[0039] During an MRI scan performed using the MRI apparatus 10, a subject can be positioned within the imaging space 18, and an acquisition protocol can be performed to acquire MR signals of the subject. The acquisition protocol can include a plurality of pulse sequences, wherein, in each pulse sequence, one or more RF pulses applied via the RF body coil unit 15 are used to prepare the contrast, and the gradient coil unit 13 is controlled to spatially encode the resulting MR signals. The spatially encoded MR signals received by the RF coil unit 14 are digitized and stored in k-space. Thus, k-space data or a k-space data set can refer to the raw MR signals before being processed into an image. In some examples, the raw MR signals can be filled for one line of k-space at each pulse sequence (also referred to as the repetition time). In other examples, the raw MR signals can be filled for one line of k-space at each echo, wherein more than one echo is generated at each pulse sequence / repetition time. The k-space data can also be referred to herein as imaging data or MR data.

[0040] Figure 2 A set of slice plots 200 illustrating a first example slice presaturation sequence that can be performed by an MRI system (e.g., Figure 1 the MRI apparatus 10) to jointly acquire non-inverted contrast (T2 contrast herein) and inverted contrast of a scan volume including N slices. In Figure 2 the example shown, the inverted contrast is T1 FLAIR. The set of slice plots 200 includes a first slice plot 201 showing the playout of a first repetition (TR1) and a second slice plot 210 showing the playout of a second repetition (TR2). For Figure 2 each slice plot in the shown slice plots, time is depicted along a horizontal axis (e.g., the x-axis) and relative slice position is depicted along a vertical axis (e.g., the y-axis). The relative slice position can be relative to a central position represented by 0 (e.g., the isocenter of the aperture of the MRI apparatus), where the slice position extends in two directions (positive and negative) from the center.

[0041] Each of TR1 and TR2 of the first example slice presaturation sequence includes nine playouts, including a first playout (P1), a second playout (P2) up to a ninth playout (P9). In Figure 2In the example shown, nine slices are imaged in each of TR1 and TR2 (e.g., the same nine slices are imaged in each TR), and these slices may include a subset of all N slices of the scan volume imaged according to the first example slice advance inversion sequence. Additional slices of the volume are imaged in a later TR, as explained in more detail below. In the example shown, the first example slice advance inversion sequence may be performed in the following slice acquisition order: for TR1 and TR2, 1, 9, 17, 25, 33, 5, 13, 21, and 29; for TR3, 2, 10, 18, 26, 34, 6, 14, 22, and 30; for TR4, 3, 11, 19, 27, 35, 7, 15, 23, and 31; and for TR5, 4, 12, 20, 28, 36, 8, 16, 24, and 32. However, the acquisition order is exemplary, and other orders with more or fewer slices imaged per TR may be used.

[0042] Each broadcast of TR1 includes an inversion sequence 202, an imaging sequence 204, and a saturation band sequence 206 (example sequences of which are shown in Figures 4 to 7 and explained in more detail below) performed in that order. Each of the inversion sequence, imaging sequence, and saturation band sequence may be slice selective, where each inversion pulse acts on a slice different from the slice imaged during that broadcast. For example, for the first broadcast (P1) of TR1, a first inversion sequence 202a is performed, a first imaging sequence 204a is performed, and a first saturation band sequence 206a is performed. During the first imaging sequence 204a, the MRI system (e.g., MRI device 10) acquires k-space data that can be used to reconstruct an image of the slice on which the first imaging sequence 204a acts. The first saturation band sequence 206a may act to terminate the magnetization in the imaged slice, which may improve inversion uniformity. Thus, the first imaging sequence 204a may act on the first slice in the acquisition order (e.g., which is slice 1, centered around slice position 52) (e.g., image the first slice), and the first saturation band sequence 206a may also act on the first slice (e.g., terminate the magnetization of the first slice). The first saturation band sequence 206a is parallel to the imaged slice (e.g., the first slice) and may be centered on the imaged slice or a different slice of the volume. As shown, the first saturation band sequence 206a is shifted towards the center / bottom to improve the transition from slice group to slice group. The first inversion sequence 202a may include an RF inversion pulse that prepares the magnetization for a subsequent inversion recovery imaging sequence. Thus, the first inversion sequence 202a may act on a later slice (e.g., the fifth slice in the acquisition order, slice 33) imaged during a later broadcast (e.g., the fifth broadcast) of TR1.

[0043] For the second acquisition (P2) of TR1, a second inversion sequence 202b, a second imaging sequence 204b, and a second saturation band sequence 206b are performed. The second imaging sequence 204b and the second saturation band sequence 206b act on the second slice (slice 9) in the acquisition order, while the second inversion sequence 202b can act on a different slice (the sixth slice in the acquisition order, slice 5) that is imaged during a later acquisition of TR1 (e.g., during the sixth acquisition). The third acquisition of TR1 includes an imaging sequence and a saturation band sequence that act on the third slice in the acquisition order (e.g., slice 17) and an inversion sequence that acts on the seventh slice in the acquisition order (e.g., slice 13); the fourth acquisition of TR1 includes an imaging sequence and a saturation band sequence that act on the fourth slice in the acquisition order (e.g., slice 25) and an inversion sequence that acts on the eighth slice in the acquisition order (e.g., slice 21); the fifth acquisition of TR1 includes an imaging sequence and a saturation band sequence that act on the fifth slice in the acquisition order (e.g., slice 33) and an inversion sequence that acts on the ninth slice in the acquisition order (e.g., slice 29).

[0044] Midway through TR1, the inversion sequences begin to act on the slices that will be imaged in TR2. For example, during the sixth acquisition, a third inversion sequence 202c is performed that acts on the first slice in the acquisition order (e.g., slice 1), but the first slice is not imaged again in TR1, but rather in TR2 (as explained below). Similarly, for the remaining acquisitions of TR1 (e.g., the seventh, eighth, and ninth acquisitions), slice-selective imaging sequences and saturation band sequences are performed (on the seventh, eighth, and ninth slices in the acquisition order), and slice-selective inversion sequences are performed for the slices that are imaged in TR2 (on the second, third, and fourth slices in the acquisition order).

[0045] Because each inversion sequence acts on a later slice in the acquisition order, a subset of the slices that are imaged in TR1 are imaged without the earlier inversion sequences having acted on those slices. For example, the first inversion sequence 202a acts on slice 33 that is imaged during the fifth acquisition. Thus, the initial slices that are imaged in TR1 (e.g., the slices that are imaged in the first four acquisitions) are imaged when the slices exhibit non-inverted contrast (e.g., T2 contrast), and the remaining slices (e.g., the slices that are imaged in the last five acquisitions) are imaged when the slices exhibit inverted contrast (here T1 FLAIR, which is because the inversion time (TI) is a first inversion time of approximately 1000 ms (e.g., where TI is the time between the inversion sequence and the time when the slice on which the inversion sequence acts is imaged)). Thus, at least in some examples, TR1 can be a non-inverted repetition in which at least some k-space data of non-inverted contrast is acquired.

[0046] It should be understood that immediately and without delay after the termination of the first inversion sequence 202a, the first imaging sequence 204a is executed. For example, the first inversion sequence 202a may end approximately 10 ms after the initiation of TR1, and the first imaging sequence 204a may start approximately 10 ms after the initiation of TR1. The first imaging sequence 204a may end approximately 360 ms after the initiation of TR1, and the first saturation band sequence 206a may start approximately 360 ms after the initiation of TR1 and have a duration of approximately 6 ms. The second inversion sequence 202b may start immediately after the termination of the first saturation band sequence 206a, and thus may start approximately 366 ms after the initiation of TR1. In this way, the imaging sequence is executed for almost the entire TR1 except for the time during which the inversion sequence and the saturation band sequence are being executed.

[0047] Similar to TR1, TR2 includes multiple slice-selective imaging sequences, saturation band sequences, and inversion sequences that are executed across multiple acquisitions (e.g., nine), where each acquisition includes an inversion sequence (where magnetization is prepared for a subsequent inversion recovery imaging sequence), an imaging sequence (where k-space data for reconstructing an image is acquired), and a saturation band sequence (where magnetization is terminated), where the imaging sequence and the saturation band sequence act on the same slice and the inversion sequence acts on a different slice. For example, the first acquisition (P1) includes a first inversion sequence 212a, a first imaging sequence 214a, and a first saturation band sequence 216a, where each of the first imaging sequence 214a and the first saturation band sequence 216a acts on the first slice (slice 1) in the acquisition order, and the first inversion sequence 212a acts on a different later slice (e.g., the fifth slice in the acquisition order). Since the third inversion sequence 202c of TR1 acts on the first slice in the acquisition order, when the first slice exhibits inversion contrast, the first imaging sequence 214a acquires k-space data for the first slice. Thus, the first slice is imaged with both non-inversion contrast (e.g., T2 contrast) and inversion contrast (e.g., T1 FLAIR contrast) across TR1 and TR2. The remaining acquisitions of TR2 are similar to the first acquisition (e.g., since they each include an inversion sequence, an imaging sequence, and a saturation band sequence) and act on the same slices as in TR1. However, starting at the sixth acquisition (P6), the inversion sequences act on the slices that will be imaged in TR3, which include slices that were not imaged in TR1 and TR2. For example, the second inversion sequence 212b acts on slice 2, which is adjacent to slice 1 in slice position. Thus, the inversion sequences for acquisitions 6 - 9 are shifted so as to invert, for example, slices 2, 10, 18, and 26. Thus, in at least some examples, TR2 can be an inversion repetition where k-space data with inversion contrast is acquired.

[0048] As can be seen from Figure 2As understood, each imaging sequence of TR1 and TR2 can act only on a specified slice. For example, the first imaging sequence 204a of TR1 acts only on slice 1, and the second imaging sequence 204b of TR1 acts only on slice 5. However, each inversion sequence can have a slice thickness greater than the thickness of each slice / greater than the slice thickness of each imaging sequence, such that each inversion sequence acts on the selected slice and also on a portion of an adjacent slice. For example, each inversion pulse can have a slice thickness twice as thick as the slice thickness of the imaging sequence and can be centered on the selected slice. As an example, the second inversion sequence 202b of TR1 acts on slice 5 (which is imaged during P6) and has a thickness centered on slice 5 but spanning a portion of slice 4 and a portion of slice 6. Similarly, each saturation band sequence has a slice thickness greater than the slice thickness of each imaging sequence and is centered on the slice on which the saturation band sequence acts, but in some examples, the saturation band sequence can be centered on different slices of the scan volume.

[0049] TR3, TR4, and TR5 can be executed to image each remaining slice in the order specified by the acquisition order. Since each slice imaged in TR3, T4, and TR5 is inverted by an earlier inversion sequence (whether in an earlier TR or in this TR), only one TR is executed for each remaining subset of slices in the acquisition order. In other words, for the first subset of slices imaged in TR1, two TRs are executed to prepare the inversion contrast and image the first subset of slices. However, since the inversion contrast preparation for the second subset of slices can start in TR2, two separate TRs are not required for the second subset of slices, the third subset of slices, or the fourth subset of slices. For the final TR of the slice advance inversion sequence for the first example slice (TR5 in this particular example), only some inversion pulses are executed and the saturation band sequence is deactivated because no additional slices remain to be imaged.

[0050] Figure 3 The final TR of the slice advance inversion sequence for the first example slice is shown. Specifically, Figure 3Shows a third slice plot 300 having a plurality (e.g., nine) of broadcasts for imaging a final subset of slices in the acquisition order (e.g., slices 4, 12, 20, 28, 36, 8, 16, 24, and 32). Each broadcast of the final TR (e.g., TR5) includes an imaging sequence. Additionally, the first portion of the broadcast additionally includes an inversion sequence. For example, the first broadcast includes a first inversion sequence 302a and a first imaging sequence 304a. A saturation band sequence is not performed in the final TR (e.g., the saturation band sequence is deactivated, which is schematically shown to some extent by the marker centered at slice position 0). The second, third, fourth, and fifth broadcasts similarly include an inversion sequence and an imaging sequence. The inversion sequence of the fifth broadcast acts on the final slice of the slice acquisition order, and thus for the sixth, seventh, eighth, and ninth broadcasts, the inversion pulse is deactivated. For example, the sixth broadcast of the final TR includes only a second imaging sequence 304b. It should be understood that Figure 2 and Figure 3 each repetition of the slice advance inversion sequence shown has the same duration such that the repetition times of the non-inverted repetitions (TR1) and the inverted repetitions (e.g., TR2, TR3, TR4, and TR5) are constant.

[0051] Figure 4 Shows an example pulse sequence diagram 400 of the inversion sequence of the slice advance inversion sequence disclosed herein. For example, Figure 2 and Figure 3 any of the inversion sequences in may be performed according to the example pulse sequence diagram 400. The pulse sequence diagram 400 includes a first plot 410 showing the magnitude of the readout / frequency encoding gradient (e.g., along the readout axis, X) over time, a second plot 420 showing the magnitude of the phase encoding gradient (e.g., along the phase encoding axis, Y) over time, a third plot 430 showing the magnitude of the slice selection gradient (e.g., along the slice selection axis, Z) over time, a fourth plot 440 showing the RF magnitude transmitted by an RF transmitter coil (e.g., RF body coil unit 15) over time, and a fifth plot 450 showing the phase modulation (e.g., the phase modulation of the RF pulse, labeled θ) over time. In some examples, the gradient coil unit 13 may be controlled to generate Figure 4 the gradients shown.

[0052] At time T1, the slice selection gradient (e.g., the Z-axis gradient) is controlled to apply a slice selection gradient that acts on the selected slice, as shown in the third plot 430. For example, referring back to Figure 2, the first broadcast of the first repetition TR1 includes a first inversion sequence 202a that acts on slice 33. Thus, the slice selection gradient of the first inversion sequence 202a can act on slice 33. Immediately after T1, an RF pulse is applied until time T2, as shown in the fourth plot 440. The RF pulse can have a hyperbolic secant shape and a flip angle of 180°, and can be an adiabatic pulse (e.g., as shown by phase modulation). However, other inversion sequences can be used without departing from the scope of the present disclosure, such as an inversion sequence without an adiabatic RF pulse. After time T2, the slice selection gradient is deactivated, and spoiler gradients are performed in each of frequency, phase, and slice selection gradient to terminate the inversion pulse.

[0053] Figure 5 and Figure 6 FIG. 500 is an example pulse sequence diagram of an imaging sequence showing a slice early inversion sequence disclosed herein. For example, Figure 2 and Figure 3 any imaging sequence in the imaging sequence of can be performed according to the example pulse sequence diagram 500. Figure 6 FIG. 600 shows an enlarged version of the first 100 ms of the pulse sequence diagram 500. The pulse sequence diagram 500 includes a first plot 510 showing the magnitude of the readout / frequency encoding gradient (e.g., along the readout axis, X) over time, a second plot 520 showing the magnitude of the phase encoding gradient (e.g., along the phase encoding axis, Y) over time, a third plot 530 showing the magnitude of the slice selection gradient (e.g., along the slice selection axis Z) over time, and a fourth plot 540 showing the RF magnitude transmitted by an RF transmitter coil (e.g., the RF body coil unit 15) over time. In some examples, the Figure 1 gradient coil unit 13 of can be controlled to generate Figure 5 and Figure 6 the gradients shown.

[0054] The imaging sequence illustrated by the pulse sequence diagram 500 can be a fast spin echo (FSE) sequence, and thus includes an initial excitation pulse 602 (e.g., a 90° RF pulse), followed by a plurality of refocusing pulses 604 (e.g., RF pulses with a relatively low flip angle), which are visualized in the Figure 6 plot 540 of. During each RF pulse, a slice selection gradient is applied to select a slice, as shown in plot 530. For example, for the first imaging sequence 204a, a slice selection gradient will be applied to select slice 1, and the same slice will be selected whenever a slice selection gradient is applied during the imaging sequence. As shown in plot 520, the phase encoding gradient can be pulsed after each RF pulse, where the magnitude of the phase encoding pulse decreases and then increases during the course of the imaging sequence. Additionally, a readout gradient is applied after each refocusing RF pulse, as shown in plot 510. Although inFigure 5 and Figure 6 is not shown, but signal acquisition (e.g., via local RF coil unit 14) occurs during each pulse of the readout gradient. Figure 5 and Figure 6 The FSE sequence shown is a single-shot sequence in which all of the k-space data for reconstructing an image of the slice is acquired during the imaging sequence (e.g., without performing any additional excitation RF pulses). However, other imaging sequences are possible without departing from the scope of the present disclosure, such as a diffusion-weighted imaging (DWI) sequence.

[0055] Figure 7 An example pulse sequence diagram 700 of a saturation band sequence of the slice presaturation sequence disclosed herein is shown. For example, Figure 2 any saturation band sequence in the saturation band sequence of can be performed according to example pulse sequence diagram 700. Pulse sequence diagram 700 includes a first plot 710 showing the magnitude of the readout / frequency-encoding gradient (e.g., along the readout axis, X) over time, a second plot 720 showing the magnitude of the phase-encoding gradient (e.g., along the phase-encoding axis, Y) over time, a third plot 730 showing the magnitude of the slice-selection gradient (e.g., along the slice-selection axis, Z) over time, a fourth plot 740 showing the RF magnitude transmitted by an RF transmitter coil (e.g., RF body coil unit 15) over time, and a fifth plot 750 showing the phase modulation (e.g., phase modulation of the RF pulse, labeled θ) over time. In some examples, gradient coil unit 13 can be controlled to generate Figure 7 the gradients shown.

[0056] Pulse diagram 700 shows that the saturation band sequence includes applying a slice-selection gradient shown in plot 730 to select an appropriate slice, and the slice-selection gradient is applied from time T1 to time T2. No other gradient pulses are applied during the time period from T1 to T2. Between T1 and T2, an RF pulse with phase modulation is applied, which produces a composite saturation pulse to achieve increased saturation efficiency. However, other saturation pulses can be applied without departing from the scope of the present disclosure, such as a spatially selective 90° pulse transmitted at a carrier frequency different from the RF pulse applied for imaging. Each of the X-gradient, Y-gradient, and Z-gradient (e.g., frequency gradient, phase gradient, and slice-selection gradient) is spoilt with a relatively large magnitude after time T2. In this way, the saturation band sequence generates a saturation band at the selected slice within the scan volume.

[0057] Figure 8 A set of slice plots 800 illustrating a second example slice presaturation sequence, which can be performed by an MRI system (e.g., Figure 1The MRI apparatus 10) performs to jointly acquire a non-inverted contrast (e.g., T2 contrast) and an inverted contrast of a scan volume including N slices. In Figure 2 the example shown, the inverted contrast is T2FLAIR. The set of slice plots 800 includes a first slice plot 801 showing the broadcast of a first repetition (TR1) and a second slice plot 810 showing the broadcast of a second repetition (TR2). For Figure 8 each slice plot in the slice plots shown, time is depicted along the horizontal axis (e.g., the x-axis) and the relative slice position is depicted along the vertical axis (e.g., the y-axis). The relative slice position can be relative to a central position represented by 0 (e.g., the isocenter of the aperture of the MRI apparatus), where the slice positions extend from the center in two directions (positive and negative).

[0058] Each of TR1 and TR2 of the second example slice pre-inversion sequence includes 18 broadcasts, including a first broadcast (P1), a second broadcast (P2) up to the 18th broadcast. In Figure 8 the example shown, 18 slices are imaged in each of TR1 and TR2 (e.g., the same 18 slices are imaged in each TR), and these slices can include a subset of all the slices of the volume imaged according to the second example slice pre-inversion sequence. Additional slices of the volume are imaged in later TRs. In the example shown, the second example slice pre-inversion sequence can be performed such that the odd-numbered slices are imaged first (e.g., during TR1 and TR2), followed by the even-numbered slices (e.g., in TR3 and TR4), where the slice acquisition order is 1, 5, 9, 13, 17, 21, 25, 29, 33, 3, 7, 11, 15, 19, 23, 27, 31, and 35 for TR1 and TR2, and 2, 6, 10, 14, 18, 22, 26, 30, 34, 4, 8, 12, 16, 20, 24, 28, 32, and 36 for TR3 and TR4. However, the acquisition order shown is exemplary and can include more or fewer slices imaged per TR.

[0059] Each TR1 acquisition includes an imaging sequence and a saturation band sequence performed in that order, where an inversion sequence is activated midway through TR1 (e.g., starting at the 14th acquisition). Each inversion sequence, imaging sequence, and saturation band sequence can be slice-selective, where each inversion pulse acts on a slice different from the slice imaged during that acquisition. For example, for the first acquisition (P1) of TR1, a first imaging sequence 804a is performed, and a first saturation band sequence 806a is performed. During the first imaging sequence 804a, the MRI system (e.g., MRI device 10) acquires k-space data that can be used to reconstruct an image of the slice on which the first imaging sequence 804a acts. The first saturation band sequence 806a can act to terminate magnetization in the imaged slice, which can improve inversion uniformity. Thus, the first imaging sequence 804a can act on the first slice in the acquisition order (e.g., which is slice 1, centered around slice location 70) (e.g., image the first slice), and the first saturation band sequence 806a can also act on the first slice (e.g., terminate the magnetization of the first slice). The first saturation band sequence 806a is parallel to the imaged slice (e.g., the first slice) and can be centered on the imaged slice or on a different slice of the scan volume / offset from the imaging slice. During the first acquisition of TR1 and multiple subsequent acquisitions, no inversion sequence is activated, as shown by the deactivated inversion sequences such as deactivated inversion sequence 803 centered at slice location 0.

[0060] For the second acquisition (P2) of TR1, a second imaging sequence 804b and a second saturation band sequence 806b are performed. The second imaging sequence 804b and the second saturation band sequence 806b act on the second slice (slice 5) in the acquisition order. The third acquisition of TR1 includes an imaging sequence and a saturation band sequence that act on the third slice (e.g., slice 9) in the acquisition order; the fourth acquisition of TR1 includes an imaging sequence and a saturation band sequence that act on the fourth slice (e.g., slice 13) in the acquisition order, and so on.

[0061] Midway through TR1, the inversion sequence is activated and acts on the slice to be imaged in TR2. The activation of the inversion sequence is exemplified by a marker indicating that the deactivated inversion sequence stops and shifts to the activated inversion sequence located at the slice being inverted. For example, during the 14th broadcast (P14), a first inversion sequence 802a, a third imaging sequence 804c, and a third saturation band sequence 806c are executed. The first inversion sequence 802a may include an RF inversion pulse that prepares the magnetization for a subsequent inversion recovery imaging sequence. Thus, the first inversion sequence 802a may act on a later slice (e.g., the first slice in the acquisition order, slice 1) to be imaged during TR2. The third imaging sequence 804c and the third saturation band sequence 806c each act on the 14th slice (e.g., slice 19) of the acquisition order. Similarly, for the remaining broadcasts of TR1 (e.g., the 15th broadcast to the 18th broadcast), slice-selective imaging sequences and saturation band sequences are executed (for the 15th slice to the 18th slice of the acquisition order), and a slice-selective inversion sequence is executed for the slices to be imaged in TR2 (the second slice, the third slice, the fourth slice, and the fifth slice of the acquisition order). In some examples, the imaging sequence of the second example slice pre-inversion sequence may be an FSE sequence executed according to Figure 5 and Figure 6 of the pulse diagram 500; the saturation band sequence of the second example slice pre-inversion sequence may be executed according to Figure 7 of the pulse diagram 700; and the inversion sequence of the second example slice pre-inversion sequence may be executed according to Figure 4 of the pulse diagram 400.

[0062] Because each inversion sequence executed during TR1 acts on the slice to be imaged in TR2, each slice among the slices imaged in TR1 is imaged without an earlier inversion sequence acting on those slices. Thus, the slices imaged in TR1 are imaged when the slices exhibit non-inverted contrast (e.g., T2 contrast). Thus, TR1 can be a non-inverted repetition in which k-space data of non-inverted contrast is acquired. Once the inversion sequence is activated, the inversion contrast is prepared for subsequent imaging in TR2.

[0063] It should be understood that immediately and without delay after the termination of the first imaging sequence 804a, the first saturation band sequence 806a is executed. The second imaging sequence 804b can be executed after a delay corresponding to the length of the inversion sequence, which is the duration of the deactivated inversion sequence 803. Once the inversion sequence is activated, the inversion sequence is executed, immediately followed by the imaging sequence (without any delay), then immediately followed by the saturation band sequence, and then a new inversion sequence. In this way, the imaging sequence is executed for almost the entire TR1 except for the time when the inversion sequence and the saturation band sequence are being executed and the time when the delay of the deactivated inversion sequence occurs. Similar timing can be applied during TR2 such that the imaging sequence is executed for almost the entire TR2 except for the time when the inversion sequence is being executed and the time when the delay of the deactivated saturation band sequence and / or inversion sequence occurs (explained below).

[0064] TR2 includes multiple slice-selective imaging and inversion sequences performed across multiple broadcasts (e.g., 18), where each broadcast includes an inversion sequence (where magnetization is prepared for a subsequence inversion recovery imaging sequence) and an imaging sequence (where k-space data for reconstructing an image is acquired), and the imaging sequence and the inversion sequence act on different slices. No saturation band sequence is executed in TR2 (e.g., the saturation band sequence is deactivated, which is schematically shown to some extent by the deactivated saturation band sequence 813 centered at slice position 0). For example, the first broadcast (P1) of TR2 includes a first inversion sequence 812a and a first imaging sequence 814a, where the first imaging sequence 814a acts on the first slice (slice 1) in the acquisition order, and the first inversion sequence 812a acts on a different later slice (e.g., the sixth slice in the acquisition order). Since the first inversion sequence 802a of TR1 acts on the first slice in the acquisition order, when the first slice exhibits inversion contrast, the first imaging sequence 814a acquires the k-space data of the first slice. Thus, the first slice is imaged with both non-inversion contrast (e.g., T2 contrast during TR1) and inversion contrast (e.g., T2FLAIR contrast during TR2). The remaining broadcasts in the first half of the broadcasts of TR2 are similar to the first broadcast (e.g., because they each include an inversion sequence and an imaging sequence) and act on the same slices as in TR1. However, starting at the 10th broadcast (P10), the inversion sequence is deactivated (schematically shown to some extent by an additional marker centered at slice position 0), and thus the broadcasts 10 - 18 of TR2 only include imaging sequences.

[0065] Thus, for the slices imaged during TR1 and TR2, the slices are first imaged with T2 contrast and then with T2 FLAIR contrast. The inversion time (TI) can be a second inversion time of approximately 2500 ms (e.g., where TI is the time between the inversion sequence and the time at which the slice on which the inversion sequence acts is imaged), which is longer than the TI of the first example slice presaturation sequence. For TR1, the first subset of the broadcasts can each include a slice selective imaging sequence and a saturation band sequence (without an inversion sequence), and the second subset of the broadcasts can each include a slice selective imaging sequence (acting on the same slice) and a saturation band sequence as well as a slice selective inversion sequence acting on a different slice. For TR2, the first subset of the broadcasts can each include a slice selective inversion sequence and a slice selective imaging sequence acting on different slices (and without a saturation band sequence), and the second subset of the broadcasts can each include a slice selective imaging sequence (and without a saturation band sequence or an inversion sequence). Thus, TR2 can be an inversion repetition in which k-space data of the inversion contrast is acquired.

[0066] As understood from Figure 8 it, each imaging sequence of TR1 and TR2 can act only on a specified slice. For example, the first imaging sequence 804a of TR1 acts only on slice 1, and the second imaging sequence 804b of TR1 acts only on slice 5. However, each inversion sequence can have a slice thickness greater than the thickness of each slice / greater than the slice thickness of each imaging sequence, such that each inversion sequence acts on the selected slice and also on a portion of the adjacent slices. For example, each inversion pulse can have a slice thickness twice as thick as the slice thickness of the imaging sequence and can be centered on the selected slice.

[0067] TR3 and TR4 can be executed to image each remaining slice in the order specified by the acquisition order. TR3 can be executed similarly to TR1, but where the even-numbered slices are imaged with T2 contrast and the magnetization is prepared for inversion recovery imaging during TR4. TR4 can be executed similarly to TR2, but acting on the even-numbered slices. It should be understood that Figure 8 each repetition of the shown slice presaturation sequence has the same duration, such that the repetition times of the non-inversion repetitions (TR1, TR3) and the inversion repetitions (e.g., TR2, TR4) are constant.

[0068] Figure 9 and Figure 10 shows an example slice plot of a third example slice presaturation sequence, which can be performed by an MRI system (e.g., Figure 1The MRI apparatus 10) performs to jointly acquire non-inverted contrast (e.g., T2 contrast) of a scan volume including N slices and multiple inverted contrasts. The third slice pre-inversion sequence may be similar to the second slice pre-inversion sequence, but may include more slices being imaged, and may include additional TRs where TI is varied to prepare and acquire different inverted contrasts. Thus, Figure 9 includes a first set of slice plots 900, which includes a first slice plot 901 showing the broadcast of the first repetition (TR1) and a second slice plot 910 showing the broadcast of the second repetition (TR2). For Figure 9 and Figure 10 each slice plot in the shown slice plots, time is depicted along the horizontal axis (e.g., the x-axis) and the relative slice position is depicted along the vertical axis (e.g., the y-axis). The relative slice position may be relative to the central position represented by 0 (e.g., the isocenter of the aperture of the MRI apparatus), where the slice positions extend from the center in both directions (positive and negative).

[0069] Each of TR1 and TR2 of the third example slice pre-inversion sequence includes 26 broadcasts, which include the first broadcast (P1), the second broadcast (P2) up to the 26th broadcast. In Figure 9 the shown example, 26 slices are imaged in each of TR1 and TR2 (e.g., the same 26 slices are imaged in each TR), and these slices may include a subset of all slices of the volume imaged according to the third example slice pre-inversion sequence. Additional slices of the volume are imaged in later TRs. In the shown example, the third example slice pre-inversion sequence may be executed such that first the odd-numbered slices are imaged (e.g., during TR1 and TR2 and subsequent TRs), followed by the even-numbered slices being imaged (e.g., in the TR after the odd-numbered slices are imaged), where the slice acquisition order for the odd-numbered slices is 1, 5, 9, 13, 17, 21, 25, 29, 33 up to 49, 3, 7, 11, 15, 19, 23, 27, 31, 35 up to 51, and for the even-numbered slices is 2, 6, 10, 14, 18, 22, 26, 30, 34 up to 50, 4, 8, 12, 16, 20, 24, 28, 32, 36 up to 52. However, it should be understood that the acquisition order is exemplary, and more or fewer total slices may be imaged, with more or fewer slices being imaged per TR.

[0070] Similar to the second example slice presaturation sequence, each TR1 of the third example slice presaturation sequence includes an imaging sequence and a saturation band sequence that are executed in that order, where the presaturation sequence is initially deactivated and then activated midway through TR1 (e.g., starting at the 20th broadcast). Each presaturation sequence, imaging sequence, and saturation band sequence can be slice selective, where each presaturation sequence acts on a slice different from the slice imaged during that broadcast. For example, for the first broadcast (P1) of TR1, a first imaging sequence 904a is executed, and a first saturation band sequence 906a is executed. During the first imaging sequence 904a, the MRI system (e.g., MRI device 10) acquires k-space data that can be used to reconstruct an image of the slice on which the first imaging sequence 904a acts. The first saturation band sequence 906a can act to terminate magnetization in the imaged slice, which can improve presaturation uniformity. Thus, the first imaging sequence 904a can act on the first slice in the acquisition order (e.g., which is slice 1, centered around slice position 74) (e.g., image the first slice), and the first saturation band sequence 906a can also act on the first slice (e.g., terminate the magnetization of the first slice). The first saturation band sequence 906a is parallel to the imaged slice (e.g., the first slice) and can be centered on the imaged slice or another slice of the scan volume. During the first broadcast of TR1 and multiple subsequent broadcasts, no presaturation sequence is activated, as shown by the deactivated presaturation sequence such as deactivated presaturation sequence 903 centered at slice position 0.

[0071] For the second broadcast (P2) of TR1, a second imaging sequence 904b and a second saturation band sequence 906b are executed. The second imaging sequence 904b and the second saturation band sequence 906b act on the second slice (slice 5) in the acquisition order. The third broadcast of TR1 includes an imaging sequence and a saturation sequence that act on the third slice in the acquisition order (e.g., slice 9); the fourth broadcast of TR1 includes an imaging sequence and a saturation sequence that act on the fourth slice in the acquisition order (e.g., slice 13), and so on.

[0072] Midway through TR1, the inversion sequence is activated and acts on the slice to be imaged in TR2. Activation of the inversion sequence is exemplified by a marker that indicates the deactivated inversion sequence to stop and shift to the activated inversion sequence located at the slice being inverted. For example, during the 20th broadcast (P20), a first inversion sequence 902a, a third imaging sequence 904c, and a third saturation band sequence 906c are executed. The first inversion sequence 902a may include an RF inversion pulse that prepares the magnetization for a subsequent inversion recovery imaging sequence. Thus, the first inversion sequence 902a may act on a later slice (e.g., the first slice in the acquisition order, slice 1) to be imaged during TR2. The third imaging sequence 904c and the third saturation band sequence 906c each act on the 20th slice of the acquisition order (e.g., slice 27). Similarly, for the remaining broadcasts of TR1 (e.g., the 21st broadcast - the 26th broadcast), slice-selective imaging sequences and saturation band sequences are executed on the 21st slice - the 26th slice of the acquisition order, and slice-selective inversion sequences are executed on the slices to be imaged in TR2 (the second slice to the seventh slice of the acquisition order). In some examples, the imaging sequence of the second example slice advance inversion sequence may be an FSE sequence executed according to Figure 5 and Figure 6 the pulse diagram 500 of; the saturation band sequence of the second example slice advance inversion sequence may be executed according to Figure 7 the pulse diagram 700 of; and the inversion sequence of the second example slice advance inversion sequence may be executed according to Figure 4 the pulse diagram 400 of.

[0073] Since each inversion sequence executed during TR1 acts on the slice to be imaged in TR2, each slice among the slices imaged in TR1 is imaged without an earlier inversion sequence acting on those slices. Thus, the slices imaged in TR1 are imaged when the slices exhibit non-inverted contrast (e.g., T2 contrast), and TR1 may be a non-inverted repetition in which k-space data of non-inverted contrast is acquired. Once the inversion sequence is activated, the inversion contrast is prepared for subsequent imaging in TR2.

[0074] It should be understood that after the first imaging sequence 904a is terminated, the first saturation band sequence 906a is executed immediately and without delay. The second imaging sequence 904b may be executed after a delay corresponding to the length of the inversion sequence (which is the duration of the deactivated inversion sequence 903). Once the inversion sequence is activated, the inversion sequence is executed, followed immediately by the imaging sequence (without any delay), then immediately followed by the saturation band sequence, and then the new inversion sequence. In this way, the imaging sequence is executed for substantially the entire TR1, except for the time when the inversion sequence and the saturation band sequence are being executed and the time when the delay of the deactivated inversion sequence occurs. Similar timing may apply during TR2 and any subsequent TRs, such that the imaging sequence (explained below) is executed for substantially the entire TR, except for the time when the inversion sequence is being executed and the time when the delay of the deactivated saturation band sequence and / or inversion sequence occurs.

[0075] TR2 includes multiple slice-selective imaging and inversion sequences performed across multiple broadcasts (e.g., 26), wherein each broadcast (except for one broadcast in which the inversion sequence is deactivated, as explained below) includes an inversion sequence (in which magnetization is pre-prepared for a subsequence inversion recovery imaging sequence) and an imaging sequence (in which k-space data for reconstructing an image is acquired), wherein the imaging sequence and the inversion sequence are performed on different slices. Saturation band sequences are not performed in TR2 (e.g., the saturation band sequences are deactivated, as illustrated by the deactivated saturation band sequences, such as the deactivated saturation band sequence 913 centered at slice position 0). For example, the first broadcast (P1) of TR2 includes a first inversion sequence 912a and a first imaging sequence 914a, wherein the first imaging sequence 914a is performed on the first slice (slice 1) of the acquisition order, and the first inversion sequence 912a is performed on a different, later slice (e.g., the eighth slice of the acquisition order). Because the first inversion sequence 902a of TR1 is performed on the first slice of the acquisition order, the first imaging sequence 914a acquires k-space data for the first slice when the first slice exhibits inversion contrast. Thus, the first slice is imaged with both non-inversion contrast (e.g., T2 contrast during TR1) and first inversion contrast (T1 during TR2). The T1 of the first inversion contrast of the third example slice advance inversion sequence is exemplarily shown in slice plot 910 as being between the second inversion sequence 912b applied to slice 3 and the second imaging sequence 914b applied to slice 3. T1 is the time between the inversion sequence and the imaging sequence. The first inversion contrast is generated with a first inversion time (T1), such as approximately 2500 ms (e.g., T2 FLAIR).

[0076] The remaining broadcasts during the first half of TR2 are similar to the first broadcast (e.g., because they each include an inversion sequence and an imaging sequence), and act on the same slices as in TR1. However, during the 19th broadcast, the inversion sequence (P19) is deactivated, as indicated by marker 915 having an increased thickness relative to the marker representing the deactivated saturation band sequence. The deactivated inversion sequence is still broadcast to maintain timing orderly, but the RF of the inversion pulses is turned off so as not to invert any slices. Thus, the 19th broadcast of TR2 includes only the imaging sequence. Then, starting at the 20th broadcast (P20), the inversion sequence is reactivated, where the third inversion sequence 912c acting on the first slice (e.g., slice 1) of the acquisition order is shown. Broadcasts 21 - 26 each include inversion pulses acting on slices 2 - 6 of the acquisition order, respectively. Thus, by skipping one inversion pulse, the TI is shifted to generate a second inversion contrast of the slices imaged in TR3. TR2 can be an inversion repetition where k-space data of the inversion contrast is acquired.

[0077] Figure 10Shows the second set of slice plots 1000 of the third example slice pre-inversion sequence. The second set of slice plots 1000 includes a third slice plot 1001 showing the broadcast of the third repeat (TR3) of the third example slice pre-inversion sequence and a fourth slice plot 1010 showing the broadcast of the sixth repeat (TR6). Similar to TR2, TR3 includes a plurality of slice-selective imaging and inversion sequences performed across multiple broadcasts (e.g., 26), where each broadcast (except one broadcast where the inversion sequence is skipped, explained below) includes an inversion sequence (where magnetization is pre-prepared for a subsequence inversion recovery imaging sequence) and an imaging sequence (where k-space data for reconstructing an image is acquired), where the imaging sequence and the inversion sequence act on different slices. In TR3, no saturation band sequence is performed (e.g., the saturation band sequence is deactivated, as shown by the deactivated saturation band sequence 1003a centered at slice position 0). For example, the first broadcast (P1) of TR3 includes a first inversion sequence 1002a and a first imaging sequence 1004a (and the deactivated saturation band sequence 1003a), where the first imaging sequence 1004a acts on the first slice (slice 1) in the acquisition order, and the first inversion sequence 1002a acts on a different later slice (e.g., the seventh slice in the acquisition order). Since the first inversion sequence 912a of TR2 acts on the first slice in the acquisition order, when the first slice exhibits an inversion contrast, the first imaging sequence 1004a acquires the k-space data of the first slice. Thus, the first slice is imaged with a non-inversion contrast (e.g., T2 contrast during TR1), a first inversion contrast (Ti1 during TR2), and a second inversion contrast (Ti2 during TR3). The TI of the second inversion contrast of the third example slice pre-inversion sequence is exemplarily shown in slice plot 1001 between the second inversion sequence 1002b acting on slice 3 and the second imaging sequence 1004b acting on slice 3. T1 is the time between the inversion sequence and the imaging sequence. The second inversion contrast is generated with a second inversion time (Ti2) such as approximately 2200 ms.

[0078] A remaining portion of the TR3 acquisitions is similar to the first acquisitions (e.g., because they each include an inversion sequence and an imaging sequence) and acts on the same slice as in TR1 and TR2. However, the inversion sequence is deactivated during the 20th acquisition (P20). Thus, the 20th acquisition of TR3 includes only the imaging sequence. Then, starting at the 21st acquisition, the inversion sequence is reactivated, where a third inversion sequence 1002c acting on the first slice in the acquisition order (e.g., slice 1) is shown. Acquisitions 22-26 each include an inversion pulse acting on slices 2-5 in the acquisition order, respectively. Thus, by skipping one inversion pulse, the TI is shifted to generate a third inversion contrast for the slice imaged in TR4. TR4 can be similar to T3, but where the inversion sequence is separated from the corresponding imaging sequence by a third different TI (e.g., Ti3) to generate a third inversion contrast, and where the inversion sequence of the 21st acquisition is skipped to shift the subsequent inversion sequences, thereby generating a fourth inversion contrast. This process can be repeated for a desired number of TRs to generate a desired number of inversion contrasts, and more than one inversion sequence can be deactivated during a TR (e.g., continuously) to produce a desired inversion contrast.

[0079] For example, fourth slice plot 1010 illustrates the imaging and inversion sequences for the sixth repetition (TR6) of the third example slice advance inversion sequence. Similar to TR3, TR6 includes multiple slice-selective imaging and inversion sequences performed across multiple plays (e.g., 26), where each play (except for one play in which the inversion sequence is skipped, as explained below) includes an inversion sequence and an imaging sequence, where the imaging and inversion sequences are applied to different slices. Each inversion sequence prepares magnetization for a subsequent inversion recovery imaging sequence, and each imaging sequence acquires k-space data for reconstructing an image. In TR6, saturation band sequences are not performed (e.g., they are deactivated, as illustrated by the deactivated saturation band sequences, such as deactivated saturation band sequence 1003b centered at slice position 0). For example, the first play (P1) of TR6 includes a first inversion sequence 1012a and a first imaging sequence 1014a, where the first imaging sequence 1014a is applied to the first slice (slice 1) in the acquisition order, and the first inversion sequence 1012a is applied to a different, later slice (e.g., the fourth slice in the acquisition order). Because the TR5 inversion sequence is applied to the first slice in the acquisition order, the first imaging sequence 1014a acquires k-space data for the first slice while the first slice exhibits inversion contrast. Thus, the first slice is imaged with non-inversion contrast (e.g., T2 contrast during TR1), first inversion contrast (Ti1 during TR2), second inversion contrast (Ti2 during T3), third inversion contrast during TR4, fourth inversion contrast during TR5, and fifth inversion contrast during TR6. The TI of the fifth inversion contrast of the third example slice advance inversion sequence is exemplarily shown in slice plot 1010 as occurring between the second inversion sequence 1012b applied to slice 3 and the second imaging sequence 1014b applied to slice 3. T1 is the time between the inversion sequence and the imaging sequence. The fifth inversion contrast is generated with a fifth inversion time (Ti5) that is less than each of Ti1, Ti2, Ti3, and Ti4, such as approximately 1500 ms.

[0080] The remaining part of the TR6 broadcast is similar to the first broadcast (e.g., because they each include an inversion sequence and an imaging sequence). However, the inversion sequence is deactivated during the 24th broadcast (P24). Thus, the 24th broadcast of TR6 only includes the imaging sequence. Then, starting at the 25th broadcast, the inversion sequence is reactivated, where the third inversion sequence 1002c acting on the first slice (e.g., slice 1) of the acquisition order is shown. Broadcast 26 includes an inversion pulse acting on slice 2 of the acquisition order. Thus, by deactivating one inversion pulse, the TI is shifted to generate the sixth inversion contrast of the slice imaged in TR7. It should be understood that in the final TR of the sequence for odd-numbered slices, only the inversion sequence preceding the imaging sequence performed in the final TR is executed, since no slice remains to be prepared. Then, the sequence can be repeated for even-numbered slices (e.g., the next repeat similar to TR1 can be performed for even-numbered slices, followed by additional repeats for preparing and acquiring various inversion contrasts). It should be understood that Figure 9 and Figure 10 each repeat of the slice advance inversion sequence shown has the same duration, such that the repetition times of the non-inversion repeats (e.g., TR1 and the first repeat for even-numbered slices) and the inversion repeats (e.g., TR2, TR3, and the remaining inversion repeats) are constant.

[0081] Figure 11 is a flowchart illustrating an advanced method 1100 for MRI scanning according to an embodiment of the present disclosure. Method 1100 can be implemented using Figure 1 the MRI apparatus 10. Method 1100 can be executed according to instructions stored in a non-transitory memory and executed by one or more processors, such as instructions stored in the memory of the controller unit 25 and executed by one or more processors or the controller unit 25. Method 1100 can be executed in response to the initiation of an MRI scan protocol including a slice advance inversion sequence, and thus can be initiated after the patient has been positioned in the aperture of the MRI apparatus.

[0082] At 1102, method 1100 includes: acquiring k-space data of a plurality of slices of a scan volume using an MRI system according to a slice advance inversion sequence. Acquiring k-space data of a plurality of slices according to a slice advance inversion sequence can include: generating a non-inversion contrast (e.g., a contrast without inversion preparation) such as a T2 contrast, and acquiring first k-space data of the non-inversion contrast during a non-inversion repeat (e.g., during the first repeat (TR1)), as indicated at 1104. For example, as described above with respect to Figure 2 、 Figure 8 and Figure 9As explained, the first repetition of the slice-pre-inversion sequence may include multiple acquisitions, where an imaging sequence is performed in each acquisition without performing an earlier inversion sequence on the slice imaged via the imaging sequence. The non-inverted contrast may thus include a contrast where the longitudinal steady state of magnetization is not reached. In some examples such as the second example slice-pre-inversion sequence and the third example slice-pre-inversion sequence, each of the plurality of slices may be imaged during TR1, where each slice generates a non-inverted contrast during imaging. In other examples such as the first example slice-pre-inversion sequence, only a portion of the slices imaged during TR1 may be imaged while generating a non-inverted contrast (e.g., the first four slices in the acquisition order). In some examples, during at least the non-inverted repetition, a slice-selective saturation band for terminating magnetization and increasing the uniformity of subsequent inverted contrast may follow the imaging sequence performed.

[0083] Acquiring k-space data for a plurality of slices may also include: generating one or more inverted contrasts during a non-inverted repetition and / or one or more inverted repetitions (e.g., a second repetition (TR2) and / or one or more subsequent TRs after TR2), as indicated at 1106. The one or more inverted contrasts may be generated by performing a slice-selective inversion sequence that is spaced from a corresponding slice-selective imaging sequence by an inversion time (TI), where the TI may be varied across repetitions to generate more than one inverted contrast. For example, the first example slice-pre-inversion sequence may have a TI of approximately 1000 ms to generate a T1 FLAIR inverted contrast. The second slice-pre-inversion sequence may have a TI of approximately 2500 ms to generate a T2 FLAIR inverted contrast. The third example slice-pre-inversion sequence may have, for example, a first TI (Ti1) of 2500 ms and one or more additional TIs less than Ti1. Acquiring second k-space data for the one or more inverted contrasts during the non-inverted repetition and / or one or more inverted repetitions, as indicated at 1108. For example, the first example slice-pre-inversion sequence generates an inverted contrast for some of the slices that are subsequently imaged during the non-inverted repetition / TR1 (e.g., the last five slices imaged during TR1 are generating an inverted contrast when being imaged), where the remaining slices of the plurality of slices are imaged during the inverted repetition (e.g., TR2, and in some examples, also during TR3, TR4, and TR5) (while generating an inverted contrast). The second example slice-pre-inversion sequence acquires second k-space data for the plurality of slices only during the inverted repetition (TR2) (while generating an inverted contrast). The third example slice-pre-inversion sequence acquires second k-space data for the plurality of slices when generating a first inverted contrast during a first inverted repetition (e.g., TR2), when generating a second inverted contrast during a second inverted repetition (e.g., TR3), when generating a third inverted contrast during a third inverted repetition (e.g., TR4), etc.

[0084] As explained above, to generate an inversion contrast in a given slice, an inversion sequence that acts on the given slice is performed. An imaging sequence is performed on the given slice after a delay corresponding to the inversion time. However, each slice advance inversion sequence in the slice advance inversion sequences disclosed herein is interleaved with slice imaging and inversion preparation such that slice imaging and / or inversion preparation of other slices is performed during the inversion time of a given slice. For example, in Figure 2 the first slice advance inversion sequence of, a first inversion sequence that acts on the fifth slice in the acquisition order is performed. During the time between the time of performing the first inversion sequence and the time of performing the imaging sequence that acts on the fifth slice in the acquisition order, corresponding imaging sequences are performed on each of the first through fourth slices in the acquisition order (when those slices are generating T2 contrast), and corresponding inversion sequences are performed on later slices in the acquisition order (e.g., the sixth, seventh, eighth, and ninth slices in the acquisition order). As another example, for Figure 8 the second slice advance inversion sequence of, the first inversion sequence performed acts on the first slice in the acquisition order. During the time between the time of performing the first inversion sequence and the time of performing the next imaging sequence that acts on the first slice in the acquisition order (e.g., the first imaging sequence of TR2), corresponding imaging sequences are performed on each of the 14th through 18th slices in the acquisition order (when those slices are generating T2 contrast), and corresponding inversion sequences are performed on later slices in the acquisition order (e.g., the second through fifth slices in the acquisition order). In doing so, each of the inversion repetitions and non-inversion repetitions can have the same repetition time.

[0085] At 1110, method 1100 includes: repeating the slice presaturation sequence for a second plurality of slices. For example, during the non-saturated repeats (e.g., TR1) and one or more saturated repeats (e.g., TR2, and subsequent TRs when included) described above, only a portion of the scan volume to be imaged is imaged. In a first example slice presaturation sequence, one quarter of the total slices of the volume to be imaged are imaged in TR1 and TR2; the remaining slices are imaged across TR3, TR4, and TR5. In a second example slice presaturation sequence, one half of the total slices of the volume to be imaged are imaged in TR1 and TR2; the remaining slices are imaged across TR3 and TR4. In a third example slice presaturation sequence, one half of the total slices of the volume to be imaged are imaged in TR1, TR2, and subsequent TRs; the remaining slices are imaged across a second set of TRs. Thus, the slice presaturation sequence can be repeated for different slices at least once until the entire volume is imaged. The number of slices imaged when generating non-saturated contrast can be flexible and can vary based on the specific imaging sequence. For example, some saturation sequences such as the first example slice presaturation sequence image only those slices of the volume that are generating non-saturated contrast, while other saturation sequences such as the second example slice presaturation sequence image all slices of the volume when generating non-saturated contrast.

[0086] At 1112, an image is reconstructed from the k-space data. For example, a non-saturated image (e.g., a T2 image) can be reconstructed from the first k-space data, and a saturated image (e.g., a T1 FLAIR, T2 FLAIR) can be reconstructed from the second k-space data. When more than one saturated contrast is generated / imaged, an image can be reconstructed for each different saturated contrast. Thus, at least for some of the slices of the volume, a non-saturated contrast image can be reconstructed, and for each slice of the volume, at least one saturated contrast image can be reconstructed. In this way, some slice presaturation sequences can include reconstructing two or more images for each slice of the volume, while other slice presaturation sequences can include reconstructing only one image for some slices of the volume and two images for other slices of the volume. At 1114, the reconstructed images are displayed (e.g., on a display device such as display unit 33) and / or saved in memory. Then, method 1100 ends.

[0087] Figure 12 Method 1200, which illustrates a method for performing the first example slice presaturation sequence, is a more detailed version of method 1100 and is specific to performing the first example slice presaturation sequence such as Figure 2 and Figure 3 the first example slice presaturation sequence. Thus, method 1200 can utilize Figure 1implemented by the MRI apparatus 10 and executed according to instructions stored in a non-transitory memory and executed by one or more processors, such as instructions stored in the memory of the controller unit 25 and executed by one or more processors or the controller unit 25. The method 1200 may be executed in response to the initiation of an MRI scan protocol including a slice presaturation inversion sequence and may thus be initiated after the patient has been positioned in the aperture of the MRI apparatus.

[0088] At 1202, an acquisition protocol for the slice presaturation inversion sequence to be executed is obtained. Among other parameters, the acquisition protocol may also include the number of slices to be imaged, the slice acquisition order for imaging the slices, and which non-inverted and inverted contrasts will be generated and imaged. At 1204, a first broadcast of TR1 is performed, which includes an inversion sequence for a later slice of TR1, an imaging sequence for the first slice of the acquisition order, and an optional saturation band sequence for the first slice of the acquisition order. The inversion sequence may prepare an inverted contrast for a slice different from the first slice of the acquisition order (e.g., the fifth slice of the acquisition order), where the timing of the inversion sequence and the later imaging of the slice are selected to generate an inversion time (TI), which may be T1FLAIR in a first example slice presaturation inversion sequence. The first slice of the acquisition order is imaged without a previous inversion sequence acting on the first slice and thus, based on the imaging sequence executed (which may be an FSE sequence as Figure 5 and Figure 6 shown), a non-inverted contrast may be acquired when the first slice is imaged.

[0089] At 1206, the broadcast is repeated for the remaining slices of TR1. The acquisition order may specify that only some of the total slices of the volume to be imaged in TR1 are imaged, and each of those slices may be imaged via a corresponding broadcast including an imaging sequence and an optional saturation band sequence. Each remaining broadcast of TR1 may also include an inversion sequence acting on a slice different from the slice imaged during that broadcast. Additionally, when some of the slices imaged during TR1 (e.g., the fifth to ninth slices of the acquisition order) are imaged, those slices may exhibit an inverted contrast. As indicated at 1208, a subset of the inversion sequences executed in TR1 prepares the contrast to be imaged in TR2.

[0090] At 1210, method 1200 includes: performing a broadcast of TR2. The broadcast of TR2 can be the same as the broadcast of TR1, where each broadcast includes an inversion sequence, an imaging sequence, and optionally a saturation band sequence. Some of the inversion sequences in the inversion sequence act on the slices imaged during TR2, while other inversion sequences act on the slices that will be imaged in TR3 (assuming the acquisition protocol dictates imaging less than half of the slices per TR pair of volumes). However, since each slice has been prepared using an earlier inversion sequence, each slice imaged in TR2 is imaged while exhibiting an inversion contrast. Thus, some of the slices (e.g., the fifth to ninth slices in the acquisition order) can be imaged twice while generating the same inversion contrast.

[0091] At 1212, method 1200 includes: performing a first broadcast of TR3, which includes an inversion sequence for a later slice of TR3 (e.g., the fifth slice imaged in TR3, which can be the 14th slice in the acquisition order), an imaging sequence for a second slice, and an optional saturation band sequence for the second slice. It should be understood that the second slice can be positioned adjacent to the first slice in the acquisition order and thus can be the second slice in position but the 10th slice in the acquisition order. At 1214, the broadcast is repeated for the remaining slices of TR3 such that each broadcast includes an inversion sequence for a later slice, as well as an imaging sequence and an optional saturation band sequence. Some of the inversion sequences in the inversion sequence act on the slices imaged during TR3, while other inversion sequences act on the slices that will be imaged in TR4. However, since each slice has been prepared using an earlier inversion sequence, each slice imaged in TR3 is imaged while exhibiting an inversion contrast. As indicated at 1216, a subset of the inversion sequences performed in TR3 prepares the contrast for the slices that will be imaged in TR4.

[0092] At 1218, method 1200 determines whether the next TR to be performed is the final TR of the acquisition protocol. If the next TR is not the final TR, method 1200 proceeds to 1220 to perform the broadcasts of TR4 and any remaining TRs of the protocol until the final TR is reached. TR4 can be performed similarly to TR3 but on the next set of slices of the volume. Method 1200 continues to 1218 to again determine whether the next TR is the final TR. If the next TR is the final TR, method 1200 proceeds to 1222 to perform the broadcast of the final TR, where the first subset of the broadcast of the final TR includes an inversion sequence and an imaging sequence, and the second subset of the broadcast of the final TR includes only an imaging sequence. Thus, during the final TR, the inversion contrast for the slices that will be imaged in the next TR is not required, nor is the saturation band sequence (when performed in an earlier TR). Then, method 1200 ends.

[0093] Figure 13 Illustrates method 1300 for performing a second example slice presaturation reversal sequence. Method 1300 is a more detailed version of method 1100 and is specific to performing a second example slice presaturation reversal sequence such as Figure 8 . Thus, method 1300 can be implemented using MRI device 10 of Figure 1 and is performed in accordance with instructions stored in a non-transitory memory and executed by one or more processors, such as instructions stored in the memory of controller unit 25 and executed by one or more processors or controller unit 25. Method 1300 can be executed in response to the initiation of an MRI scan protocol that includes a slice presaturation reversal sequence and can thus be initiated after the patient has been positioned in the bore of the MRI device.

[0094] At 1302, an acquisition protocol for the slice presaturation reversal sequence to be performed is obtained. Among other parameters, the acquisition protocol can also include the number of slices to be imaged, the slice acquisition order for imaging the slices, and which non-inverted and inverted contrasts will be generated and imaged. At 1304, a first broadcast of TR1 is performed, which includes an imaging sequence for the first slice of the acquisition order and an optional saturation band sequence for the first slice of the acquisition order. The first slice of the acquisition order is imaged without a previous inversion sequence acting on the first slice, and thus, based on the imaging sequence performed (which can be an FSE sequence as shown in Figure 5 and Figure 6 ), a non-inverted contrast can be acquired when the first slice is imaged.

[0095] At 1306, the broadcast is repeated for the remaining slices of TR1. The acquisition order can specify that only some of the total slices of the volume will be imaged during TR1, and each of those slices can be imaged via a corresponding broadcast that includes an imaging sequence and an optional saturation band sequence. Each slice imaged during TR1 is imaged without a previous inversion sequence acting on that slice, and thus, based on the imaging sequence performed (which can be an FSE sequence as shown in Figure 5 and Figure 6 ), a non-inverted contrast can be acquired when each slice is imaged. As indicated at 1308, for the last part of the broadcast of TR1, such as the last five broadcasts, an inversion sequence is activated. Each inversion sequence can prepare an inverted contrast for a slice different from the slice imaged in that broadcast, where the timing of the inversion sequence and the later imaging of that slice are selected to generate an inversion time (TI), which can be T2FLAIR in the second example slice presaturation reversal sequence.

[0096] At 1310, method 1300 includes: performing a first broadcast of TR2, the first broadcast including an inversion sequence for a later slice of TR2 (e.g., the sixth slice in the acquisition order) and an imaging sequence for the first slice. At 1312, the broadcast is repeated for the remaining slices of TR2, but as indicated at 1314, for the last portion of the broadcast of TR2, the inversion sequence is terminated. Thus, some of the remaining broadcasts of TR2 may be the same as the first broadcast of TR2 (but acting on different slices), where those broadcasts include an inversion sequence and an imaging sequence. The remaining broadcasts of the remaining broadcasts of TR2 (e.g., the 10th to 18th broadcasts of TR2) may include only the imaging sequence. All of the inversion sequences performed in TR2 act on the slices imaged during TR2. Since each slice has been prepared with an earlier inversion sequence, each slice imaged during TR2 is imaged while exhibiting inversion contrast.

[0097] At 1316, method 1300 includes: performing a first broadcast of TR3, the first broadcast including an imaging sequence for a second slice and an optional saturation band sequence for the second slice. It should be understood that the second slice may be positioned adjacent to the first slice in the acquisition order and thus may be the second slice in position but the 19th slice in the acquisition order. The second slice is imaged without a previous inversion sequence acting on the second slice and thus, based on the imaging sequence performed (which may be an FSE sequence as shown in Figure 5 and Figure 6 ), non-inversion contrast may be acquired when the second slice is imaged.

[0098] At 1318, the broadcast is repeated for the remaining slices of TR3 such that each broadcast includes an imaging sequence and an optional saturation band sequence. Each slice imaged during TR3 is imaged without a previous inversion sequence acting on the slice and thus, based on the imaging sequence performed (which may be an FSE sequence as shown in Figure 5 and Figure 6 ), non-inversion contrast may be acquired when each slice is imaged. As indicated at 1320, for the last portion of the broadcast of TR3 such as the last five broadcasts, the inversion sequence is activated. Each inversion sequence may prepare the inversion contrast of a slice different from the slice imaged in that broadcast, where the timing of the inversion sequence and the later imaging of the slice are selected to generate an inversion time (TI) which may be T2FLAIR in the second example slice advance inversion sequence.

[0099] At 1322, method 1300 includes: performing a first broadcast of TR4, the first broadcast including an inversion sequence for a later slice of TR4 and an imaging sequence for a second slice. At 1324, the broadcast is repeated for the remaining slices of TR4, but as indicated at 1326, for the last part of the broadcast of TR4, the inversion sequence is terminated. Thus, some of the remaining broadcasts of TR4 may be the same as the first broadcast of TR4 (but acting on different slices), where those broadcasts include an inversion sequence and an imaging sequence. The remaining broadcasts in the remaining broadcasts of TR2 (e.g., the 10th to 18th broadcasts of TR4) may include only the imaging sequence. All inversion sequences performed in TR4 act on the slices imaged during TR4. Since each slice has been prepared with an earlier inversion sequence, each slice imaged during TR4 is imaged while exhibiting inversion contrast. Then, method 1300 ends.

[0100] Figure 14 Illustrated is method 1400 for performing a third example slice advance inversion sequence. Method 1400 is a more detailed version of method 1100 and is specific to performing, for example Figure 9 and Figure 10 the third example slice advance inversion sequence. Thus, method 1400 may be implemented using Figure 1 MRI device 10 and is performed according to instructions stored in a non-transitory memory and executed by one or more processors, such as instructions stored in the memory of controller unit 25 and executed by one or more processors or controller unit 25. Method 1400 may be executed in response to the initiation of an MRI scan protocol that includes a slice advance inversion sequence and may thus be initiated after the patient has been positioned in the aperture of the MRI device. Method 1400 may be similar to method 1300, but may include the generation and acquisition of multiple different inversion contrasts.

[0101] At 1402, an acquisition protocol for the slice advance inversion sequence to be performed is obtained. Among other parameters, the acquisition protocol may also include the number of slices to be imaged, the slice acquisition order for imaging the slices, and which non-inversion contrast(s) and inversion contrast(s) will be generated and imaged. At 1404, a first broadcast of TR1 is performed, the first broadcast including an imaging sequence for the first slice of the acquisition order and an optional saturation band sequence for the first slice of the acquisition order. The first slice of the acquisition order is imaged without a previous inversion sequence acting on the first slice and thus, based on the imaging sequence performed (which may be an FSE sequence as shown in Figure 5 and Figure 6 ), a non-inversion contrast may be acquired when the first slice is imaged.

[0102] At 1406, the remaining slices for TR1 are repeatedly broadcast. The acquisition order may specify that only some of the total slices of the volume will be imaged in TR1, and each of those slices may be imaged via a corresponding broadcast that includes an imaging sequence and optionally a saturation band sequence. Each slice imaged during TR1 is imaged without a prior inversion sequence having been applied to that slice, and thus based on the imaging sequence performed (which may be an FSE sequence as shown in Figure 5 and Figure 6 ), a non-inverted contrast may be acquired when each slice is imaged. As indicated at 1408, for the last part of the broadcast for TR1 such as the last five or seven broadcasts, an inversion sequence is activated. Each inversion sequence may prepare an inverted contrast for a slice different from the slice imaged in that broadcast, where the timing of the inversion sequence and the later imaging of that slice are selected to generate a first inversion time (Ti1).

[0103] At 1410, method 1400 includes: performing a first broadcast of TR2 that includes an inversion sequence for a later slice of TR2 (e.g., the sixth slice or the eighth slice of the acquisition order) and an imaging sequence for the first slice. At 1412, the broadcast is repeated for the remaining slices of TR2, but as indicated at 1414, one inversion sequence is skipped to shift the timing of the remaining inversion sequences of TR2 so as to generate a second inverted contrast at a second inversion time (Ti2). Thus, some of the remaining broadcasts of TR2 may be the same as the first broadcast of TR2 (but acting on different slices), where those broadcasts include an inversion sequence and an imaging sequence. One broadcast (e.g., the 19th broadcast) may include only the imaging sequence. The remaining broadcasts of the remaining broadcasts of TR2 (e.g., the 20th to 26th broadcasts of TR2) may include an imaging sequence and an inversion sequence acting on a later slice to be imaged in a subsequent TR (e.g., where the inversion sequence acts on slices 1-6 of the acquisition order). Since each slice imaged in TR2 has been prepared with an earlier inversion sequence, each slice imaged in TR2 is imaged while exhibiting an inverted contrast (and specifically the first inverted contrast formed at Ti1).

[0104] At 1416, method 1400 includes: performing a first broadcast of a next TR, the first broadcast including an imaging sequence for a first slice and an inversion sequence for a later slice of the TR. At 1418, method 1400 determines whether the acquisition protocol includes more Tis that will be formed to produce more inversion contrast and imaged. As previously explained, slices are first imaged when generating non-inversion contrast (e.g., during TR1), then imaged when generating a first inversion contrast (e.g., during TR2), and imaged during the next TR (e.g., TR3) when generating a second inversion contrast. If more than two inversion contrasts will be generated and imaged, method 1400 proceeds to 1420 to repeat the broadcast for the remaining slices of the next TR, but as indicated at 1422, skips one inversion sequence to shift the timing of the remaining inversion sequences of the next TR to generate another inversion contrast (e.g., a third inversion contrast) at another inversion time Tiy (e.g., Ti3). Thus, some of the remaining broadcasts in the next TR may be the same as the first broadcast of the next TR (but act on different slices), where those broadcasts include an inversion sequence and an imaging sequence. One broadcast (e.g., the 20th broadcast) may include only the imaging sequence. The remaining broadcasts in the remaining broadcasts of TR2 (e.g., the 21st broadcast to the 26th broadcast) may include an imaging sequence and an inversion sequence acting on later slices to be imaged in subsequent TRs (e.g., where the inversion sequence acts on slices 1-5 of the acquisition order). Since each slice imaged in the next TR has been prepared with an earlier inversion sequence, each slice imaged in the next TR is imaged while exhibiting inversion contrast (and specifically the second inversion contrast formed at Ti2 or another inversion contrast formed at Tiy). Then, method 1400 returns to 1416 to perform the first broadcast of the next TR. Thus, the third example slice inversion sequence can continue to perform TRs with new inversion contrasts generated at each TR by skipping one or more inversion sequences to shift the timing of subsequent inversion sequences. In some examples, the imaging sequence performed can change across TRs based on the inversion contrast being imaged. For example, the first inversion contrast can be imaged with a FSE having a late echo view ordering (e.g., T2-weighted), while the second inversion contrast can be imaged with a center-outward view ordering (e.g., for T1-weighted). In some examples, other different imaging sequences can be used as long as the imaging sequences have the same duration (although shorter sequences can be extended by dead time).

[0105] If it is determined at 1418 that the acquisition protocol does not include more inversion contrasts to be generated and imaged (e.g., the current TR is the final TR of a batch of slices), then method 1400 proceeds to 1424 to repeat the broadcast for the remaining slices of the current TR. For example, a broadcast similar to the first broadcast of the current TR performed at 1416 but acting on different slices can be performed for the remaining slices, where the inversion sequence of the last part of the broadcast is deactivated, as indicated at 1426. Once each slice to be imaged in the final TR has been prepared with the inversion sequence, the inversion sequence is deactivated. At 1428, method 1400 includes repeating the slice pre-inversion sequence for the next batch of slices. For example, TR1, TR2, and subsequent TRs after TR2 can image the first batch of slices (such as half of the slices of the volume) of the volume to be imaged. The remaining slices of the volume (e.g., the next batch of slices) can be imaged similarly to the first batch, for example, first when exhibiting non-inversion contrast, and then when exhibiting two or more inversion contrasts (e.g., across multiple TRs). Once all slices of the volume have been imaged to generate the specified inversion contrasts and image them, method 1400 ends.

[0106] It should be understood that while method 1400 includes skipping one inversion sequence per TR to change the inversion contrast of the next TR, more than one inversion sequence can be skipped per TR. However, the inversion contrast with the longest TI (e.g., T2FLAIR) is imaged first, followed by inversion contrasts with shorter TIs.

[0107] Additionally, each of methods 1100, 1200, 1300, and 1400 includes a broadcast having an inversion sequence, an imaging sequence, and / or a saturation band sequence. Any of the inversion sequences performed in methods 1100, 1200, 1300, and 1400 can be Figure 4 the example inversion sequence shown. Any of the imaging sequences performed in methods 1100, 1200, 1300, and 1400 can be Figure 5 and Figure 6 the example imaging sequence shown. Any of the saturation band sequences performed in methods 1100, 1200, 1300, and 1400 can be Figure 7The exemplary saturation band sequences shown. However, other inversion sequences, imaging sequences, and / or saturation band sequences may be performed without departing from the scope of the present disclosure. Although examples have been provided herein for FSE or SSFSE imaging with T2, T2FLAIR, and phase-sensitive T1, other specific implementations are possible, including other TIs for WM nulling or GM nulling contrast (e.g., in a single fast sequence such as NeuroMix that includes multiple image contrast acquisitions). Contrary to other parametric mapping techniques such as fingerprinting, the slice presaturation inversion sequences of the present disclosure may allow sampling of the complete inversion curve including WM and GM null points that can be crucial for identifying early pathology. By sampling the inversion curve at any number of TIs, the slice presaturation inversion sequences disclosed herein may also be used for rapid T1 mapping. If adiabatic inversion pulses are used, the slice presaturation inversion sequences are very robust to B1 inhomogeneities. The slice presaturation inversion sequences may also be used to rapidly acquire DWI data at different TIs, thereby adding T1 as another dimension for tissue modeling.

[0108] Figure 15 An example image reconstructed from k-space data that may be acquired according to the slice presaturation inversion sequences disclosed herein is shown. Specifically, Figure 15 The image shown is reconstructed from k-space data acquired according to a second example slice presaturation inversion sequence and thus includes a joint acquisition of T2 and T2FLAIR in a relatively short time frame (e.g., 32 s total), where the T2 contrast is acquired in a transitional state to prepare the magnetization for subsequent acquisition of T2FLAIR. The k-space data may be acquired using SSFSE readout, where the acquisition protocol includes imaging of 36 slices at a 24 cm FOV and a 260x220 matrix, each slice being 4 mm thick. Deep learning-based reconstruction is used to reconstruct the k-space data of one slice into a first image 1502 and a second image 1504. The first image 1502 is reconstructed from the first k-space data of the T2 contrast, and the second image 1504 is reconstructed from the second k-space data of the T2FLAIR contrast.

[0109] Figure 16Shows a set of images 1600 reconstructed from k-space data acquired with a slice-advanced inversion sequence according to the third example disclosed herein. The set of images 1600 are images of the same slice. The set of images 1600 includes a first image 1602 and a second image 1604 reconstructed from the acquired k-space data of T2 contrast. The set of images 1600 includes 13 additional images, each additional image reconstructed from the corresponding acquired k-space data of a different inversion contrast. For example, the first contrast image 1606 is reconstructed from the k-space data of the first inversion contrast, the second contrast image 1608 is reconstructed from the k-space data of the second inversion contrast, the third contrast image 1610 is reconstructed from the k-space data of the third inversion contrast, and so on. The k-space data can be acquired using SSFSE readout, where the acquisition protocol includes imaging of 70 slices at a FOV of 24 cm and a matrix of 200x200, with each slice being 2 mm thick. The images are reconstructed using deep learning-based reconstruction. Thus, using the slice-advanced inversion sequence of the third example, for each slice, the T2 contrast can be imaged one or more times together with multiple different inversion contrasts (e.g., 13). In Figure 16 In the example shown, all slices are imaged in a total time of 4:10 minutes. It should be understood that any inversion contrast in the inversion contrasts can be skipped, and some of the TEs in the TEs can be omitted to reduce the scan time.

[0110] Therefore, a new acquisition order (e.g., slice-advanced inversion sequence) is disclosed herein, in which the first contrast is acquired without an inversion pulse and then one or more inversion contrasts are acquired. The steady state of each slice is always maintained across the volume, no dummy TR or other non-acquisition time is introduced, and uniform contrast is achieved across the slice stack. The prior art for multi-TI acquisition relies on 3D inversion pulses followed by various 2D readouts at different positions of the inversion curve. The disadvantage of this method is that the same inversion time of each slice of the volume is not sampled unless as many TIs as there are slices in the volume are sampled, which is not feasible in most cases. With the new method disclosed herein, the desired TI (even only one, only T2 contrast and T2FLAIR) can be flexibly selected, and a uniform volume is obtained for each TI.

[0111] The technical effect of the slice-advanced inversion sequence in which both non-inversion contrast and inversion contrast are imaged is that the delay associated with the dummy TR used to prepare the inversion contrast can be reduced or eliminated, thereby increasing the scan speed.

[0112] In another representation, the MRI sequence for acquiring N slices includes an imaging sequence and an inversion sequence, where the imaging sequence acquires k-space data for creating an image, where the inversion sequence includes an inversion pulse, where one acquisition includes the inversion sequence and the imaging sequence, where the TR of the MRI sequence includes more than one acquisition, where the inversion sequence of the acquisition acts on a slice different from the imaging sequence of that acquisition, where the inverted slice of the previous acquisition is acquired by the imaging sequence of a later acquisition after an inversion time, where at least in the first TR of at least some acquisitions, the inversion pulse of the inversion sequence is turned off. In some examples, one TR of the MRI sequence includes an acquisition for only a subset of the N slices. In some examples, additionally or alternatively, the inversion sequence has a slice thickness different from that of the imaging sequence. In some examples, additionally or alternatively, the imaging sequence is an FSE sequence. In some examples, additionally or alternatively, the imaging sequence is a DWI sequence. In some examples, additionally or alternatively, the imaging sequence is a single-shot sequence.

[0113] In another representation, the MRI sequence for acquiring N slices includes an imaging sequence and an inversion sequence, where the imaging sequence acquires k-space data for creating an image, where the inversion sequence includes an inversion pulse, where one acquisition includes the inversion sequence and the imaging sequence, where the TR of the MRI sequence includes more than one acquisition, where the inversion sequence of the acquisition acts on a slice different from the imaging sequence of that acquisition, where the inverted slice of the previous acquisition is acquired by the imaging sequence of a later acquisition after a first inversion time, where in a later TR, the acquisition of the inversion sequence is delayed such that the imaging sequence acquires the k-space data at a second inversion time. In some examples, one TR of the MRI sequence includes an acquisition for only a subset of the N slices. In some examples, additionally or alternatively, the inversion sequence has a slice thickness different from that of the imaging sequence. In some examples, additionally or alternatively, the imaging sequence is an FSE sequence. In some examples, additionally or alternatively, the imaging sequence is a DWI sequence. In some examples, additionally or alternatively, the imaging sequence is a single-shot sequence. In some examples, additionally or alternatively, the TE of the imaging sequence is different for the first inversion time and the second inversion time.

[0114] In another representation, an MRI sequence for acquiring N slices includes an imaging sequence, an inversion sequence, and a saturation band sequence, where the imaging sequence acquires k-space data for creating an image, where the inversion sequence includes an inversion pulse, where the saturation band sequence includes a saturation pulse, where one acquisition consists of the inversion sequence, the imaging sequence, and the saturation band sequence, where the TR includes more than one acquisition, where the inversion sequence of an acquisition acts on a slice different from the imaging sequence, where the inverted slice of a previous acquisition is acquired by the imaging sequence of a later acquisition after an inversion time, and where the saturation pulse is activated and the saturation band is within the scan volume in at least some acquisitions. In some examples, the saturation band is parallel to the imaging slice and centered on the imaging slice. In some examples, additionally or alternatively, the saturation band has a slice thickness different from that of the imaging sequence. In some examples, additionally or alternatively, the saturation band is parallel to the imaging slice but centered on a slice of the slice stack different from the imaging slice of the same acquisition. In some examples, additionally or alternatively, the saturation band has a slice thickness different from that of the imaging sequence.

[0115] In another representation, a method for imaging a patient using a magnetic resonance imaging (MRI) system that utilizes a slice presaturation inversion sequence for multiple slices of a scanned volume includes: performing, using the MRI system, a first repetition of the slice presaturation inversion sequence, the first repetition including a first plurality of excitations for acquiring k-space data for a plurality of slices, where each excitation of the first plurality of excitations includes a respective imaging sequence, during which k-space data for a respective slice of the plurality of slices is acquired, and where at least a first excitation of the first plurality of excitations further includes an inversion sequence that acts on a slice of the plurality of slices different from the slice imaged during the imaging sequence of the first excitation. In a first example of the method, for at least a selected slice of the plurality of slices, the imaging sequence performed to acquire k-space data for the at least selected slice is performed without an earlier inversion sequence acting on the at least selected slice. In a second example of the method, which optionally includes the first example, each excitation of the first plurality of excitations further includes a saturation band sequence. In a third example of the method, which optionally includes one or both of the first example and the second example, each inversion sequence has a slice thickness different from that of each imaging sequence. In a fourth example of the method, which optionally includes one or more or each of the first example to the third example, each imaging sequence is a fast spin echo (FSE) sequence or a diffusion weighted imaging (DWI) sequence. In a fifth example of the method, which optionally includes one or more or each of the first example to the fourth example, each imaging sequence is a single-shot sequence. In a sixth example of the method, which optionally includes one or more or each of the first example to the fifth example, each excitation of the first plurality of excitations includes an inversion sequence and an imaging sequence, and some of the inversion sequences act on slices imaged in a second repetition of the slice presaturation inversion sequence. In a seventh example of the method, which optionally includes one or more or each of the first example to the sixth example, the method further includes: performing, using the MRI system, a second repetition, the second repetition including a second plurality of excitations for acquiring k-space data for a plurality of slices, where each excitation of the second plurality of excitations includes a respective imaging sequence and a respective inversion sequence, during which k-space data for a respective slice of the plurality of slices is acquired in each imaging sequence of the second repetition, each inversion sequence of the second repetition acts on a slice different from the slice imaged during the corresponding imaging sequence of the excitation, and some of the inversion sequences act on slices of a second plurality of slices imaged in a third repetition of the slice presaturation inversion sequence of the scanned volume.In an eighth example of the method, optionally including one or more or each of the first example to the seventh example, the method further includes: performing a third repetition using an MRI system, the third repetition including a third plurality of excitations for acquiring k-space data of a second plurality of slices, wherein each excitation of the third plurality of excitations includes a respective imaging sequence and a respective inversion sequence, wherein during each imaging sequence of the third repetition, k-space data of a respective slice of the second plurality of slices is acquired, and wherein each inversion sequence acts on a slice different from the slice imaged during the corresponding imaging sequence of the excitation. In a ninth example of the method, optionally including one or more or each of the first example to the eighth example, the method further includes: performing a final repetition using an MRI system, the final repetition including a fourth plurality of excitations for acquiring k-space data of a third plurality of slices of a scan volume, wherein each excitation of the fourth plurality of excitations includes a respective imaging sequence, wherein during each imaging sequence of the final repetition, k-space data of a respective slice of the third plurality of slices is acquired, and wherein only a portion of the excitations in the fourth plurality of excitations includes an inversion sequence. In a tenth example of the method, optionally including one or more or each of the first example to the ninth example, for each slice of the plurality of slices, the imaging sequence performed during the first repetition to acquire k-space data of the slice is performed without an earlier inversion sequence acting on the slice. In an eleventh example of the method, optionally including one or more or each of the first example to the tenth example, each inversion sequence acts on a slice of the plurality of slices imaged in the second repetition of the slice presaturation sequence. In a twelfth example of the method, optionally including one or more or each of the first example to the eleventh example, the method further includes: performing a second repetition using an MRI system, the second repetition including a second plurality of excitations for acquiring k-space data of a plurality of slices, wherein each excitation of the second plurality of excitations includes a respective imaging sequence and a respective inversion sequence, wherein during each imaging sequence of the second plurality of excitations, k-space data of a respective slice of the plurality of slices is acquired, and wherein each inversion sequence of the second plurality of excitations acts on a slice different from the slice imaged during the corresponding imaging sequence of the excitation. In a thirteenth example of the method, optionally including one or more or each of the first example to the twelfth example, for the last portion of the second plurality of excitations, the inversion sequence is deactivated.In a fourteenth example of the method, optionally including one or more or each of the first through thirteenth examples, the method further includes: performing a third repetition of a slice presaturation sequence using an MRI system, the third repetition including a third plurality of excitations for acquiring k-space data for a plurality of slices, wherein each excitation of the third plurality of excitations includes a respective imaging sequence and a respective presaturation sequence, wherein during each imaging sequence of the third plurality of excitations, k-space data for a respective one of the plurality of slices is acquired, and wherein each presaturation sequence of the third plurality of excitations acts on a slice different from the slice imaged during the corresponding imaging sequence of the excitation. In a fifteenth example of the method, optionally including one or more or each of the first through fourteenth examples, each imaging sequence performed during the second repetition is inverted by an earlier presaturation sequence, wherein the time between each earlier presaturation sequence and the corresponding imaging sequence of the second repetition is a first presaturation time. In a sixteenth example of the method, optionally including one or more or each of the first through fifteenth examples, each imaging sequence performed during the third repetition is inverted by an earlier presaturation sequence, wherein the time between each earlier presaturation sequence and the corresponding imaging sequence of the third repetition is a second presaturation time different from the first presaturation time.

[0116] The present disclosure also provides support for a method for a magnetic resonance imaging (MRI) system, the method comprising: acquiring k-space data using the MRI system according to a slice presaturation sequence that jointly generates non-inversion prepared contrast for a plurality of slices in a scan volume of a subject and one or more inversion contrasts, wherein the k-space data includes first k-space data of the non-inversion prepared contrast acquired during one or more non-inversion repetitions and second k-space data of the one or more inversion contrasts acquired during one or more inversion repetitions, wherein the repetition time for each of the one or more non-inversion repetitions and the one or more inversion repetitions is constant; and reconstructing one or more images from the k-space data for each of the plurality of slices. In a first example of the method, the non-inversion prepared contrast includes T2 contrast. In a second example of the method, optionally including the first example, the one or more inversion contrasts include T1 FLAIR or T2 FLAIR. In a third example of the method, optionally including one or both of the first example and the second example, the one or more inversion contrasts include two or more different inversion contrasts. In a fourth example of the method, optionally including one or more or each of the first example to the third example, the non-inversion prepared contrast includes a contrast in which a longitudinal steady state of magnetization is not reached, and wherein the first k-space data includes first k-space data for each of the plurality of slices or only a subset of the slices in the plurality of slices. In a fifth example of the method, optionally including one or more or each of the first example to the fourth example, the slice presaturation sequence includes a first plurality of imaging sequences performed during a first repetition of the one or more non-inversion repetitions to acquire the first k-space data and a second plurality of imaging sequences performed during a second repetition of the one or more inversion repetitions to acquire the second k-space data. In a sixth example of the method, optionally including one or more or each of the first example to the fifth example, at least one of the first plurality of imaging sequences and / or the second plurality of imaging sequences is a single-shot sequence. In a seventh example of the method, optionally including one or more or each of the first example to the sixth example, the slice presaturation sequence includes a first plurality of inversion sequences performed during the first repetition and a second plurality of inversion sequences performed during the second repetition, and wherein for a given slice among the plurality of slices, the first imaging sequence of the first repetition acting on the given slice and the first inversion sequence of the first repetition or the second repetition acting on the given slice generate one or more inversion contrasts for the given slice. In an eighth example of the method, optionally including one or more or each of the first example to the seventh example, the slice presaturation sequence further includes a plurality of slice-selective saturation band sequences, wherein each respective slice-selective saturation band sequence is performed immediately after the respective imaging sequence.In a ninth example of the method, which optionally includes one or more or each of the first example to the eighth example, the slice thickness of each corresponding slice selective saturation band sequence is different from the slice thickness of the corresponding imaging sequence. In a tenth example of the method, which optionally includes one or more or each of the first example to the ninth example, the slice position of each corresponding slice selective saturation band sequence is different from the slice position of the corresponding imaging sequence.

[0117] The present disclosure also provides support for a magnetic resonance imaging (MRI) system configured to image a scan volume of a subject, the MRI system including: a set of gradient coils configured to provide magnetic gradients along respective orthogonal directions; a radio frequency (RF) system configured to transmit RF pulses and receive MR signals representative of the scan volume; and a controller configured to control the set of gradient coils and the RF system to perform a slice presaturation inversion sequence that jointly generates non-inverted contrast and one or more inverted contrasts across one or more non-inverted repetitions and one or more inverted repetitions, wherein during the slice presaturation inversion sequence, the controller acquires k-space data from the MR signals, wherein the k-space data includes first k-space data of the non-inverted contrast acquired during one or more non-inverted repetitions and second k-space data of one or more inverted contrasts acquired during one or more inverted repetitions, wherein the repetition time of each of the one or more non-inverted repetitions and the one or more inverted repetitions is constant. In a first example of the system, the one or more inverted contrasts include two or more different inverted contrasts.

[0118] The present disclosure also provides support for a method for a magnetic resonance imaging (MRI) system, the method comprising: acquiring k-space data using the MRI system according to a slice presaturation sequence that generates two or more inversion contrasts for a plurality of slices in a scan volume of a subject, wherein the k-space data includes first k-space data of a first inversion contrast of two or more inversion contrasts acquired during one or more first inversion repetitions and second k-space data of a second inversion contrast of two or more inversion contrasts acquired during one or more second inversion repetitions, wherein the repetition time of each of the one or more first inversion repetitions and the one or more second inversion repetitions is constant; and reconstructing two or more images from the k-space data for each of the plurality of slices. In a first example of the method, the first repetition of the one or more first inversion repetitions includes a first plurality of broadcasts, each of the first plurality of broadcasts including a respective imaging sequence and a respective inversion sequence that acts on a slice different from the slice imaged during the respective imaging sequence of the broadcast, such that each imaging sequence performed during the first repetition is inverted by an earlier inversion sequence, wherein the time between each earlier inversion sequence and the respective image sequence of the first repetition is a first inversion time that produces the first inversion contrast. In a second example of the method, optionally including the first example, each inversion sequence has a slice thickness different from that of each imaging sequence, and / or each imaging sequence is a fast spin echo (FSE) sequence or a diffusion weighted imaging (DWI) sequence. In a third example of the method, optionally including one or both of the first example and the second example, the second repetition of the one or more second inversion repetitions includes a second plurality of broadcasts, each of the second plurality of broadcasts including a respective imaging sequence and a respective inversion sequence that acts on a slice different from the slice imaged during the respective imaging sequence of the broadcast, such that each imaging sequence performed during the second repetition is inverted by an earlier inversion sequence, wherein the time between each earlier inversion sequence and the respective image sequence of the second repetition is a second inversion time that produces the second inversion contrast and is different from the first inversion time. In a fourth example of the method, optionally including one or more or each of the first example to the third example, the slice presaturation sequence also generates a non-inversion contrast for the plurality of slices, and wherein the k-space data further includes third k-space data of the non-inversion contrast acquired during one or more non-inversion repetitions.In a fifth example of the method, optionally including one or more or each of the first to fourth examples, one or more first inversion repeats and one or more second inversion repeats each include a plurality of imaging sequences, wherein the slice presaturation sequence further includes a plurality of slice-selective saturation band sequences performed during one or more of the one or more first inversion repeats and / or one or more second inversion repeats, and wherein each respective slice-selective saturation band sequence is performed immediately after the respective imaging sequence. In a sixth example of the method, optionally including one or more or each of the first to fifth examples, the slice thickness of each respective slice-selective saturation band sequence is different from the slice thickness of the respective imaging sequence, and / or wherein the slice position of each respective slice-selective saturation band sequence is different from the slice position of the respective imaging sequence.

[0119] As used herein, unless otherwise specified, the term "about" is understood to mean ±5% of that range.

[0120] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of said elements or steps, unless expressly stated to the contrary. Further, a reference to "one embodiment" of the present invention is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless expressly stated to the contrary, an embodiment that "comprises," "comprises of," or "has" an element or elements with a particular property may include additional such elements that do not have that property. The terms "comprises" and "in" are used as the plain language equivalents of the respective terms "includes" and "wherein." Further, the terms "first," "second," and "third," etc. are used merely as labels and are not intended to impose numerical requirements or a particular positional order on their objects.

[0121] This written description uses examples to disclose the invention, including the best mode, and also enables one of ordinary skill in the relevant art to practice the invention, including making and using any device or system and performing any incorporated method. The scope of the invention that can be patented is defined by the claims and may include other examples that occur to one of ordinary skill in the art. If such other examples have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims, then such other examples are intended to fall within the scope of the claims.

[0122] The following claims particularly point out certain combinations and sub-combinations that are regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or their equivalents. Such claims should be understood to cover the combination of one or more such elements, neither requiring nor precluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by modifying these claims or presenting new claims in this application or a related application. Such claims, whether broader, narrower, the same, or different in scope than the original claims, are considered to be included within the subject matter of this disclosure.

Claims

1. A method for a magnetic resonance imaging (MRI) system, comprising: acquiring (1102) k-space data using the MRI system according to a slice presaturation sequence that jointly generates non-inversion-prepared contrast for a plurality of slices in a scan volume of a subject and one or more inversion contrasts, wherein the k-space data includes first k-space data (1104) of the non-inversion-prepared contrast acquired during one or more non-inversion repetitions and second k-space data (1106) of the one or more inversion contrasts acquired during one or more inversion repetitions, and wherein the repetition time for each of the one or more non-inversion repetitions and the one or more inversion repetitions is constant; and reconstructing (1112) one or more images from the k-space data for each of the plurality of slices.

2. The method according to claim 1, wherein the non-inversion-prepared contrast includes T2 contrast.

3. The method according to claim 1, wherein the one or more inversion contrasts include T1 FLAIR or T2 FLAIR.

4. The method according to claim 1, wherein the one or more inversion contrasts include two or more different inversion contrasts.

5. The method according to claim 1, wherein the non-inversion-prepared contrast includes a case where a longitudinal steady state of magnetization is not reached, and wherein the first k-space data includes the contrast of the first k-space data for each of the plurality of slices or only a subset of the slices of the plurality of slices.

6. The method according to claim 1, wherein the slice presaturation sequence includes a first plurality of imaging sequences (204a, 804a, 904a) performed during a first repetition of the one or more non-inversion repetitions to acquire the first k-space data and a second plurality of imaging sequences (214a, 814a, 914a) performed during a second repetition of the one or more inversion repetitions to acquire the second k-space data.

7. The method according to claim 6, wherein at least one of the first plurality of imaging sequences and / or the second plurality of imaging sequences is a single-shot sequence.

8. The method according to claim 6, wherein the slice presaturation sequence includes a first plurality of inversion sequences (202a, 802a, 902a) performed during the first repetition and a second plurality of inversion sequences (212a, 812a, 912a) performed during the second repetition, and wherein for a given slice of the plurality of slices, the first imaging sequence of the first repetition acting on the given slice and the first inversion sequence of the first repetition or the second repetition acting on the given slice generate the one or more inversion contrasts of the given slice.

9. The method according to claim 6, wherein the slice pre-inversion sequence further comprises a plurality of slice selective saturation band sequences (206a, 806a, 906a), and each respective slice selective saturation band sequence is performed immediately after the respective imaging sequence.

10. The method according to claim 9, wherein the slice thickness of each respective slice selective saturation band sequence is different from the slice thickness of the respective imaging sequence.

11. The method according to claim 9, wherein the slice position of each respective slice selective saturation band sequence is different from the slice position of the respective imaging sequence.

12. A magnetic resonance imaging (MRI) system (10) configured to image a scan volume of a subject, the MRI system comprising: a set of gradient coils (13) configured to provide magnetic gradients along respective orthogonal directions; a radio frequency (RF) system (14, 15) configured to transmit RF pulses and receive MR signals representative of the scan volume; and a controller (25) configured to control the set of gradient coils (13) and the RF system (14, 15) to perform a slice pre-inversion sequence that jointly generates a non-inverted contrast and one or more inverted contrasts across one or more non-inverted repetitions and one or more inverted repetitions, wherein during the slice pre-inversion sequence, the controller (25) acquires k-space data from the MR signals, and the k-space data includes first k-space data (1104) of the non-inverted contrast acquired during the one or more non-inverted repetitions and second k-space data (1108) of the one or more inverted contrasts acquired during the one or more inverted repetitions, and the repetition time of each of the one or more non-inverted repetitions and the one or more inverted repetitions is constant.

13. The MRI system according to claim 12, wherein the one or more inverted contrasts include two or more different inverted contrasts.

Images