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Method and apparatus for spin-echo-train MR imaging using prescribed signal evolutions

a signal evolution and spinechotrain technology, applied in the field of pulse sequence for use in the operation of magnetic resonance imaging apparatus, can solve the problems of substantial degradation of image contrast, introduction of artifacts such as blurring, etc., and achieve the effects of reducing image acquisition time, increasing spatial resolution, and prolonging the usable duration of the echo train

Inactive Publication Date: 2015-10-06
UNIV OF VIRGINIA ALUMNI PATENTS FOUND
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patent describes a way to use a series of RF pulses with specific flip angles and phases to improve magnetic resonance imaging (MRI) techniques. This allows for a longer echo train duration, which can decrease image acquisition time and increase spatial resolution.

Problems solved by technology

When high flip angles are used for the refocusing RF pulses, echo-train durations that are longer than these limits can substantially degrade image contrast and introduce artifacts such as blurring (See Mulkern et al.

Method used

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  • Method and apparatus for spin-echo-train MR imaging using prescribed signal evolutions
  • Method and apparatus for spin-echo-train MR imaging using prescribed signal evolutions
  • Method and apparatus for spin-echo-train MR imaging using prescribed signal evolutions

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examples

[0080]Specific implementations of the present invention methodology are useful to illustrate its nature. These examples are non-limiting and are offered as exemplary only. For this purpose, set forth herein are experimental studies in which the present invention method was used to generate variable-flip-angle series for three-dimensional (3D) T2-weighted MR imaging of the human brain and cervical spine using a “turbo-SE” type (i.e., RARE-as set forth in Henning et al., Magn. Res. Med. 1986, 3:823-833) spin-echo-train pulse sequence, of which is hereby incorporated by reference in its entirety. Brain studies were performed at 1.5 Tesla and 3 Tesla; spine studies were performed at 1.5 Tesla. MR images were obtained using a 1.5-Tesla commercial whole-body imager (MAGNETOM SYMPHONY, Siemens Medical Systems, Iselin, N.J.) or a 3-Tesla commercial whole-body imager (MAGNETOM ALLEGRA, Siemens Medical Systems, Iselin, N.J.). The standard head RF coil supplied with the imager was used. Inform...

example no.1

Example No. 1

[0082]FIGS. 4B-4F show an example of MR brain images obtained at 1.5 Tesla using the variable-flip-angle series of FIG. 3 in a “turbo-SE” type spin-echo-train pulse sequence; collectively. In particular, the T2-weighted two-dimensional and three-dimensional SE images of FIGS. 4(A) and 4(B)-4(C), respectively, were obtained from a 59 year old volunteer for demonstrating age-related non-specific white-matter lesions. As can be observed, arrows mark several of these lesions. The adjacent 1-mm thick 3D images, as shown in FIGS. 4B-4D, correspond to the single 3-mm thick 2D image in FIG. 4A. In the 3D images, the phase-encoding direction corresponding to the 160-echo train is left-to-right in FIGS. 4B-4D and 4F. No image artifacts secondary to this very long spin-echo train are apparent. Pulse sequence parameters for the 10 minute 3D acquisition included the following: repetition time / effective echo time, 2750 / 328 ms; matrix, 256×160×216; field of view, 25.6×16.0×21.6 cm; vo...

example no.2

Example No. 2

[0085]Next, referring to FIGS. 5A-5C, using the same pulse-sequence parameters as described above in FIGS. 2-4FIGS. 2-4F, T2-weighted images were also obtained at 3 Tesla from the brain of a healthy volunteer. The three 1-mm thick images were all reconstructed from the same 3D acquisition. These images appeared similar to those obtained at 1.5 Tesla, but exhibited higher signal-to-noise ratios. Of particular importance, the partial-body and local values for the specific absorption rate (SAR) were 1.29 W / kg and 3.16 W / kg, respectively, compared to the FDA limits for partial-body and local SAR of 3.0 and 8.0 W / kg, respectively. The SAR values at 3 Tesla were much less than the FDA limits, indicating that there remains substantial latitude in the pulse-sequence design from the perspective of power deposition, including the possibility for even more refocusing RF pulses per excitation. Thus, according to the present invention, although the use of spin-echo-train methods has...

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Abstract

A magnetic resonance imaging “MRI” method and apparatus for lengthening the usable echo-train duration and reducing the power deposition for imaging is provided. The method explicitly considers the t1 and t2 relaxation times for the tissues of interest, and permits the desired image contrast to be incorporated into the tissue signal evolutions corresponding to the long echo train. The method provides a means to shorten image acquisition times and / or increase spatial resolution for widely-used spin-echo train magnetic resonance techniques, and enables high-field imaging within the safety guidelines established by the Food and Drug Administration for power deposition in human MRI.

Description

[0001]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 7,164,268. The reissue applications are application Ser. Nos. 14 / 053,190 (the present application filed Oct. 14, 2013), 14 / 708,875 (a continuation reissue of 14 / 053,190 filed May 11, 2015), and 12 / 354,471 (a reissue application filed Jan. 15, 2009, and is now RE44,644). 14 / 053,190 and 14 / 708,875 are reissue continuations, of application Ser. No. 12 / 354,471 for the reissue of U.S. Pat. No. 7,164,268.RELATED APPLICATIONS[0002]This application is a continuation application of U.S. patent application Ser. No. 12 / 354,471, filed Jan. 15, 2009, which is an application for the reissue of U.S. Pat. No. 7,164,268, issued Jan. 16, 2007 from U.S. application Ser. No. 10 / 451,124, which is a national stage filing of International Application No. PCT / US01 / 50551, filed 21 Dec. 2001, which claims benefit under 35 U.S.C. Section 119(e) from U.S. Provisional Application Ser. No. 60 / 257,182, filed on Dec. 21...

Claims

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Application Information

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IPC IPC(8): G01R33/50G01V3/00G01R33/58G01R33/561A61B5/055
CPCG01R33/5602G01R33/5617G01R33/5615G01R33/586
Inventor MUGLER, III, JOHN P.BROOKEMAN, JAMES R.
Owner UNIV OF VIRGINIA ALUMNI PATENTS FOUND
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