Method for co-localization of lymphatic vessel and blood vessel under magnetic resonance

Abstract

The invention discloses a lymphatic vessel and blood vessel co-localization method under magnetic resonance. According to the method, a mixed contrast agent of gadotetrol and lidocaine is subjected to intradermal micro-injection, and an optimized three-dimensional T1 weighted imaging sequence is adopted for scanning. Under the sequence, the lymphatic vessel presents a high signal due to the contrast agent, and the blood vessel presents a low signal due to the empty flow effect, so that clear distinguishing of the lymphatic vessel and the blood vessel is realized, and imaging and space co-positioning are realized. According to the method, extra injection of vascular contrast agents is not needed, vein pollution can be effectively avoided, and accurate preoperative planning and incision positioning can be provided for lymphatic vein anastomosis.

Description

Technical Field

[0001] This invention belongs to the field of medical imaging technology, specifically a method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging. Background Technology

[0002] Lymphedema is a common complication after surgery for gynecological malignancies or breast cancer. Currently, lymphovenous anastomosis (LVA) is the mainstream surgical treatment. The key to the success of LVA surgery lies in the accurate preoperative localization of functional lymphatic vessels and adjacent veins in order to design the surgical incision and perform efficient anastomosis.

[0003] Currently, the main imaging methods used in clinical practice for the diagnosis and preoperative assessment of lymphedema include ultrasound, indocyanine green (ICG) imaging, radionuclide imaging, and magnetic resonance lymphangiography (MRL). However, these methods all have certain limitations:

[0004] Ultrasound: It requires high skill and experience from the operator, makes it difficult to observe lymphatic vessels in a 360° range of the limbs at the same time, has poor imaging effect for patients with severe edema, and carries the risk of misdiagnosis.

[0005] ICG imaging: The imaging depth is limited (usually <1.5 cm). For patients with stage II and III edema, skin reflux can obscure the observation of subcutaneous lymphatic vessels, making it difficult to obtain clear linear lymphatic vessel structures.

[0006] Radionuclide imaging: Although it is the gold standard for diagnosis, it has low spatial resolution and cannot clearly show the anatomical structure of lymphatic vessels, thus limiting its guiding role in surgery.

[0007] Traditional MRL: is subject to interference from venous contamination, i.e., veins and lymphatic vessels are visualized simultaneously, making them difficult to distinguish and affecting the accurate identification and localization of lymphatic vessels.

[0008] Therefore, there is an urgent need in this field for an imaging method that can non-invasively and clearly visualize lymphatic vessels and blood vessels simultaneously, achieve co-localization of both, and effectively avoid venous contamination. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for co-localization of lymphatic vessels and blood vessels under magnetic resonance imaging. This method does not require additional injection of contrast agents, can clearly distinguish lymphatic vessels and blood vessels, and assists in the preoperative incision localization of LVA surgery.

[0010] To achieve the above objectives, the present invention employs the following technical means:

[0011] A method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging includes the following steps:

[0012] A contrast agent containing gadolinium is mixed with lidocaine to form a contrast agent mixture;

[0013] The contrast agent mixture is injected intradermally into a designated injection point on the target limb, with a dose of 0.1-0.2 ml at each injection point;

[0014] The target limb was subjected to magnetic resonance imaging (MRI) scans, and the scan sequence included a three-dimensional T1-weighted imaging sequence based on flow void effect for blood suppression, i.e., a 3D-T1WI sequence.

[0015] In the images obtained by the 3D-T1WI sequence, lymphatic vessels show high signal due to the gadolinium-containing contrast agent, while blood vessels show low signal due to blood inhibition, thereby achieving simultaneous imaging, differentiation, and determination of the spatial relationship between lymphatic vessels and blood vessels.

[0016] Preferably, the gadolinium-containing contrast agent is gadoterol, the lidocaine is a 1% lidocaine solution, and the contrast agent mixture is prepared by mixing 15 ml of gadoterol with 1 ml of 1% lidocaine.

[0017] Preferably, the designated injection points for the intradermal injection are the first and fourth toe webs for the lower limbs, and the first and fourth finger webs for the upper limbs, as well as a point 1 cm lateral to the midline on the palmar side of the wrist.

[0018] Preferably, the 3D-T1WI sequence is a multi-echo three-dimensional perturbation gradient echo sequence, i.e., the mDIXONFFE sequence.

[0019] Preferably, the scanning parameters of the mDIXON FFE sequence include: repetition time of 5.6 ms, echo time of 2.1 ms, slice thickness of 1 mm, field of view of 300 mm × 300 mm, voxel size of 1.2 × 1.2 × 1.2, flip angle of 15°, and signal averaging times of 1.

[0020] Preferably, the nuclear magnetic resonance scan further includes a high-resolution fast spin echo volume sequence, namely, the VISTA sequence.

[0021] Preferably, the scanning parameters of the VISTA sequence include: a repetition time of 550 ms, an echo time of 20 ms, a slice thickness of 1.2 mm, a field of view of 300 mm × 300 mm, a voxel size of 1.2 × 1.2 × 1.2, a flip angle of 90°, and a signal averaging count of 1.

[0022] The present invention has the following beneficial effects:

[0023] 1. First achievement of single-sequence dual-system imaging and co-localization: By optimizing conventional MRI sequences, without the need for additional injection of contrast agents, lymphatic vessels and blood vessels can be clearly displayed simultaneously in a single scan, and their spatial relative positional relationship can be determined.

[0024] 2. Effectively avoids vein contamination: By strictly controlling the injection method and dosage of contrast agent, combined with the flow void effect of specific sequence parameters, vein visualization is effectively suppressed, solving the problem of vein interference in traditional MRL.

[0025] 3. Precise preoperative planning: Through three-dimensional image reconstruction, the course and diameter of lymphatic vessels can be displayed intuitively, and whether there is tortuosity, dilation or skin reflux. It can also accurately locate the position where the lymphatic vessels are closest to the adjacent veins and the diameter is most compatible, so as to design the best incision for LVA surgery, significantly shorten the operation time and improve the success rate of surgery.

[0026] 4. Non-invasive, safe, and highly reproducible: This method uses only conventionally approved MRI contrast agents, without the need to introduce new or experimental contrast agents, reducing patient trauma and potential risks, and making it easy to promote in clinical practice.

[0027] 5. Breaking equipment dependence: This method is based on widely used MRI equipment, reducing dependence on expensive and difficult-to-operate ultra-high frequency ultrasound equipment, enabling more medical institutions to conduct accurate preoperative assessments for LVA. Attached Figure Description

[0028] Figure 1 : Upper limb magnetic resonance lymphatic imaging image, showing lymphatic vessels (white arrows) and blood vessels (red arrows).

[0029] Figure 2 : Lower extremity magnetic resonance lymphangiography, showing lymphatic vessels (white arrows) and blood vessels (red arrows).

[0030] Figure 3 Image of the reflux zone on the inner side of the right calf, showing the reflux zone (blue triangle) and the responsible lymphatic vessels (white arrows).

[0031] Figure 4 Image of the reflux zone on the inner side of the left calf, showing the reflux zone (blue triangle) and the responsible lymphatic vessels (white arrows).

[0032] Figure 5 Example image showing successful location of lymphatic vessels and veins during surgery based on MRI localization.

[0033] Figure 6 Example diagram of incision design and anastomosis based on NMR localization.

[0034] Figure 7Example diagram of end-to-end anastomosis performed based on NMR localization. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides a method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging, comprising the following steps:

[0037] 1. Contrast agent preparation and injection

[0038] Contrast agent preparation: Mix 15 ml of gadolinium ether (e.g., Omni-Im) with 1 ml of 1% lidocaine.

[0039] Injection method: Intradermal injection.

[0040] For patients with lower limb edema, the injection site should be the web between the first and fourth toes.

[0041] For patients with upper limb edema, the injection site is the web between the first and fourth fingers, and a supplementary injection is also performed on the palmar side of the wrist, 1 cm away from the midline.

[0042] Injection dosage: Inject 0.1-0.2 ml of the above contrast agent mixture at each injection point.

[0043] 2. Nuclear magnetic resonance scan

[0044] Using an MRI scanner with a field strength of 3.0T or higher, employing a multi-channel body coil, with the patient in a supine position (feet first), the target limb is covered segmentally (such as the lower leg, knee, and thigh), and 3-5 cycles of MR scanning are performed.

[0045] The sequences acquired during the scan include:

[0046] The key scanning parameters of the multi-echo three-dimensional scrambled gradient echo sequence (mDIXON FFE) are: repetition time (TR) = 5.6 ms, echo time (TE) = 2.1 ms, slice thickness = 1 mm, field of view (FOV) = 300 mm × 300 mm, voxel size = 1.2 × 1.2 × 1.2, flip angle = 15°, and signal averaging times (NSA) = 1.

[0047] The key scanning parameters for the high-resolution fast spin echo volume sequence (VISTA) are: repetition time (TR) = 550 ms, echo time (TE) = 20 ms, slice thickness = 1.2 mm, field of view (FOV) = 300 mm × 300 mm, voxel size = 1.2 × 1.2 × 1.2, flip angle = 90°, and signal averaging times (NSA) = 1.

[0048] The principle of this invention is as follows: A microinjection of gadolinium ether containing lidocaine is administered intradermally, and blood suppression is achieved using the mDIXONFFE sequence (a 3D-T1WI sequence) based on the flow void effect. Under this sequence, lymphatic vessels containing the contrast agent exhibit a high signal, while suppressed blood vessels (veins) exhibit a low black signal, thus achieving clear differentiation and simultaneous imaging of lymphatic vessels and blood vessels.

[0049] Example

[0050] Preoperative assessment of patients with limb lymphedema using the method of this invention.

[0051] 1. Research Subjects

[0052] This study included 5 patients with limb lymphedema, including 3 patients with upper limb lymphedema after breast cancer surgery and 2 patients with lower limb lymphedema after gynecological tumor surgery. All patients gave informed consent and underwent the magnetic resonance lymphangiography examination described in this invention.

[0053] 2. Inspection Method

[0054] (1) Contrast agent preparation and injection

[0055] According to the method of this invention, 15 ml of gadolinium chloride (Omni-Import) is mixed with 1 ml of 1% lidocaine solution. The mixed contrast agent is then drawn using a 1 ml insulin syringe.

[0056] For patients with lower extremity edema, intradermal injections of 0.15 ml were administered at the webs of the first and fourth toes.

[0057] For patients with upper limb edema, intradermal injections were administered at the webs of the first and fourth fingers, and simultaneously at the palmar side of the wrist, 1 cm lateral to the midline, with 0.1 ml injected at each point.

[0058] (2) Nuclear magnetic resonance scan

[0059] A Philips Ingenia Elition 3.0T MRI scanner equipped with two 8-channel body coils was used. The patient was placed in a supine position (feet first), and the scanning range was segmented to cover the target limb (such as the lower leg and thigh), with 3 cycles of MR scans performed.

[0060] The collected sequences include:

[0061] mDIXON FFE sequence: Parameters set as follows: repetition time (TR) = 5.6 ms, echo time (TE) = 2.1 ms, slice thickness = 1 mm, field of view (FOV) = 300 mm × 300 mm, voxel size = 1.2 × 1.2 × 1.2, flip angle = 15°, signal averaging times (NSA) = 1.

[0062] VISTA sequence: Parameters set as follows: repetition time (TR) = 550 ms, echo time (TE) = 20 ms, slice thickness = 1.2 mm, field of view (FOV) = 300 mm × 300 mm, voxel size = 1.2 × 1.2 × 1.2, flip angle = 90°, signal averaging times (NSA) = 1.

[0063] 3. Results and Analysis

[0064] All patients successfully completed the examination without any adverse reactions. On mDIXON FFE sequence (3D-T1WI) images, lymphatic vessels showed clear high signal due to the presence of contrast agent, while blood vessels were suppressed due to flow void effect and showed black low signal, making the two contrasting and easily distinguishable.

[0065] (1) Clear imaging and differentiation of lymphatic vessels and blood vessels

[0066] like Figure 1 The image shown is the imaging result of a 62-year-old female patient with right upper limb lymphedema after breast cancer surgery. On the 3D-T1WI sequence image, functional lymphatic vessels can be clearly seen on the radial and dorsal side of the right upper limb (white arrow), and the black circular cavity next to them is the accompanying vein (red arrow).

[0067] like Figure 2 The image shown is the imaging result of a 68-year-old female patient with right lower extremity lymphedema after gynecological tumor surgery. The image shows that the lymphatic vessels on the medial side of the right calf are significantly enhanced and tortuous (white arrow), and the accompanying veins are visible as black low signal (red arrow).

[0068] (2) Identification of skin reflux zones and responsible lymphatic vessels

[0069] The method of this invention can effectively visualize deep structures that are difficult to observe with ICG and lymphatic vessels that are obscured by skin reflux.

[0070] like Figure 3 As shown, the patient (same) Figure 2 A large area of ​​skin reflux (blue triangle) is visible on the inner side of the right calf. (In axial images) Figure 3In diagram A), a lymphatic vessel (white arrow) can be clearly identified connecting to and draining into the reflux zone; this is the "responsible lymphatic vessel." Through multiplanar reconstruction, the origin of this lymphatic vessel can be traced retrospectively.

[0071] like Figure 4 As shown, another 70-year-old female patient also had a skin reflux area (blue triangle) on the posteromedial aspect of the mid-section of her left calf. MIP images and axial and coronal images ( Figure 4 Both A and B show a lymphatic vessel (white arrow) entering the reflux zone.

[0072] (3) Preoperative precise localization and surgical verification

[0073] The core advantage of this invention lies in its ability to co-locate lymphatic vessels and veins, allowing for the design of optimal incisions for LVA surgery.

[0074] like Figure 5 As shown, a patient with left upper limb edema for 5 years. Preoperative MRI ( Figure 5 AD images showed a functional lymphatic vessel (white arrow) on the radial dorsolateral aspect of the left forearm, with a matching vein nearby (red arrow). Based on this image, the surgeon precisely designed the surgical incision preoperatively. Figure 5 E). After intraoperative incision, the target lymphatic vessels and veins were successfully located ( Figure 5 F) verified the accuracy of the positioning.

[0075] like Figure 6 As shown, another patient with upper limb edema. MRI image ( Figure 6 AD showed two functional lymphatic vessels (white arrows) and adjacent veins (red arrows) on the palmar side of the left forearm. Based on this co-localization information, an incision was designed, and the anastomosis target was quickly and accurately located during the operation. Figure 6 E, F).

[0076] like Figure 7 The image shows a patient with left lower extremity edema. MRI scan ( Figure 7 AD) shows two functional lymphatic vessels (white arrows) on the posteromedial aspect of the tibia in the left lower leg, and two small veins (red arrows) with similar course and matching diameter nearby. Figure 7 The rotational MIP image of E provides a more intuitive view of the lymphatic vessels' course. Based on this result, an incision of approximately 3 cm was designed. Figure 7 F), during the operation, lymphatic vessels and veins were rapidly separated and successfully anastomosed end to end. Postoperatively, the patient's lower limb circumference improved significantly. Figure 7 G).

[0077] 4. Conclusion

[0078] This embodiment fully demonstrates the effectiveness and superiority of the magnetic resonance imaging (MRI) scanning sequence described in this invention. By intradermal microinjection of a specific combination of contrast agents and scanning using an optimized mDIXON FFE sequence, it is possible to:

[0079] Simultaneous imaging: Lymphatic vessels (high signal) and veins (low signal) are clearly visualized in a single step without the need for additional injection of contrast agents.

[0080] Precise co-location: Clearly displays the relative positions, course relationships, and distances of lymphatic vessels and veins in three-dimensional space.

[0081] Surgical guidance: Based on colocalization information, the optimal incision location is planned for LVA surgery, which significantly shortens the time for finding the target blood vessel during surgery and improves surgical efficiency and success rate.

[0082] Overcoming traditional limitations: It effectively avoids venous contamination and allows observation of deep lymphatic vessels and skin reflux areas, solving the pain points of ICG imaging and traditional MRL.

[0083] The examples provided in this invention are not intended to limit the implementation. Those skilled in the art will recognize that various variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of this invention.

Claims

1. A method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging, characterized in that, Includes the following steps: A contrast agent containing gadolinium is mixed with lidocaine to form a contrast agent mixture; The contrast agent mixture is injected intradermally into a designated injection point on the target limb, with a dose of 0.1-0.2 ml at each injection point; The target limb was subjected to magnetic resonance imaging (MRI) scans, and the scan sequence included a three-dimensional T1-weighted imaging sequence based on flow void effect for blood suppression, i.e., a 3D-T1WI sequence. In the images obtained by the 3D-T1WI sequence, lymphatic vessels show high signal due to the gadolinium-containing contrast agent, while blood vessels show low signal due to blood inhibition, thereby achieving simultaneous imaging, differentiation, and determination of the spatial relationship between lymphatic vessels and blood vessels.

2. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 1, characterized in that, The gadolinium-containing contrast agent is gadoterol, the lidocaine is a 1% lidocaine solution, and the contrast agent mixture is prepared by mixing 15 ml of gadoterol with 1 ml of 1% lidocaine.

3. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 1, characterized in that, The designated injection points for the intradermal injection are the first and fourth toe webs for the lower limbs; and the first and fourth finger webs for the upper limbs, as well as a point 1 cm lateral to the midline on the palmar side of the wrist.

4. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 1, characterized in that, The 3D-T1WI sequence is a multi-echo three-dimensional perturbation gradient echo sequence, namely, the mDIXON FFE sequence.

5. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 4, characterized in that, The scanning parameters of the mDIXON FFE sequence include: repetition time of 5.6 ms, echo time of 2.1 ms, slice thickness of 1 mm, field of view of 300 mm × 300 mm, voxel size of 1.2 × 1.2 × 1.2, flip angle of 15°, and signal averaging times of 1.

6. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 1, characterized in that, The nuclear magnetic resonance scan also includes a high-resolution fast spin echo volume sequence, namely the VISTA sequence.

7. The method for co-localizing lymphatic vessels and blood vessels under magnetic resonance imaging according to claim 6, characterized in that, The scanning parameters of the VISTA sequence include: repetition time of 550 ms, echo time of 20 ms, slice thickness of 1.2 mm, field of view of 300 mm × 300 mm, voxel size of 1.2 × 1.2 × 1.2, flip angle of 90°, and signal averaging times of 1.

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