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. 2024 Mar 26:17:17562864241239739.
doi: 10.1177/17562864241239739. eCollection 2024.

Improved visualization of median, ulnar nerves, and small branches in the wrist and palm using contrast-enhanced magnetic resonance neurography

Jiamin Kang  1   2 , Wenjun Wu  1   3 , Xiangchuang Kong  1   3 , Yu Su  1 , Dingxi Liu  1   3 , Chungao Li  1   3 , Nan Gao  4 , Youzhi Wang  1 , Chuansheng Zheng  1   3 , Yuxiong Weng  4 , Lixia Wang  5   3
Affiliations

Improved visualization of median, ulnar nerves, and small branches in the wrist and palm using contrast-enhanced magnetic resonance neurography

Jiamin Kang et al. Ther Adv Neurol Disord. .

Abstract

Background: Magnetic resonance imaging of peripheral nerves in the wrist and palm is challenging due to the small size, tortuous course, complex surrounding tissues, and accompanying blood vessels. The occurrence of carpal palmar lesions leads to edema, swelling, and mass effect, which may further interfere with the display and identification of nerves.

Objective: To evaluate whether contrast-enhanced magnetic resonance neurography (ceMRN) improves the visualization of the morphology and pathology of the median, ulnar nerves, and their small branches in the wrist and palm.

Design: An observational study.

Methods: In total 57 subjects, including 36 volunteers and 21 patients with carpal palmar lesions, were enrolled and underwent ceMRN and non-contrast MRN (ncMRN) examination at 3.0 Tesla. The degree of vascular suppression, nerve visualization, diagnostic confidence, and lesion conspicuity was qualitatively assessed by two radiologists. Kappa statistics were obtained for inter-reader agreement. The signal-to-noise ratio, contrast ratio (CR), and contrast-to-noise ratio (CNR) of the median nerve were measured. The subjective ratings and quantitative measurements were compared between ncMRN and ceMRN.

Results: The inter-reader agreement was excellent (k > 0.8) for all qualitative assessments and visualization assessment of each nerve segment. Compared with ncMRN, ceMRN significantly improved vascular suppression in volunteers and patients (both p < 0.001). The ceMRN significantly enhanced nerve visualization of each segment (all p < 0.05) and diagnostic confidence in volunteers and patients (both p < 0.05). The ceMRN improved lesion conspicuity (p = 0.003) in patients. Quantitatively, ceMRN had significantly higher CRs of nerve versus subcutaneous fat, bone marrow, and vessels and CNR of nerve versus vessel than ncMRN (all p < 0.05).

Conclusion: The ceMRN significantly improves the visualization of peripheral nerves and pathology in the wrist and palm by robustly suppressing the signals of fat, bone marrow, and especially vessels in volunteers and patients.

Keywords: common palmar digital nerve; magnetic resonance imaging; magnetic resonance neurography; median nerve; palm; proper digital nerve; thenar muscular branch; ulnar nerve; wrist.

Plain language summary

Study on the improvement of magnetic resonance imaging and lesion display of small nerves in the wrist and palm using contrast agents Why was the study done? Because the nerves and branches in the wrist and palm are numerous, small, tortuous, and surrounded by muscles, fat, bones, blood vessels and other tissues, it is difficult to show their complete shape with conventional magnetic resonance imaging. Hand lesions often lead to swelling, edema and masses, which interfere with the display of nerves. Therefore, it is difficult to directly diagnose the relationship between the lesions and nerves in clinical practice. What did the researchers do? The research team used contrast agent plus three-dimensional high-resolution magnetic resonance sequence to display the nerves of volunteers and patients with hand lesions, and used subjective and objective evaluation methods to compare the display effect of the sequence on the nerves before and after the use of contrast agent. What did the researchers find? The imaging method of contrast agent plus three-dimensional high-resolution magnetic resonance sequence can reduce the interference of fat, blood vessels, etc. on nerve display, improve the display effect of each nerve segment of the wrist and palm, increase readers’ confidence in identifying nerves, and improve the detection of lesions. What do the findings mean? This study verified the feasibility and advantages of using contrast agents for magnetic resonance imaging of nerves in the wrist and palm. It provides a new method for clinical and imaging diagnosis of hand lesions, which can simultaneously display the morphological characteristics of nerves and lesions, reducing the difficulty of clinical diagnosis and improving the efficiency of imaging diagnosis.

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Conflict of interest statement

The authors declare that there is no conflict of interest.

Figures

Figure 1.
Figure 1.
Nerve visualization scores between ncMRN and ceMRN in all subjects. ceMRN, contrast-enhanced magnetic resonance neurography; CPDN, common palmar digital nerve; MN, median nerve; ncMRN, non-contrast MRN; PDN, proper digital nerve; TMB, thenar muscular branch; UN, ulnar nerve.
Figure 2.
Figure 2.
Comparison of vascular suppression, diagnostic confidence, and lesion conspicuity scores between ncMRN and ceMRN in all subjects. ceMRN, contrast-enhanced magnetic resonance neurography; ncMRN, non-contrast MRN.
Figure 3.
Figure 3.
Volunteer, 45-year-old, female. The ncMRN (a) and ceMRN (b) show coronal views of the median and ulnar nerves and their branches in the wrist and palm. The visualization of the nerves is significantly improved on the ceMRN image. The median nerve passes through the transverse carpal ligament and gives off the common palmar digital nerves (white circle), and the proper digital nerves (arrowhead) of the thumb. The superficial ulnar nerve passes through the palmar carpal ligament and gives off the common digital nerves (long arrow, white ★) and communication branch to the median (short arrow). The signal of the palmar vessel (stubby arrows) is significantly suppressed on the ceMRN image. (c) ceMRN delineates the first common palmar digital nerve further divided into two proper digital nerves to the thumb and one proper digital nerve to the radial side of the index finger at a distal level (short arrows). The proper digital nerves to the thumb include the medial and lateral branches (d). ceMRN, contrast-enhanced magnetic resonance neurography; ncMRN, non-contrast MRN.
Figure 4.
Figure 4.
Volunteer, 29-year-old, male. The coronal image (a), sagittal image (b), and axial image (c) of ceMRN show the TMB of the median nerve. ceMRN, contrast-enhanced magnetic resonance neurography; TMB, thenar muscular branch.
Figure 5.
Figure 5.
Images of carpal tunnel syndrome obtained with ceMRN. The coronal (a) and sagittal (b) images show a hypointense lesion of the median nerve at the level of the distal edge of the transverse carpal ligament (arrow), which seems to be interrupted. ceMRN, contrast-enhanced magnetic resonance neurography.
Figure 6.
Figure 6.
An example of hemangioma along the median nerve on ncMRN (a) and ceMRN (b) images shows the relationship between lesions and median nerves. (a) The hemangioma surrounding the median nerve was spindle shaped and hyperintense on the ncMRN image. The hemangioma encapsulates the nerve with ill-defined borders. (b) On the ceMRN image, the malformed vessel exhibits hypointense (long arrow), and the vascular signal of the superficial palmar arch (short arrow) is suppressed, distinguishing it from the proper digital nerve (thick arrow). ceMRN, contrast-enhanced magnetic resonance neurography; ncMRN, non-contrast MRN.
Figure 7.
Figure 7.
An example of edema of the hypothenar on ncMRN (a) and ceMRN (b) images. (a) The median nerve (long arrow) and ulnar nerve (short arrow) are obscured by the hyperintensity of edema and vessels on the ncMRN image. (b) The edema signal in the thenar region is significantly reduced (thick arrow) and the delineation of the median nerve branches in the carpometacarpal region (circle) and the ulnar nerve at the entrance of the carpal tunnel (short arrow) are significantly improved on ceMRN image. ceMRN, contrast-enhanced magnetic resonance neurography; ncMRN, non-contrast MRN.
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