Diagnostic contribution of contrast-enhanced 3D MR imaging of peripheral nerve pathology

Visualization of the Extracranial Branches of the Trigeminal Nerve Using Improved Motion-Sensitized Driven Equilibrium-Prepared 3D Inversion Recovery TSE Sequence

BACKGROUND AND PURPOSE

Visualization of the extracranial trigeminal nerve is crucial to detect nerve pathologic alterations. This study aimed to evaluate visualization of the extracranial trigeminal nerve using 3D inversion recovery TSE with an improved motion-sensitized driven equilibrium (iMSDE) pulse.

MATERIALS AND METHODS

In this prospective study, 35 subjects underwent imaging of the trigeminal nerve using conventional 3D inversion recovery TSE, 3D inversion recovery TSE with an iMSDE pulse, and contrast-enhanced 3D inversion recovery TSE. The visibility of 7 extracranial branches of the trigeminal nerve, venous/muscle suppression, and identification of the relationship between nerves and lesions were scored on a 5-point scale system. In addition, SNR, nerve-muscle contrast ratio, nerve-venous contrast ratio, nerve-muscle contrast-to-noise ratio, and nerve-venous contrast-to-noise ratio were calculated and compared.

RESULTS

Images acquired with iMSDE 3D inversion recovery TSE had significantly higher nerve-muscle contrast ratio, nerve-venous contrast ratio, and nerve-to-venous contrast-to-noise ratio (all P < .001); improved venous/muscle suppression and clearer visualization of the trigeminal nerve branches except the ophthalmic nerve than with conventional 3D inversion recovery TSE (all P < .05). Compared with contrast-enhanced 3D inversion recovery TSE, images acquired with iMSDE 3D inversion recovery TSE had significantly higher SNR, nerve-muscle contrast ratio, and nerve-to-venous contrast-to-noise ratio (all P < .05), and demonstrated comparable diagnostic quality (scores ≥3) of the maxillary nerve, mandibular nerve, inferior alveolar nerve, lingual nerve, and masseteric nerve (P > .05). As for the identification of the relationship between nerves and lesions, iMSDE 3D inversion recovery TSE showed the highest scores among these 3 sequences (all P < .05).

CONCLUSIONS

The iMSDE 3D inversion recovery TSE is a promising alternative to conventional 3D inversion recovery TSE and contrast-enhanced 3D inversion recovery TSE for visualization of the extracranial branches of trigeminal nerve in clinical practice.

Multimodality imaging review of ulnar nerve pathologies

The ulnar nerve is the second most commonly entrapped nerve after the median nerve. Although clinical evaluation and electrodiagnostic studies remain widely used for the evaluation of ulnar neuropathy, advancements in imaging have led to increased utilization of these newer / better imaging techniques in the overall management of ulnar neuropathy. Specifically, high-resolution ultrasonography of peripheral nerves as well as MRI has become quite useful in evaluating the ulnar nerve in order to better guide treatment. The caliber and fascicular pattern identified in the normal ulnar nerves are important distinguishing features from ulnar nerve pathology. The cubital tunnel within the elbow and Guyon's canal within the wrist are important sites to evaluate with respect to ulnar nerve compression. Both acute and chronic conditions resulting in deformity, trauma as well as inflammatory conditions may predispose certain patients to ulnar neuropathy. Granulomatous diseases as well as both neurogenic and non-neurogenic tumors can also potentially result in ulnar neuropathy. Tumors around the ulnar nerve can also lead to mass effect on the nerve, particularly in tight spaces like the aforementioned canals. Although high-resolution ultrasonography is a useful modality initially, particularly as it can be helpful for dynamic evaluation, MRI remains most reliable due to its higher resolution. Newer imaging techniques like sonoelastography and microneurography, as well as nerve-specific contrast agents, are currently being investigated for their usefulness and are not routinely being used currently.

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

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.

Society of skeletal radiology position paper - recommendations for contrast use in musculoskeletal MRI: when is non-contrast imaging enough?

The following White Paper will discuss the appropriateness of gadolinium administration in MRI for musculoskeletal indications. Musculoskeletal radiologists should consider the potential risks involved and practice the judicious use of intravenous contrast, restricting administration to cases where there is demonstrable added value. Specific nuances of when contrast is or is not recommended are discussed in detail and listed in table format. Briefly, contrast is recommended for bone and soft tissue lesions. For infection, contrast is reserved for chronic or complex cases. In rheumatology, contrast is recommended for early detection but not for advanced arthritis. Contrast is not recommended for sports injuries, routine MRI neurography, implants/hardware, or spine imaging, but is helpful in complex and post-operative cases.

Diagnostic performance of deep learning-based reconstruction algorithm in 3D MR neurography

OBJECTIVE

The study aims to evaluate the diagnostic performance of deep learning-based reconstruction method (DLRecon) in 3D MR neurography for assessment of the brachial and lumbosacral plexus.

MATERIALS AND METHODS

Thirty-five exams (18 brachial and 17 lumbosacral plexus) of 34 patients undergoing routine clinical MR neurography at 1.5 T were retrospectively included (mean age: 49 ± 12 years, 15 female). Coronal 3D T2-weighted short tau inversion recovery fast spin echo with variable flip angle sequences covering plexial nerves on both sides were obtained as part of the standard protocol. In addition to standard-of-care (SOC) reconstruction, k-space was reconstructed with a 3D DLRecon algorithm. Two blinded readers evaluated images for image quality and diagnostic confidence in assessing nerves, muscles, and pathology using a 4-point scale. Additionally, signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNR) between nerve, muscle, and fat were measured. For comparison of visual scoring result non-parametric paired sample Wilcoxon signed-rank testing and for quantitative analysis paired sample Student's t-testing was performed.

RESULTS

DLRecon scored significantly higher than SOC in all categories of image quality (p < 0.05) and diagnostic confidence (p < 0.05), including conspicuity of nerve branches and pathology. With regard to artifacts there was no significant difference between the reconstruction methods. Quantitatively, DLRecon achieved significantly higher CNR and SNR than SOC (p < 0.05).

CONCLUSION

DLRecon enhanced overall image quality, leading to improved conspicuity of nerve branches and pathology, and allowing for increased diagnostic confidence in evaluation of the brachial and lumbosacral plexus.

Peripheral Nerve Imaging

Magnetic resonance (MR) neurography and high-resolution ultrasound are complementary modalities for imaging peripheral nerves. Advances in imaging technology and optimized techniques allow for detailed assessment of nerve anatomy and nerve pathologic condition. Diagnostic accuracy of imaging modalities likely reflects local expertise and availability of the latest imaging technology.

Role of MR Neurography for Evaluation of the Lumbosacral Plexus: A Scoping Review

Purpose

MR neurography (MRN) is an imaging technique optimized to visualize the peripheral nerves. This review aimed to discover an optimized protocol for MRN of the lumbosacral plexus (LSP) and identify evidence for the clinical benefit of lumbosacral plexopathies.

Materials and Methods

We performed a systematic search of the two medical databases until September 2021. 'Magnetic resonance imaging', 'lumbosacral plexus', 'neurologic disease', or equivalent terms were used to search the literature. We extracted information on indications, MRN protocols for LSP, and clinical efficacy from 55 studies among those searched.

Results

MRN of the LSP is useful for displaying the distribution of peripheral nerve disease, guiding perineural injections, and assessing extraspinal causes of sciatica. Three-dimensional short-tau inversion recovery turbo spin-echo combined with vascular suppression is the mainstay of MRN.

Conclusion

Future work on the MRN of LSP should be directed to technical maturation and clinical validation of efficacy.