Neda Faridian-Aragh

3-T High-Resolution MR Neurography of Sciatic Neuropathy

OBJECTIVE The sciatic nerve may normally exhibit mild T2 hyperintensity in MR neurography (MRN) images, rendering assessment of sciatic neuropathy difficult. The purpose of this case-control study was to evaluate whether a quantitative and qualitative analysis of the sciatic nerves and regional skeletal muscles increases the accuracy of MRN in detecting sciatic neuropathy. MATERIALS AND METHODS We retrospectively reviewed the MRN studies of the pelvis and thighs of 34 subjects (12 men and 22 women; mean [± SD] age, 50 ± 15 years), of which 17 had a final diagnosis of sciatic neuropathy according to electrodiagnostic or surgical confirmation, and 17 had no evidence of sciatic neuropathy and served as control subjects. On each side, the sciatic nerves were evaluated for signal intensity (SI), size, course, and fascicular shape, whereas the regional skeletal muscles were evaluated for edema, fatty replacement, and atrophy. In addition, the nerve-to-vessel SI ratio was registered for each side at the same time and 8 months later. RESULTS The sciatic nerves of the abnormal sides exhibited higher nerve-to-vessel SI ratios and higher incidences of T2 hyperintensity, enlargement, and abnormal fascicular shape compared to the nerves of the normal sides. The regional muscles of the abnormal sides demonstrated a higher grade of fatty infiltration and higher frequencies of edema and atrophy. A cutoff value of nerve-to-vessel SI ratio of 0.89 exhibited high sensitivity and specificity in predicting sciatic neuropathy. Calculation of the nerve-to-vessel SI ratio demonstrated excellent inter- and intraobserver reliability. CONCLUSION Both qualitative and quantitative criteria should be used to suggest the MRN diagnosis of sciatic neuropathy.

High-Resolution 3-T MR Neurography of Femoral Neuropathy

OBJECTIVE The femoral nerve is subject to a variety of diseases that may affect the nerve anywhere from the nerve roots to the distal branches. High-resolution 3-T MR neurography (MRN) is being increasingly used for peripheral nerve evaluation because it complements information gained from electrodiagnostic testing. CONCLUSION There are scattered case reports describing femoral nerve diseases using MRI. This article comprehensively reviews different pathologic abnormalities involving the femoral nerve and illustrates their MRN features with case examples.

High-resolution 3-T MR neurography of peroneal neuropathy

The common peroneal nerve (CPN), a major terminal branch of the sciatic nerve, can be subject to a variety of pathologies, which may affect the nerve at any level from the lumbar plexus to its distal branches. Although the diagnosis of peripheral neuropathy is traditionally based on a patient’s clinical findings and electrodiagnostic tests, magnetic resonance neurography (MRN) is gaining an increasing role in the definition of the type, site, and extent of peripheral nerve disorders. Current high-field MR scanners enable high-resolution and excellent soft-tissue contrast imaging of peripheral nerves. In the lower extremities, MR neurography has been employed in the demonstration of the anatomy and pathology of the CPN, as well as in the detection of associated secondary muscle denervation changes. This article reviews the normal appearance of the CPN as well as typical pathologies and abnormal findings at 3.0-T MR neurography of the lower extremity.

High-resolution 3T MR neurography of suprascapular neuropathy.

RATIONALE AND OBJECTIVES The purpose of this study was to illustrate the imaging findings on high-resolution 3T magnetic resonance neurography (MRN) in patients with suprascapular nerve (SSN) neuropathy. MATERIALS AND METHODS From 3T MRN examinations performed for brachial plexus evaluation in 51 patients over a 3-year period, 15 patients with final diagnosis of suprascapular neuropathy were recruited. The diagnosis was confirmed by electrodiagnostic studies (EDS), clinical, and/or surgical follow-up examinations. Studies performed for the evaluation of tumor, neurofibromatosis, or known diffuse polyneuropathy were excluded. RESULTS Two cases were excluded due to suboptimal imaging related to motion degradation and poor signal-to-noise ratio. MRN depicted asymmetric enlargement and/or abnormal T2 hyperintensity of C5 nerve root (10/13 cases), C6 nerve root (10/13 cases), both C5 and C6 nerve roots (7/13 cases), upper trunk (11/13 cases) and SSN (11/13 cases), and other brachial plexus segments involvement (4/13 cases). MR findings of denervation changes in the ipsilateral supraspinatus and infraspinatus muscles were detected in 12/13 cases. In all seven cases where contrast-enhanced images were available, MRN demonstrated enhancement of the denervated muscles but did not provide any additional information regarding the nerve abnormality. None of the MRN studies revealed a mass lesion along the course of the SSN. CONCLUSION 3T MRN is a valuable diagnostic tool in clinically suspected cases of suprascapular neuropathy, because it can directly demonstrate the nerve abnormality, as well as secondary muscle denervation changes. The reader should be aware that brachial plexopathy may coexist in patients with clinical diagnosis of SSN neuropathy.

3-Tesla Magnetic Resonance Imaging Evaluation of Posterior Tibial Tendon Dysfunction with Relevance to Clinical Staging

The posterior tibial tendon (PTT) is the most important dynamic stabilizer of the medial ankle and longitudinal arch of the foot. PTT dysfunction is a degenerative disorder of the tendon, which secondarily involves multiple ligaments, joint capsules, fascia, articulations, and bony structures of the ankle, hindfoot, midfoot, and forefoot. When the tendon progressively attenuates, the patient develops a painful, progressive collapsed flatfoot or pes planovalgus deformity. This comprehensive review illustrates the 3-Tesla magnetic resonance imaging (3T MRI) features of PTT dysfunction. In addition, the reader will gain knowledge of the expected pathologic findings on MRI, as they are related to clinical staging of PTT dysfunction.

Magnetic resonance imaging phenotyping of Becker muscular dystrophy

Introduction: There is little information on magnetic resonance imaging (MRI) phenotypes of Becker muscular dystrophy (BMD). This study presents the MRI phenotyping of the upper and lower extremities of a large cohort of BMD patients. Methods: In this retrospective study, MRI images of 33 BMD subjects were evaluated for severity, distribution, and symmetry of involvement. Results: Teres major, triceps long head, biceps brachii long head, gluteus maximus, gluteus medius, vasti, adductor longus, adductor magnus, semitendinosus, semimembranosus, and biceps femoris muscles showed the highest severity and frequency of involvement. All analyzed muscles had a high frequency of symmetric involvement. There was significant variability of involvement between muscles within some muscle groups, most notably the arm abductors, posterior arm muscles, medial thigh muscles, and lateral hip rotators. Conclusions: This study showed a distinctive pattern of involvement of extremity muscles in BMD subjects. Muscle Nerve 50: 962–967, 2014

3T Magnetic Resonance Neurography of Tibial Nerve Pathologies

Diagnosis of tibial neuropathy has been traditionally based on clinical examination and electrodiagnostic studies; however, cross‐sectional imaging modalities have been used to increase the diagnostic accuracy and provide anatomic mapping of the abnormalities. In this context, magnetic resonance neurography (MRN) offers high‐resolution imaging of the tibial nerve (TN), its branches and the adjacent soft tissues, and provides an objective assessment of the neuromuscular anatomy, abnormality, and the surrounding pathology. This review describes the pathologies affecting the TN and illustrates their respective 3 Tesla (T) MRN appearances with relevant case examples.

High-resolution 3T MR neurography of radial neuropathy

The radial nerve is a continuation of the posterior cord of the brachial plexus and one of the major nerves that provide motor and sensory innervations to the forearm. MR imaging evaluation of the radial nerve pathology has been described in scattered case reports. Current high-field MR scanners enable high resolution and high contrast imaging of the peripheral nerves. This article reviews the 3 Tesla magnetic resonance neurography imaging of radial nerve anatomy and various pathologies affecting it with relevant case examples.