Matthew A. Frick

MRI Findings of 26 Patients with Parsonage-Turner Syndrome

OBJECTIVE The objective of our study was to describe the MRI features of patients with Parsonage-Turner syndrome. Familiarity with the MRI features associated with this entity is important because radiologists may be the first to suggest the diagnosis. Twenty-six patients with Parsonage-Turner syndrome were treated at our institution between 1997 and 2005. We retrospectively reviewed the MR images of patients with clinical or electromyographic evidence (or both) of acute brachial neuritis without a definable cause. CONCLUSION MRI of the brachial plexus and shoulder in patients with Parsonage-Turner syndrome showed intramuscular denervation changes involving one or more muscle groups of the shoulder girdle. The supraspinatus and infraspinatus muscles were the most commonly involved. MRI is sensitive for detecting signal abnormalities in the muscles of the shoulder girdle of patients with Parsonage-Turner syndrome. MRI may be instrumental in accurately diagnosing the syndrome.

B0 concomitant field compensation for MRI systems employing asymmetric transverse gradient coils

Imaging gradients result in the generation of concomitant fields, or Maxwell fields, which are of increasing importance at higher gradient amplitudes. These time‐varying fields cause additional phase accumulation, which must be compensated for to avoid image artifacts. In the case of gradient systems employing symmetric design, the concomitant fields are well described with second‐order spatial variation. Gradient systems employing asymmetric design additionally generate concomitant fields with global (zeroth‐order or B0) and linear (first‐order) spatial dependence.

Tumefactive appearance of peripheral nerve involvement in hematologic malignancies: a new imaging association

ObjectiveIn neurolymphomatosis (NL), the affected nerves are typically described to be enlarged and hyperintense on T2W MR sequences and to avidly enhance on gadolinium-enhanced T1WI. This pattern is highly non-specific. We recently became aware of a “tumefactive pattern” of NL, neuroleukemiosis (NLK) and neuroplasmacytoma (NPLC), which we believe is exclusive to hematologic diseases affecting peripheral nerves.Materials and methodsWe defined a “tumefactive” appearance as complex, fusiform, hyperintense on T2WI, circumferential tumor masses encasing the involved peripheral nerves. The nerves appear to be infiltrated by the tumor. Both structures show varying levels of homogenous enhancement. We reviewed our series of 52 cases of NL in search of this pattern; two extra outside cases of NL, three cases of NLK, and one case of NPLC were added to the series.ResultsWe identified 20 tumefactive lesions in 18 patients (14 NL, three NLK, one NPLC). The brachial plexus (n = 7) was most commonly affected, followed by the sciatic nerve (n = 6) and lumbosacral plexus (n = 3). Four patients had involvement of other nerves. All were proven by biopsy: the diagnosis was high-grade lymphoma (n = 12), low-grade lymphoma (n = 3), acute leukemia (n = 2), and plasmacytoma (n = 1).ConclusionsWe present a new imaging pattern of “tumefactive” neurolymphomatosis, neuroleukemiosis, or neuroplasmacytoma in a series of 18 cases. We believe this pattern is associated with hematologic diseases directly involving the peripheral nerves. Knowledge of this association can provide a clue to clinicians in establishing the correct diagnosis. Bearing in mind that tumefactive NL, NLK, and NPLC is a newly introduced imaging pattern, we still recommend to biopsy patients with suspicion of a malignancy.

Safety Studies for Use of Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells in a Rabbit Model for Osteoarthritis to Support a Phase I Clinical Trial

Adipose‐derived mesenchymal stem cells (AMSCs) offer potential as a therapeutic option for clinical applications in musculoskeletal regenerative medicine because of their immunomodulatory functions and capacity for trilineage differentiation. In preparation for a phase I clinical trial using AMSCs to treat patients with osteoarthritis, we carried out preclinical studies to assess the safety of human AMSCs within the intra‐articular joint space. Culture‐expanded human AMSCs grown in human platelet‐lysate were delivered via intra‐articular injections into normal healthy rabbit knees and knees at risk for the development of osteoarthritis after bilateral medial anterior hemimeniscectomy. Treatment outcomes and safety were evaluated by assessing the general health, function, and behavior of the animals. Joint tissues were analyzed by x‐ray, magnetic resonance imaging, and histopathology. Intra‐articular AMSC therapy was well tolerated in this study. We did not observe adverse systemic reactions, nor did we find evidence of damage to intra‐articular joint tissues. Thus, the data generated in this study show a favorable safety profile for AMSCs within the joint space in support of a phase I clinical trial evaluating the clinical utility of AMSCs to treat osteoarthritis. Stem Cells Translational Medicine 2017;6:910–922

Lightweight, compact, and high-performance 3T MR system for imaging the brain and extremities: FOO et al.

To build and evaluate a small‐footprint, lightweight, high‐performance 3T MRI scanner for advanced brain imaging with image quality that is equal to or better than conventional whole‐body clinical 3T MRI scanners, while achieving substantial reductions in installation costs.

Imaging of the Proximal and Distal Radioulnar Joints.

The proximal and distal radioulnar joints form a unique articular arrangement between the radius and ulna, allowing pivot motion of the forearm and positioning the hand in space. Typically imaged in conjunction with the elbow, radiographs, computed tomography (CT), and MR imaging of the proximal radioulnar joint contribute unique diagnostic information. Because dysfunction of the distal radioulnar joint is often a result of instability, dynamic CT protocols stressing the joint in addition to anatomic imaging with radiographs and MR imaging is valuable. Detailed knowledge of the patients clinical condition and careful selection of imaging protocols will maximize the benefits.

MR Imaging of the Nerves of the Upper Extremity: Elbow to Wrist

The peripheral nervous system is susceptible to a diverse array of pathologic insults, broadly categorizable into those entities intrinsic to the nerves themselves, either primarily arising within the nerve(s) or direct involvement of the nerve(s) secondary to a systemic process, and those processes external to the nerve(s) proper but affecting them extrinsically via mass effect, such as entrapment neuropathies. The soft tissue contrast inherent to high-quality MR imaging allows for outstanding visualization of the peripheral nervous system and surrounding structures. This review focuses on the use of MR imaging in the diagnosis and management of peripheral nerve disorders of the upper extremity.

Magnetic Resonance Imaging Appearance of Schwannomas from Head to Toe: A Pictorial Review

Schwannomas are benign soft-tissue tumors that arise from peripheral nerve sheaths throughout the body and are commonly encountered in patients with neurofibromatosis Type 2. The vast majority of schwannomas are benign, with rare cases of malignant transformation reported. In this pictorial review, we discuss the magnetic resonance imaging (MRI) appearance of schwannomas by demonstrating a collection of tumors from different parts of the body that exhibit similar MRI characteristics. We review strategies to distinguish schwannomas from malignant soft-tissue tumors while exploring the anatomic and histologic origins of these tumors to discuss how this correlates with their imaging findings. Familiarity with the MRI appearance of schwannomas can help aid in the differential diagnosis of soft-tissue masses, especially in unexpected locations.

Charcot arthropathy of the hip simulating a neoplastic lesion.

Our group recently reported on an atypical finding of a patient with neuropathic arthropathy of the shoulder and neurovascular compression due to synovitis (Alai et al., 2012). By coincidence, in the weeks following its online publication, we treated another patient with a new neurologic sequela from a Charcot joint. A 68-year-old man presented with a severe lumbosacral plexopathy. He was referred to our institution for a presumed malignant peripheral nerve