Darryl B. Sneag

Magnetic resonance imaging of cartilage repair.

Magnetic resonance imaging is an important noninvasive modality in characterizing cartilage morphology, biochemistry, and function. It serves as a valuable objective outcome measure in diagnosing pathology at the time of initial injury, guiding surgical planning, and evaluating postsurgical repair. This article reviews the current literature addressing the recent advances in qualitative and quantitative magnetic resonance imaging techniques in the preoperative setting, and in patients who have undergone cartilage repair techniques such as microfracture, autologous cartilage transplantation, or osteochondral transplantation.

Extrahepatic spread of hepatocellular carcinoma: spectrum of imaging findings.

OBJECTIVE The purpose of this article is to describe the imaging findings of extrahepatic spread of hepatocellular carcinoma (HCC). CONCLUSION Detecting extrahepatic metastases in HCC is critical in determining the optimal treatment plan for patients. Identifying the presence of extrahepatic metastases in patients with advanced disease may eliminate unnecessary surgery, such as liver transplantation or partial hepatic resection, and help direct the appropriate therapy.

MRI bullseye sign: An indicator of peripheral nerve constriction in parsonage-turner syndrome

The role of MRI in identifying hourglass constrictions (HGCs) of nerves in Parsonage‐Turner syndrome (PTS) is largely unknown.

Magnetic Resonance Imaging Evaluation of the Painful Total Knee Arthroplasty

Optimization of metal artifact reduction pulse sequences over the past decade has rendered MRI valuable in knee arthroplasty assessment. MRI can reliably predict the presence and extent of infection, component loosening and polyethylene wear, and component malrotation, and it can evaluate the integrity of surrounding soft tissue structures. Using dynamic contrast-enhanced angiographic techniques, vascular pathology such as pseudoaneurysm formation and recurrent hemarthrosis can also be assessed.

Peripheral nerve diffusion tensor imaging: Overview, pitfalls, and future directions

Diffusion tensor imaging (DTI) is a noninvasive magnetic resonance imaging (MRI) technique that measures the extent of restricted water diffusion and anisotropy in biological tissue. Although DTI has been widely applied in the brain, more recently researchers have used it to characterize nerve pathology in the setting of entrapment neuropathy, traumatic injury, and tumor. DTI artifacts are exacerbated when imaging off isocenter in the body. Anecdotally, the most significant artifacts in peripheral nerve DTI include magnetic field inhomogeneity, motion, incomplete fat suppression, aliasing, and distortion. High spatial resolution is also required to reliably evaluate smaller peripheral nerves. This article provides an overview of such technical issues, particularly when trying to apply DTI in the clinical setting, and offers potential solutions.

Sclerotic osseous metastases from renal cell carcinoma

This case series describes and illustrates three cases of sclerotic osseous metastases from untreated renal cell carcinoma (RCC). RCC is commonly metastatic to the skeleton but almost always produces lytic metastases, with only three prior reports of sclerotic metastases identified in the literature. Sclerotic metastasis causing low back pain was the initial disease presentation in two of the three patients in this case series and the first manifestation of metastatic disease in one. The most common metastatic sites of RCC, i.e., retroperitoneal lymph nodes, lung, and liver, were not identified in any of the cases, and skeletal involvement with epidural extension was the only site of metastasis in two. Pathologic specimens from all three cases revealed RCC of high nuclear grade.

Success of scaphoid nonunion surgery is independent of proximal pole vascularity

We followed 35 consecutive patients with scaphoid nonunions in a prospective longitudinal registry. All nonunions were treated with curettage, non-vascularized autogenous grafting and headless screw fixation. Preoperative magnetic resonance imaging, intraoperative bleeding points and histopathological analysis of cancellous bone in the proximal pole were recorded as measures of viability. Healing was categorized as ≥50% bony bridging on computed tomographic images in the plane of the scaphoid. Nine of 23 proximal poles demonstrated ischaemia on magnetic resonance imaging but none were interpreted as infarcted. Twenty-eight of 33 were found to have impaired vascularity as assessed by intraoperative bleeding. Fourteen of 32 demonstrated ≥50% trabecular necrosis and four of 33 demonstrated ≥50% tissue necrosis on histopathological analysis. Thirty of 33 demonstrated focal or robust remodelling activity. Despite pathological evidence of impaired vascularity in over half of the patients, 33 of the 35 scaphoids had healed by 12 weeks. We conclude that proximal pole infarction is decidedly rare and that vascularized bone grafting is seldom required. Level of evidence: IV

Pins and Needles From Fingers to Toes: High-Resolution MRI of Peripheral Sensory Mononeuropathies.

OBJECTIVE The purpose of this article is to review advanced MRI techniques and describe the MRI findings of pure sensory mononeuropathy with relevant clinical and anatomic correlation. CONCLUSION Peripheral sensory mononeuropathy can be challenging to evaluate with MRI because of the small caliber of pure sensory nerves and the lack of changes in secondary muscular denervation. Advances in MRI afford the necessary signal-intensity contrast and resolution for adequate evaluation of many of these small peripheral nerves.

MRI findings of spinal accessory neuropathy

AIM To characterise the magnetic resonance imaging (MRI) appearance of patients with spinal accessory nerve (SAN) denervation. MATERIAL AND METHODS Twelve patients who had SAN denervation on electromyography (EMG) were included. The sternocleidomastoid and trapezius muscles and the SAN were assessed using MRI. RESULTS Trapezius muscle atrophy was seen in 11 (92%), and of those patients, T2/short tau inversion recovery (STIR) signal hyperintensity was also demonstrated in seven (58%). All three patients with prior neck surgery had scarring around the SAN, and one of these patients demonstrated a neuroma, which was confirmed surgically. CONCLUSION Features of SAN neuropathy on MRI include atrophy and T2/STIR signal hyperintensity of the trapezius, and in patients who have had posterior triangle neck surgery, scarring may be seen around the nerve.

Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome: Brachial Plexitis or Neuritis?

Introduction: This study seeks to characterize lesion distribution in Parsonage–Turner Syndrome (PTS) using high‐resolution MRI. Methods: MRIs of 27 patients with clinically confirmed PTS were reviewed. Two radiologists independently evaluated the brachial plexus proper, side and terminal plexus branches, and more distal, upper extremity nerves. Results: All patients had at least 1 clinically involved nerve. MRI revealed that the plexus appeared normal in 24 of 27 patients; in 3 other patients, signal hyperintensity was seen immediately proximal to the take‐off of abnormal side or terminal branch nerves. Focal intrinsic constrictions were detected in 32 of 38 nerves. MRI interobserver agreement was high (Cohens κ = 0.839). Discussion: MRI findings, corroborated by electrodiagnostic testing, localized abnormalities to plexus branches and peripheral nerves, suggesting that PTS is characterized by 1 or more mononeuropathies rather than changes involving a portion of or the complete plexus proper. These results may improve diagnosis, prognostication, and management. Muscle Nerve 58: 359–366, 2018