Imaging of Peripheral Nerves: AJR Expert Panel Narrative Review.

Peripheral nerve imaging provides information that can be critical to the diagnosis, staging, and management of peripheral neuropathies. MRI and ultrasound are the imaging modalities of choice for clinical evaluation of the peripheral nerves given their high soft tissue contrast and high resolution, respectively. This AJR Expert Panel Narrative Review describes MRI- and ultrasound-based techniques for peripheral nerve imaging; highlights considerations for imaging in the settings of trauma, entrapment syndromes, diffuse inflammatory neuropathies, and tumor; and discusses image-guided nerve interventions, focusing on nerve blocks and ablation.

Assessing Femoral Trochlear Morphologic Features on Cross-Sectional Imaging Before Trochleoplasty: Dejour Classification Versus Quantitative Measurement.

OBJECTIVE. The purpose of this study is to assess the use of cross-sectional imaging to qualitatively and quantitatively categorize trochlear dysplasia as low grade (type A) or high grade (types B-D) according to the Dejour classification. MATERIALS AND METHODS. A retrospective review of CT and MRI knee examinations performed before patients underwent deepening trochleoplasty was independently conducted by two musculoskeletal radiologists. Each case of trochlear dysplasia was qualitatively assigned a Dejour type. Subsequently, quantitative measurements of the sulcus angle, distance from the tibial tubercle to the trochlear groove, trochlear depth, lateral trochlear inclination, trochlear facet asymmetry, and degree of patellar lateralization were performed. RESULTS. A total of 35 patients (29 female patients and six male patients; mean age, 21.1 years) with 39 affected knees (17 right knees and 22 left knees) were included. Readers had exact qualitative agreement using Dejour classification for 30 of 39 knees (77% [κ = 0.77; 95% CI, 0.62-0.91]) and agreement on classification of low-grade versus high-grade dysplasia for 36 of 39 knees (92%). For these 36 knees, the mean differences in measurements of low- versus high-grade dysplasia, respectively, were as follows: for sulcus angle, 153° versus 168° (p < 0.001); for trochlear depth, 4 versus 1 mm (p < 0.001); for lateral trochlear inclination, 12 versus 7 mm (p < 0.02); and for decreased trochlear facet asymmetry, 13% versus 92% (p < 0.001). Trochlear depth, lateral trochlear inclination, and trochlear facet asymmetry were also different in comparisons of knees with Dejour type B and C trochlear dysplasia versus those with Dejour types B and D (all p < 0.05). No quantitative measurement differentiated between trochlear dysplasia of Dejour types C and D. The distance from the tibial tubercle to the trochlear groove and the degree of patellar lateralization were not statistically different between low- and high-grade dysplasia. CONCLUSION. Qualitative use of the Dejour classification accurately categorizes trochlear dysplasia as low grade or high grade in 92% of cases, with exact agreement reached in 77% of cases. Furthermore, the trochlear depth, lateral trochlear inclination, trochlear facet asymmetry, and sulcus angle can differentiate between low-grade and high-grade dysplasia, with trochlear depth, lateral trochlear inclination, and trochlear facet asymmetry useful for differentiating between Dejour types B and C and Dejour types B and D.

Spinal blastomycosis: unusual musculoskeletal presentation with literature review.

We report a case of a 41-year-old male who presented to our institution with a large groin mass. CT, MRI and PET imaging was performed and was concerning for a soft tissue abscess likely originating in the lumbar spine. Differential considerations included infection, with atypical infections such as tuberculosis strongly considered. Biopsy revealed fungal elements preliminarily reported as consistent with Cryptococcus neoformans but later revealed to be Blastomyces dermatitidis. The patient responded positively following the introduction of appropriate treatment. This case illustrates the imaging similarities between spinal blastomycosis, spinal tuberculosis, and other fungal infections as well as the need for biopsy to differentiate.

Percutaneous image-guided bone biopsy of osteomyelitis in the foot and pelvis has a low impact on guiding antibiotics management: a retrospective analysis of 60 bone biopsies.

OBJECTIVE: Image-guided percutaneous bone biopsy may be requested by clinicians to guide antibiotics management decisions in patients with extremity osteomyelitis. Much of the clinical literature describes a high rate of bone biopsy culture positivity in patients with osteomyelitis, but anecdotally biopsy is felt to be fairly low yield in many musculoskeletal radiology practices. The objective of the study is to determine the culture positivity rate and clinical utility of bone biopsy in guiding the management of patients with osteomyelitis. MATERIALS AND METHODS: All image-guided bone biopsy procedures of the pelvis or foot performed at a single institution were identified by a retrospective report search, and only those with a clinical suspicion for infection were included. Cases were included based on convincing imaging findings of osteomyelitis on retrospective review. Microbiology results were reviewed in the clinical chart, as were antibiotics management decisions and response to antibiotics therapy. RESULTS: A total of 60 bone biopsies met the inclusion criteria, 25 within the foot and 35 biopsies of the pelvis. Overall, 11 out of 60 core biopsies (18%) yielded positive cultures. Antibiotics management was altered in only 27% patients with a positive culture; thus, only 5% of patients with MRI findings of osteomyelitis undergoing biopsy had an impact on management. CONCLUSION: Percutaneous bone biopsies may have a low rate of culture positivity, and even when positive, frequently do not have an impact on antibiotics choice. These data differ from much of the clinical literature, which describes a very high rate of culture positivity.

MRI and Arthroscopic Correlation of the Wrist.

Since its introduction in 1979, the practice of and indications for wrist arthroscopy in the diagnosis and treatment of pathologic conditions in the wrist continues to grow. Magnetic resonance imaging (MRI) is another commonly used tool to noninvasively examine the anatomy and pathology of the wrist joint. Here, we review the normal wrist anatomy as seen arthroscopically and through MRI. We then examine the various common pathologic entities and define both the arthroscopic findings and correlated MRI findings in each of these states.

Magnetic resonance imaging of the knee: An overview and update of conventional and state of the art imaging.

Magnetic resonance imaging (MRI) has become the preferred modality for imaging the knee to show pathology and guide patient management and treatment. The knee is one of the most frequently injured joints, and knee pain is a pervasive difficulty that can affect all age groups. Due to the diverse pathology, complex anatomy, and a myriad of injury mechanisms of the knee, the MRI knee protocol and sequences should ensure detection of both soft tissue and osseous structures in detail and with accuracy. The knowledge of knee anatomy and the normal or injured MRI appearance of these key structures are critical for precise diagnosis. Advances in MRI technology provide the imaging necessary to obtain high-resolution images to evaluate menisci, ligaments, and tendons. Furthermore, recent advances in MRI techniques allow for improved imaging in the postoperative knee and metal artifact reduction, tumor imaging, cartilage evaluation, and visualization of nerves. As treatment and operative management techniques evolve, understanding the correct application of these advancements in MRI of the knee will prove to be valuable to clinical practice. LEVEL OF EVIDENCE: 5 J. MAGN. RESON. IMAGING 2017;45:1257-1275.

Postoperative Shoulder Imaging: Rotator Cuff, Labrum, and Biceps Tendon.

Imaging interpretation of the postoperative shoulder is a challenging and difficult task for both the radiologist and the orthopedic surgeon. The increasing number of shoulder rotator cuff, labrum, and biceps tendon repairs performed in the United States also makes this task a frequent occurrence. Whether treatment is surgical or conservative, imaging plays a crucial role in patient care. Many imaging findings can be used to predict prognosis and functional outcomes, ultimately affecting treatment. In addition, evolving surgical techniques alter the normal anatomy and imaging appearance of the shoulder such that accepted findings proved to be pathologic in the preoperative setting cannot be as readily described as pathologic after surgery. An understanding of common surgical procedures of the shoulder can aid in recognizing normal expected postoperative findings and discerning common complications. Although magnetic resonance (MR) imaging and MR arthrography are widely used, implementing a multimodality imaging approach for evaluation of the postoperative shoulder can provide additional imaging information that may be decisive and vital to diagnosis. The high spatial resolution of both computed tomography with arthrography and ultrasonography makes them additional modalities to consider, especially when dealing with metal artifact. To provide an accurate radiologic interpretation of high clinical value, radiologists should approach the postoperative shoulder comprehensively with knowledge of the anatomy, surgical techniques and complications, clinical outcomes, and imaging pitfalls. ©RSNA, 2016.