Faculty Bibliography

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

ABSTRACT/UNASSIGNED:Musculoskeletal magnetic resonance imaging (MRI) is a careful negotiation between spatial, temporal, and contrast resolution, which builds the foundation for diagnostic performance and value. Many aspects of musculoskeletal MRI can improve the image quality and increase the acquisition speed; however, 3.0-T field strength has the highest impact within the current diagnostic range. In addition to the favorable attributes of 3.0-T field strength translating into high temporal, spatial, and contrast resolution, many 3.0-T MRI systems yield additional gains through high-performance gradients systems and radiofrequency pulse transmission technology, advanced multichannel receiver technology, and high-end surface coils. Compared with 1.5 T, 3.0-T MRI systems yield approximately 2-fold higher signal-to-noise ratios, enabling 4 times faster data acquisition or double the matrix size. Clinically, 3.0-T field strength translates into markedly higher scan efficiency, better image quality, more accurate visualization of small anatomic structures and abnormalities, and the ability to offer high-end applications, such as quantitative MRI and magnetic resonance neurography. Challenges of 3.0-T MRI include higher magnetic susceptibility, chemical shift, dielectric effects, and higher radiofrequency energy deposition, which can be managed successfully. The higher total cost of ownership of 3.0-T MRI systems can be offset by shorter musculoskeletal MRI examinations, higher-quality examinations, and utilization of advanced MRI techniques, which then can achieve higher gains and value than lower field systems. We provide a practice-focused review of the value of 3.0-T field strength for musculoskeletal MRI, practical solutions to challenges, and illustrations of a wide spectrum of gainful clinical applications.

Medial and lateral elbow pain are often due to degenerative tendinosis and less commonly due to trauma. The involved structures include the flexor-pronator tendon origin in medial-sided pain and the extensor tendon origin in lateral-sided pain. Multimodality imaging is often obtained to verify the clinically suspected diagnosis, evaluate the extent of injury, and guide treatment decisions. Image-guided procedures can provide symptom relief to support physical therapy and also induce tendon healing. Surgical debridement and repair are typically performed in refractory cases, resulting in good to excellent outcomes in most cases. In this article, we review and illustrate pertinent anatomical structures of the distal humerus, emphasizing the structure and contributions of the flexor-pronator and extensor tendon origins in acute and chronic tendon abnormalities. We also discuss approaches to image-guided treatment and surgical management of medial and lateral epicondylitis.

OBJECTIVES/OBJECTIVE:To determine the performances of clinical examination, ultrasonography, and MRI for diagnosing non-displaced and displaced ulnar collateral ligament (UCL) tears. METHODS:Based on a literature search of Medline, ISI Web of Science, Embase, and Scopus between January 1990 and December 2019, all published original articles which met the inclusion criteria were included. We determined the pooled sensitivities, specificities, and accuracies of clinical examination, ultrasonography, and MRI using a meta-analysis based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Diagnostic Test Accuracy (PRISMA-DTA) guidelines. RESULTS:A total of 17 studies with 519 subjects reporting diagnostic performances of clinical examination (8), ultrasonography (12), and MRI (5) met the inclusion criteria. For ruling out UCL tears, the pooled sensitivities were similarly high for clinical examination (97% (95% confidence interval [CI], 93-99%)), ultrasonography (96% (95% CI, 94-98%)), and MRI (99% (95% CI, 92-100%)) (p = 0.3). For ruling in UCL tears, the pooled specificities were higher for MRI (100% (95% CI, 87-100%)) when compared to ultrasonography (91% (95% CI, 86-95%)) (p = 0.1) and clinical examination (85% (95% CI, 78-91%)) (p = 0.04). For the diagnosis of displaced UCL tears, MRI had a higher specificity (92% (95% CI, 73-99%)) than ultrasonography (72% (95% CI, 63-80%)) (p = 0.2). CONCLUSIONS:Clinical examination, ultrasonography, and MRI have similarly high sensitivities for ruling out UCL tears in patients presenting with a thumb injury. MRI and ultrasonography have high specificities to confirm the presence of suspected UCL tears. MRI performs best for differentiating non-displaced from displaced UCL tears. KEY POINTS/CONCLUSIONS:• Clinical examination followed by ultrasonography is the most appropriate test for ruling out ulnar collateral ligament (UCL) tears of the thumb. • MRI and ultrasonography both have high specificities to confirm the presence of a suspected UCL tear. • MRI outperforms ultrasonography for differentiating non-displaced from displaced UCL tears.

MATERIALS AND METHODS:This single-center study was approved by the institutional review board. Artificial intelligence-based FS MRI scans were created from non-FS images using a deep learning system with a modified convolutional neural network-based U-Net that used a training set of 25,920 images and validation set of 16,416 images. Three musculoskeletal radiologists reviewed 88 knee MR studies in 2 sessions, the original (proton density [PD] + FSPD) and the synthetic (PD + AFSMRI). Readers recorded AFSMRI quality (diagnostic/nondiagnostic) and the presence or absence of meniscal, ligament, and tendon tears; cartilage defects; and bone marrow abnormalities. Contrast-to-noise rate measurements were made among subcutaneous fat, fluid, bone marrow, cartilage, and muscle. The original MRI sequences were used as the reference standard to determine the diagnostic performance of AFSMRI (combined with the original PD sequence). This is a fully balanced study design, where all readers read all images the same number of times, which allowed the determination of the interchangeability of the original and synthetic protocols. Descriptive statistics, intermethod agreement, interobserver concordance, and interchangeability tests were applied. A P value less than 0.01 was considered statistically significant for the likelihood ratio testing, and P value less than 0.05 for all other statistical analyses. RESULTS:Artificial intelligence-based FS MRI quality was rated as diagnostic (98.9% [87/88] to 100% [88/88], all readers). Diagnostic performance (sensitivity/specificity) of the synthetic protocol was high, for tears of the menisci (91% [71/78], 86% [84/98]), cruciate ligaments (92% [12/13], 98% [160/163]), collateral ligaments (80% [16/20], 100% [156/156]), and tendons (90% [9/10], 100% [166/166]). For cartilage defects and bone marrow abnormalities, the synthetic protocol offered an overall sensitivity/specificity of 77% (170/221)/93% (287/307) and 76% (95/125)/90% (443/491), respectively. Intermethod agreement ranged from moderate to substantial for almost all evaluated structures (menisci, cruciate ligaments, collateral ligaments, and bone marrow abnormalities). No significant difference was observed between methods for all structural abnormalities by all readers (P > 0.05), except for cartilage assessment. Interobserver agreement ranged from moderate to substantial for almost all evaluated structures. Original and synthetic protocols were interchangeable for the diagnosis of all evaluated structures. There was no significant difference for the common exact match proportions for all combinations (P > 0.01). The conspicuity of all tissues assessed through contrast-to-noise rate was higher on AFSMRI than on original FSPD images (P < 0.05). CONCLUSIONS:Artificial intelligence-based FS MRI (3D AFSMRI) is feasible and offers a method for fast imaging, with similar detection rates for structural abnormalities of the knee, compared with original 3D MR sequences.

OBJECTIVE:To describe and illustrate the magnetic resonance imaging (MRI) anatomy of the anterior femoral cutaneous nerve (AFCN) and a new technique for cryoanalgesia of the AFCN for long-term analgesic treatment of recalcitrant AFCN-mediated neuropathic pain. MATERIALS AND METHODS/METHODS:Using a procedural high-resolution MRI technique, we describe the MRI anatomy of the AFCN. Three patients (mean age, 48 years; range, 41-67 years) with selective nerve block-verified recalcitrant AFCN-mediated anterior thigh pain were enrolled to undergo cryoanalgesia of the AFCN. Procedures were performed under MRI guidance using clinical wide-bore MR imaging systems and commercially available cryoablation system with MR-conditional probes. Outcome variables included technical success, clinical effectiveness including symptom relief measured on an 11-point visual analog scale, frequency of complications, and procedure time. RESULTS:Procedural MRI allowed to successfully demonstrate the course of the AFCN, accurate cryoprobe placement, and monitoring of the ice ball, which resulted in technically successful iceball growth around the AFCN in all cases. All procedures were clinically effective, with median pain intensity decreasing from 8 (7-9) before the procedure to 1 (0-2) after the procedure. The cryoanalgesia effect persisted during a 12-month follow-up period in all three patients. No major complications occurred. The average total procedure time was 98 min (range, 85-125 min). CONCLUSION/CONCLUSIONS:We describe the MRI anatomy of the AFCN and a new technique for cryoanalgesia of the AFCN using MRI guidance, which permits identification of the AFCN, selective targeting, and iceball monitoring to achieve long-term AFCN-mediated neuropathic pain relief.

Magnetic resonance imaging (MRI) is a powerful imaging modality for visualizing a wide range of ankle disorders that affect ligaments, tendons, and articular cartilage. Standard two-dimensional (2D) fast spin-echo (FSE) and turbo spin-echo (TSE) pulse sequences offer high signal-to-noise and contrast-to-noise ratios, but slice thickness limitations create partial volume effects. Modern three-dimensional (3D) FSE/TSE pulse sequences with isotropic voxel dimensions can achieve higher spatial resolution and similar contrast resolutions in ≤ 5 minutes of acquisition time. Advanced acceleration schemes have reduced the blurring effects of 3D FSE/TSE pulse sequences by affording shorter echo train lengths. The ability for thin-slice partitions and multiplanar reformation capabilities eliminate relevant partial volume effects and render modern 3D FSE/TSE pulse sequences excellently suited for MRI visualization of several oblique and curved structures around the ankle. Clinical efficiency gains can be achieved by replacing two or three 2D FSE/TSE sequences within an ankle protocol with a single isotropic 3D FSE/TSE pulse sequence. In this article, we review technical pulse sequence properties for 3D MRI of the ankle, discuss practical considerations for clinical implementation and achieving the highest image quality, compare diagnostic performance metrics of 2D and 3D MRI for major ankle structures, and illustrate a broad spectrum of ankle abnormalities.

In the last few years, major developments have been observed in the field of magnetic resonance imaging (MRI). Advances in both scanner hardware and software technologies have witnessed great leaps, enhancing the diagnostic quality and, therefore, the value of MRI. In musculoskeletal radiology, three-dimensional (3D) MRI has become an integral component of the diagnostic pathway at our institutions. This technique is particularly relevant in patients with hand and wrist symptoms, due to the intricate nature of the anatomical structures and the wide range of differential diagnoses for most presentations. We review the benefits of 3D MRI of the hand and wrist, commonly used pulse sequences, clinical applications, limitations, and future directions. We offer guidance for enhancing the image quality and tips for image interpretation of 3D MRI of the hand and wrist.