Does the presence of macroscopic intralesional fat exclude malignancy? An analysis of 613 histologically proven malignant bone lesions.

OBJECTIVE: To determine if macroscopic intralesional fat detected in bone lesions on CT by Hounsfield unit (HU) measurement and on MRI by macroscopic assessment excludes malignancy. MATERIALS AND METHODS: All consecutive CT-guided core needle biopsies (CNB) of non-spinal bone lesions performed at a tertiary center between December 2005 and September 2021 were reviewed. Demographic and histopathology data were recorded. All cases with malignant histopathology were selected, and imaging studies were reviewed. Two independent readers performed CT HU measurements on all bone lesions using a circular region of interest (ROI) to quantitate intralesional fat density (mean HU < -30). MRI images were reviewed to qualitatively assess for macroscopic intralesional fat signal in a subset of patients. Inter-reader agreement was assessed with Cronbach's alpha and intraclass correlation coefficient. RESULTS: In 613 patients (mean age 62.9 years (range 19-95 years), 47.6% female), CT scans from the CNB of 613 malignant bone lesions were reviewed, and 212 cases had additional MRI images. Only 3 cases (0.5%) demonstrated macroscopic intralesional fat on either CT or MRI. One case demonstrated macroscopic intralesional fat density on CT in a case of metastatic prostate cancer. Two cases demonstrated macroscopic intralesional fat signal on MRI in cases of chondrosarcoma and osteosarcoma. Inter-reader agreement was excellent (Cronbach's alpha, 0.95-0.98; intraclass correlation coefficient, 0.90-0.97). CONCLUSION: Malignant lesions rarely contain macroscopic intralesional fat on CT or MRI. While CT is effective in detecting macroscopic intralesional fat in primarily lytic lesions, MRI may be better for the assessment of heterogenous and infiltrative lesions with mixed lytic and sclerotic components. CLINICAL RELEVANCE STATEMENT: Macroscopic intralesional fat is rarely seen in malignant bone tumors and its presence can help to guide the diagnostic workup of bone lesions. KEY POINTS: • Presence of macroscopic intralesional fat in bone lesions has been widely theorized as a sign of benignity, but there is limited supporting evidence in the literature. • CT and MRI are effective in evaluating for macroscopic intralesional fat in malignant bone lesions with excellent inter-reader agreement. • Macroscopic intralesional fat is rarely seen in malignant bone lesions.

Myositis and Its Mimics: Guideline Updates, MRI Characteristics, and New Horizons.

Myositis is defined as inflammation within skeletal muscle and is a subcategory of myopathy, which is more broadly defined as any disorder affecting skeletal muscle. Myositis may be encountered as a component of autoimmune and connective tissue disease, where it is described as idiopathic inflammatory myopathy. Myositis can also be caused by infections, as well as toxins and drugs, including newer classes of medications. MRI plays an important role in the diagnosis and evaluation of patients with suspected myositis, but many entities may have imaging features similar to myositis and can be considered myositis mimics. These include muscular dystrophies, denervation, deep venous thrombosis, diabetic myonecrosis, muscle injury, heterotopic ossification, and even neoplasms. In patients with suspected myositis, definitive diagnosis may require integrated analysis of imaging findings with clinical, laboratory, and pathology data. The objectives of this article are to review the fundamental features of myositis, including recent updates in terminology and consensus guidelines for idiopathic inflammatory myopathies, the most important MRI differential diagnostic considerations for myositis (i.e., myositis mimics), and new horizons, including the potential importance of artificial intelligence and multimodal integrated diagnostics in the evaluation of patients with muscle disorders.

MRI of patellar stabilizers: Anatomic visibility, inter-reader reliability, and intra-reader reproducibility of primary and secondary ligament anatomy.

OBJECTIVE: To compare MRI features of medial and lateral patellar stabilizers in patients with and without patellar instability. METHODS: Retrospective study of 196 patients (mean age, 33.1 ± 18.5 years; 119 women) after diagnosis of patellar instability (cohort-1, acute patellar dislocation; cohort-2, chronic patellar maltracking) or no patellar instability (cohort-3, acute ACL rupture; cohort-4, chronic medial meniscus tear). On MRI, four medial and four lateral stabilizers were evaluated for visibility and injury by three readers independently. Inter- and intra-reader agreement was determined. RESULTS: Medial and lateral patellofemoral ligaments (MPFL and LPFL) were mostly or fully visualized in all cases (100%). Of the secondary patellar stabilizers, the medial patellotibial ligament was mostly or fully visualized in 166 cases (84.7%). Other secondary stabilizers were mostly or fully visualized in only a minority of cases (range, 0.5-32.1%). Injury scores for all four medial stabilizers were higher in patients with acute patellar dislocation than the other 3 cohorts (p < .05). Visibility inter- and intra-reader agreement was good for medial stabilizers (κ 0.61-0.78) and moderate-to-good for lateral stabilizers (κ 0.40-0.72). Injury inter- and intra-reader agreement was moderate-to-excellent for medial stabilizers (κ 0.43-0.90) and poor-to-moderate for lateral stabilizers (κ 0-0.50). CONCLUSION: The MPFL and LPFL were well visualized on MRI while the secondary stabilizers were less frequently visualized. The secondary stabilizers were more frequently visualized medially than laterally, and patellotibial ligaments were more frequently visualized compared to the other secondary stabilizers. Injury to the medial stabilizers was more common with acute patellar dislocation than with chronic patellar maltracking or other knee injuries.

Distant migration of gluteal augmentation fat presenting as a soft tissue knee mass.

Gluteal augmentation with autologous fat grafting is an increasingly popular procedure. While complication rates are low, the clinical and imaging evaluation of the various complications can be challenging. We report a case of distal migration of a failed gluteal fat graft in a young female patient presenting as a soft tissue mass in the knee, mimicking a soft tissue sarcoma. Surgical resection of the migrated fat graft confirmed the diagnosis. The diagnosis was challenging as the patient was initially reluctant to disclose her surgical history due to perceived negative social stigmas related to cosmetic contouring procedures. This case highlights the imaging findings of a rare complication following autologous fat grafting for gluteal augmentation and the importance of obtaining a thorough medical history.

Association of aspirin and other non-steroidal anti-inflammatory drugs with bleeding complications in image-guided musculoskeletal biopsies.

OBJECTIVE: To evaluate the safety of continuing aspirin and other non-steroidal anti-inflammatory drugs (NSAID) in patients undergoing image-guided musculoskeletal biopsies. MATERIAL AND METHODS: Prior to October 2017, patients undergoing image-guided musculoskeletal biopsy had aspirin and NSAIDs withheld for the preceding 5-7 days. The policy changed in October 2017 based on new guidelines from the Society of Interventional Radiology such that aspirin and other NSAIDs were not withheld. A retrospective review of patient records was performed for all biopsies prior to and after the policy change to assess for differences in biopsy-related bleeding complications. Additional clinical and biopsy factors including age, gender, liver disease, coagulopathy, biopsy tissue type, and histological diagnosis were assessed. RESULTS: In the pre-policy change group, there were 1853 total biopsies with 43 biopsy-related bleeding complications (2.3%). Within this group, 362 patients were on aspirin with 7 bleeding complications (1.9%) and 260 patients were on NSAIDs with 5 bleeding complications (1.9%). There were 409 total biopsies in the post-policy change group and 7 bleeding complications (1.7%). Within this group, 71 patients were on aspirin with 1 bleeding complication (1.4%). No bleeding complications were recorded in patients on NSAIDs (0%). There was no significant difference in bleeding complication between the pre- and post-policy change groups overall (p = 0.58) and in patients on aspirin (p = 1.00) or other NSAIDs (p = 1.00). CONCLUSION: Bleeding complications for musculoskeletal biopsies are rare. Leaving patients on aspirin or other NSAIDs during a musculoskeletal biopsy does not increase the incidence of bleeding complications.

Troubleshooting Challenging Musculoskeletal Tumor Biopsies: Tricks of the Trade.

Image-guided core needle biopsy of musculoskeletal lesions can be challenging due to a variety of technical, patient-related, and lesion-related factors. Poor preprocedural planning can result in low diagnostic yield, misdiagnosis, delay in care, and the need for additional procedures. Furthermore, suboptimal procedural technique may place the patient at an increased risk of iatrogenic complications. Optimizing pre-procedural planning by considering potential complications is important in ensuring a safe and successful procedure. We provide a review of strategies for troubleshooting challenging image-guided musculoskeletal tumor biopsies.

VDAC oligomers form mitochondrial pores to release mtDNA fragments and promote lupus-like disease.

Mitochondrial stress releases mitochondrial DNA (mtDNA) into the cytosol, thereby triggering the type Ι interferon (IFN) response. Mitochondrial outer membrane permeabilization, which is required for mtDNA release, has been extensively studied in apoptotic cells, but little is known about its role in live cells. We found that oxidatively stressed mitochondria release short mtDNA fragments via pores formed by the voltage-dependent anion channel (VDAC) oligomers in the mitochondrial outer membrane. Furthermore, the positively charged residues in the N-terminal domain of VDAC1 interact with mtDNA, promoting VDAC1 oligomerization. The VDAC oligomerization inhibitor VBIT-4 decreases mtDNA release, IFN signaling, neutrophil extracellular traps, and disease severity in a mouse model of systemic lupus erythematosus. Thus, inhibiting VDAC oligomerization is a potential therapeutic approach for diseases associated with mtDNA release.

Undersized Rigid Nonplanar Annuloplasty: The Key to Effective and Durable Repair of Functional Tricuspid Regurgitation.

BACKGROUND: Previous clinical experiences have demonstrated high early and late recurrence rates after repair of functional tricuspid regurgitation (TR). We investigated the results of functional TR repair with undersized rigid nonplanar annuloplasty rings. METHODS: From January 2007 to December 2013, 216 consecutive patients with moderate or greater functional TR were treated with undersized (size 26 mm or 28 mm) rigid nonplanar annuloplasty rings. RESULTS: The mean age was 69 ± 13 years. There was a previous history of cardiac operation in 25% (54 of 216 patients). Tricuspid regurgitation was graded as severe in 47% (102 of 216) and moderate in 53% (114 of 216). Concomitant operations included mitral valve procedures in 92% (198 of 216), coronary artery bypass grafting in 21% (45 of 216), aortic valve procedures in 9% (20 of 216), and cryomaze procedures in 35% (76 of 216). Size 26 mm rings were used in 38% of patients (81 of 216), and size 28 mm in 62% (135 of 216). The perioperative mortality rate was 6% (14 of 216). On predischarge echocardiography, TR grade was none or mild in 94% (176 of 187 patients), moderate in 4% (7 of 187), and severe in 2% (4 of 187). At a mean follow-up of 33.0 ± 24.0 months, TR grade was none or mild in 81% of patients (130 of 160), moderate in 16% (26 of 160), and severe in 2% (4 of 160). There were no reoperations for recurrent TR, and no patients have had tricuspid stenosis or annuloplasty ring dehiscence. CONCLUSIONS: Treatment of functional TR with undersized (26 mm or 28 mm) nonplanar rigid annuloplasty rings is safe and highly effective, with a near absence of recurrent severe TR at midterm follow-up.

Assessment of Injuries During Brazilian Jiu-Jitsu Competition.

BACKGROUND: Brazilian jiu-jitsu (BJJ) is a unique style of martial arts with rapid growth in the United States and internationally. Although studies have examined injuries in other martial arts and combat sports, to date, no published medical study has examined injuries in BJJ competitions. PURPOSE: (1) To estimate the incidence of injuries in BJJ competitions and (2) to identify and describe the types and mechanisms of injuries associated with competitive BJJ. STUDY DESIGN: Descriptive epidemiology study. METHODS: Injury data were obtained from records of on-site medical coverage at 8 statewide BJJ tournaments in Hawaii, USA, between 2005 and 2011. RESULTS: The identified injury incidence on the day of matches was 9.2 per 1000 exposures (46 injuries out of 5022 exposures, ie, match participations). Orthopaedic injuries were the most common and accounted for 78% of all injuries (n = 36), followed by costochondral or rib injuries (n = 7) and lacerations requiring medical care (n = 3). The elbow was found to be the joint most commonly injured during BJJ competitions, with the arm bar being the most common mechanism. We propose that this BJJ-specific injury mechanism, the "arm bar," be recognized as another mechanism of hyperextension injury to the elbow in sports. CONCLUSION: Comparison of the BJJ injury data with injury data reported for judo, taekwondo, wrestling, and mixed martial arts showed that BJJ competitors were at substantially lower risk of injury compared with these other sports. With orthopaedic injuries being most common and the elbow being the area most vulnerable to injury in BJJ, it is important that participants, referees, and physicians be properly educated about the unique mechanisms of injury that can occur, particularly to the elbow.