Imaging of lower extremity infections: predisposing conditions, atypical infections, mimics, and differentiating features.

Imaging evaluation for lower extremity infections can be complicated, especially in the setting of underlying conditions and with atypical infections. Predisposing conditions are discussed, including diabetes mellitus, peripheral arterial disease, neuropathic arthropathy, and intravenous drug abuse, as well as differentiating features of infectious versus non-infectious disease. Atypical infections such as viral, mycobacterial, fungal, and parasitic infections and their imaging features are also reviewed. Potential mimics of lower extremity infection including chronic nonbacterial osteomyelitis, foreign body granuloma, gout, inflammatory arthropathies, lymphedema, and Morel-Lavallée lesions, and their differentiating features are also explored.

Lower extremity infections: Essential anatomy and multimodality imaging findings.

In modern practice, imaging plays an integral role in the diagnosis, evaluation of extent, and treatment planning for lower extremity infections. This review will illustrate the relevant compartment anatomy of the lower extremities and highlight the role of plain radiographs, CT, US, MRI, and nuclear medicine in the diagnostic workup. The imaging features of cellulitis, abscess and phlegmon, necrotizing soft tissue infection, pyomyositis, infectious tenosynovitis, septic arthritis, and osteomyelitis are reviewed. Differentiating features from noninfectious causes of swelling and edema are discussed.

Charcot-Marie-Tooth Disease of the Foot and Ankle: Imaging Features and Pathophysiology.

Charcot-Marie-Tooth disease (CMT) is the most common inherited peripheral polyneuropathy, resulting in length-dependent motor and sensory deficiencies. Asymmetric nerve involvement in the lower extremities creates a muscle imbalance, which manifests as a characteristic cavovarus deformity of the foot and ankle. This deformity is widely considered to be the most debilitating symptom of the disease, causing the patient to feel unstable and limiting mobility. Foot and ankle imaging in patients with CMT is critical for evaluation and treatment, as there is a wide range of phenotypic variation. Both radiography and weight-bearing CT should be used for assessment of this complex rotational deformity. Multimodality imaging including MRI and US is also important to help identify changes in the peripheral nerves, diagnose complications of abnormal alignment, and evaluate patients in the perioperative setting. The cavovarus foot is susceptible to distinctive pathologic conditions including soft-tissue calluses and ulceration, fractures of the fifth metatarsal, peroneal tendinopathy, and accelerated arthrosis of the tibiotalar joint. An externally applied brace can assist with balance and distribution of weight but may be appropriate for only a subset of patients. Many patients will require surgical correction, which may include soft-tissue releases, tendon transfers, osteotomies, and arthrodesis when necessary, with the goal of creating a more stable plantigrade foot. The authors focus on the cavovarus deformity of CMT. However, much of the information discussed may also be applied to a similar deformity that may result from idiopathic causes or other neuromuscular conditions. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Incidence, Impact, and Management of Incidentalomas on Preoperative Computed Tomographic Angiograms for Breast Cancer Patients with and without Genetic Mutations.

BACKGROUND: Preoperative abdominal computed tomographic angiograms for free flap breast reconstruction improve operative safety and efficiency, but incidental findings are common and potentially affect management. In addition, the authors hypothesized that patients with genetic mutations might have a higher rate of significant findings. The authors present the largest series of computed tomographic angiogram "incidentalomas" in these two populations and an evidence-based algorithm for managing common findings. METHODS: All patients undergoing free flap breast reconstruction at Northwell Health between 2009 and 2017 were eligible. Medical history, perioperative details, and radiology reports were examined with abnormal findings recorded. Published literature was reviewed with radiologists to develop standardized guidelines for incidentaloma management. RESULTS: Of 805 patients included, 733 patients had abdominal imaging. One hundred ninety-five (27 percent) had a completely negative examination. In the remaining 538 patients, benign hepatic (22 percent) and renal (17 percent) findings were most common. Sixteen patients (2.2 percent) required additional imaging (n = 15) or procedures (n = 5). One finding was concerning for malignancy-renal cell carcinoma-which interventional radiology ablated postoperatively. Seventy-nine patients (10.8 percent) had a genetic mutation but were not found to have a statistically significant higher rate of incidentalomas. CONCLUSIONS: The authors' rate of computed tomographic angiography incidental findings (73 percent) is consistent with previous studies, but the rate requiring further intervention (2.2 percent) is lower. Incidental findings were no more common or pathologic among genetic mutation carriers. The authors also introduce an evidence-based algorithm for the management of common incidentalomas. Using these guidelines, plastic surgeons can reassure patients, regardless of mutation status, that incidentalomas are most commonly benign and have minimal impact on their surgical plan.

Sports Hernia/Athletic Pubalgia Among Women.

BACKGROUND: "Athletic pubalgia," a term that has gained acceptance over "sports hernia," is more common in men than women; however, it represents a significant source of morbidity for patients of both sexes. Inconsistent terminology surrounding this entity poses a diagnostic challenge and makes studying the populations at risk difficult. PURPOSE: To review a case series of women with athletic pubalgia by analyzing their presentations, concomitant pathologies, and surgical outcomes. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between 2013 and 2016, 197 patients were seen and evaluated for the diagnosis of athletic pubalgia. Eighteen patients seen during this time were women. All patients received "pubalgia protocol" magnetic resonance imaging and subsequent surgical intervention for their pathologies. Outcomes among 17 women were assessed with a patient questionnaire >1 year after surgery. RESULTS: Of the 17 women, 9 had rectus aponeurotic plate injury only, or pure athletic pubalgia; the remaining 8 had athletic pubalgia in combination with ≥1 inguinal, obturator, and femoral hernias. Regarding female patients in both groups, 88.2% reported that the surgery was a success at follow-up. CONCLUSION: Surgical repair of athletic pubalgia among women is successful in dramatically reducing pain levels in this important subset of patients.

Congenital Rhabdomyosarcoma Presenting as a Neck Mass at Birth.

Rhabdomyosarcoma is a malignant tumor of the soft tissues which preferentially affects the pediatric population. Neonatal rhabdomyosarcoma is rare, and much of the published literature concerning this entity consists of isolated case reports and small case series. Recent work involving the classification of rhabdomyosarcoma has helped to delineate prognostic information based on gene rearrangements. Here, we present a case of congenital rhabdomyosarcoma seen in utero which manifested as a neck mass at birth and was found to harbor a favorable gene fusion.

Bone SPECT/CT of the Spine, Foot, and Ankle: Evaluation of Surgical Patients.

Radionuclide bone scanning has been used routinely in the evaluation of bone pathology for decades. The greatest strength of the procedure is its extreme sensitivity for bone metabolism, allowing it to distinguish between active and inactive bony abnormalities. The downside of this reliance on abnormal bone turnover is the relative lack of anatomical detail compared with ever-improving CT and MRI technology. Fusion imaging using SPECT/CT (SCT), PET/CT, and PET/MRI offers an opportunity to combine the sensitivity of nuclear medicine examinations with the anatomical detail of CT and MRI. This fusion of technologies is especially important in situations where anatomical imaging modalities alone provide insufficient diagnostic information. In this review, we highlight the utility of SPECT/CT bone imaging in the pre- and postoperative evaluation of patients undergoing procedures of the spine, foot, and ankle.