MRI of skeletal muscles in patients with idiopathic inflammatory myopathies: characteristic findings and diagnostic performance in dermatomyositis.

Objective: To define the characteristic findings on MRI of skeletal muscles in patients with dermatomyositis (DM) relative to those in patients with other idiopathic inflammatory myopathies (IIMs) and to assess their diagnostic performance in DM. Methods: Thirty-six patients with DM, 17 patients with amyopathic DM, 19 patients with polymyositis and 16 patients with non-IIM classified by the 2017 European League Against Rheumatism/American College of Rheumatology criteria were included in this study. The following MRI findings (short-tau inversion recovery [STIR] and gadolinium-enhanced fat-suppressed T1-weighted imaging [Gd-T1WI]) for proximal limb muscles were compared between the disease groups and between myositis-specific autoantibodies/myositis-associated autoantibodies (MSAs/MAAs)-positive and MSAs/MAAs-negative groups: structures with high signal intensity (HSI) (subcutaneous, fascia, muscle); distributions of HSI areas in muscle (diffuse, patchy, peripheral) and patterns of HSI in muscle (honeycomb, foggy, strong HSI). Univariate, multivariate and receiver-operating characteristic [ROC] analyses were performed to assess the diagnostic performance of MRI in DM. Results: The characteristic MRI findings in patients with DM were subcutaneous HSI, fascial HSI, peripheral distribution and honeycomb pattern. The MRI findings in the MSAs/MAAs-positive group included more frequent fascial HSI but less frequent foggy pattern compared with the MSAs/MAAs-negative group. Likelihood of DM score ≥ 3 (obtained by counting the number of characteristic MRI findings in patients with DM) showed good diagnostic performance in DM (STIR: sensitivity 72.2%, specificity 88.5%, area under ROC curve [AUC] 84.9%; Gd-T1WI: sensitivity 81.2%, specificity 91.5%, AUC 89.9%). Conclusion: The characteristic MRI findings of skeletal muscles can predict patients with DM as well as patients with MSAs/MAAs.

Enhanced four-detector row computed tomography imaging of laryngeal and hypopharyngeal cancers.

PURPOSE: Four-detector row computed tomography (4D CT) enables imaging of the larynx and hypopharynx with high temporal resolution and rapid reformatting of coronal planes. The aim of our study was to assess the usefulness of postcontrast biphasic 4D CT in diagnosing tumor extent. METHODS: Forty-seven patients with laryngeal or hypopharyngeal cancer were investigated using 4D CT. Two radiologists retrospectively evaluated transverse and reformatted coronal images in both the early and late phases. RESULTS: Images in the late phase were superior to those in the early phase in the conspicuity of the depicted lesions. The coronal images facilitated assessment of the craniocaudal extension of tumors and obliteration of the paraglottic space. The maximal diameter of tumors tended to be larger on the coronal image than on the transverse image. CONCLUSIONS: Images in the late phase were more informative than images in the early phase to demonstrate tumor extension. Reformatted coronal imaging was useful in evaluating craniocaudal extension.