Evaluation of the extracranial "multifocal arcuate sign," a novel MRI finding for the diagnosis of giant cell arteritis, on STIR and contrast-enhanced T1-weighted images.

BACKGROUND: While early diagnosis of giant cell arteritis (GCA) based on clinical criteria and contrast-enhanced MRI findings can lead to early treatment and prevention of blindness and cerebrovascular accidents, previously reported diagnostic methods which utilize contrast-enhanced whole head images are cumbersome. Diagnostic delay is common as patients may not be aware of initial symptoms and their significance. To improve current diagnostic capabilities, new MRI-based diagnostic criteria need to be established. This study aimed to evaluate the "multifocal arcuate sign" on short tau inversion recovery (STIR) and contrast-enhanced T1-weighted (CE-T1W) images as a novel extracranial finding for the diagnosis of GCA. METHODS: A total of 17 consecutive patients (including five with GCA) who underwent CE-T1W and whole-brain axial STIR imaging simultaneously between June 2010 and April 2020 were enrolled. We retrospectively reviewed their MR images. The "multifocal arcuate sign" was defined as "multiple distant arcuate areas with high signal intensity in extracranial soft tissues such as subcutaneous fat, muscles, and tendons." Extracranial abnormal high-signal-intensity areas were classified as "None," when no lesions were detected; "Monofocal," when lesions were detected only in one place; and "Multifocal," when lesions were detected in multiple places. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of "Multifocal" areas were calculated using cross tabulation. Fisher's exact test was used to compare "Multifocal" areas in five patients with GCA and those with other diseases. In addition, mean Cohen's kappa and Fleiss' kappa statistics were used to compare inter-reader agreement. RESULTS: The sensitivity, specificity, PPV, and NPV of the "multifocal arcuate sign" in patients with GCA were 60%, 92-100%, 75-100%, and 85-86%, respectively. Significantly more patients with GCA had "Multifocal" areas compared to those with other diseases (Fisher's exact test, p = 0.008-0.027). Mean Cohen's kappa and Fleiss' kappa for inter-reader agreement with respect to the five GCA patients were 0.52 and 0.49, respectively, for both STIR and CE-T1W sequences. CONCLUSIONS: The new radiologic finding of "multifocal arcuate sign" on STIR and CE-T1W images may be used as a radiologic criterion for the diagnosis of GCA, which can make plain MRI a promising diagnostic modality.

MET amplification in endometrial cancers with clear-cell carcinoma components.

Endometrial clear-cell carcinoma (ECC) is relatively rare. The expression of diagnostic markers in this disease is similar to that of clear-cell carcinoma, but the molecular carcinogenic events and therapeutic targets are mostly unknown. MET gene amplification has been reported in various cancers, including ovarian clear-cell carcinomas; however, the MET gene status has not previously been examined in ECC. We performed real-time quantitative PCR (QPCR) and fluorescence in situ hybridization (FISH) to analyze the MET gene statuses of 12 ECC cases. We found MET amplifications in two cases (2/12; 16.7%) by both methods. Of the 12 cases, 9 were pure clear-cell carcinomas, and 3 were mixed types that included mixes with endometrioid carcinomas in 2 cases, and the remaining case was a heterologous-type carcinosarcoma that primarily consisted of a clear-cell carcinoma component and a scarce chondrosarcoma component. Both of the MET amplification cases were mixed; one contained endometrioid features, and the other chondrosarcoma features. This is the first report to analyze the statuses of the MET gene in ECCs, and the two mixed cases exhibited amplifications that are shared with ovarian clear-cell carcinomas. Further studies with larger numbers of cases are necessary to reveal the relationship between ECC and MET amplification.