Teaching Point: Radiologists need to be familiar with that ovarian vein thrombosis can occur as a complication of urinary tract infection.

We fabricated a 0.18-μm gate-length AlGaN/GaN high electron mobility transistor (HEMT) on SiC substrate fabricated by using two-step gate recessing which was composed of inductively coupled plasma (ICP) dry etching with a gas mixture of BCl3/Cl2 and wet chemical etching using the oxygen plasma treatment and HCl-based cleaning. The two-step gate recessing process exhibited an etch depth of 4.5 nm for the AlGaN layer and the clean surface of AlGaN layer at the AlGaN/gate metal contact region for the AlGaN/GaN HEMT structure. The recessed 0.18 μm × 200 μm AlGaN/GaN HEMT devices showed good DC characteristics, having a good Schottky diode ideality factor of 1.25, an extrinsic transconductance (g_m) of 345 mS/mm, and a threshold voltage (V_th) of −2.03 V. The recessed HEMT devices exhibited high RF performance, having a cut-off frequency (f_T) of 48 GHz and a maximum oscillation frequency (f_max) of 130 GHz. These devices also showed minimum noise figure of 0.83 dB and associated gain of 12.2 dB at 10 GHz.

In this work, we analyzed the effects of hot carrier injection in short-channel AlGaN/GaN high electron mobility transistors by identifying hot carrier stress conditions using electroluminescence (EL) spectroscopy. After applying hot carrier stress, degradation of the device parameters was observed. This degradation worsened under conditions of peak EL signal intensity (VG = -3 V, VD = 40 V), which accelerated the generation of hot carriers. However, when the devices were subjected to on-state stress while maintaining the same power consumption as in hot carrier stress conditions, almost no degradation was detected. This suggests that the primary cause of degradation under hot carrier stress conditions is the continuous generation of hot carriers, which is accelerated by a high electric field. This further demonstrates the feasibility of using EL spectroscopy to identify conditions for the accelerated degradation of device parameters caused by hot carriers.

A vas deferens abscess is a very rare complication of acute vasitis and lower urinary tract infection. A case of vas deferens rupture due to an abscess with severe pelvic inflammation requiring surgical drainage is reported.

Background: Accurate non-invasive assessment of liver fibrosis is needed in patients with chronic liver disease. Gadoxetic acid (Gd-EOB-DTPA)-enhanced hepatobiliary phase (HBP) magnetic resonance (MR) imaging reflects hepatocyte function and parenchymal heterogeneity, and the coefficient of variation (CV), which quantifies pixel-level signal inhomogeneity, has been proposed as a quantitative imaging biomarker of liver fibrosis. However, previous studies were retrospective, single-center, and lacked direct pathological validation. Objectives: To investigate the factors associated with CV on HBP images, evaluate the correlation between CV and pathologically confirmed liver fibrosis stage, and compare the diagnostic performance of CV with serum biomarkers, including the aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 (FIB-4), in a prospective multicenter setting. Methods: This prospective multicenter study was conducted between April 2017 and August 2020 at three medical centers. Ninety-nine participants who underwent Gd-EOB-DTPA-enhanced HBP T1-weighted MRI and liver biopsy or surgery were enrolled. CV was measured on HBP images, and the METAVIR fibrosis stage was used as the reference standard. Univariate and multivariable linear regression analyses, including an additional model adjusted for institution and pathology confirmation method, Welch’s analysis of variance with the Games–Howell post hoc test, Spearman’s rank correlation analysis, receiver operating characteristic (ROC) curve analysis with DeLong’s method for AUROC comparison, and intraclass correlation coefficient (ICC) analyses were performed. Results: Ninety-nine participants (64 men and 35 women; mean age, 55.5 ± 15.1 years) were enrolled. In multivariable linear regression analysis adjusted for institution and pathology confirmation method, pathologic fibrosis stage (B = 0.468; 95% CI, 0.358–0.578; p < 0.001) and serum albumin level (B = −0.341; p = 0.015) were independently associated with CV. Spearman’s correlation coefficient between CV and fibrosis stage was 0.74 (p < 0.001). The AUROCs of CV for significant fibrosis (≥F2), advanced fibrosis (≥F3), and cirrhosis (F4) were 0.92, 0.88, and 0.86, respectively (all p < 0.001). CV outperformed APRI and FIB-4 across most fibrosis thresholds (p < 0.001 to p = 0.045), except for FIB-4 in the diagnosis of ≥F2 fibrosis (p = 0.09). The intra- and inter-observer ICC values were 0.94 and 0.84, respectively. Conclusions: In this prospective multicenter study with pathologically confirmed fibrosis stages, CV derived from Gd-EOB-DTPA-enhanced HBP MR images showed a strong correlation with liver fibrosis stage and higher diagnostic performance than APRI and FIB-4 across most fibrosis thresholds. Because CV can be calculated from routine clinical MRI acquisitions without additional hardware or blood tests, it may serve as a practical biomarker for non-invasive liver fibrosis assessment. However, because this study was conducted in a Korean cohort with predominantly hepatitis B virus-related liver disease, further validation in other ethnic groups and etiologies is needed.