森 墾

Abstract Background Large-scale CT-based reference standards for abdominal organ volume, incorporating age, sex, and body size, are limited. Purpose To establish sex- and age-specific reference distributions for major abdominal organ volumes on non-contrast abdominopelvic CT in a nationwide Japanese cohort to provide a foundation for automated clinical assessment and dose optimization. Materials and Methods In this retrospective, multicenter study, using the Japan Medical Image Database, we identified all non-contrast abdominopelvic CT examinations performed in 2024. Unique adults with available data on age, sex, height, and weight were included in this study. The final sample comprised 49,764 examinations (26,456 men and 23,308 women) conducted at nine institutions. Automated segmentation (TotalSegmentator v2.10.0) was used to produce organ volumes, excluding hollow viscera. The sex-specific 10th, 25th, 50th, 75th, and 90th percentiles were calculated. Age–volume relationships of body surface area (BSA)-normalized volumes (mL/m ² ) were modeled using natural cubic splines (four degrees of freedom) separately by sex. Results Median (mL) male vs female volumes were as follows: liver, 1194.7 vs 1024.0; pancreas, 63.6 vs 52.2; spleen, 118.1 vs 95.1; kidneys (total), 268.3 vs 221.2; adrenals (total), 6.6 vs 4.2; iliopsoas (total), 483.4 vs 317.7; prostate, 24.9 (men only). Age–volume relationships of BSA-normalized volumes showed convex patterns for the liver, pancreas, and kidneys in both sexes and for male adrenal glands; lower values in older age groups for the spleen and iliopsoas in both sexes; and higher values in older age groups for the prostate and female adrenal glands. Conclusion This nationwide Japanese CT cohort provides sex- and age-resolved volumetric reference standards. These standards enable objective identification of abnormalities, support personalized medicine, and facilitate automated AI-based reporting to reduce radiologist workload and optimize radiation dose protocols. Key Results Median volumes (men vs women, mL): liver 1195/1024; pancreas 64/52; spleen 118/95; kidneys 268/221; adrenals 6.6/4.2; iliopsoas 483/318; prostate 25. Body surface area–normalized age–volume relationships were convex for liver, pancreas, and kidneys in both sexes and for male adrenal glands. Spleen and iliopsoas declined monotonically with age in both sexes, whereas prostate and female adrenal glands increased monotonically.

Acetabular fractures are usually caused by high-energy trauma, and seizure-induced cases resulting from strong muscle contractions are extremely rare. We report the case of a 90-year-old man with osteoporosis who incurred a nontraumatic acetabular fracture during a seizure. Computed tomography revealed an internal iliac artery injury, which was promptly treated with transcatheter arterial embolization. As such vascular injuries, though rare, require early diagnosis and treatment, radiologists must be aware of the associated imaging findings and management, particularly in cognitively impaired patients.

BACKGROUND AND PURPOSE: Bell palsy (BP) is the most common cause of facial nerve (FN) palsy. This study aimed to investigate the diagnostic ability of the 3D double-echo steady-state with water excitation (3D-DESS-WE) sequence to visualize pathologic changes in the FN of patients with BP. MATERIALS AND METHODS: We retrospectively analyzed 30 patients with BP who underwent 3T MRI including 3D-DESS-WE within 30 days of onset and 60 sex- and age (SD, 2) matched controls. Qualitative evaluation of FN signal intensity (SIFN) and thickness (THFN) was performed using a 3-point scale. Quantitative metrics included SIFN and THFN measurements and affected-to-unaffected signal intensity and thickness ratios (SRA/U and TRA/U) in the BP group, and right-to-left ratios in controls. Interobserver agreement, group comparisons, correlations with clinical severity (Yanagihara score), and diagnostic performance were assessed. In a subset of 17 matched pairs, the diagnostic performance of contrast-enhanced (CE) T1WI was assessed, and its agreement with 3D-DESS-WE-based qualitative assessment was evaluated. RESULTS: Qualitative scores for SIFN and THFN were significantly higher in the BP group than in controls (P < .001), with high interobserver agreement (κ = 0.810, 0.788, respectively). When dichotomized (score 0 versus 1-2), qualitative assessments showed good diagnostic performance with a sensitivity and specificity of 0.87 and 0.82 for SIFN, and 0.90 and 0.80 for THFN, respectively. Neither qualitative score correlated significantly with clinical severity. Agreement between 3D-DESS-WE-based and CE T1WI-based qualitative assessments was substantial to almost perfect (κ = 0.766-0.882). In quantitative analysis, both SIFN and THFN were significantly higher on the affected side in the BP group (P < .001), whereas no significant lateral differences were observed in controls. Although SIFN, THFN, and SRA/U did not correlate significantly with clinical severity, TRA/U was significantly inversely correlated with the Yanagihara score (r = -0.413, P = .02), which corresponds to a positive correlation with clinical severity. The Yanagihara score was the only independent predictor of TRA/U in multiple regression analysis (β = -0.425, P = .04). Receiver operating characteristic analysis showed high diagnostic performance: area under the curve = 0.908 for SRA/U and 0.927 for TRA/U. CONCLUSIONS: 3D-DESS-WE may be a valuable tool for the routine clinical assessment of BP.

We report a rare case of squamous cell carcinoma (SCC) arising from a subcutaneous epidermoid cyst in the buttock of an 80-year-old man who presented with a painful mass. MRI revealed a well-defined subcutaneous mass, measuring approximately 10 cm, in the medial aspect of the left buttock, which exhibited internal features typical of an epidermoid cyst. However, MRI also demonstrated a significant finding: a 45-mm solid mural component protruding into the cyst. This solid component exhibited mild high signal intensity on T2-weighted images and heterogeneous signal intensity on DWI, differing from the cystic portion. Color Doppler ultrasound demonstrated internal blood flow within this solid component. Crucially, this solid component was absent on a CT scan performed 2 years prior. Resection and subsequent pathological examination confirmed well-differentiated squamous cell carcinoma (SCC) arising from the epidermoid cyst. This case highlights the importance of considering malignant transformation in epidermoid cysts, especially when imaging findings such as interval development of a solid mural component and internal vascularity are observed.