Minobu Kamo

Background: Dual‐type deep learning reconstruction (DLR) may improve the pancreatic MRI image quality; however, the effects of different DLR strengths at 1.5 T compared with the conventional 1.5 T and 3 T MRI without DLR remain unclear. Purpose: To evaluate the image quality of 1.5 T MRI reconstructed with different DLR strengths for pancreatic cystic lesions, compared with conventional 1.5 T and 3 T MRI without DLR. Study Type: Retrospective, single‐center study. Population: Ninety‐nine patients with pancreatic cystic lesion (53 men, 46 women; age range, 29.2–93.8 years) underwent 1.5 T MRI; 54 had undergone 3 T MRI within the preceding 2 years. Field Strength/Sequence: 1.5 T and 3 T MRI; axial single‐shot turbo spin‐echo T2‐weighted imaging and heavily T2‐weighted single‐shot turbo spin‐echo two‐dimensional MRCP. The 1.5 T images were reconstructed using dual‐type DLR with 80% and 50% denoising levels and compressed sensing (CS) without DLR. The 3 T images used CS without DLR. Assessment: Three blinded radiologists independently assessed eight image‐quality items using a 5‐point Likert scale. Signal‐to‐noise ratio, contrast‐to‐noise ratio, and edge rise distance were measured. Statistical Tests: Friedman tests followed by Wilcoxon signed‐rank tests with Holm correction were used. Results: At 1.5 T, 80% DLR yielded significantly higher scores than CS for all qualitative items except for texture naturalness with higher SNR (40.20 vs. 23.23) and CNR (24.67 vs. 13.57) and lower ERD (1.59 vs. 1.98 mm). ERD did not differ between 80% and 50% DLR ( p = 0.825). Compared with 3 T CS, 1.5 T 80% DLR showed significantly higher scores for seven of eight items, significantly higher SNR and CNR, and lower ERD (39.69 vs. 30.62; CNR, 24.33 vs. 16.17; and 1.49 vs. 2.16 mm, respectively). Texture naturalness was significantly lower with 80% DLR, indicating a trade‐off between image enhancement and naturalness. Data Conclusion: In this exploratory, non‐simultaneous comparison, 1.5 T DLR showed favorable image‐quality metrics relative to 3 T CS without DLR. Evidence Level: 3. Technical Efficacy: Stage 1.

The widely held dogma of three physiological narrowings in the upper urinary tract has proven incorrect by recent several studies using computed tomography images. There are only two common obstruction sites: the upper ureter and the ureterovesical junction. The second narrowing, where the ureter crosses the iliac vessels, cannot be regarded anymore as a common obstruction site. The mechanism by which stones lodge in the upper ureter is explained anatomically by the change in ureteral mobility and compliance at the level where the ureter exits the perirenal space. This level can be identified radiologically as the point where the ureter crosses under the ipsilateral gonadal veins, termed the “crossing point”. Kinking of the upper ureter is another manifestation of this anatomical phenomenon, visible in radiological images. It is caused by loosening of the ureter at or above the crossing point (within the perirenal space), corresponding with renal descent such as during the inspiratory phase. This new anatomical discovery in the retroperitoneum will not only bring about a paradigm shift in terms of the physiological narrowings in the upper urinary tract, but may also lead to the development of new surgical concepts and approaches in the area.

OBJECTIVE. IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and fibrosis in various organs. The objective of this study is to investigate CT findings of IgG4-related lesions involving the upper urinary tract and compare them with those of urothelial carcinomas. MATERIALS AND METHODS. This study reviewed pretreatment CT images of 13 consecutive patients with IgG4-related disease with upper urinary tract lesions and 80 consecutive patients with urothelial carcinomas. The findings assessed were laterality, location, growth pattern, margins, internal structure, presence of calcification and lipid component, enhancement pattern, and extraurinary findings. RESULTS. Bilaterality (p < 0.0001), an extramural growth pattern (p < 0.0001), a greater number of affected segments (p = 0.04), and a gradual dynamic enhancement pattern (p < 0.001) were significantly more frequent in patients with IgG4-related disease. With regard to extraurinary findings, paraaortic fat stranding (p = 0.03), presacral fat stranding (p < 0.001), fat stranding of the pelvic walls (p < 0.001), and aortic involvement (p < 0.001) were seen more frequently in patients with IgG4-related disease; on the other hand, there was no statistically significant difference in terms of frequency of pancreatic involvement. Hydronephrosis and renal involvement were seen more frequently in patients with urothelial carcinoma, although the difference was not statistically significant. CONCLUSION. CT findings suggestive of IgG4-related upper urinary tract lesions in comparison with urothelial carcinoma are bilateral and have a longer urinary tract involvement and exhibit an extramural growth pattern, ill-defined margins, a gradual enhancement pattern, aortic involvement, and fat stranding in the paraaortic, presacral, or pelvic wall areas.

Non-occlusive mesenteric ischemia (NOMI) is a mesenteric ischemic disease with considerably high mortality rate, although little has been known about what factors affect the patients’ prognosis. The purpose of this study was to investigate prognostic factors of clinical data and computed tomography (CT) findings in patients with NOMI.

Dir Journal Diagnostic and Interventional Radiology

A 61-year-old man with a history of septic portal vein thrombosis presented with an enlarging duodenal varix. Prominent atrophic changes of the intrahepatic and extrahepatic portal veins were observed on computed tomography. Balloon-occluded retrograde transvenous obliteration (BRTO) of the varix was performed, approaching from the right jugular vein, using 50% glucose and 5% ethanolamine oleate as a sclerosant. During venography, flow to the hepatic hilum was observed, which suggested a hepatopetal flow directly through the varices. Complete occlusion of the varix was obtained without complications. Neither recurrence nor new varix formation was observed during the 5-year follow-up period. Gradual re-enlargement of the main trunk of the portal vein was also observed.

Mucinous tubular and spindle cell carcinoma (MTSCC) is a relatively rare renal epithelial neoplasm. Although MTSCC is considered to be a low‑grade and indolent neoplasm, aggressive cases have been recently reported. The present study discussed two additional cases of high‑grade MTSCC causing multiple distant metastases with a fatal course. In case 1, a 71‑year‑old patient presented with hematuria and pyuria. Computed tomography (CT) scan of the right kidney revealed a mass lesion, for which partial nephrectomy was performed. However, a follow‑up CT imaging revealed distant metastases in the liver, the paraaortic lymph nodes and the bone. Despite molecular targeted therapy and irradiation, the patient succumbed due to tumor progression. In case 2, a 64‑year‑old patient presented with an incidentally identified mass lesion in the right kidney. A laparoscopic nephrectomy was performed, and a follow‑up CT imaging revealed metastases in the skin and lungs. The cytology of pleural effusion revealed pleuritis carcinomatosa. Histologically, both cases were diagnosed as mucin‑poor MTSCC with high‑grade transformation, which comprised uniform tumor cells primarily forming slender tubules. The tumors contained low‑ and high‑grade regions. In addition, venous invasion and necrosis were observed. The tumor cells also demonstrated increased Ki‑67 labeling indices and cellular tumor antigen p53 (p53) nuclear accumulation. High‑grade transformation, large tumor size, necrosis, venous invasion, high Ki‑67 labeling index and p53 nuclear accumulation are generally predictive findings for aggressive behavior of malignant tumors. In the current report, it was emphasized that MTSCC possesses a wide spectrum of clinicopathological features. Thus, careful postoperative investigation is required for MTSCC with high‑grade elements due to its aggressive nature.