Extratesticular masses focusing on MRI findings.

Scrotal masses, whether cystic or solid lesions, are routinely evaluated using ultrasonography. Magnetic resonance imaging (MRI) may be used for further investigation in cases with atypical findings, difficult diagnoses, large masses, and/or unclear relationships with the surrounding tissues. Scrotal solid masses are divided into intra- and extra-testicular masses. A staggering 90% of the intratesticular masses are malignant, whereas 75% of extratesticular masses are benign. Extratesticular masses are less common than intratesticular masses; however, some extratesticular masses present characteristic MRI findings. Familiarity with these specific MRI features of extratesticular masses is beneficial to radiologists, as appropriate diagnoses can help avoid unnecessary invasive treatments such as orchiectomy. In this review, we describe fibrous pseudotumors, polyorchidism, adenomatoid tumors, and scrotal leiomyoma as benign paratesticular masses, focusing on their characteristic imaging features on MRI. Although these tumors are extremely rare, their MRI findings are distinctive, and accurate diagnoses can prevent unnecessary orchiectomy. In addition, to demonstrate the pitfalls of diagnosing extratesticular masses, we present a case of seminoma misidentified as extratesticular masses due to large extensions outside the testis. Spermatic cord sarcoma, including rhabdomyosarcoma, leiomyosarcoma, and liposarcoma, and metastasis to the spermatic cord are described as malignant extratesticular masses. This review focused on extratesticular masses and elaborates the imaging findings that can aid in the accurate diagnosis using MRI.

Utility of radiomics features of diffusion-weighted magnetic resonance imaging for differentiation of fat-poor angiomyolipoma from clear cell renal cell carcinoma: model development and external validation.

PURPOSE: To investigate the utility of radiomics features of diffusion-weighted magnetic resonance imaging (DW-MRI) to differentiate fat-poor angiomyolipoma (fpAML) from clear cell renal cell carcinoma (ccRCC). MATERIALS AND METHODS: This multi-institutional study included two cohorts with pathologically confirmed renal tumors: 65 patients with ccRCC and 18 with fpAML in the model development cohort, and 17 with ccRCC and 13 with fpAML in the external validation cohort. All patients underwent magnetic resonance imaging (MRI) including DW-MRI. Radiomics analysis was used to extract 39 imaging features from the apparent diffusion coefficient (ADC) map. The radiomics features were analyzed with unsupervised hierarchical cluster analysis. A random forest (RF) model was used to identify radiomics features important for differentiating fpAML from ccRCC in the development cohort. The diagnostic performance of the RF model was evaluated in the development and validation cohorts. RESULTS: The cases in the developmental cohort were classified into three groups with different frequencies of fpAML by cluster analysis of radiomics features. RF analysis of the development cohort showed that the mean ADC value was important for differentiating fpAML from ccRCC, as well as higher-texture features including gray-level run length matrix (GLRLM)_long-run low gray-level enhancement (LRLGE), and GLRLM_low gray-level run emphasis (LGRE). The area under the curve values of the development [0.90, 95% confidence interval (CI) 0.80-1.00] and validation cohorts (0.87, 95% CI 0.74-1.00) were similar (P = 0.91). CONCLUSION: The radiomics features of ADC maps are useful for differentiating fpAML from ccRCC.

Three-dimensional evaluation of the coccyx movement between supine and standing positions using conventional and upright computed tomography imaging.

Currently, no three-dimensional reference data exist for the normal coccyx in the standing position on computed tomography (CT); however, this information could have utility for evaluating patients with coccydynia and pelvic floor dysfunction. Thus, we aimed to compare coccygeal parameters in the standing versus supine positions using upright and supine CT and evaluate the effects of sex, age, and body mass index (BMI) on coccygeal movement. Thirty-two healthy volunteers underwent both upright (standing position) and conventional (supine position) CT examinations. In the standing position, the coccyx became significantly longer and straighter, with the tip of the coccyx moving backward and downward (all p < 0.001). Additionally, the coccygeal straight length (standing/supine, 37.8 ± 7.1/35.7 ± 7.0 mm) and sacrococcygeal straight length (standing/supine, 131.7 ± 11.2/125.0 ± 10.7 mm) were significantly longer in the standing position. The sacrococcygeal angle (standing/supine, 115.0 ± 10.6/105.0 ± 12.5°) was significantly larger, while the lumbosacral angle (standing/supine, 21.1 ± 5.9/25.0 ± 4.9°) was significantly smaller. The migration length of the tip of the coccyx (mean, 7.9 mm) exhibited a moderate correlation with BMI (r = 0.42, p = 0.0163). Our results may provide important clues regarding the pathogenesis of coccydynia and pelvic floor dysfunction.

Incidentally detected microcystic serous cystadenoma of the pancreas with splenic invasion: a case report and literature review.

Serous cystic neoplasms are relatively uncommon and rarely possess malignant potential. We report a rare case of pancreatic serous cystadenoma with splenic invasion in a female in her 60s. Dynamic contrast-enhanced CT revealed a 3 cm mass in the tail of the pancreas. The lesion showed marked enhancement in the arterial phase on dynamic CT, which extended into the spleen. No cystic components were detected in the pancreatic mass on either magnetic resonance cholangiopancreatography or T 2 weighted imaging. No metastasis or lymph node swelling was detected. Based on the hypervascularity of the tumour, the pre-operative diagnosis was pancreatic neuroendocrine tumour with splenic invasion. The patient underwent laparoscopic distal pancreatectomy with splenectomy. The pathological diagnosis was microcystic serous cystadenoma with locally aggressive features (infiltration into spleen, lymph nodes, and splenic vein). A few cases of pancreatic serous cystadenomas with splenic invasion have been reported; all were symptomatic, with diameters greater than approximately 9 cm. This is the first known case of incidentally detected serous cystadenoma with splenic invasion, reported with detailed imaging findings of dynamic CT and MRI.