Computed tomography findings of intersigmoid hernia.

Purpose: To evaluate the computed tomography findings of intersigmoid hernias. Material and methods: Between April 2010 and March 2018, 7 patients who were surgically diagnosed with intersigmoid hernia in 3 institutions were enrolled in this study. Two radiologists evaluated imaging findings for the herniated small bowel, the distance between the occlusion point and bifurcation of the left common iliac artery, and the anatomic relationship with adjacent organs. Results: All patients were male, and their mean age (standard deviation, range) was 61.0 (13.5, 36-85) years. The mean size of the bowel loops was 5.2 (1.3, 4.0-8.3) cm in the caudal direction, 3.6 (0.8, 2.5-5.1) cm in the lateral, and 3.4 (0.6, 2.5-4.7) cm in the anterior-posterior direction. The volume was 37.9 (27.8, 15.6-103.0) cm3 approximated by an ellipse, and 24.0 (17.7, 9.9-65.6) cm3 approximated by a truncated cone. The obstruction point was located 3.6 (0.6, 2.8-4.7) cm inferior to the bifurcation of the left common iliac artery. In all cases, the small bowel ran under the point at which the inferior mesenteric vessels bifurcated to the superior rectal vessels and the sigmoid vessels and formed a sac-like appearance between the left psoas muscle and the sigmoid colon. The ureter ran dorsal to the point of the bowel stenosis, and the left gonadal vein ran outside the small bowel loops. Conclusions: All cases showed common imaging findings, which may be characteristic of men's intersigmoid hernia. In addition, the fossa's position was lower, and the size was larger than in the previous study, which may be a risk factor.

Magnetic Resonance Imaging of a Urethral Caruncle and the Pathologic Correlation: A Report of 3 Cases.

A urethral caruncle is the most common disease of the urethra in postmenopausal women. A definitive diagnosis can usually be reached based on physical examination. Cross-sectional imaging is performed when malignant urethral tumor is suspected, such as a urethral carcinoma. No articles have discussed the detailed imaging of urethral caruncles. We present 3 patients with symptomatic urethral caruncles who underwent magnetic resonance imaging preoperatively.

Magnetic resonance imaging-based radiomics analysis of the differential diagnosis of ovarian clear cell carcinoma and endometrioid carcinoma: a retrospective study.

PURPOSE: To retrospectively evaluate the diagnostic potential of magnetic resonance imaging (MRI)-based features and radiomics analysis (RA)-based features for discriminating ovarian clear cell carcinoma (CCC) from endometrioid carcinoma (EC). MATERIALS AND METHODS: Thirty-five patients with 40 ECs and 42 patients with 43 CCCs who underwent pretherapeutic MRI examinations between 2011 and 2022 were enrolled. MRI-based features of the two groups were compared. RA-based features were extracted from the whole tumor volume on T2-weighted images (T2WI), contrast-enhanced T1-weighted images (cT1WI), and apparent diffusion coefficient (ADC) maps. The least absolute shrinkage and selection operator (LASSO) regression with tenfold cross-validation method was performed to select features. Logistic regression analysis was conducted to construct the discriminating models. Receiver operating characteristic curve (ROC) analyses were performed to predict CCC. RESULTS: Four features with the highest absolute value of the LASSO algorithm were selected for the MRI-based, RA-based, and combined models: the ADC value, absence of thickening of the uterine endometrium, absence of peritoneal dissemination, and growth pattern of the solid component for the MRI-based model; Gray-Level Run Length Matrix (GLRLM) Long Run Low Gray-Level Emphasis (LRLGLE) on T2WI, spherical disproportion and Gray-Level Size Zone Matrix (GLSZM), Large Zone High Gray-Level Emphasis (LZHGE) on cT1WI, and GLSZM Normalized Gray-Level Nonuniformity (NGLN) on ADC map for the RA-based model; and the ADC value, spherical disproportion and GLSZM_LZHGE on cT1WI, and GLSZM_NGLN on ADC map for the combined model. Area under the ROC curves of those models were 0.895, 0.910, and 0.956. The diagnostic performance of the combined model was significantly superior (p = 0.02) to that of the MRI-based model. No significant differences were observed between the combined and RA-based models. CONCLUSION: Conventional MRI-based analysis can effectively distinguish CCC from EC. The combination of RA-based features with MRI-based features may assist in differentiating between the two diseases.

CT urography in the urinary bladder: to compare excretory phase images using a low noise index and a high noise index with adaptive noise reduction filter.

BACKGROUND: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure. PURPOSE: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF). MATERIAL AND METHODS: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI(vol)) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale. RESULTS: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI(vol) demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences. CONCLUSION: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.

Spectrum of CT findings in amebic colitis.

Entamoeba histolytica is distributed throughout the world. Invasive amebiasis affects millions of people globally, and the associated complications cause 40,000-100,000 deaths per year. In countries where fecal-oral transmission is unusual, amebic colitis is not common, and the infection may be seen in travelers to and emigrants from endemic areas. Without adequate treatment, amebic colitis may develop into fulminant and become rapidly fatal. With the current increase in global mobility, amebic colitis should be suspected even in patients not in the endemic areas. CT plays an important role in the diagnosis of amebic colitis by demonstrating the presence of colitis with the typical involvement of the cecum and rectum. Pathological features of atypical involvement are also demonstrated. Since preoperative diagnosis can reduce the mortality associated with necrotizing colitis, radiologists need to recognize the typical as well as atypical CT findings of amebic colitis. Considering this requirement, this paper aims to describe the histopathologic features of amebic colitis and to illustrate the spectrum of corresponding CT findings.

CT findings in a patient with Coronavirus Disease-19-associated acute pericarditis.

Coronavirus Disease-19 (COVID-19)-associated acute pericarditis is a rare complication. Several cases have been reported, but those reports have not discussed any imaging findings. Here, we report a case of a 76-year-old female diagnosed with COVID-19-associated pericarditis without pneumonia, and present image findings of the patient's contrast-enhanced CT.

Collateral pulmonary vein after catheter ablation therapy for atrial fibrillation.

A patient with previous catheter ablation therapy for atrial fibrillation was examined for an abnormal shadow on a chest radiograph. ECG-gated multidetector CT clearly showed the left upper pulmonary vein connected with the left inferior pulmonary vein. We hypothesize an intrapulmonary venous connection as a collateral.

Spatial statistical smoothing function to analytical data from cerebral blood flow imaging.

Spatial statistics is widely used in fields where analysis of large-scale distributions is performed, such as synoptic meteorology and geostatistics. We constructed a smoothing function as part of a fundamental study aimed at introducing spatial statistics to the Z score map of cerebral blood flow-single photon emission tomography (CBF-SPET) and examined the applicability of spatial statistics to CBF-SPET imaging. The free statistical processing language R was chosen as the development language, and the smoothing function was constructed by use of a kernel function, a thin-plate spline function, and the Bayesian method. A Gaussian function was used as the kernel function, and three values for the smoothing parameters (0.25, 0.5, standard deviation (SD)) were used. Furthermore, the smoothing parameters of the thin-plate spline function were estimated by use of generalized cross validation (GCV), the Gibbs sampling method was adopted for the Bayesian method, and the number of iterations and the value for the burn-in were set to 500 and 250, respectively. In performing the visual assessment of the source image and the smoothed image, there were no differences caused by the smoothing process. However, there were discrepancies in the contour map at each step of the smoothing iteration. Comparing the residual sum of squares of the source image and the resulting image after each smoothing iteration, the minimum and maximum values for the image after processing with a kernel function were 1.329x10(-11) and 21.96 when the smoothing parameters were 0.25 and SD, respectively. The smoothing function, which was examined for the purpose of applying the spatial statistical method to CBF-SPET imaging, successfully performed a smoothing without generating visible discrepancies when compared with the source image. In conclusion, our research showed that spatial statistics as performed by us is applicable as an analytical method for better cerebral blood flow-SPET imaging.

CT features for diagnosing acute torsion of uterine subserosal leiomyoma.

PURPOSE: To evaluate the usefulness of computed tomographic (CT) features for identifying acute torsion of uterine subserosal leiomyoma (USL). SUBJECTS AND METHODS: We analyzed contrast-enhanced CT examinations of 7 USLs with torsion and 44 USLs without torsion. Two radiologists evaluated the CT features, which consisted of poor contrast enhancement inside the USL, thin rim enhancement around the USL, calcification within the USL, a beak sign between the uterus and USL, fan-shaped poor contrast enhancement in the uterus area adjacent to the USL (dark fan sign), and ascites. We analyzed the frequencies of these CT features in the USLs with versus without torsion using Fisher's exact test. RESULTS: The respective frequencies of CT features in USLs with and without torsion were as follows: poor contrast enhancement, 86 and 5% (P = 0.001); thin rim enhancement, 71 and 9% (P = 0.001); calcification, 29 and 18% (P = 0.61); beak sign, 57 and 86% (P = 0.10); dark fan sign, 57 and 0% (P = 0.001); and ascites, 100 and 20% (P = 0.01). CONCLUSIONS: The CT features of poor contrast enhancement, thin rim enhancement, and dark fan sign are valuable for identifying acute torsion of USL.

Ultrasonography-guided percutaneous transhepatic portacaval shunt creation.

We successfully created a percutaneous transhepatic portacaval shunt under ultrasonography (US) guidance in a 46-year-old man with refractory ascites. The shunt was created to salvage an attempt to create a transjugular intrahepatic portosystemic shunt (TIPS) that failed because of the elevated level of portal vein bifurcation due to alcoholic liver cirrhosis. Under US guidance, we simultaneously punctured the right branch of the portal vein and the inferior vena cava (IVC) using a two-step biliary drainage set. An Amplatz gooseneck snare was introduced transjugularly to retrieve the percutaneously inserted guidewire. The intrahepatic tract between the portal vein and the IVC was dilated using a balloon catheter, and a stent was placed in the tract. The patient showed complete resolution of ascites at discharge. We assume that our method is an alternative method for TIPS creation in patients with inadequate anatomical relations between the portal vein branches and the hepatic veins. This approach is thought to be feasible for patients with occluded or small hepatic veins.

Stent graft treatment for thoracic and thoracoabdominal aortic disease using a unibody Z-stent that adapts to flexure.

Positioning a stent graft (SG) that adapts to the anatomical shape of the aorta is important to prevent complications after SG procedures to treat aortic disease. The Gianturco Z-stent has several benefits, but its rigid structure prevents adaptation to flexure. We improved this stent and studied its ability to adapt in the clinical environment. We positioned SGs and inspected their adaptability to flexure in an aortic arch model. We examined several gap lengths and strut directions, and determined the distance generated between the stent and the aortic wall. We found that adaptation was quite satisfactory with a gap of more than 10 mm or when the struts faced the major flexure or the side of the model aorta. Based on these findings and to facilitate placement, we manufactured the unibody Z-stent with 10-mm gaps. The unibody Z-stent was applied to treat thoracic and thoracoabdominal aortic disease in seven patients. The SG was positioned from the femoral or iliac artery in five patients and from an anastomosed graft to the ascending aorta after median sternotomy and bypass of the arch branches in two patients. A minor endoleak developed in one patient. None of the other six patients developed complications or died during the procedure, although one patient died in the hospital due to cerebral infarction. The unibody Z-stent was applied as a SG that adapts to flexure of the aorta and was easy to apply. The frequency of complications was apparently decreased after clinical application of the unibody Z-stent in SG treatment for thoracic and thoracoabdominal aortic disease.

Dynamic MRI for distinguishing high-flow from low-flow peripheral vascular malformations.

OBJECTIVE: The purpose of our study was to assess the usefulness of dynamic MRI in distinguishing high-flow vascular malformations from low-flow vascular malformations, which do not need angiography for treatment. SUBJECTS AND METHODS: Between September 2001 and January 2003, 16 patients who underwent conventional and dynamic MRI had peripheral vascular malformations (six high- and 10 low-flow). The temporal resolution of dynamic MRI was 5 sec. Time intervals between beginning of enhancement of an arterial branch in the vicinity of a lesion in the same slice and the onset of enhancement in the lesion were calculated. We defined these time intervals as "artery-lesion enhancement time." Time intervals between the onset of enhancement in the lesion and the time of the maximal percentage of enhancement above baseline of the lesion within 120 sec were measured. We defined these time intervals as "contrast rise time" of the lesion. Diagnosis of the peripheral vascular malformations was based on angiographic or venographic findings. RESULTS: The mean artery-lesion enhancement time of the high-flow vascular malformations (3.3 sec [range, 0-5 sec]) was significantly shorter than that of the low-flow vascular malformations (8.8 sec [range, 0-20 sec]) (Mann-Whitney test, p < 0.05). The mean maximal lesion enhancement time of the high-flow vascular malformations (5.8 sec [range, 5-10 sec]) was significantly shorter than that of the low-flow vascular malformations (88.4 sec [range, 50-100 sec]) (Mann-Whitney test, p < 0.01). CONCLUSION: Dynamic MRI is useful for distinguishing high-flow from low-flow vascular malformations, especially when the contrast rise time of the lesion is measured.