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.

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.

Intraductal oncocytic papillary neoplasm of the pancreas: clinical and radiological features compared to those of intraductal papillary mucinous neoplasm.

PURPOSE: This study aimed to characterize the clinical and imaging findings of intraductal oncocytic papillary neoplasm of the pancreas (IOPN-P) compared to those of intraductal papillary mucinous adenoma/carcinoma (IPMA/IPMC). METHODS: This multi-institutional retrospective study reviewed the clinical, imaging, and pathological findings of 21 patients with pathologically proven IOPN-P. Twenty-one computed tomography (CT) and magnetic resonance imaging, and seven 18F-fluorodeoxyglucose (FDG)-positron emission tomography were performed before surgery. The following findings were evaluated: preoperative blood test results, lesion size and location, pancreatic duct diameter, contrast-enhancement effect, bile duct and peripancreatic invasion, maximum standardized uptake (SUVmax) value, and pathological stromal invasion. RESULTS: Serum carcinoembryonic antigen (CEA) and cancer antigen 19-9 (CA19-9) levels were significantly higher in the IPMN/IPMC group than in the IOPN-P group. Except in one patient, IOPN-P showed multifocal cystic lesions with solid components or a tumor in the main pancreatic duct (MPD) with dilatation. IOPN-P had a higher frequency of solid parts and a lower frequency of downstream MPD dilatation than IPMA. IPMC showed smaller overall cyst size, more radiological peripancreatic invasion, and worse recurrence-free and overall survival than IOPN-P. The average SUVmax value of IOPN-P was 7.5. Pathologically, 17 of the 21 IOPN-Ps had a malignant component, and six showed stromal invasion. CONCLUSION: IOPN-P shows cystic-solid lesions similar to IPMC but has lower serum CEA and CA19-9 levels, larger overall cyst size, lower frequency of peripancreatic invasion, and more favorable prognosis than IPMC. Moreover, the high FDG uptake by IOPN-Ps may be a characteristic finding of this study.

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.

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.

Evaluation of hepatocellular carcinoma ablative margins using fused pre- and post-ablation hepatobiliary phase images.

PURPOSE: To retrospectively evaluate the utility of fusion images of pre- and post-ablation hepatobiliary phase (HBP) series to assess the ablation margins after radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs). Additionally, to identify factors indicative of an adequate ablation margin and predictors of local tumor progression (LTP). METHODS: Fifty-nine HCCs in 29 patients were treated by RFA and followed-up for > 1 year (mean 37.9 months). Fusion images of pre- and post-ablation HBP series were created using a non-rigid registration and manual correlation. The ablation margin appearance was classified as ablation margin + (ablation margin completely surrounding the tumor), ablation margin-zero (a partially discontinuous ablation margin without protrusion of HCC), ablation margin-(a partially discontinuous ablation margin with protrusion of HCC), and indeterminate (index tumor was not visible). The minimal ablation margin was measured, and clinical factors were examined to identify other risk factors for LTP. RESULTS: LTP was observed at follow-up in 12 tumors. The mean minimal ablation margin was 3.6 mm. Multivariate analysis revealed that the ablation margin status was the only significant factor (p = 0.028). The cumulative LTP rates (3.3%, 3.3%, and 3.3% at 1, 2, and 3 years, respectively) in 30 ablation margin + nodules were significantly lower (p = 0.006) than those (20.0%, 28.0%, and 32.2% at 1, 2, and 3 years, respectively) in 25 ablation margin-zero nodules. CONCLUSIONS: Fusion images enable an early assessment of the ablation efficacy in the majority of HCCs. The ablation margin status is a significant factor for LTP.

Three cases of intracystic papillary neoplasm of gallbladder.

Intracystic papillary neoplasm (ICPN) of gallbladder is a comparatively new concept and is described as pre-malignant lesions in Nakanuma et al. (In: Bosman et al. (eds) WHO Classification of Tumours of the Digestive System, World Health Organization of Tumours, IARC, Lyon, 2010). ICPN with high-grade intraepithelial neoplasia is understood to include intraepithelial carcinoma or noninvasive carcinoma. And lesions with invasive cancer components are classified as ICPN with an associated invasive carcinoma [1]. According to Adsay et al., more than half of patients diagnosed with ICPN have invasive cancer components (Adsay et al., Am J Surg Pathol 36:1279-1301, 2012).Polypoid masses in the gallbladder including benign, malignant, and non-neoplastic lesions have been called gallbladder polyps, and ICPN is also a polypoid lesion in the gallbladder. However, it is difficult to differentiate between them. In the literature, it is said that the possibility of malignancy is high in lesions exceeding 1 cm (Terzi et al., Surgery 127:622-627, 2000). And there are few reports on characteristic imaging findings of ICPN.We have experienced three cases (two females and one male) of ICPN and report our imaging findings. Contrast-enhanced computed tomography revealed large papillary polypoid lesions approximately 2-4 cm in size in the gallbladder. Findings suggestive of deformation of the gallbladder wall and extrinsic progression were absent in all cases. T2-weighted magnetic resonance imaging revealed intense signals and diffusion-weighted imaging showed high intensity. Expanding of the gallbladder was seen in case 1, and a tumor stalk-like appearance was seen in the papillary mass in cases 2 and 3. Surgery was performed in all three cases and ICPN was diagnosed pathologically. The cancer was localized to the mucosa, with no infiltration of surrounding tissue in all three cases.

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.

[Numerical and Visual Evaluation of Compressed Sensing MRI Using 3D Cartesian Sampling].

We performed numerical and visual evaluation of compressed sensing MRI (CS-MRI) using 3D Cartesian sampling by numerical simulation. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for numerical evaluation. Sampling ratio of the Cartesian grid was 30%. Reconstruction was performed by the projection onto convex sets (POCS) method with soft thresholding, subject to data fidelity constraints. In the absence of noise, RMSE of 3D-T1WI was 1.50, ant that of the 2D-T1WI of the transverse plane was in the range of 1.06 to 1.54; anatomical ROIs was in the range of 0.75 to 2.80; those of T2WI were 3.20, 2.77 to 3.06, and 1.81 to 4.51; those of PDWI were 1.69, 1.33 to 1.49, and 1.08 to 1.86. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average score of the visual evaluation indicated that anatomical structure and tissue contrast of CS images were equal to those of the original image, although a few artifacts were visible. If noise level was assumed to be 20 dB or less, anatomical structure and tissue contrast were not significantly degraded compared to noise-free CS images.

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.

A resected case of two branch duct-type intraductal papillary mucinous neoplasms showing different clinical courses after a two-year follow-up.

The patient was a 60-year-old man without any particular complaints, but he underwent abdominal computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) due to a fatty liver, which revealed two similar cystic lesions regarded as branch duct-type intraductal papillary mucinous neoplasm (BD-IPMN) in the pancreatic body [BD-IPMN (b), 16 mm in size] and tail [BD-IPMN (t), 13 mm in size] without a "high-risk stigmata" or "worrisome features". He subsequently received follow-up by MRCP every 6 months. Two years later, MRCP showed prominent dilation of the main pancreatic duct (MPD) and mural nodule formation within the dilated MPD adjacent to the BD-IPMN (b). Distal pancreatectomy specimens revealed that the BD-IPMN (b) was lined by low-papillary gastric mucinous epithelium with low-to-intermediate-grade dysplasia and involved the MPD, forming a malignant mural nodule showing pancreatobiliary-type IPMN. In contrast, the BD-IPMN (t) was lined by flat, monolayer columnar gastric mucinous epithelium without atypia, which suggested the possibility of a "simple mucinous cyst". A genetic analysis showed KRAS mutation only in BD-IPMN (b). Differences in the histological and genetic findings between two similar BD-IPMNs in the present case may suggest what kinds of examinations should be performed in patients with BD-IPMNs without any worrisome features.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Radial Sampling].

Two-dimensional radial MRI using compressed sensing (2D radial CS) enables incoherence sampling in k space unlike conventional Cartesian MRI, however 2D radial CS has not been sufficiently investigated. Numerical and visual evaluations of 2D radial CS were performed in this paper. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weigthted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. The Brainweb MRI Data Base was used for test images. Projection of 80 spokes with linear sampling of 256 pixels was used. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and spatial finite-differences (total variation), subject to data fidelity constraint. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 3.75 to 5.05; that of the anatomical region of interests (ROIs) was in the range of 1.54 to 10.24; those of T2WI were 8.75 to 11.65 and 4.31 to 6.99; and those of PDWI were 3.44 to 4.46 and 1.34 to 3.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, and tissue contrast. Average percent scores of the visual evaluation were 96% for T1WI, 74-81% for T2WI, and 81-89% for PDWI.

[Numerical and Visual Evaluations of Compressed Sensing MRI Using 2D Cartesian Sampling].

This paper describes numerical and visual evaluations of compressed sensing MRI (CS-MRI) using 2D Cartesian sampling by numerical simulation. The BrainWeb MRI Data Base was used for test images. Three brain anatomical ROIs (white matter, gray matter, cerebrospinal fluid) of a T1-weighted image (T1WI), a T2-weighted image (T2WI) and a proton density-weighted image (PDWI) were used for the numerical evaluation. Sampling ratio was 50%. Reconstruction was performed by minimizing the L1 norm of a transformed image using wavelet transform and total variation, subject to data fidelity constraints. The conjugate gradient method was used in the minimization of the object function. In the absence of noise, the root mean square error (RMSE) of T1WI was in the range of 2.99 to 3.57; that of the anatomical region of interests (ROIs) was in the range of 1.77 to 8.53; those of T2WI were 4.72 to 5.65 and 3.28 to 5.54; and those of PDWI were 1.91 to 2.36 and 1.32 to 2.09. Visual evaluation was performed by three radiologists on the basis of three categories: artifact, anatomical structure, tissue contrast. CS image quality was nearly equal to that of the original image, although a few artifacts were visible. If the noise level was assumed to be 30 dB or less, T1-CS image and PD-CS images were not significantly degraded compared to noise-free images.

Does hepatobiliary phase sequence qualitatively outperform unenhanced T1-weighted imaging in assessment of the ablation margin 24 hours after thermal ablation of hepatocellular carcinomas?

PURPOSE: To retrospectively determine whether hepatobiliary phase (HBP) sequence outperforms unenhanced T1-weighted imaging (uT1wI) in distinguishing the ablation margin (AM) from hepatocellular carcinoma (HCC) 24 h after thermoablation. MATERIAL AND METHODS: Ninety-one patients [mean age, 65.7 years; 68 M/23F] with 138 HCCs (>6 months follow-up) underwent pre- and postablation gadoxetate disodium-enhanced MRI. AM showed a hyperintense middle zone (MZ) surrounding central hypo- or hyperintense HCCs on uT1wI, and an intermediate-intense MZ encompassing central hypo- or hyperintense HCCs during HBP. The visible AM was defined as persistent MZ around HCCs, which were demarcated from MZ, or peripherally band encompassing MZ, which were not demarcated from HCC. The indefinite AM was defined as no demarcating HCCs from MZ. The ability to distinguish AM from HCC was classified as visible or indefinite on axial (ax)-uT1wI, ax-HBP, coronal (cor)-HBP, and combined all images. To investigate the AM visibility during HBP, significance of differences upon comparison of ax-uT1wI with combined images was analyzed. Preablation liver-tumor contrast ratio (LTCR) on ax-uT1wI and ax-HBP sequence is compared between the visible and indefinite AM. RESULTS: The McNemar test demonstrated a significant increase (p < 0.05) in visible AM from ax-uT1wI (60), to ax-HBP (70), cor-HBP (79), and combined images (83). TLCR with visible AM was significantly higher than that with indefinite AM on ax-uT1wI (0.4 vs. 0.2, p = 0.001) and ax-HBP sequence (0.9 vs. 0.6, p = 0.004). CONCLUSIONS: HBP sequence might have higher feasibility to distinguish AM from tumor than ax-uT1wI. The TLCR value in visible AM was higher than that in indefinite AM on both ax-uT1wI and ax-HBP sequences.

MR Imaging of Fetuses to Evaluate Placental Insufficiency.

PURPOSE: To evaluate morphological and signal intensity (SI) changes of placental insufficiency on magnetic resonance imaging (MRI) and to assess morphological changes and decreased flow voids (FVs) on T2-weighted rapid acquisition with relaxation enhancement (RARE) images for diagnosing placental insufficiency. METHODS: Fifty singleton fetuses underwent MRI using a 1.5-T MR scanner. Placental thickness, area, volume, SI, amniotic fluid SI, and size of FVs between the uterus and the placenta were measured on MR images. Two radiologists reviewed T2-weighted RARE images for globular appearance of the placenta and FVs between the uterus and the placenta. Data were analyzed using t-tests, McNemar's tests, and areas under the receiver operating characteristic curve (AUCs) at 5% level of significance. RESULTS: Twenty-five of the 50 pregnancies were categorized as having an insufficient placenta. Significant differences were observed between insufficient and normal placentas in mean placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs (49.0 mm vs. 36.9 mm, 1.62 × 10(4) mm(2) vs. 2.67 × 10(4) mm(2), 5.13 × 10(5) mm(3) vs. 6.56 × 10(5) mm(3), 0.549 vs. 0.685, and 3.4 mm vs. 4.3 mm, respectively). The sensitivity and accuracy using globular appearance plus decreased FVs were greater than those using decreased FVs (P < 0.01). There was no significant difference among AUCs using globular appearance and decreased FVs, and globular appearance plus decreased FVs. CONCLUSIONS: Placental insufficiency was associated with placental thickness, area, volume, placenta to amniotic fluid SI ratio, and size of FVs. Evaluating FVs on T2-weighted RARE images can be useful for detecting placental insufficiency, particularly in placentas without globular appearance on MR images.

Preoperative T staging of urinary bladder cancer: efficacy of stalk detection and diagnostic performance of diffusion-weighted imaging at 3T.

PURPOSE: We evaluated the ability of diffusion-weighted imaging (DWI) at 3 tesla for diagnosing T stage and detecting stalks in bladder cancer. METHODS: In total, 39 consecutive patients with bladder tumors underwent magnetic resonance (MR) imaging that included T2-weighted imaging (T2WI) and DWI using a 3T MR scanner. Two radiologists interpreted T2WI plus DWI and T2WI for diagnosis of T stage and for detection of stalks. We used McNemar's test to examine differences in diagnostic performance and Fisher's exact test to evaluate differences in stalk detection frequency. RESULTS: Specificity and accuracy in differentiating T1 tumors from T2 to T4 tumors were significantly better with T2WI plus DWI (83% [20/24] and 85% [33/39]) than T2WI (50% [12/24] and 67% [26/39]; P = 0.02), and accuracy for diagnosing tumor stage was significantly better with T2WI plus DWI (82% [32/39]) than T2WI alone (59% [23/39]; P = 0.03). The observers identified stalks in 11 tumors by T2WI (48% [11/23]) and 17 by DWI (74% [17/23]) (P < 0.03). CONCLUSION: DWI at 3T was superior to T2WI for evaluating the T stage of bladder cancer, particularly in differentiating T1 tumors from those T2 or higher, and in detecting stalks of papillary bladder tumors.

A case of pulmonary papillary adenoma: possible relationship between tumor histogenesis/tumorigenesis and fibroblast growth factor receptor 2 IIIb.

Pulmonary papillary adenoma is a rare tumor. We analyzed a tumor which appeared in a 16-year-old Japanese woman. The tumor histologically showed papillary proliferation of one-layered tumor cells coating inflammatory fibrovascular cores. At the periphery of the tumor, the tumor cells grew in a lepidic fashion. The tumor cells were confirmed as type-II pneumocytes with electron-microscope. In this study, using immunohistochemistry, in situ hybridization and real-time reverse transcription polymerase chain reaction, we examined the expressions and quantities of fibroblast growth factor 10 (FGF10), keratinocyte growth factor (KGF) and fibroblast growth factor receptor 2 (FGFR2) IIIb, based on the extent of their abilities of proliferation and differentiation of type II pneumocytes. The tumor cells expressed FGFR 2 and produced 350 times more FGFR2IIIb messenger RNA (mRNA) than did the nontumorous lung. The quantity of KGF mRNA in the tumor tissue was twice that of the nontumorous lung. Moreover, there was dysregulation of FGFR2IIIb transcription in the tumor. According to these findings, we expect overexpression of FGFR2IIIb to play an important role in causing tumor. Because FGFR is suspected to be connected with lung carcinoma, we also treat similar tumorigenesis via FGFR as carcinoma; complete resection of adenoma might be indicated.

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.

Right pleural effusion in Fitz-Hugh-Curtis syndrome.

Right pleural effusion was diagnosed in a 36-year-old woman with right upper quadrant pain and fever. Enhanced pelvic computed tomography performed because of irregular genital bleeding revealed the pelvic inflammatory disease. Upon further questioning, the patient confirmed that she had recently undergone therapy for Chlamydia trachomatis infection. Therefore she was given an injection of tetracycline because we suspected Fitz-Hugh-Curtis syndrome (FHCS), a pelvic inflammatory disease characterized by perihepatitis associated with chlamydial infection. A remarkable clinical response to antibiotics was noted. The right upper quadrant pain was due to perihepatitis, and the final diagnosis was FHCS. Right pleural effusion may be caused by inflammation of the diaphragm associated with perihepatitis. Once chlamydial infection reaches the subphrenic liver, conditions in the closed space between the liver and diaphragm due to inflammatory adhesion may be conductive to chlamydial proliferation. The possibility of FHCS should be considered in patients and carefully distinguished from other abdominal diseases.

CT of internal hernias.

Computed tomography (CT) plays an important role in diagnosis of acute intestinal obstruction and planning of surgical treatment. Although internal hernias are uncommon, they may be included in the differential diagnosis in cases of intestinal obstruction, especially in the absence of a history of abdominal surgery or trauma. CT findings of internal hernias include evidence of small bowel obstruction (SBO); the most common manifestation of internal hernias is strangulating SBO, which occurs after closed-loop obstruction. Therefore, in patients suspected to have internal hernias, early surgical intervention may be indicated to reduce the high morbidity and mortality rates. In a study of 13 cases of internal hernias, nine different types of internal hernias were found and the surgical and radiologic findings were correlated. The following factors may be helpful in preoperative diagnosis of internal hernias with CT: (a) knowledge of the normal anatomy of the peritoneal cavity and the characteristic anatomic location of each type of internal hernia; (b) observation of a saclike mass or cluster of dilated small bowel loops at an abnormal anatomic location in the presence of SBO; and (c) observation of an engorged, stretched, and displaced mesenteric vascular pedicle and of converging vessels at the hernial orifice.