Hitoshi Aibe

Diffusion-weighted echo-planar MR imaging and ADC mapping in the differential diagnosis of ovarian cystic masses: Usefulness of detecting keratinoid substances in mature cystic teratomas

To elucidate whether apparent diffusion coefficient (ADC) values calculated from echo‐planar diffusion‐weighted MR imaging (EPDWI) are useful in the differential diagnosis of ovarian cystic masses.

Natural history of pancreatic intraductal papillary mucinous tumor of branch duct type: follow-up study by magnetic resonance cholangiopancreatography.

Objective: The purpose of this study was to elucidate the natural history of branch duct type pancreatic intraductal papillary mucinous tumor (IPMT) by evaluating serial changes in the magnetic resonance cholangiopancreatography (MRCP) findings of patients diagnosed with pancreatic IPMT of branch duct type. Methods: Thirty-five patients had branch duct type IPMT, including 9 patients with separate lesions, and underwent initial and follow-up MRCP over a period of more than 12 months. The maximum diameter of the cystic lesion, the presence of associated main pancreatic duct (MPD) dilatation, and the presence of a filling defect were evaluated. Serial changes in these findings were analyzed. Results: Tumor enlargement on follow-up MRCP was observed in 7 cases. Of the 29 branch duct IPMTs without associated MPD dilatation or a filling defect identified on initial MRCP, only 1 showed gradual tumor enlargement. In 4 cases, the cyst size decreased on follow-up MRCP. Conclusions: Branch duct type IPMTs grow slowly and can be monitored without operation provided that the tumor shows no associated MPD dilatation or filling defect.

Radiologic diagnosis of adenomyomatosis of the gallbladder: comparative study among MRI, helical CT, and transabdominal US.

Purpose The goal of this work was to evaluate the diagnostic accuracy of transabdominal ultrasound (US), helical CT, and MRI in the diagnosis of adenomyomatosis (ADM) of the gallbladder. Method Twenty patients with surgically proven ADM were included, all of whom underwent preoperative US, helical CT with 3 mm collimation, and MRI with half-Fourier rapid acquisition with relaxation enhancement (RARE). All images were retrospectively reviewed by two radiologists, and the presence of ADM was assessed at three compartments (neck, body, and fundus) of the organ. Receiver operating characteristic analysis was performed, and sensitivity, specificity, and accuracy were calculated for each modality. Results The A z values (area under the curve) for MRI, helical CT, and US were 0.98, 0.85, and 0.72 for the Reader 1, respectively, showing no statistically significant interobserver difference in any of the three modalities. MRI showed a significantly higher A z value than helical CT or US (p < 0.1). The accuracies of MRI, helical CT, and US were 93, 75, and 66%, respectively. Conclusion Among the three modalities tested, MRI with half-Fourier RARE sequence was the most accurate for diagnosing ADM.

Usefulness of the calculated apparent diffusion coefficient value in the differential diagnosis of retroperitoneal masses

To elucidate whether or not the apparent diffusion coefficient (ADC) values calculated from echo‐planar diffusion‐weighted (EPDW) MR images are useful in the differential diagnosis of retroperitoneal masses.

Pulmonary Complications after Hepatic Artery Chemoembolization or Infusion via the Inferior Phrenic Artery for Primary Liver Cancer

PURPOSE The purpose of this study was to determine the frequency, patterns of disease, and risk factors for development of pulmonary complications after liver chemoembolization via the inferior phrenic artery (IPA). MATERIALS AND METHODS Forty-four selective transcatheter hepatic chemoembolization (THCE) procedures via the IPA were performed in patients with primary liver cancers with use of a mixture of anticancer agents and iodized oil (Lipiodol) with or without transcatheter arterial embolization. The grades of pulmonary complications were assessed on triphasic helical computed tomographic (CT) images after THCE and were correlated with angiographic findings of the IPA, infused dosages of Adriamycin and Lipiodol, and hepatic venous tumor thrombus on triphasic CT images before THCE. RESULTS THCE via the IPA frequently resulted in lung CT changes: Lipiodol accumulation in the lung field (52%), consolidation (68%), and pleural effusion (41%). Among 44 patients, two (5%) developed respiratory symptoms. An excellent correlation was shown between Lipiodol accumulation and the presence of angiographic abnormalities of the IPA (P <.005). A significant correlation was also shown between the grades of pulmonary complications and the numbers of angiographic abnormalities (P <.01). The grades of pulmonary complications increased according to the infused dosage of Adriamycin and Lipiodol (P <.05). CONCLUSIONS Angiographic abnormalities such as arteriovenous shunts, dilated anastomotic branches, and dense pleural staining are important risk factors for pulmonary complications of THCE via the IPA. Embolization for shunts may be required to prevent such complications, especially in cases with shunts to pulmonary vessels or hepatic veins.

Fitz-Hugh-Curtis syndrome. Radiologic manifestation.

Objectives To clarify radiologic findings of Fitz-Hugh-Curtis syndrome (FHCS). Methods Thirteen women with right upper abdominal pain who were clinically diagnosed with FHCS were included. Biphasic helical computed tomography (CT) of the abdomen was performed in all patients. Posttherapeutic follow-up CT was available in 7 patients. Ultrasonography (US) was also performed in 12 patients. These imaging findings were reviewed retrospectively. Results On enhanced CT, hepatic and splenic capsular enhancement was identified in 13 and 4 patients, respectively. Hepatic capsular enhancement on the early phase, which was detected in all patients, disappeared after treatment. No adhesive band or fluid collection around the liver was evident. No enhancement of the “bare area” of the liver and spleen was seen. No definite abnormality of the liver or perihepatic region was detected by US. Conclusions Hepatic and splenic capsular enhancement on abdominal enhanced CT may be characteristic of FHCS. Enhanced CT may be a useful and noninvasive modality to help a diagnosis of FHCS, especially in young women with right upper abdominal pain without significant findings on US and gastrointestinal endoscopy.

MR imaging of ampullary carcinomas.

Objective The purpose of this study was to demonstrate the appearance of ampullary carcinomas on MR images. Methods Sixteen patients with ampullary carcinomas underwent MR imaging. Tumor detectability, signal intensity of the tumor, and enhancement pattern on dynamic study were analyzed. MR cholangiopancreatography (MRCP) findings were assessed and were compared with the endoscopic retrograde cholangiopancreatography (ERCP) findings. Results Signal intensities of the tumor on each image were various. Dynamic study detected all tumors except one, and all detected tumors showed delayed enhancement. MRCP delineated more than half of the tumors as a filling defect within the duodenal fluid and clearly demonstrated pancreaticobiliary ductal. Conclusions Dynamic study is mandatory in diagnosing ampullary carcinoma, because it can depict most of the tumors, and delayed enhancement of such tumors is characteristic in case of ampullary carcinoma. MRCP can provide reliable information about pancreaticobiliary duct and it can replace diagnostic ERCP.

Measurement of the apparent diffusion coefficient in intraductal mucin-producing tumor of the pancreas by diffusion-weighted echo-planar MR imaging

AbstractBackground: We investigated whether diffusion-weighted echo-planar magnetic resonance (MR) imaging can help differentiate intraductal mucin-producing tumors of the pancreas from other cystic lesions. Methods: Diffusion-weighted echo-planar MR imaging was performed in patients with mucin-producing tumors (n= 19), pseudocysts (n= 9), chronic pancreatitis with diffuse main pancreatic dilatation (n= 5), and serous cystadenomas (n= 2). Images were obtained with diffusion sensitizing gradients of 30, 300, and 900 s/mm2. The apparent diffusion coefficient (ADC) was calculated. Results: The mean (± standard deviation) ADCs of mucin-producing tumors (2.8 × 10−3 mm2/s ± 1.0 × 10−3), pseudocysts (2.9 × 10−3 mm2/s ± 1.2 × 10−3), dilated main pancreatic duct in chronic pancreatitis (3.3 × 10−3 mm2/s ± 1.2 × 10−3), serous cystadenomas (2.9 × 10−3 and 2.6 × 10−3 mm2/s), and cerebrospinal fluid (3.5 × 10−3 mm2/s ± 1.1 × 10−3) were not statistically different. Conclusion: It is difficult to differentiate between mucin-producing tumors and other cystic lesions by ADC measurements when using diffusion-weighted echo-planar MR imaging.

Intrahepatic splenosis mimicking a liver tumor

A rare case of ectopic splenic tissue in the liver is presented which mimicked a liver tumor. It is considered that some splenic tissue was seeded in the liver during the splenectomy that the patient underwent 23 years ago. Computed tomography (CT), magnetic resonance imaging (MRI), and angiographic features of this lesion were almost indistinguishable from those of other liver tumors.

Inflammatory pseudotumors of the spleen: CT and MRI findings

OBJECTIVE Our goal was to elucidate the CT and MRI findings of inflammatory pseudotumors of the spleen. METHODS The CT and MRI findings of three patients with inflammatory pseudotumors of the spleen were reviewed and compared with the pathologic findings. RESULTS On the early phase of CT, the masses were hypodense to the normal spleen, and on the delayed phase, they demonstrated delayed enhancement. On T1-weighted MR images, the masses were isointense to the normal spleen, and on T2-weighted images, the masses had heterogeneous low signal intensities. After administration of Gd-DTPA, the masses showed delayed enhancement. CONCLUSION Inflammatory pseudotumors of the spleen were characterized by low signal intensity on T2-weighted MR images and delayed enhancement after contrast material administration on CT and MRI. The fibrous stroma may contribute to these unusual findings.