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Biomedical subjects

K Ohtomo

Publications and source records attributed to K Ohtomo.

At least 163 records · Page 9Linked to original sources
PubMed1988

Segmental intensity differences in the liver on MR images: a sign of intrahepatic portal flow stoppage.

Segmental intensity differences (SIDs) in hepatic parenchyma free of tumor were noted in six patients with hepatic masses (hepatocellular carcinoma in five and metastatic liver cancer in one). Areas of SID were homogeneous in intensity. The intensity of the affected region was high in all six patients on T2-weighted magnetic resonance (MR) images and low in two on T1-weighted images. Three of five patients examined with plain computed tomography (CT) had corresponding segmental areas of low attenuation. Angiograms obtained in five patients showed occlusion of the intrahepatic portal vein, segmental staining corresponding to the region of the SID, or both. Twelve of 82 patients examined with MR imaging and angiography had similar findings on angiograms, and ten of them had abnormal intensity of anatomic distribution around or beside the liver tumors on MR images. MR imaging may be more sensitive than plain CT in the detection of secondary changes caused by intrahepatic portal flow stoppage.

Angiography↗
PubMed1988

Mucin-hypersecreting intrahepatic biliary neoplasms.

The radiologic findings are described in six patients with "mucin-hypersecreting" intrahepatic biliary neoplasms (biliary cystadenocarcinoma or papillary cholangiocarcinoma). Massive amounts of mucin were confirmed in the dilated bile ducts at surgery or autopsy. Computed tomography (CT) and ultrasound (US) demonstrated severe dilatation of the intrahepatic bile ducts distal to the tumor in all patients and of extrahepatic ducts in five. On cholangiograms, large, amorphous filling defects caused by retention of mucin were found in the dilated ducts in three patients. The tumor was multilocular and cystic in five patients; in the other patient it was too small to be detected at CT or US. The presence of liver tumor (mostly multilocular and cystic), marked biliary dilatation distal to the tumor, and filling defects in the dilated bile ducts are important findings that indicate a mucin-hypersecreting intrahepatic biliary neoplasm.

Adenoma, Bile Duct↗
PubMed1988

Hepatocellular carcinoma and cavernous hemangioma: differentiation with MR imaging. Efficacy of T2 values at 0.35 and 1.5 T.

Seventy-two patients with hepatocellular carcinoma (hepatoma) and 56 with hemangioma were studied with magnetic resonance (MR) imaging at 0.35 or 1.5 T to evaluate the efficacy of T2 values in differential diagnosis. T2 values were calculated with the two-point method. The mean T2 values of hepatoma and hemangioma were 58.9 msec +/- 8.9 and 101.6 msec +/- 25.8 at 0.35 T and 49.1 msec +/- 9.8 and 85.3 msec +/- 21.2 at 1.5 T. The difference in the T2 values for hepatoma and hemangioma was statistically significant (P less than .001) at both 0.35 and 1.5 T. Fifty-three of 56 lesions (94.6%) at 0.35 T and 86 of 102 lesions (84.3%) at 1.5 T were correctly classified when the T2 borderline between hepatoma and hemangioma was set at 80 msec. All misdiagnosed lesions were hemangioma, and all but one were smaller than 2 cm. However, over 90% of lesions smaller than 2 cm were correctly diagnosed when 70 msec at 0.35 T and 60 msec at 1.5 T were used as borderline T2 values. MR imaging with T2 measurement was very useful for differentiating between hepatoma and hemangioma (including small lesions) at 1.5 T as well as at 0.35 T.

Adult↗
PubMed1987

Hepatic tumors: dynamic MR imaging.

Thirty-six patients with hepatic tumors (28 hepatocellular carcinomas, seven cavernous hemangiomas, one metastatic tumor) were examined with serial magnetic resonance (MR) imaging, after a bolus intravenous injection of 0.05 mmol/kg gadolinium-diethylenetriaminepentaacetic acid. A typical MR imaging pattern for hemangiomas (present in five of seven cases [71.4%]) was a lesion of diminished signal intensity on precontrast images, peripheral contrast enhancement during the bolus dynamic phase, and complete fill-in of high signal intensity on delayed scan images. Twenty-eight hepatocellular carcinomas showed a variety of contrast enhancement patterns during the dynamic phase. In 21 patients (75%), there was no area of high signal intensity within the tumor on the delayed phase. A peripheral halo with delayed enhancement was noticed in 12 patients (42.8%) Histologic correlation in hepatocellular carcinomas showed that the degree of contrast enhancement corresponded to tumor vascularity and that the peripheral halo corresponded to fibrous capsular structure.

Carcinoma, Hepatocellular↗
PubMed1987

Regenerating nodules of liver cirrhosis: MR imaging.

A large number of tiny (0.5-1.5 cm), low-intensity nodules of the liver were retrospectively observed on T2-weighted magnetic resonance (MR) images of eight patients with cirrhosis of the liver. The lesions were not detected with other imaging modalities and were considered to be regenerating nodules. Twenty-five consecutive cases of liver cirrhosis referred for MR examination were prospectively investigated to study the detectability of regenerating nodules and the optimal pulse sequence for detection. A large number of small, low-intensity nodules were demonstrated in nine of 25 cases on T2-weighted spin-echo (SE) images, in nine of 22 cases on T1-T2 complex fast low-angle shot (FLASH) images, and in one of eight cases on T1-weighted SE images. FLASH images obtained with respiratory suspension most clearly revealed regenerating nodules. However, T2-weighted SE images clearly permit differentiation of high-intensity hepatocellular carcinoma, including small daughter lesions, from low-intensity regenerating nodules.

Aged↗
PubMed1987

Retained surgical sponges: CT and US appearance.

The computed tomographic (CT) and ultrasonographic (US) appearances of retained surgical sponges are described. In each case, the presence of a sponge was confirmed at repeat operation. CT examinations were performed in nine patients. In six cases, a low-density mass was demonstrated; in two cases, a complex mass with areas of both low and medium density was seen. The remaining case was a high-density mass. After intravenous administration of contrast material, dense and prolonged enhancement of the rim of the mass was noted in five of eight cases. Calcification was found in four cases, and spongiform gas in one. US performed in six patients revealed an echogenic area with strong acoustic shadowing in three cases and a complex mass, a hypoechoic mass, and a cystic mass with irregular internal echoes in one case each. Granuloma caused by a retained surgical sponge should be considered as a cause of an abdominal mass in patients with a history of prior abdominal surgery.

Abdomen↗
PubMed1987

Prominent collateral vein in portal hypertension mimicking liver tumours: a pitfall in computed tomography.

Computed tomography (CT) was performed on four patients with a prominent porto-systemic collateral vein, including three with an enlarged para-umbilical vein. We have observed a pitfall in non-contrast CT scans of patients with portal hypertension, in which a prominent collateral vein may mimic a liver tumour. Dynamic CT as well as magnetic resonance imaging is of great value in such cases.

Diagnosis, Differential↗
PubMed1987

Hepatic haemangioma: dynamic MRI using gadolinium-DTPA.

Six patients with hepatic haemangioma were examined with a 1.5 tesla magnetic resonance scanner before and immediately after bolus injection of 0.05 mmol/kg gadolinium-DTPA. Eight to ten spin-echo images (TR: 100 msec, TE: 20 msec, scanning time: 26 sec) were obtained through the region of the haemangioma. In all cases, dense contrast enhancement of the lesion was demonstrated. The enhancement spread in all directions from the lesion on subsequent delayed scans (high signal fill-in); a signal higher than that from surrounding hepatic parenchyma was present two minutes after contrast injection. Dynamic MRI is a promising method for the evaluation of hepatic haemangioma and it is more easily tolerated by patients than dynamic CT using iodinated contrast medium.

Adult↗