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Biomedical subjects

O Masamune

Publications and source records attributed to O Masamune.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Accuracy of liver puncture under US guidance: re-evaluation by microcomputer simulation model.

OBJECTIVE: To evaluate, using microcomputer simulation models, the degree of distortion of the puncture needle in sonograms used during a liver puncture under ultrasound guidance. METHODS: We made a simplified simulation model of the puncture needle passing through the abdominal wall to the target lesion in the liver (cases without ascites), and additionally through ascites between the abdominal wall and the liver (cases with ascites), to evaluate the degree of distortion of the puncture needle in the sonogram. We considered the thicknesses and sound velocities of the abdominal wall and the ascites fluid, as well as the puncture angle, on the degree of distortion. RESULTS: (1) Cases without ascites: The puncture needle displayed on sonogram shifted predominantly anteriorly with a displacement error between 6 mm forward and 1 mm backward and with an angular error between 2.2 degrees forward and 0.1 degree backward when the abdominal wall was muscular, and the pattern of distortion had an inverted S-shape. It was displayed predominantly posteriorly with a displacement error between 14 mm backward and 2 mm forward and with an angular error between 3.7 degrees backward and 1.2 degrees forward when the abdominal wall was fatty, and the pattern was S-shaped. Regardless of the composition of the abdominal wall, when the abdominal wall was thin, the more obtuse the puncture angle was, the larger the shift was, and when the abdominal wall was thick, the more acute the puncture angle was, the larger the shift was. (2) Cases with ascites: (a) Regardless of the quantity and sound velocity of the ascites, the puncture needle shifted predominantly anteriorly with a displacement error between 7 mm forward and 3 mm backward and with an angular error between 3.1 degrees forward and 1.9 degrees backward when the abdominal wall was muscular, and showed the inverted S-shaped pattern. In contrast, it shifted predominantly posteriorly with a displacement error between 17 mm backward and 5 mm forward and with an angular error between 3.7 degrees backward and 3.9 degrees forward when the abdominal wall was fatty, and showed the S-shaped pattern. (b) Regardless of the sound velocity of the ascites fluid and the composition of the abdominal wall, the shift of the puncture needle changed little with differing amounts of ascites. CONCLUSION: It is highly recommended that a liver puncture under US guidance be performed taking into account the pattern of distortion of the puncture needle in each situation.

Artifacts↗
PubMedDate not supplied

Color Doppler findings in Castleman's disease of the mesentery.

Castleman's disease is a relatively rare lymphoproliferative disease. We report an asymptomatic case of Castleman's disease isolated to the mesentery and detected incidentally by sonography. In this case, color Doppler sonography demonstrated an artery penetrating the mass's hilum, suggesting a lymphatic origin of the lesion, as well as fine accessory peripheral arteries, suggesting malignancy. To our knowledge, there has been no previous report of detailed color Doppler findings in Castleman's disease.

Aged↗
PubMedDate not supplied

Color Doppler findings in small abdominal aneurysms.

Four cases of small abdominal aneurysms were assessed by color Doppler ultrasonography. The aneurysms demonstrated interesting and highly complicated internal hemodynamics, including a swirling blood flow pattern and/or a color mosaic pattern. These findings suggested the usefulness of color Doppler ultrasonography for obtaining details on internal hemodynamics, which cannot be obtained with other modalities, such as angiography or computed tomography (CT).

Adult↗
PubMedDate not supplied

Portal hypertension in children and young adults: sonographic and color Doppler findings.

Portal hypertension is a relatively uncommon pathologic condition in children and young adults in contrast with older adults. The aim of this study is to evaluate the utility of sonography and color Doppler sonography in the diagnosis of portal hypertension in children and young patients and to evaluate the sonographic pattern of each disease. We reviewed 25 such patients who were younger than 30 years old and obtained the following sonographic findings: (1) liver cirrhosis: (a) multiple intrahepatic venovenous shunts in patients with primary Budd-Chiari syndrome and (b) intrahepatic vascular narrowing and nodular coarse parenchymal texture, with multiple very-high-echo spots along the portal vein in patients with Wilson disease; (2) congenital hepatic fibrosis: marked and developed collaterals, wide periportal echogenic band, and a heterogeneous parenchymal texture comprised of multiple high echoes but without portal thrombus; and (3) extrahepatic portal thrombosis: invisible portal lumen except as an echogenic band. Sonography and color Doppler sonography are very useful in diagnosing these portal hypertensive diseases. However, there are no specific sonographic findings, and the role of sonography is limited to follow-up observation of associated secondary hepatobiliary changes in patients with congenital biliary atresia.

Adolescent↗
PubMedDate not supplied

Large extrahepatic portosystemic shunt without portal hypertension.

Extrahepatic portosystemic shunt usually occurs secondary to severe portal hypertension, and it is rare to encounter it in patients without portal hypertension. We report herein a large extrahepatic portosystemic shunt between the left gastric vein and left renal vein without portal hypertension in which color Doppler sonography was useful not only for detection but evaluation of the effect of embolization.

Embolization, Therapeutic↗
PubMedDate not supplied

Portal vein aneurysm: report of six cases and review of the literature.

Portal vein aneurysm is very rare, and its relation to portal hypertension has been emphasized. We report six cases of portal vein aneurysm (five extrahepatic and one intrahepatic). All patients were asymptomatic and had no signs suggestive of portal hypertension; the lesion was incidentally detected by ultrasound. Color Doppler sonography showed a constant hepatopetal flow along the aneurysmal wall, which immediately led to the diagnosis. We stress the usefulness of color Doppler sonography for studying the hemodynamics of this vascular anomaly and briefly review the literature.

Aneurysm↗
PubMedDate not supplied

Color Doppler findings of gastrointestinal varices.

BACKGROUND: Compared with esophageal varices, gastrointestinal varices are relatively rare, but they are clinically important because they tend to bleed massively. Color Doppler sonography is now widely used to diagnose the collaterals, but few color Doppler findings of gastric or intestinal varices have been reported. The aim of this study was to investigate the sonographic and color Doppler findings of gastrointestinal varices and to determine the role of color Doppler sonography in the diagnosis of these varices. METHODS: We studied 30 patients who were diagnosed by endoscopy as having gastrointestinal varices (24 gastric, four duodenal, two intestinal) with color Doppler sonography and compared the results with the clinical data. The causes of gastric varices included liver cirrhosis (16/24, 66.7%), idiopathic portal hypertension (3/24, 12. 5%), chronic pancreatitis with splenic vein thrombosis (2/24, 8.3%), congenital biliary atresia (1/24, 4.2%), congenital hepatic fibrosis (1/24, 4.2%), and unknown (1/24, 4.2%). The causes of duodenal varices included idiopathic portal hypertension with portal thrombosis (3/4, 75%) and liver cirrhosis (1/4, 25%). RESULTS: The gastric wall at the fundus was thickened in 17 of 24 cases (70.8%) with gastric varices, and the duodenal wall was thickened in four of four cases (100%) with duodenal varices. Sonography revealed thrombosis in the splenic vein in two of two cases with gastric varices secondary to chronic pancreatitis and in the confluence of the superior mesenteric vein and the splenic vein in three of four cases with duodenal varices. Color Doppler sonography demonstrated multiple, slow constant blood flows in the thickened wall in 15 of 24 cases (62.5%) with gastric varices and in four of four cases (100%) with duodenal varices. It demonstrated accumulated slow constant blood flows in the cecum in the case with cecal varices. Color Doppler showed also the communication between the varices and the neighboring vascular system (superior mesenteric vein and inferior vena cava) in the case with cecal varices, but it did not directly reveal such a communication in the other 29 cases (96.7%). Color Doppler showed a hepatofugal flow in the left gastric vein in all the hemorrhagic gastric varicose patients with esophageal varices, but it showed a hepatopetal flow in the left gastric vein in the isolated nonhemorrhagic gastric varicose patients. CONCLUSION: Color Doppler sonography was very useful for the diagnosis of gastric and duodenal varices and for visualizing fine venous flows in the thickened gastric or duodenal wall. When it shows portal thrombosis in the confluence of the splenic vein and the superior mesenteric vein, duodenal varices should be suspected. The flow direction of the left gastric vein helps to differentiate hemorrhagic gastric varices from nonhemorrhagic ones.

Adolescent↗
PubMedDate not supplied

Sonographic findings of anomalous position of the gallbladder.

Anomalous position of the gallbladder is relatively rare and has been reported only in isolated case reports. We tried to determine its ultrasound (US) findings on the basis of 18 such patients. In the left-side gallbladder group (nine patients), the gallbladder was imaged as an oval cystic mass in front of the pancreas. In all patients, the narrow neck of the gallbladder was clearly detected by US in the usual location before the main portal vein. Four of nine patients had small gallbladder stones. The retrohepatic gallbladder group (four patients) showed marked atrophy of the right lobe of the liver. Two patients had multiple gallstones in the bile ducts of the right lobe. All patients in the suprahepatic retrohepatic gallbladder group (four patients) were cirrhotic, and the anterior segment of the right lobe was markedly atrophied. In the intercostal scan, the gallbladder mimicked a perihepatic fluid. In the floating gallbladder group (one patient), the gallbladder was imaged as a cystic mass in the anterior abdominal wall. Surgical intervention showed a severely inflamed gallbladder, with small stones adhered into the anterior abdominal wall and partially ruptured. Knowledge of the wide range of US findings of malposition of the gallbladder helps in avoiding misdiagnosis.

Adult↗
PubMedDate not supplied

Lobar atrophy of the liver.

Lobar atrophy of the liver due to causes other than liver tumor or liver cirrhosis is a relatively rare pathological condition, and there are only a few reports in the literature. We report six such cases and try to evaluate the relationship between lobar atrophy and portal flow disturbance. The patients could be divided into two groups according to the site of the atrophy: those with atrophy of the left lobe (two cases) and those with atrophy of the right lobe (four cases). The two cases with atrophy of the right lobe had hepatholithiasis in the involved segments, but the cause was not determined in the remaining four cases. In all six cases, portal flow disturbance was noted, including invisibility of the portal vein in four cases, narrowing in one case, and portal thrombus in one case. Collateral circulation was not recognized in any of our cases. Of interest is the mode of lobar atrophy. Atrophy of the right lobe was always associated with marked enlargement of the left lobe, but that of the left lobe did not induce an enlargement of the right lobe.

Aged↗