Biomedical subjects
Publications and source records attributed to Y Hamashima.
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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.
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.
BACKGROUND: Fatty liver and liver tumors are very frequent diseases. Sonography (US) currently is the initial diagnostic tool for hepatic exploration. However, there is a marked paucity of US findings of tumors in fatty liver. METHODS: We studied the US findings of 41 lesions (31 patients) with this combination, with special attention paid to internal echoes, marginal echoes, and especially the mode of back echoes, and compared them with the US results of 64 lesions (38 patients) without fatty liver. RESULTS: Comparing the group having liver tumor without fatty liver with the group having liver tumor with fatty liver showed that (a) the number of hypoechoic lesions increased (29 of 41, 70.7%, vs. 16 of 64, 25.0.%), (2) the tumor margin appeared indistinct (32 of 41, 78.0%, vs. nine of 64, 14.1%), and (c) the lesions showing posterior echo enhancement increased (34 of 41, 82.9%, vs. eight of 64, 12.5%). CONCLUSION: Liver tumors in fatty liver are expected to show unusual patterns on US, so we should consider this difficulty when interpreting these US findings and we should not make a conclusion without including other imaging modalities.
BACKGROUND: In chronic cholecystitis, the gallbladder (GB) wall is usually evenly involved, whereas marked segmental thickening of the GB wall (segmental cholecystitis) seldom is reported. We wanted to define its clinical manifestations and sonographic (US) findings. METHODS: We reviewed the clinical and US data of 13 cases and compared these results with those of 30 patients with chronic cholecystitis with evenly thickened GB walls (usual-cholecystitis group). RESULTS: (a) All cases of segmental cholecystitis showed the portion distal to the kinking to be markedly thickened. (b) The thickened portion corresponded to the fundus in three cases, the body and fundus in seven cases, and the fundus, body, and infundibulum in three cases; and the thickened distal portion contained many stones in 11 cases. (c) There was no difference in the maximal diameters of the GB walls between the segmental-cholecystitis group and the usual-cholecystitis group. However, there was a significant difference in the minimal diameters of the GB walls between groups. CONCLUSION: Knowledge of the US findings and clinical presentations of segmental cholecystitis can help in the development of appropriate diagnostic and therapeutic strategies.
BACKGROUND: We investigated whether the addition of Doppler sonography (US) increases the diagnostic confidence of US for estimating the nature of ascites. METHODS: Of the 127 cases reviewed in this study, there were 42 cases of transudate and 85 of exudate ascites. We reviewed the US, power Doppler, and pulsed Doppler images of these cases. RESULTS: With US, the transudate ascites was imaged as free of echo in 38 of 42 cases (90.5%). The exudate ascites was imaged as free of echo in 22 of 85 cases (25.9%) and with internal echo spots in 63 of 85 cases (74.1%). With Doppler US, we obtained distinct pulsed signals from the transudate ascites in only two of 36 cases (5.6%). In contrast, we obtained distinct Doppler signals from the exudate ascites in 66 of 79 cases (83.5%). Those 66 cases included 16 of the 22 cases with echo-free ascites. CONCLUSION: The presence or absence of echo spots within the ascites helped differentiate transudate from exudate ascites, as reported in the literature. However, the addition of Doppler US contributed to the differentiation of echo-free exudate (Doppler signals present) from echo-free transudate (Doppler signals absent) ascites.
BACKGROUND AND METHODS: Sonographic (US) findings of Chilaiditi syndrome have been rarely reported in the literature. We reviewed 18 cases of Chilaiditi syndrome to pinpoint its US pattern. RESULTS: (1) US showed gas echoes of different sizes superimposed over the entire liver in two cases and over the right hepatic lobe in six cases, leading to a high suspicion of Chilaiditi syndrome. (2) US showed a small gas echo in the hepatodiaphragmatic space, mimicking pneumoperitoneum in eight cases. In this instance, altering the patient's position allowed for confirmation of the lack of a change in the location of the gas echo, unlike cases of pneumoperitoneum. (3) The hepatic surface appeared as a hyperechoic mass in two cases. CONCLUSION: Knowledge of US patterns of Chilaiditi syndrome helps avoid confusion with pneumoperitoneum or hepatic masses.
BACKGROUND: Liver tumors are a relatively rare pathologic condition in children and young patients. The aim of the present study was to categorize the sonographic (US) and color Doppler results of liver tumors in these patients. METHODS: We retrospectively reviewed the US findings of 23 such cases: malignant tumor (13 cases)-hepatoblastoma (four cases), hepatocellular carcinoma (HCC; four cases), and hepatic metastasis (five cases); benign tumor (10 cases)-hepatocellular adenoma (four cases), focal nodular hyperplasia (two cases), mesenchymal hamartoma (two cases), cystadenoma (one case), and hemangioendothelioma (one case). RESULTS: There was no specific US findings for each tumor type. HCC usually developed on a normal liver and was imaged as multiple nodules. Color Doppler US helped in differentiating multiple metastatic nodules (hypovascular) from multiple HCC nodules (hypervascular). Presence of intratumoral cystic areas was usually suggestive of benign tumors. Follow-up US was useful for detecting small nodules in high-risk groups (congenital biliary atresia, glycogen storage disease). Color Doppler US helped in diagnosing portal thrombus or intratumoral shunt. CONCLUSION: Although there were no highly specific findings, US and color Doppler results contributed, to a certain degree, to the diagnosis of liver tumors in children and young adults by showing intratumoral cystic areas or vascularity.
BACKGROUND: Neurofibromatosis 1 (NF1) has been studied from many viewpoints, but its abdominal involvement has rarely been reported. Sonography (US) is now the initial diagnostic tool for abdominal exploration, which prompted us to determine the clinical manifestations and US findings of abdominal involvement in NF1. METHODS: We analyzed the US findings and clinical data of eight NF1 cases with abdominal involvement. RESULTS: Abdominal involvement included neurofibromatous tumor growth in the liver, mesentery, and retroperitoneum, in addition to mesenteric leiomyomatosis and gastric carcinoma. Color Doppler US was useful not only in detecting blood flows in the lesions but also in preventing hazardous vascular injury during tumor biopsy. CONCLUSION: A better understanding of the clinical manifestations and US findings of abdominal involvement in NF1 translates into improved NF1 patient care.