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Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 199 records · Page 11Linked to original sources
PubMed1990

[Avascular necrosis of the femoral head: chronological change of MR images].

Tl-weighted MR images of thirty-six hips in 25 patients with avascular necrosis of the femoral head were obtained two to five times during the course of 2 to 26 months. We investigated these MR images in the light of the chronological change and compared them with plain radiographs. MR images change in 16 femoral heads; in general, the abnormal low intensity area in the femoral head reduced in extent and the internal high intensity area became smaller of disappeared. Thirteen femoral heads among them became more flattened on plain radiographs in the same period. It is noted that four different zones are defined in the femoral head after bone necrosis takes place: the dead bone marrow, the dead marrow which still contains fat, the reactive interface and the hyperemic bone marrow. In Tl-weighted MR images, the dead bone marrow, the reactive interface and the hyperemic bone marrow are demonstrated as low intensity area, while the dead marrow containing fat may remain high in intensity. On the basis of this knowledge of histopathology and MR images of this disease, we suggest that reduction of the abnormal low intensity area and disappearance of the internal high intensity area on MR images can be regarded as diminution of hyperemia in the living bone marrow and loss of fat in the dead bone marrow, respectively.

Adult↗
PubMed1990

Regenerating nodules of liver cirrhosis: MR imaging with pathologic correlation.

To determine the pathologic basis for low-intensity nodules seen on MR images of the liver in patients with cirrhosis, we obtained spin-echo and gradient-echo MR images in 20 cirrhotic patients in whom partial hepatectomies were subsequently performed for hepatocellular carcinoma. Low-intensity liver nodules were shown on gradient-echo and spin-echo images in eight patients. Pathologic study of the liver in these patients showed that these nodules were regenerating nodules containing hemosiderin. Low-intensity nodules were seen only on T2-weighted spin-echo images in four other patients. Microscopic examination of the liver in these patients showed regenerating nodules without hemosiderin deposits. Broad fibrous septa containing vascular spaces were present in two of these four patients. These results suggest that regenerating nodules containing hemosiderin or those that are surrounded by vascular fibrous septa are visible on MR images as low-intensity nodules and that gradient-echo images are useful in demonstrating nodules with hemosiderin.

Aged↗
PubMed1990

[Difference between T1 and T2 weighted MR images in avascular necrosis of the femoral head].

T1 and T2 weighted MR images were compared in 32 hips with avascular necrosis, and the difference between them was discussed. In 27 of 32 hips, abnormal low intensity area in the affected femoral head is smaller in T2 weighted images than in T1 weighted images. The area of low intensity on T1 weighted image and high on T2 weighted image might be granuloma in reactive tissue and surrounding hyperemia. The difference between T1 and T2 weighted images must be taken into consideration especially in determination of the border of affected bone.

Adult↗
PubMed1990

[MR imaging of idiopathic transient osteoporosis of the hip].

Four patients with idiopathic transient osteoporosis of the hip were examined by magnetic resonance imaging (MRI). MRI clearly showed low signal intensity in the affected femoral head on T1-weighted images and high signal intensity on T2-weighted images. After regression of hip pain, MR images became normal. MRI was a useful method for diagnosis and follow-up study of idiopathic transient osteoporosis of the hip.

Adult↗
PubMed1989

[MRI demonstration of pseudolobules of liver cirrhosis--particular reference to iron deposits on autopsy specimens].

MRI was performed on formalin-fixed autopsied liver specimens of nine patients with liver cirrhosis. Tiny low-intensity nodules were demonstrated in four specimens, in which microscopic examination revealed hemosiderin deposits in pseudolobules. In one specimen with mild hemosiderin deposits, low-intensity nodule was not seen on MRI. This result suggests that there is a close relationship between MRI demonstration of low-intensity nodules and iron deposits in pseudolobules of liver cirrhosis.

Adult↗
PubMed1989

Well-defined, dense and continuously spreading enhancement on single level dynamic CT of the liver: a characteristic sign of hepatic cavernous haemangioma.

The findings of single-level dynamic CT were reviewed in 83 lesions of cavernous haemangioma, 90 lesions of hepatocellular carcinoma, 29 lesions of metastatic tumour and 10 lesions of other hepatic masses in order to see the validity of characteristic findings of hepatic cavernous haemangioma. Well-defined, dense and continuously spreading enhancement (WDCSE) being defined as follows: 1. well-defined contour of enhanced area, 2. the density of maximally enhanced area almost same as that of enhanced vessel and 3. continuously spreading enhancement continuing over 20 seconds, WDCSE was noted definitely in 47 lesions of cavernous haemangioma alone (57%; 77% over 3 cm, 64% between 2 and 3 cm, and 19% under 2 cm in diameter) and, suggestively in 16 lesions of cavernous haemangioma and 4 lesions of hepatocellular carcinoma, but in no lesions of other tumours. WDCSE did not show a high sensitivity for cavernous haemangioma but it had a 100% positive predictive value for the disease. If WDCSE is noticed even in oncology patients with hepatic mass, no further examination may be necessary.

Carcinoma, Hepatocellular↗
PubMed1989

Hepatic epithelioid hemangioendothelioma: report of five cases.

Results of computed tomography (CT), ultrasonography (US), angiography, and radionuclide imaging were analyzed in five cases of histologically proved hepatic epithelioid hemangioendothelioma (EHE), a rare vascular tumor of adults that has a variable but often long clinical course. All patients received palliative treatment. CT and US were performed repeatedly over a period of up to 53 months. Initial radiologic examination showed two types of hepatic lesions: multiple nodules in both lobes (nodular lesions, n = 2) and large masses with or without calcifications that generally spread along the hepatic margins (diffuse lesions, n = 3). Nodular lesions may be an earlier form of hepatic EHE, as they later gradually changed into the diffuse type. Follow-up CT after treatment showed definite regression of tumors in two cases. In the differential diagnosis, the radiologic findings of diffuse lesions were considered to be specific to hepatic EHE, while those of nodular lesions were nonspecific.

Adult↗
PubMed1989

Cystic neoplasms of the pancreas: comparison of MR imaging with CT.

Cystic neoplasms of the pancreas are divided into two major groups: microcystic adenomas and mucinous cystic neoplasms. Five microcystic adenomas and seven mucinous cystic neoplasms (three cystadenomas and four cystadenocarcinomas) were examined with both magnetic resonance (MR) imaging and computed tomography (CT). The cystic content was differentiated more easily with MR imaging than with CT. It was homogeneous in four of the five microcystic adenomas, all of which had lobulated borders best seen on T2-weighted images. The mucinous cystadenomas and cystadenocarcinomas were all composed of multiple compartments that varied in signal intensity. The septa, shape, and wall thickness were demonstrated on T1- and/or T2-weighted MR images almost as well as on CT scans. Overall, MR imaging was equal or slightly superior to CT in the diagnosis of pancreatic cystic neoplasms, except in its limited ability to demonstrate calcifications of the tumor wall and septa.

Adult↗
PubMed1989

Small hepatocellular carcinoma and cavernous hemangioma: differentiation with dynamic FLASH MR imaging with Gd-DTPA.

Forty patients with hepatocellular carcinoma (HCC) (n = 22) or cavernous hemangioma (diameter, 3 cm or less) (n = 18) were examined with serial magnetic resonance (MR) imaging at 1.5 T with the fast low-angle shot (FLASH) technique and an intravenously administered bolus injection of 0.05 mmol/kg Gd-DTPA. Two images per minute were obtained for 5 minutes, and one per minute thereafter until about 10 minutes. Dynamic MR studies revealed five criteria for differentiating these tumors. With HCC there was a hyperintense mass before contrast material enhancement (32%), peak contrast enhancement at about 10 seconds after injection (55%), slight to moderate peak contrast enhancement (73%), absent or minimal delayed enhancement (100%), and, at morphologic study, a capsule or nodules-in-nodule appearance (59%). With hemangioma there was a hypointense mass before contrast enhancement (72%), peak contrast enhancement more than 2 minutes after injection (72%), marked peak contrast enhancement (83%), moderate to marked delayed enhancement (100%), and, at morphologic study, spreading phenomenon (39%). Seventy-seven percent of HCCs and 83% of hemangiomas satisfied three or more criteria and thus could be differentiated from each other with certainty.

Adult↗
PubMed1989

Siderotic nodules in the spleen: MR imaging of portal hypertension.

The authors retrospectively evaluated magnetic resonance (MR) images obtained at 1.5 T in 233 patients with portal hypertension and 91 subjects without it and pathologic findings in four resected spleens (one normal). Multiple, tiny (3-8 mm in diameter), low-intensity spots in the spleen were observed in 21 of 233 patients. Among the imaging studies performed in these 21 patients, the spots were seen on five of 14 T1-weighted images, 11 of 20 proton density images, and 12 of 20 T2-weighted images obtained with spin-echo techniques and on 14 of 14 fast-scan images obtained with gradient-echo rephasing. MR images in the 91 subjects did not show such lesions. MR images of the three spleens resected from patients with portal hypertension showed the low-intensity spots, which corresponded to siderotic nodules found at pathologic analysis. Despite limited pathologic confirmation, siderotic nodules (so-called Gamna-Gandy nodules) are considered the most likely cause of multiple low-intensity spots in the spleen.

Female↗
PubMed1989

Biliary malignancies occurring in choledochal cysts.

Eight cases of choledochal cyst associated with biliary malignancy (gallbladder carcinoma in three and bile duct carcinoma in five) were reviewed to evaluate the roles and limitations of computed tomography (CT) (n = 8), ultrasound (US) (n = 6), cholangiography (n = 8), and angiography (n = 6). In cases of gallbladder carcinoma, both CT and US revealed mass lesions in the gallbladder consistent with cancer. CT also depicted either a mass lesion or an irregular thickened wall in all cases of bile duct carcinoma; however, US failed to demonstrate a thickened wall in one of three cases in which CT findings were positive. Cholangiography universally revealed malunion of the pancreatico-biliary duct, and the findings were suggestive of malignancy in seven cases in which CT depicted abnormalities. Angiography showed tumor stain in three of six cases. Lymph node metastases were present in four cases but were detected preoperatively in only one. One case showing a thickened bile duct wall was erroneously diagnosed as malignancy among 27 cases of choledochal cyst unassociated with biliary malignancy.

Adult↗
PubMed1989

MR differentiation of hepatocellular carcinoma from cavernous hemangioma: complementary roles of FLASH and T2 values.

Forty-two patients with hepatocellular carcinoma (hepatoma) and 18 patients with hemangioma were studied with MR imaging at 1.5 T to evaluate the efficacy of single-slice breath-hold FLASH (fast low-angle shot) images in distinguishing between the lesions and to compare with T2 differentiation using conventional spin-echo images. The difference between mean tumor-to-liver signal ratio on FLASH imaging of hepatocellular carcinoma (1.46 +/- 1.06) and hemangioma (0.86 +/- 0.45) was statistically significant (p less than .01). Fifty-one (82%) of 62 lesions were classified correctly when the borderline of tumor-to-liver signal ratio between hepatoma and hemangioma was set at 0.9. The mean T2 values of hepatomas and hemangiomas were 48 +/- 10 msec and 89 +/- 20 msec, respectively. Fifty-seven (92%) of 62 lesions were correctly diagnosed with the T2 borderline of 80 msec. The five misdiagnosed lesions with the T2 borderline were hemangiomas smaller than 2 cm with tumor-to-liver signal ratios less than 0.9. FLASH images appear promising for differentiating between hepatoma and hemangioma, and they complement T2 values in characterizing small lesions.

Carcinoma, Hepatocellular↗