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Biomedical subjects

T Kokubo

Publications and source records attributed to T Kokubo.

At least 271 records · Page 15Linked to original sources
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↗
PubMed1989

[Collaterals of portal hypertension running through the liver. Part 1. Paraumbilical vein].

Seven cases of portosystemic collateral running through the left lobe of the liver (6 in the medial segment and 1 in the lateral segment) were reported. Six cases were diagnosed by CT and/or ultrasound, and one case was confirmed by autopsy. This collateral originated from the umbilical vein recess of the left portal vein and connected with enlarged vein in front of the left lobe of the liver. All the patients had other portosystemic collaterals of severe and moderate degrees. Paraumbilical veins demonstrated on portography did not differ from ordinary paraumbilical veins in portal hypertension except for prominent tortuosity and dilatation noted in half cases. In markedly dilated cases, intrahepatic portosystemic collateral can be a pitfall in the diagnosis of hepatic tumor on CT. Careful examination of portal hypertension with ultrasound, dynamic CT and/or magnetic resonance imaging will detect such portosystemic collaterals running through the hepatic parenchyma.

Collateral Circulation↗
PubMed1989

[Magnetic resonance imaging and histopathology in the femoral head].

To correlate the magnetic resonance (MR) images with the histopathological findings in the femoral head, the histopathology of 24 femoral heads, 15 with osteonecrosis, five with osteoarthritis and four with other hip disorders were subjected to preoperative MR imaging which demonstrated low intensity areas due to long T1 relaxation time in the femoral head. The MR signal was low where fibrovascular tissue, disintegrated fibrovascular tissue, amorphous necrotic material, bone, or cartilagenous tissue occupied the medullary space. From this study, it seems possible to predict the histopathologic changes in the femoral head using MR images.

Adult↗
PubMed1989

Bonding behavior of a glass-ceramic containing apatite and wollastonite in segmental replacement of the rabbit tibia under load-bearing conditions.

Glass-ceramic implants containing apatite and wollastonite were studied under load-bearing conditions in a segmental replacement model in the tibia of the rabbit. Alumina-ceramic implants were used as a control. A sixteen-millimeter segment of the middle of the shaft of the tibia was resected at a point distal to the junction of the tibia and the fibula. The defect was replaced by a fifteen-millimeter-long hollow, cylindrical implant that was fixed by intramedullary nailing using a Kirschner wire. Two groups of eight rabbits each (one group with a glass-ceramic implant and the other with an alumina implant) were killed twelve weeks after implantation. Two similar groups were killed twenty-five weeks after implantation. The segment of the tibia that contained the implant was excised and tension-tested. The load to failure of glass-ceramic implants containing apatite and wollastonite increased with time. The loads to failure of the glass-ceramic and alumina implants at twelve weeks after implantation were 19.8 +/- 7.06 and zero newtons, respectively. The loads to failure of glass-ceramic and alumina implants at twenty-five weeks after implantation were 126.4 +/- 32.54 and 19.6 +/- 13.92 newtons, respectively. No glass-ceramic implants broke. A calcium-phosphorus layer at the interface of the glass-ceramic and the bone was observed by scanning electron microscopy and electron-probe microanalysis. There was no interposition of soft tissue between the glass-ceramic and the bone, as observed by Giemsa surface staining.

Aluminum Oxide↗
PubMed1988

Apatite-wollastonite containing glass ceramic-fibrin mixture as a bone defect filler.

The purpose of this study was to evaluate the usefulness of a mixture of apatite-wollastonite containing glass ceramic (A-W.GC, 42-60 mesh in granule size) with fibrin as a bone defect filler. A bone defect was drilled in the proximal metaphysis of the rat tibia and was filled with (1) fibrin glue, (2) A-W.GC granules, or (3) A-W.GC-fibrin mixture. Nothing was placed in the defect of the controls. The animals were serially sacrificed until 8 weeks after the operation, and the defect site was histologically examined and histomorphometrically analyzed for quantitative evaluation of newly formed bone and blood vessels. The use of fibrin glue as the binder markedly increased the ease of handling the A-W.GC granules. In the controls, little trabecular regeneration was observed in the defect site. Early vascularization (confirmed by microangiography) increased and the repairing process was accelerated in the defects filled with fibrin. In these defects filled with A-W.GC granules, good bone formation was observed around the granules. Bone formation was accelerated in the defects filled with A-W.GC fibrin mixture. Thus, the mixture showed good osteoconductive potential as well as acceleration of the repair process. Therefore, A-W.GC-fibrin mixture is considered to be a useful bone defect filler.

Animals↗
PubMed1988

Strength of bonding between A-W glass-ceramic and the surface of bone cortex.

We examined the bonding strength of apatite- and wollastonite-containing glass-ceramics (A-W.GC) to the surface of bone cortex. Semi-column-shaped blocks of A-W.GC were fixed with screws on the surface of the tibiae of rabbits. The blocks of alumina-ceramic were used as the control. The load required to detach the implant from the surface of bone cortex was measured 2, 4, 8, and 25 weeks after the implantation. The bonding strength between A-W.GC and the surface of bone cortex increased with time. It increased remarkably 4 weeks after the implantation, suggesting that the chemical bonding advanced rapidly between 2 and 4 weeks after the implantation. The tensile strength of bonding reached a maximum of 15.1 +/- 3.1 kg/cm2 25 weeks after the implantation. The shear strength of bonding reached a maximum of 17.1 +/- 2.3 kg/cm2 25 weeks after the implantation. From these studies, we conclude that A-W.GC has a capability of making relatively quick bonding to the surface of bone cortex.

Animals↗
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↗