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Biomedical subjects

Y Kawamori

Publications and source records attributed to Y Kawamori.

At least 19 recordsLinked to original sources
PubMed2001

Accumulation of iodized oil within the nonneoplastic liver adjacent to hepatocellular carcinoma via the drainage routes of the tumor after transcatheter arterial embolization.

PURPOSE: After transcatheter arterial embolization (TAE) with iodized oil (Lipiodol), a relatively dense accumulation of Lipiodol is often seen in the nontumorous liver adjacent to a hypervascular hepatocellular carcinoma (HCC) nodule. We compared this phenomenon with the findings obtained with single-level dynamic CT during hepatic arteriography (SLDCTHA) and presumed its possible mechanism. METHODS: Fifty-six patients with HCC underwent hepatic angiography including SLDCTHA followed by segmental or subsegmental TAE with a mixture of an anticancer drug and Lipiodol. We compared the drainage area of the HCC depicted on SLDCTHA with the Lipiodol accumulation in the nontumorous liver adjacent to the HCC on CT after TAE (LpCT). RESULTS: In 26 of the 56 patients, a definite corona enhancement around the HCC, suggesting the drainage of blood from the tumor into the surrounding liver parenchyma, was seen on the late phase of SLDCTHA. In 17 of these 26 patients (65.4%), LpCT showed a more intense accumulation of Lipiodol in the nontumorous liver adjacent to the HCC that corresponded to the drainage area revealed on SLDCTHA. CONCLUSION: The drainage of blood from the HCC was considered to be a possible mechanism of the accumulation of Lipiodol in the nontumorous liver adjacent to the HCC.

Carcinoma, Hepatocellular↗
PubMed2001

Discrimination of small hepatic hemangiomas from hypervascular malignant tumors smaller than 3 cm with three-phase helical CT.

PURPOSE: To compare the appearance of small hepatic hemangiomas at nonenhanced and contrast material-enhanced helical computed tomography (CT) with that of small (<3-cm) hypervascular malignant liver tumors and to evaluate the accuracy of multiphase helical CT for differentiating small hemangiomas from small hypervascular malignant tumors. MATERIALS AND METHODS: Radiologists reviewed multiphase helical CT liver images in 86 patients with 37 hemangiomas and 49 malignant liver tumors. They evaluated lesion type and degree of enhancement for change from arterial to portal venous phase. They rated their confidence in the discrimination of hemangiomas from malignant tumors. RESULTS: At arterial phase CT, enhancement similar to aortic enhancement was observed in 19%-32% of hemangiomas and 0%-2% of malignant tumors; globular enhancement, in 62%-68% and 4%-12%, respectively. At portal venous phase CT, enhancement similar to blood pool enhancement was observed in 43%-54% of hemangiomas and 4%-14% of malignant tumors; globular enhancement, in 46%-49% and 0%-2%, respectively. For all readers and all phases of enhancement, the area under the receiver operating characteristic curves was 0.81-0.87, indicating that inherent accuracy of CT is high and that there was no significant difference (P >.28) in overall accuracy. Readers diagnosed hemangiomas with 47%-53% mean sensitivity with all enhancement phases and diagnosed malignant lesions with 95% mean specificity. CONCLUSION: Small hemangiomas frequently show atypical appearances at CT. Two-phase helical CT does not improve sensitivity but does improve specificity for differentiating hemangiomas from hypervascular malignant tumors.

Carcinoma, Hepatocellular↗
PubMed2001

Dynamic CT of hepatic abscesses: significance of transient segmental enhancement.

OBJECTIVE: The purpose of this study was to evaluate dynamic CT findings of hepatic abscesses, especially segmental hepatic enhancement, and to clarify the cause. MATERIALS AND METHODS: Twenty-four abscesses in eight patients were examined by early (30 sec) and late phase (90 sec) dynamic CT. Patients underwent abscess drainage (n = 1), hepatic resection (n = 2), or antibiotic therapy (n = 5). CT during arterial portography and CT during hepatic arteriography were performed in one patient. We retrospectively observed the frequency and changes of segmental hepatic enhancement on dynamic CT and determined its cause using radiologic and pathologic correlation. RESULTS: Sixteen abscesses (67%) showed transient segmental hepatic enhancement and three abscesses showed only segmental hepatic enhancement in the early phase. Four abscesses in one patient who underwent CT during arterial portography and CT during hepatic arteriography showed a segmental perfusion defect on CT during arterial portography and segmental enhancement on CT during hepatic arteriography. On follow-up dynamic CT performed 10-17 days after the initial CT, segmental hepatic enhancement surrounding hepatic abscesses decreased or disappeared in all abscesses. Pathologic examination of two patients showed marked inflammatory cell infiltration with stenosis of portal venules within the portal tracts surrounding hepatic abscesses without definite inflammation in the liver parenchyma. CONCLUSION: Segmental hepatic enhancement on dynamic CT is frequently associated with hepatic abscesses and may be caused by decreased portal flow resulting from inflammation of the portal tracts.

Aged↗
PubMed2000

Islet cell tumor of the pancreas: biphasic CT versus MR imaging in tumor detection.

PURPOSE: To compare the effectiveness of biphasic computed tomography (CT) and magnetic resonance (MR) imaging in the detection of pancreatic islet cell tumors. MATERIALS AND METHODS: Retrospective quantitative, qualitative, and receiver operating characteristic analyses of biphasic CT and MR imaging were performed in 19 patients with 26 histopathologically proved islet cell tumors. Delayed arterial dominant-phase (AP) and portal venous-phase (PVP) biphasic CT was performed after the administration of contrast material. MR imaging included T1-weighted spin-echo (SE) and T2-weighted SE or fast SE imaging, fat-saturated T1-weighted SE imaging, dynamic contrast material-enhanced T1-weighted gradient-echo imaging, and delayed enhanced T1-weighted SE imaging with or without fat saturation. RESULTS: PVP CT and delayed enhanced T1-weighted MR imaging had the highest A(z) values (0.98 and 0.97, respectively; P <.05). Delayed enhanced T1-weighted MR imaging had the highest relative sensitivity (14-15 [74%-79%] of 19 lesions), followed by PVP CT (18-19 [69%-73%] of 26 lesions), AP CT (17-19 [65%-73%] of 26 lesions), fat-saturated T1-weighted MR imaging (eight to 10 [57%-71%] of 14 lesions), T2-weighted (16-17 [62%-65%] of 26 lesions), T1-weighted (15-18 [58%-69%] of 26 lesions) MR imaging, and dynamic MR imaging (nine [56%] of 16 lesions). CONCLUSION: Biphasic (especially PVP) CT and MR imaging have similar effectiveness in the detection of islet cell tumors if fat-saturated T1-weighted and delayed enhanced T1-weighted MR imaging are included.

Adenoma, Islet Cell↗
PubMed1999

Histochemical study of the distribution of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-positive neurons in the chicken caecum.

The distribution of nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-positive neurones was investigated in the chicken caecum. Double staining combined NADPHd histochemistry with immunohistochemistry for neural nitric oxide synthase (nNOS) indicated that NADPHd-positive neurones also showed immunoreactivity for nNOS. NADPHd-positive nerve cell bodies were observed in both the myenteric and the submucous plexuses. Nerve fibres showing enzyme activity were mainly distributed in the circular muscle layer, but only a few fibres in the mucosal layer. Fine nerve fibres showing NADPHd activity were found running between germinal centres in the caecal tonsil. Quantitative analysis showed no significant differences in the number of enzyme-positive nerve cell bodies per ganglion of the myenteric and the submucous plexuses among three different caecal regions; proximal, middle and distal regions. Larger numbers of ganglia were detected in the submucous plexus than the myenteric plexus at all three regions. These data indicate that nitrergic neurones in the submucous plexus mainly project to the circular muscle layer in the chicken caecum. It is possible that nitrergic nerves regulate the motility of the chicken caecum.

Animals↗
PubMed1999

Correlation between the blood supply and grade of malignancy of hepatocellular nodules associated with liver cirrhosis: evaluation by CT during intraarterial injection of contrast medium.

OBJECTIVE: The purpose of this study is to evaluate the correlation between the intranodular blood supply revealed by CT during intraarterial injection of contrast medium, mainly using helical CT, and the grade of malignancy of hepatocellular nodules associated with liver cirrhosis as classified by the International Working Party of the World Congress of Gastroenterology. SUBJECTS AND METHODS: We studied 201 histologically proven nodules (101 resected and 100 biopsied nodules), including 47 low-grade dysplastic nodules (low-DNs), 56 high-grade dysplastic nodules (high-DNs), 24 well-differentiated hepatocellular carcinomas (wd-HCCs), and 74 moderately or poorly differentiated HCCs (mp-HCCs), in 139 cirrhotic patients. Findings on CT during arterial portography (n = 201) and CT during hepatic arteriography (n = 74) were reviewed and compared with the histologic diagnosis. RESULTS: CT findings were classified into four types relative to the surrounding liver: type A (isodense), type B (slightly hypodense), type C (partially hypodense), and type D (markedly hypodense) on CT during arterial portography and type I (isodense), type II (hypodense), type III (partially hyperdense), and type IV (hyperdense) on CT during hepatic arteriography. On CT during arterial portography, the distributions of each type were low-DN (n = 47 [A, n = 36; B, n = 8; C, n = 3]), high-DN (n = 56 [A, n = 18; B, n = 20; C, n = 10; D, n = 8]), wd-HCC (n = 24; [B, n = 4; C, n = 13; D, n = 7]), and mp-HCC (n = 74 [D, n = 74]). On CT during hepatic arteriography, the distributions were low-DN (n = 26 [I, n = 18; II, n = 7; III, n = 1]), high-DN (n = 19 [I, n = 6; II, n = 7; III, n = 4; IV, n = 2]), wd-HCC (n = 15 [I, n = 1; III, n = 8; IV, n = 6]), and mp-HCC (n = 14 [IV, n = 14]). We found a statistically significant correlation between the four types and the grade of malignancy of these nodules. CONCLUSION: Findings on CT during arterial portography and CT during hepatic arteriography correlated positively with histologic grading when overlap in appearance between dysplastic nodules and HCCs occurred. The concept revealed in this study can apply to diagnoses made on the basis of Doppler sonography, dynamic CT, and MR imaging.

Aged↗
PubMed1998

Hypervascular hepatocellular carcinoma: evaluation of hemodynamics with dynamic CT during hepatic arteriography.

PURPOSE: To assess the hemodynamics and the main drainage vessel of hypervascular hepatocellular carcinoma. MATERIALS AND METHODS: Single-level dynamic computed tomography during hepatic arteriography (CTHA) was performed in 32 patients with hepatocellular carcinoma. Carcinoma was confirmed with histologic (n = 9) or clinical (n = 23) examination results. Single-level CTHA findings were retrospectively analyzed. Histologic specimens from 40 livers with hepatocellular carcinoma were also examined, with special attention to vessels along the rim of the lesion. RESULTS: Contrast material enhancement on single-level CTHA images occurred in four phases: (a) inflow of the contrast material into tumor, (b) tumor enhancement, (c) inflow of the contrast material into adjacent liver, and (d) corona enhancement of adjacent liver. Corona enhancement was seen in all lesions. A bright branching structure in the corona enhancement area, suggestive of a portal venule, was visible at the start of adjacent liver staining in 21 lesions. Continuity between a tumor sinusoid and a tiny vessel in the inner layer of the pseudocapsule was histologically confirmed in 10 of 40 specimens. Continuity between a tiny vessel in the inner layer and a portal vein in the outer layer of the pseudocapsule was confirmed with findings on serial sections from one liver. CONCLUSION: The main drainage of hepatocellular carcinoma lesions may be a protal venule.

Carcinoma, Hepatocellular↗
PubMed1998

[Usefulness of T2-weighted images using single shot fast spin echo (SSFSE) pulse sequence for the evaluation of pancreatobiliary diseases: comparison with MRCP using SSFSE].

Single shot fast spin echo (SSFSE) pulse sequence provides us with a thick single-slice MR cholangiopancreatography (MRCP) as well as thin multi-slice MRCP, and T2-weighted images are also obtained with SSFSE sequences. In comparison with conventional spin-echo and fast spin-echo sequences, T2-weighted image using SSFSE sequence has the advantages of the abscence of motion artifacts and the extremely short acquisition times. MRCP using SSFSE sequence is useful in the conspicuity of bile duct, pancreatic duct, and cystic lesions. However, T2 weighted image using SSFSE is superior to MRCP not only for the differentiation between solid and cystic lesions but also for the visualization of contour of different organs and lesions.

Biliary Tract Diseases↗
PubMed1997

Aberrant gastric venous drainage in a focal spared area of segment IV in fatty liver: demonstration with color Doppler sonography.

PURPOSE: To clarify the correlation between aberrant gastric venous drainage and a focal spared area at the posterior edge of segment IV in fatty liver by using color Doppler ultrasound (US). MATERIALS AND METHODS: Seventeen patients with fatty liver were examined with gray-scale, color Doppler, and power Doppler US. In one patient with a focal spared area, arteriography and computed tomography (CT) were performed during injection of contrast medium into the right gastric artery. RESULTS: Focal spared areas of fatty liver at segment IV were shown in five of 17 patients. In all five patients with a focal spared area, aberrant gastric venous drainage was observed with color Doppler US. Power Doppler US depicted aberrant gastric venous drainage more clearly than color Doppler US. On the other hand, no definite aberrant gastric venous drainage was seen in the 12 patients who had no focal spared area. In one patient who underwent selective arteriography of the right gastric artery and CT arteriography, aberrant gastric venous drainage into segment IV was directly demonstrated. CONCLUSION: Focal spared areas at segment IV in fatty liver correlate strongly with aberrant gastric venous drainage. Noninvasive imaging methods such as color and power Doppler US are useful for depicting these aberrant drainage veins.

Adult↗
PubMed1997

Posterior aspect of hepatic segment IV: patterns of portal venule branching at helical CT during arterial portography.

PURPOSE: To determine the anatomy of the portal venous system in the posterior aspect of segment IV of the liver by using helical computed tomography (CT) during arterial portography (CTAP). MATERIALS AND METHODS: One hundred consecutive patients underwent CTAP. Helical CT during hepatic arteriography was performed in 20 patients. In seven patients with hepatocellular carcinoma in the posterior aspect of segment IV, the feeding arteries were also analyzed. RESULTS: A venule from the intrahepatic portal vein to segment IV was seen in all patients. Other findings included a tiny venule from the distal part of the main left portal vein (n = 36), from the proximal left main portal vein (n = 20), and from the right portal vein (n = 18). Aberrant right gastric venous drainage and/or parabiliary venous drainage directly into the posterior aspect was present in 14 patients. In two patients, a tiny accompanying artery was seen on images from CT during hepatic arteriography. In seven patients with hepatocellular carcinoma, the main feeding artery branched from the right (n = 2) or left (n = 5) hepatic artery. CONCLUSION: CTAP adequately demonstrates the tiny portal venous and arterial branches from the main right or left portal vein that distribute to the posterior aspect of segment IV. Knowledge of this vascular anatomy is clinically important.

Adult↗
PubMed1995

Aberrant gastric venous drainage in cirrhotic livers: imaging findings in focal areas of liver parenchyma.

PURPOSE: To analyze imaging finding in focal areas of liver parenchyma with aberrant gastric venous drainage (AGVD) in cirrhotic livers. MATERIALS AND METHODS: Eighteen patients with AGVD confirmed with computed tomography (CT) during arterial portography and arteriography underwent ultrasound (US) (n = 18), CT (n = 18), magnetic resonance (MR) imaging (n = 12), dynamic CT (n = 14), and dynamic MR imaging (n = 8). Imaging and histologic (n = 2) findings were analyzed. RESULTS: The focal area with AGVD was hypoechoic on US scans (n = 7), hypoattenuating on CT scans (n = 4), hyperintense on T1-weighted MR images (n = 6), and hypointense on T2-weighted MR images (n = 5). Early enhancement was seen with dynamic CT (n = 8) and with dynamic MR imaging (n = 6), without definite staining on arterial phase of arteriography. Histologic findings revealed hyperplastic changes of liver. CONCLUSION: The imaging findings, except for early enhancement, were very similar to those of adenomatous hyperplasia or well-differentiated hepatocellular carcinoma. The early enhancement was considered due to early venous return compared with that of the surrounding liver.

Adenoma↗
PubMed1994

Segmental iron deposition in the liver due to decreased intrahepatic portal perfusion: findings at MR imaging.

PURPOSE: To evaluate the causes of intrahepatic segmental areas of signal hypointensity [corrected] on T1- and T2-weighted spin-echo (SE) and gradient-echo (GRE) magnetic resonance (MR) images. MATERIALS AND METHODS: Six patients in whom wedge-shaped hypointense areas were seen on hepatic MR images underwent examination with ultrasound (US), computed tomography (CT), angiography, and CT during arterial portography (CTAP). Histologic examination was performed in three patients. RESULTS: The affected liver parenchymas were best depicted as segmental or lobar hypointense areas on GRE images. Angiography and CTAP revealed that portal blood supply to the hypointense areas was absent or decreased due to portal vein tumor thrombus and arterioportal shunt (n = 1), compression of a portal branch by tumor (n = 2), portal vein thrombosis (n = 1), or arterioportal shunt (n = 2). Iron deposition in the hepatocytes was evident in all three patients with histologic correlation. CONCLUSION: Segmental signal hypocoagulability was generally due to hepatocyte iron deposition and was accompanied and possibly caused by a disturbance in portal flow.

Adult↗
PubMed1992

Differentiation of hepatocellular carcinomas from hyperplastic nodules induced in rat liver with ferrite-enhanced MR imaging.

The potential of superparamagnetic ferrite particles in magnetic resonance (MR) imaging to help differentiate between hyperplastic nodular lesions in the liver and hepatocellular carcinomas was evaluated with chemically induced liver tumors in cirrhotic rats. Ferrite particles decreased the signal intensity of hyperplastic nodules but not that of hepatocellular carcinomas, and stainable iron was found in the former but not in the latter with Prussian blue iron stain. T1-weighted spin-echo images made little contribution to the differentiation between these two lesions, while T2-weighted spin-echo images were effective for this purpose, since ferrite particles cause T2 shortening. Ferrite-enhanced MR imaging may be useful in differentiating these two lesion types according to their signal intensity changes on images, because Kupffer cells are present in hyperplastic nodular lesions but rarely in hepatocellular carcinomas.

Animals↗
PubMed1991

Hepatocellular carcinomas with excessive copper accumulation: CT and MR findings.

Results of orcein staining and findings obtained with non-contrast-medium-enhanced computed tomography (CT) and magnetic resonance (MR) imaging (T1- and T2-weighted images) were compared for 53 histologically confirmed hepatocellular carcinomas (HCCs). HCCs were 5 cm in the largest diameter. Three lesions with diffuse and strong orcein staining were highly attenuating on nonenhanced CT images. Electron x-ray microanalysis of one of them revealed copper. The high attenuation value at nonenhanced CT may have been due to the abundant copper-binding protein in the cancer cells. The difference between orcein staining results and attenuation patterns at CT was statistically significant (chi 2, P less than .001). It could not be concluded that the paramagnetic effects of copper in HCC had an influence on signal intensity on MR images. The difference between orcein staining results and signal-intensity patterns on T1- and T2-weighted images was not statistically significant.

Adult↗