PubMed Health⌕ Search

Biomedical subjects

K Yoshimitsu

Publications and source records attributed to K Yoshimitsu.

At least 19 recordsLinked to original sources
PubMed2005

Portal vein occlusion or stenosis in patients with hepatolithiasis: observation by multiphasic contrast-enhanced CT.

AIMS: To analyze the dynamic findings of multiphasic contrast-enhanced CT in hepatolithiasis and to elucidate occlusive changes in portal veins and other associated abnormalities. METHODS: This was a retrospective study of 25 selected patients with hepatolithiasis who underwent various imaging examinations, including multiphasic contrast-enhanced CT. The following CT findings were evaluated in each of 71 hepatic segments: visualization of a calculus; biliary dilation or focal hepatic atrophy of the affected segment; areas that were abnormally enhanced in the hepatic arterial phase; degrees (normal, stenosis, occlusion) of portal vein calibre; and linear delayed enhancement along the bile-duct walls, suggesting cholangitis. RESULTS: On CT, calculi were depicted as a hyperdense structures in 61 of 71 segments (86%). Focal hepatic atrophy, which frequently accompanied CT findings suggesting compensatory hypertrophy of other segments, was seen in 50 of 71 segments (70%). Areas that were abnormally enhanced were recognized in 36 of 71 segments (51%). Stenosis or occlusion of portal venous branches was observed in 59 of 71 segments (83%), including 13 segments with occlusion. Findings indicating cholangitis were noted in 50 of 71 segments (70%). The degrees of portal vein calibre were significantly correlated with the presence of hepatic atrophy or cholangitis. CONCLUSION: Hepatolithiasis is associated with significant rates of stenosis or occlusion of adjacent portal veins as well as hepatic parenchymal changes in the affected area. Chronic deterioration of portal flow may cause these morphological changes.

Adult↗
PubMed2004

Liver lesions of visceral larva migrans due to Ascaris suum infection: CT findings.

The purpose of this study was to analyze computed tomographic (CT) findings of hepatic lesions due to Ascaris suum infection. CT of the liver in three patients, all of whom had immunoserologically confirmed A. suum infection, were retrospectively reviewed. Twenty-five lesions were identified in total. Two radiologists analyzed CT findings in a consensus fashion, with particular interest in the margin, shape, and location of the lesions. Hepatic lesions were ill-defined (22 of 25), small (3-35 mm; average, 11 mm), and nodular (18 of 25) or wedge (three of 25) in shape. Most were located in periportal (16 of 25) or subcapsular (six of 25) regions. Hepatic nodules due to visceral larva migrans of A. suum were located mainly in periportal or subcapsular regions, which may represent periportal eosinophilic granuloma, its pathologic feature. The results were considered to represent the pathophysiology of this entity.

Adult↗
PubMed2004

Gluteal muscular and sciatic nerve metastases in advanced urinary bladder carcinoma: case report.

We present a case of gluteal muscular and sciatic nerve metastases from urinary bladder carcinoma. T2-weighted magnetic resonance images demonstrated diffuse swelling and an increase in the signal of the right gluteus maximus muscle without destruction of the original arrangement of muscular fibers. Further, remarkable thickening of the right sciatic nerve showing a relatively hypointense signal was detected. Postcontrast T1-weighted images showed strong enhancement of these structures. Fine-needle aspiration biopsy with ultrasonographic guidance confirmed metastatic carcinoma cells in the right gluteal muscle and the sciatic nerve. These radiologic findings may represent a rare pattern of metastasis from urinary bladder carcinoma.

Adenocarcinoma↗
PubMed2001

Liver metastasis from gallbladder carcinoma: anatomic correlation with cholecystic venous drainage demonstrated by helical computed tomography during injection of contrast medium in the cholecystic artery.

BACKGROUND: The current study evaluated whether the sites of liver metastasis from gallbladder carcinoma are correlated with areas of cholecystic venous drainage (CVD) utilizing helical computed tomography (CT) during the injection of contrast medium into the cholecystic artery (cholecystic artery CT). METHODS: Cholecystic artery CT scans were performed in 26 patients with gallbladder carcinoma. Liver metastases were examined retrospectively in these patients on CT, and the sites of liver metastasis and CVD were compared closely. The patients were divided into concurrent (those who had metastasis at the time of cholecystic artery CT), early postoperative metastasis (those who developed metastasis within 6 months after surgery), and late postoperative metastasis (those who developed metastasis more than 6 months after surgery) groups. The frequency of metastasis related to CVD was compared between the three groups. RESULTS: A total of 32 metastases were identified in 11 patients, 21 of which were related to CVD. Six patients were included in the concurrent metastasis group; 18 of 20 tumors were found to be related closely to CVD. There were two patients in the early postoperative metastasis group; all three of the tumors detected were found to be closely related to CVD. Three patients were subclassified as being in the late postoperative metastasis group; none of the nine tumors detected appeared to be in areas associated with CVD. CONCLUSIONS: The sites of liver metastases were found to be well correlated with the areas with CVD, particularly in the concurrent and early postoperative metastasis groups. CVD may be a useful marker of potential areas of liver metastasis from gallbladder carcinoma, particularly in patients with early stage metastasis.

Adult↗
PubMed2001

Correlation of three-dimensional gradient echo dynamic MR imaging with CT during hepatic arteriography in patients with hypervascular hepatocellular carcinomas: preliminary clinical experience.

The purpose of this study is to elucidate the usefulness of dynamic MR study of the whole liver using 3DFISP with double dose gadolinium (Gd) enhancement in detecting enhancing lesions in 20 patients. Twenty patients with hepatocellular carcinoma (HCC) underwent 3DFISP dynamic study with double dose Gd. The demonstration of enhancing hypervascular lesions regardless of etiology was evaluated on a segment-by-segment basis with receiver operating characteristic (ROC) analysis, using findings on CT during hepatic arteriography as a gold standard. Diagnostic accuracy of 3DFISP in the detection of HCC was also evaluated. As to the demonstration of enhancing lesions, the Az value of the ROC curve was 88%. The detection rate of HCC with 3DFISP was 98%. 57% of enhancing pseudolesions were not detected on 3DFISP. We concluded that Dynamic MR study of the whole liver using 3DFISP with double dose Gd enhancement is a useful method to demonstrate hypervascular HCC.

Aged↗
PubMed2001

Hepatic nodular hyperplasia in a boy with Alagille syndrome: CT and MR appearances.

A boy with Alagille syndrome complicated by hepatic nodular hyperplasia (HNH) is reported. During pre-transplantation evaluation, CT and MRI revealed a large hepatic lesion with multiple small nodular lesions. Angiography demonstrated a large hypervascular lesion and CT arterial portography (CTAP) showed a portal perfusion defect corresponding to the lesion. CTAP also revealed large portal vein branches running through the lesion. Although hepatocellular carcinoma is known to accompany Alagille syndrome, HNH should also be considered when large vessels running through the lesion are demonstrated.

Alagille Syndrome↗
PubMed2001

MR imaging findings of uterine endometrial stromal sarcoma: differentiation from endometrial carcinoma.

Endometrial stromal sarcoma (ESS) is a rare malignant neoplasm of the uterus. We retrospectively analyzed pelvic MR imaging in 8 cases of ESS to determine the characteristic MR findings of ESS. Magnetic resonance images of 8 cases of ESS were evaluated for findings including the size, margin of the tumor, nodular lesions at the tumor margin, intramyometrial worm-like nodular extension, multiple nodular mass formation, hemorrhage, and necrosis in the tumor. The degree of contrast enhancement was also analyzed. The MR imaging findings of 21 consecutive cases of endometrial carcinoma (EC) were also evaluated and compared with those of ESS. The mean and the standard deviation of the maximum diameter of ESS and EC were 8.80 +/- 4.99 and 3.93 +/- 2.47 cm, respectively. Increased enhancement in at least a part of the tumor was observed in five of the six analyzed ESS cases and in 2 of 12 analyzed EC cases. The irregular margin, nodular lesions at the margin, intramyometrial nodular extension, and multiple nodular mass formation were more frequently seen in cases of ESS than in cases of EC. Magnetic resonance imaging can play a role in both diagnosing ESS as well as in differentiating ESS from EC.

Aged↗
PubMed2001

Unusual hemodynamics and pseudolesions of the noncirrhotic liver at CT.

Recognition of pseudolesions of the liver at computed tomography (CT) is important because of their close resemblance to primary liver cancers or metastases. Two types of pseudolesion in the noncirrhotic liver include that due to transient extrinsic compression, typically caused by ribs or the diaphragm, and that due to a "third inflow" of blood from other than the usual hepatic arterial and portal venous sources: the cholecystic, parabiliary, or epigastric-paraumbilical venous system. Although the location of both types of pseudolesion are characteristic, their appearances at CT during arterial portography and CT during selective angiography vary from nonenhanced low-attenuation areas to well-enhanced high-attenuation areas, depending on the amount and timing of the inflow and presence or absence of focal metabolic alteration of the hepatocytes. Radiologists need to understand the underlying mechanism of these pseudolesions to better recognize the wide range of their appearances at CT.

Angiography↗
PubMed2001

[Dynamic MR imaging of the upper abdomen: timing optimization and pulse sequence selection].

Since breath-hold gradient-echo MR imaging was introduced, dynamic MR study has played an important role in the MR investigation of the upper abdomen. In this article, the importance of tailoring imaging delay in each individual patient is stressed, with special attention given to a logical aspect of setting delay time based upon the bolus transfer time obtained by test injection. Also discussed is the importance of selecting types and parameters of pulse sequence to maximize the enhancement effect. It should be noted that alteration of gadolinium concentration in vivo following intravenous injection could result in a large change in signal intensity change on one sequence but little change on another. Double-dose 3DFISP with tailored delay time utilizing the test injection method, which is currently used for dynamic MR imaging in our institute, is presented.

Carcinoma, Hepatocellular↗
PubMed2001

[A safe and simple method of percutaneous transfemoral implantation of a port-catheter access system for hepatic artery chemotherapy infusion].

The purpose of this study was to perform a simple percutaneous transfemoral implantation of a portcatheter access system using a new catheter coating for hepatic artery chemotherapy infusion, and to evaluate the complications of transfemoral infusion port implantation. The methods of treatment for complications were also studied. The port-catheter system was percutaneously implanted via femoral artery access in 180 patients with malignant liver tumors. Blood flow redistribution was performed using embolization coils. An unfixed 5 Fr catheter was placed in a hepatic artery, and connected to a port implanted subcutaneously below the level of the inguinal ligament. The success rate of implantation was 99%. Complications after placement were observed as follows: port system obstruction (9.6%); dislocation of the catheter tip (8.4%); drug toxicity (4.5%); and infection (3.4%). Notable is the avoidance of cerebral infarcts. In 3 of 17 patients with port obstruction, recanalization of the port was achieved. In 11 of 15 patients with catheter dislocation, replacement of the catheter-port system was successful. In 5 patients with hepatic artery occlusion, the replacement of a microcatheter-port access system was achieved, and hepatic artery chemotherapy infusion was resumed. This percutaneous transfemoral implantation of a catheter-port access system would seem to be a very simple and useful method for many clinical doctors, and it may improve the quality of life in patients with an unresectable malignant liver tumor.

Adolescent↗
PubMed2000

Recent developments in imaging diagnostics for HCC: CT arteriography and CT arterioportography evaluation of vascular changes in premalignant and malignant hepatic nodules.

We analyzed the hemodynamic properties and vascular supply changes in relation to the carcinogenesis of hepatocellular carcinoma (HCC), selecting 18 premalignant and malignant nodules less than 3 cm diameter (from 14 patients) for our study. The computed tomographic (CT) arteriography and CT arterioportography (CTAP) findings for these nodules were correlated with the histopathologic findings. The ratios of all microscopically counted arteries (normal hepatic and abnormal arteries), normal hepatic arteries, and portal veins in each nodule to those in the surrounding liver were calculated. Well differentiated lesions had low attenuation on CT arteriography and isoattenuation on CTAP. Moderately-to-poorly differentiated lesions had high attenuation on CT arteriography and low attenuation on CTAP. In well differentiated lesions, the ratios of all arteries, normal hepatic arteries, and portal veins were 1.17+/-0.10, 0.66+/-0.12, and 0.80+/-0.10, respectively. In moderately-to-poorly differentiated lesions, the ratios were 2.64+/-0.23, 0.09+/-0.03, and 0.07+/-0.03, respectively. We concluded that blood flow does not parallel the actual number of arteries seen on the histological examination of tumors. In well differentiated lesions, the combination of normal hepatic arterial degeneration and preserved portal veins results in low attenuation on CT arteriography and isoattenuation on CTAP. In advanced HCC, the combination of neoplastic (abnormal) arterial development by angiogenesis and obliteration of portal veins results in high attenuation on CTA and low attenuation on CTAP. These findings are characteristic of early and advanced stage HCC, and may reflect a combination of sequential changes in their hemodynamic states.

Aged↗
PubMed2000

MR cholangiopancreatographic differentiation of benign and malignant intraductal mucin-producing tumors of the pancreas.

OBJECTIVE: The purpose of this study was to establish MR cholangiopancreatographic criteria for discriminating benign from malignant intraductal mucin-producing tumors of the pancreas. MATERIALS AND METHODS: Thirty-one patients with 34 intraductal mucin-producing tumors underwent MR cholangiopancreatography. Tumors were classified as either main duct type (n = 10) or branch duct type (n = 24). In patients with the main duct type, the maximum diameter and the location of the main pancreatic duct, the extent of main pancreatic duct dilatation, and the presence of a filling defect were evaluated. For branch duct type, the location and maximum diameter of the cystic lesion, the presence of a filling defect, and the presence of associated main pancreatic duct dilatation were evaluated. RESULTS: In patients with the main duct type, the main pancreatic duct was significantly narrower when associated with benign rather than malignant tumors. All malignant tumors showed diffuse main pancreatic duct dilatation, whereas all benign tumors showed segmental dilatation. Among patients with branch duct type, the cyst was smaller when it was a benign rather than malignant tumor. All but one malignant tumor showed mild associated main pancreatic duct dilatation, whereas benign tumors were not associated with main pancreatic duct dilatation. Filling defects suggested malignancy, although half of the malignant tumors had no filling defects. CONCLUSION: In patients with intraductal mucin-producing tumors of the pancreas, filling defects are indicative of malignancy. Diffuse main pancreatic duct dilatation greater than 15 mm (main duct type), or any main pancreatic duct dilatation (branch duct type), is strongly associated with malignancy.

Adenocarcinoma↗
PubMed1999

MR detection of cytoplasmic fat in clear cell renal cell carcinoma utilizing chemical shift gradient-echo imaging.

We attempted to determine whether cytoplasmic fat in clear cell renal cell carcinoma (RCC) can be identified by chemical shift gradient-echo magnetic resonance imaging (CSI). CSI was performed for 22 clear cell RCCs and 30 other renal tumors (including 16 non-clear cell RCCs), all of which were surgically proven. Signal reduction in out-of-phase images of these tumors was retrospectively evaluated and compared. The signal loss ratio (SLR) was defined and calculated. Fat staining of specimens from 16 tumors was performed and correlated with SLR. SLR was significantly higher in clear cell RCCs than in non-clear cell RCCs (P < 0.001). There was a significant correlation between degree of fat staining positivity of the specimens and SLR (P < 0.01). When signal reduction in out-of-phase images suggested the diagnosis of clear cell RCC, correct diagnosis of this entity was made in resected renal tumors with sensitivity, specificity, and accuracy of 82%, 90%, and 87%, respectively. CSI can demonstrate cytoplasmic fat in clear cell RCCs, which helps to differentiate this entity from other RCCs.

Adenocarcinoma, Clear Cell↗
PubMed1999

Pseudolesions of the liver possibly caused by focal rib compression: analysis based on hemodynamic change.

OBJECTIVE: The purpose of this study is to show and analyze the CT appearance of pseudolesions of the liver caused by rib compression and to discuss the possible mechanism on the basis of findings of incremental dynamic CT, CT during arterial portography, and CT hepatic arteriography. CONCLUSION: Focal compression of the liver caused by curved ribs can cause transient focal diminishment of portal venous perfusion without significantly altering hepatic arterial perfusion. Such diminishment may be observed as low-density areas on the early phase of incremental dynamic CT.

Aged↗
PubMed1999

MR diagnosis of adenomyomatosis of the gallbladder and differentiation from gallbladder carcinoma: importance of showing Rokitansky-Aschoff sinuses.

OBJECTIVE: We evaluated the MR imaging features of adenomyomatosis of the gallbladder with particular emphasis on Rokitansky-Aschoff sinuses. MATERIALS AND METHODS: MR images of 17 patients with histologically proven adenomyomatosis were retrospectively reviewed. The presence of Rokitansky-Aschoff sinuses was evaluated and analyzed; four T2-weighted (fast spin-echo with a surface coil, with or without breath-holding, fast spin-echo with a phased-array coil with breath-holding, and half-Fourier rapid acquisition with relaxation enhancement with breath-holding) and two contrast-enhanced dynamic pulse sequences were studied. These six pulse sequences were separately rated on a 5-point scale by two radiologists for comparison. Interobserver differences were evaluated. Other MR findings were also analyzed. RESULTS: Among the six pulse sequences studied, three T2-weighted with breath-holding sequences were found to be superior to the other three sequences in showing Rokitansky-Aschoff sinuses. In particular, the half-Fourier rapid acquisition with relaxation enhancement was scored the highest by the two observers and received the highest kappa coefficient in our statistical analysis of the scoring. Diffuse-type adenomyomatosis typically showed early mucosal and subsequent serosal enhancement. Localized adenomyomatosis exhibited homogeneous enhancement, showing smooth continuity with the surrounding gallbladder epithelium. CONCLUSION: MR imaging may be able to provide important information in the diagnosis of adenomyomatosis.

Adenomyoma↗
PubMed1999

Vascular changes in hepatocellular carcinoma: correlation of radiologic and pathologic findings.

OBJECTIVE: Our objective was to analyze the hemodynamic properties and vascular supply changes in the carcinogenesis of hepatocellular carcinoma. MATERIALS AND METHODS: Ten nodules (nine patients) (one early, three early-advanced, and six advanced cases of hepatocellular carcinoma) less than 3 cm in diameter were selected from 45 patients (50 nodules) who underwent CT arteriography and CT during arterial portography. These images were correlated with histopathologic findings. Ratios of all microscopically counted (normal hepatic and abnormal) arteries, normal hepatic arteries, and portal veins in each nodule to those in the surrounding liver were calculated. RESULTS: Early hepatocellular carcinoma (one early case and early areas in three early-advanced cases) had low attenuation on CT arteriography and isoattenuation on CT during arterial portography. Advanced hepatocellular carcinoma (six advanced cases and advanced areas in three early-advanced cases) had high attenuation on CT arteriography and low attenuation on CT during arterial portography. In early hepatocellular carcinoma, the ratios of all arteries, normal hepatic arteries, and portal veins were 1.21 +/- 0.07, 0.60 +/- 0.07, and 0.73 +/- 0.06, respectively. In advanced hepatocellular carcinoma, the ratios were 2.66 +/- 0.26, 0.08 +/- 0.04, and 0.07 +/- 0.03, respectively. CONCLUSION: In early hepatocellular carcinoma, the combination of normal hepatic artery degeneration and preserved portal veins results in low attenuation on CT arteriography and isoattenuation on CT during arterial portography. In advanced hepatocellular carcinoma, the combination of neoplastic (abnormal) arterial development by angiogenesis and obliteration of portal veins results in high attenuation on CT arteriography and low attenuation on CT during arterial portography. These findings are a characteristic difference between early and advanced hepatocellular carcinoma.

Aged↗