Biomedical subjects
Publications and source records attributed to M Kanematsu.
False-negative findings on CT angiography (CTA) in two patients with hepatocellular carcinoma (HCC) were demonstrated. CTA images of one patient with an aberrant left hepatic artery branching from the left gastric artery and another patient whose right hepatic artery was occluded owing to an unknown cause failed to demonstrate HCCs. This report suggests one of the diagnostic pitfalls of CTA for diagnosis of liver tumors.
BACKGROUND: To assess the frequency and characteristics of nonpathological focal enhancements seen on spiral computed tomographic (CT) hepatic angiography (CTA). METHODS: Spiral CTA and spiral CT arterial portography (CTAP) were performed in 31 patients with suspected liver malignancy prior to potential liver resection. The CTA images were retrospectively reviewed for focal enhancements by two radiologists. After determining nonpathological focal enhancements on CTA images based on the other radiographic tests, surgical exploration including intraoperative sonography, follow-up imagings, the frequency, size, site, and shape of nonpathological focal enhancements with CTA were assessed. RESULTS: Thirty-six nonpathological focal enhancements with CTA from 4 to 23 (mean = 11. 4) mm were seen in 14 (45.2%) of 31 patients. Thirteen (36.1%) of 36 nonpathological focal enhancements with CTA were not depicted with CTAP. Nonpathological focal enhancements with CTA were frequent in Couinaud segments III (27.8%), V (22.2%), and VI (19.4%). Twenty-three (63.9%) of 36 nonpathological focal enhancements were located in the edge of the liver. Shapes of 36 nonpathological focal enhancements with CTA included circular (n = 16), worm (n = 7), irregular (n = 6), dot (n = 6), and wedge (n = 1). CONCLUSION: In nearly half of patients, spiral CTA shows various shapes of small nonpathological focal enhancements more frequently in the liver edge.
BACKGROUND: To assess an optimal methodology of combined spiral computed tomographic (CT) angiography (CTA) and CT arterial portography (CTAP) for detection and characterization of liver tumors. METHODS: We performed spiral CTAP only in five patients with 30-32% contrast (subset A), CTAP combined with preceding spiral CTA using 30-32% contrast in 19 (subset B), and CTAP combined with preceding spiral CTA with 60-64% contrast in seven (subset C). The CT numbers of the aorta immediately before preceding CTA and subsequent CTAP and the CT numbers of malignant tumor and liver parenchyma with CTAP were measured. RESULTS: The differences of the CT number between the malignant tumor and liver parenchyma on CTAP were 61.1-161.8 (mean +/- SD, 114.5 +/- 39.3) HU, 50.7-164.8 (104.2 +/- 31.2) HU, and 101.2-368.3 (219.5 +/- 90.5) HU in subsets A, B, and C, respectively. Two cavernous hemangiomas showed pathognomonic findings with preceding CTA. CONCLUSION: Combination of preceding spiral CTA and subsequent spiral CTAP using 30% contrast with a 5-min interval is an optimal method for detection and characterization of liver tumors.
BACKGROUND: To compare the utility of arterial-phase magnetic resonance (APMR) imaging and spiral computed tomography arteriography (CTA) for detection of hepatic tumors. METHODS: Both APMR imaging and CTA were performed in 24 patients with liver tumors. APMR imaging was initiated at 25-30 s after an intravenous bolus injection of gadolinium-diethylenetriamine pentaacetic acid using the fast multiplanar spoiled GRASS technique. CTA was initiated at 3 s after hepatic arterial injection of 30-64% nonionic contrast agent. APMR and CTA images were separately reviewed retrospectively by two blinded readers. Afterward, matched pair was reviewed to determine which had better lesion conspicuity. RESULTS: The sensitivities for hepatic tumors were 67.2 and 86.6% in APMR and CTA, respectively (p < 0.01). Seven (12.5%) and 21 (23.9%) false-positive lesions were seen at APMR and CTA, respectively (NS). Lesion conspicuity was comparable between APMR and CTA. CONCLUSIONS: Although APMR imaging is an useful noninvasive method to detect hypervascular liver tumors, APMR imaging is still not an alternative to CTA with respect to tumor detectability.
PURPOSE: The purpose of this study was to assess the imaging findings of pathologically-proved small hepatic nodules 2 cm in size or smaller detected with ultrasonography in cirrhotic patients with suspected hepatocellular carcinoma (HCC). MATERIALS AND METHODS: We evaluated sonographically detected 32 small hepatic nodules which were pathologically confirmed in 23 consecutive cirrhotic patients who were suspected of having HCC. Twenty-six lesions were confirmed with ultrasonographically-guided aspiration needle-core biopsy, and six with definitive surgery. Ultrasonographic examination records were retrospectively reviewed. CT, and MR images obtained with various imaging techniques were retrospectively reviewed by two radiologists in a blind fashion. RESULTS: The 32 hepatic nodules were comprised of seven focal fatty changes, two large regenerative nodules, three low-grade dysplastic nodules, five high-grade dysplastic nodules, and fifteen HCCs. Ultrasonography showed various echogenicity for the hepatic nodules. The signal-intensity characteristics with T1-weighted spin-echo, in-phase gradient-recalled-echo, and dynamic MR imagings may be useful in distinguishing HCC from nonHCC nodules. CONCLUSIONS: Nearly half of small hepatic nodules detected with ultrasonography were nonHCC nodules. Ultrasonographic findings may not be reliable in characterizing small hepatic nodules in cirrhosis. CT and MR imaging obtained with the various techniques are still insensitive to these hepatic nodules.
BACKGROUND: To compare the diagnostic accuracy of magnetic resonance (MR) images obtained with three different pulse sequences for lymph-node metastases in patients with gastric cancer. METHODS: T1-weighted spin-echo (SE), breath-hold T2-weighted fast SE, and triphasic gadolinium-enhanced dynamic gradient-recall-echo (GRE) MR images obtained in 16 patients with gastric carcinoma were retrospectively reviewed. Regional lymph nodes were assigned to four different groups, and image review was conducted on a lymph-node group-by-group basis; 64 lymph-node groups were reviewed by two radiologists. Relative sensitivity, specificity, and accuracy were determined based on the findings with definitive surgery and follow-up imaging. Diagnostic accuracy was determined by means of receiver-operating-characteristic (ROC) analysis. RESULTS: Relative sensitivities for lymph-node metastases with T1-weighted SE, breath-hold T2-weighted fast SE, and dynamic GRE images were 61%, 94%, and 59%, respectively. Relative sensitivity with breath-hold T2-weighted fast SE images was significantly greater than that with T1-weighted SE (p < 0.05) and dynamic GRE (p < 0.05) images. Diagnostic accuracy determined by ROC analysis was marginally higher with breath-hold T2-weighted fast SE (area under ROC curve [Az] = 0.87) than with T1-weighted SE (Az = 0.78, p = 0.08) and dynamic GRE (Az = 0.79, p = 0.12) images. CONCLUSION: Breath-hold T2-weighted fast SE sequence is useful in the detection of regional lymph-node metastases in patients with gastric carcinoma.
OBJECTIVE: The purpose was to examine whether MR and CT imaging can detect extracapsular invasion of hepatocellular carcinoma (HCC) and, if this is possible, to determine its characteristic signs on MR and CT images. MATERIALS AND METHODS: Thirty-eight patients with small HCC (< or = 3.0 cm in diameter) were studied to correlate the findings in surgically resected specimens with the findings on MR and CT images. RESULTS: Ten of 38 patients had histologically proven extracapsular invasion of HCC. Of these 10 patients with extracapsular invasion, partial projections of the tumor into the surrounding area or satellite nodules in the immediate vicinity of the tumor were observed in 9 patients on T1-weighted images and in 5 patients on postcontrast CT images. Partial tumor projection or satellite nodules were not observed in patients without extracapsular invasion of HCC. The detection rate for these characteristic signs was 90% on MR and 50% on CT. CONCLUSION: Magnetic resonance and CT imaging were useful for detection of extracapsular invasion of HCC. The characteristic signs for extracapsular invasion of HCC were partial tumor projection into the surrounding area and satellite nodules in the immediate vicinity of the tumor.
OBJECTIVE: To demonstrate the appearance of the diaphragm on single-slice dynamic MRI. MATERIALS AND METHODS: We evaluated the diaphragm using gadolinium-enhanced single-slice dynamic MR in 53 patients. RESULTS: The diaphragm was partially depicted in 49 cases (92.5%). Its thickest part measured 4.4 +/- 2.2 mm, range 3 to 15 mm. Enhanced high-intensity thin layer structures were partially identified between the diaphragm and liver parenchyma in 46 cases (86.8%) at 16 to 144 s (mean +/- SD, 65.7 +/- 32.6 s) after intravenous injection of Gd-DTPA. CONCLUSION: Dynamic MR has value and limitations in demonstrating the diaphragm.
PURPOSE: Overestimating the size of hepatic malignancy with helical CT during arterial portography (CTAP) can be a potential pitfall in determining liver resection area. We evaluated the prevalence and extent of overestimation of hepatic malignancy on CTAP in correlation with helical equilibrium phase CT (EPCT) and pathologic findings. METHOD: CTAP and EPCT in 47 histologically proven malignant hepatic tumors [33 hepatocellular carcinomas (HCCs) and 14 metastases] in 39 patients were retrospectively studied. Nineteen tumors were resected and pathologically evaluated. RESULTS: The size overestimation ratios (CTAP/EPCT) ranged from 1.02 to 1.56 (mean +/- SD 1.24 +/- 0.16) in HCC and from 1.00 to 2.48 (1.34 +/- 0.42) in metastasis. In 19 surgical specimens, the overestimation ratios (CTAP/specimen) ranged from 1.05 to 1.45 (1.20 +/- 0.13) in HCC and from 1.10 to 1.38 (1.22 +/- 0.10) in metastasis. Histopathologically, flattening of parenchymal structures (100%), atrophy of hepatic cords (95%), sinusoidal congestions (95%), fibrosis and ductular proliferation (58%), and no tumor were seen in peritumoral parenchyma corresponding to perilesional perfusion defects with CTAP. CONCLUSION: CTAP frequently and significantly overestimates the size of malignant hepatic tumors. This phenomenon is attributable to either benign histopathological changes in the perilesional liver parenchyma caused by parenchymal compression or portal venous obstruction by malignant liver tumors or to a siphoning effect by hypervascular neoplasms.
PURPOSE: The purpose of this study was to evaluate the frequency and imaging characteristics of nonpathologic narrowing that is seen in the common hepatic duct on MR cholangiopancreatography (MRCP), which can be caused by impression of the right hepatic artery. METHOD: MRCP images obtained in 52 patients were reviewed by two radiologists who attained consensus for evaluation of the frequency, degree, and length of narrowing of the common hepatic duct. Subsequent endoscopic retrograde cholangiopancreatography, CT, ultrasonography, and follow-up imagings performed in 3-6 months were reviewed for evaluation of the narrowing in the common hepatic duct seen with MRCP images. RESULTS: Smooth narrowing of the common hepatic duct that was presumably due to right hepatic arterial impression was seen in 11 (21%) of 52 patients. The extrinsic impression was severe in none, moderate in five, and subtle in six patients, ranging in length from 4 to 11 mm (mean 7.9 mm). CONCLUSION: Radiologists should avoid misinterpreting a smooth and short narrowing in the common hepatic duct on MRCP images by recognizing the possible presence of the right hepatic artery that makes an impression on the common hepatic duct.
A 78-year-old man presented huge hydronephrosis with a calculus in the left kidney, and underwent left nephroureterectomy under the diagnosis of renal pelvic and ureteral tumor. Histological examination disclosed renal pelvic and ureteral tumors featuring mixed histologic types of carcinoma. Magnetic resonance (MR) imaging was superior to computed tomography (CT) in its complete, detailed demonstration of the renal pelvic lesions. The imaging characteristics of CT, MR imaging, ultrasonography, and retrograde ureterography were discussed in the report.
Delayed contrast enhancement of ascites in MR imaging performed in a 61-year-old cirrhotic patient who developed spontaneous bacterial peritonitis is discussed. Delayed T1-weighted spin-echo MR images after the IV injection of gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) showed remarkable enhancement of ascites. The ascites showed marked elevation in total protein value and neutrophil count, establishing a diagnosis of spontaneous bacterial peritonitis. This case suggests the potency of delayed-enhancement MR imaging for the prediction of spontaneous bacterial peritonitis in cirrhotic patients.
PURPOSE: To assess the reliability of the size-overestimation ratio obtained from spiral CT arterial portography (CTAP) and spiral equilibrium-phase CT (EPCT) in distinguishing malignant focal hepatic lesions from benign ones. METHODS: The CTAP images and EPCT images obtained five minutes after CTAP in 39 patients with focal hepatic lesions were retrospectively analyzed. Fifty-eight lesions (hepatocellular carcinoma [HCC], 33; metastasis, 10; liver cyst, 10; cavernous hemangioma, 2; adenomatous hyperplasia [AH], 2; focal nodular hyperplasia [FNH], 1) had their sizes measured on CTAP and EPCT images using the calipers on the CT console. RESULTS: The size-overestimation ratios (CTAP/EPCT) were 1.24+/-0.15 in HCC, 1.28+/-0.26 in metastasis, 1.02+/-0.23 in liver cyst, 0.98+/-0.34 in cavernous hemangioma, 0.94+/-0.39 in AH, and 1.00 in FNH. Mean size-overestimation ratios for benign- and malignant-lesion groups were 1.00+/-0.37 and 1.25+/-0.18, respectively (p < 0.0001). When a cutoff level was set at 1.05, sensitivity and specificity for malignancy were 91% and 93%, respectively. CONCLUSIONS: In comparison with EPCT, CTAP significantly overestimates the size of malignant hepatic tumors. This phenomenon may be an indicator of hepatic malignancy.
A 71-year-old woman with liver metastases from colon adenocarcinoma in a severe fatty liver underwent T2-weighted MR imaging with conventional spin-echo (CSE), breath-hold fast-SE (BH-fast-SE), respiratory-triggered fast-SE (RT-fast-SE), and multishot SE echo-planar (SE-EP) techniques. CSE and SE-EP T2-weighted images showed the metastases as areas of high signal intensity. In contrast, RT-fast-SE and BH-fast-SE images showed them as areas of low signal intensity. Metastatic tumors in severe fatty liver can be shown as low signal-intensity areas with T2-weighted MR imaging using fast-SE sequences without use of the fat-suppression technique.
Between June 1993 and July 1996, computed tomography during arterial portgraphy (CTAP) was performed on 22 patients with hepatocellular carcinoma (HCC) and liver cirrhosis before surgery. In 17 out of 22 patients, CT hepatic arteriography (CTA) was combined with CTAP. All 22 patients underwent definitive surgery. In 16 patients in which CTA was successfully performed, 20 HCC nodules and 28 pseudolesions were detected. The pseudolesions were depicted larger in size with CTA than with CTAP, formed a variety of shapes, and were enhanced homogeneously, while HCC nodules were depicted larger with CTAP than with CTA, formed a round or wedge shape, and were sometimes enhanced heterogeneously. Recurrence was diagnosed in 9 of 22 patients. Five recurrent lesions in 4 patients were already revealed by pre-operative CTAP. CTA was performed in only 1 of 5 lesions. The diagnostic accuracy for HCC significantly improves by recognizing by recognizing pseudolesions with CTA and CTAP.