Kengo Yoshimitsu

Diffusion-weighted echo-planar MR imaging and ADC mapping in the differential diagnosis of ovarian cystic masses: Usefulness of detecting keratinoid substances in mature cystic teratomas

To elucidate whether apparent diffusion coefficient (ADC) values calculated from echo‐planar diffusion‐weighted MR imaging (EPDWI) are useful in the differential diagnosis of ovarian cystic masses.

Usefulness of apparent diffusion coefficient map in diagnosing prostate carcinoma: Correlation with stepwise histopathology

To elucidate the performance of apparent diffusion coefficient (ADC) map in localizing prostate carcinoma (PC) using stepwise histopathology as a reference.

Natural history of pancreatic intraductal papillary mucinous tumor of branch duct type: follow-up study by magnetic resonance cholangiopancreatography.

Objective: The purpose of this study was to elucidate the natural history of branch duct type pancreatic intraductal papillary mucinous tumor (IPMT) by evaluating serial changes in the magnetic resonance cholangiopancreatography (MRCP) findings of patients diagnosed with pancreatic IPMT of branch duct type. Methods: Thirty-five patients had branch duct type IPMT, including 9 patients with separate lesions, and underwent initial and follow-up MRCP over a period of more than 12 months. The maximum diameter of the cystic lesion, the presence of associated main pancreatic duct (MPD) dilatation, and the presence of a filling defect were evaluated. Serial changes in these findings were analyzed. Results: Tumor enlargement on follow-up MRCP was observed in 7 cases. Of the 29 branch duct IPMTs without associated MPD dilatation or a filling defect identified on initial MRCP, only 1 showed gradual tumor enlargement. In 4 cases, the cyst size decreased on follow-up MRCP. Conclusions: Branch duct type IPMTs grow slowly and can be monitored without operation provided that the tumor shows no associated MPD dilatation or filling defect.

Comparison of helical CT and MR imaging in detecting and staging small pancreatic adenocarcinoma

Abstract.Background: To compare the value of helical computed tomography (CT) and various pulse sequences of magnetic resonance (MR) imaging in the detection and staging of small pancreatic adenocarcinoma. Methods: Small pancreatic adenocarcinomas (≤2 cm in diameter) in eight patients were evaluated with both helical CT and MR imaging. Five MR imaging pulse sequences that included fat-suppressed T1-weighted images and dynamic study using fast multiplanar spoiled gradient-recalled technique were compared for the tumor detectability. To evaluate the tumor vascularity, angiographic findings were also investigated. Results: Helical CT delineated the tumor in five cases, and MR imaging depicted the tumor in seven cases. MR imaging could detect the tumor of 0.8 cm in diameter clearly. Although helical CT and dynamic MR imaging missed the tumor of 2 cm with relative hypervascularity, fat-suppressed T1-weighted MR imaging demonstrated it precisely. As for the tumor staging, MR imaging was equal or slightly superior to helical CT. Conclusion: MR imaging is the first modality of choice to evaluate small pancreatic adenocarcinoma, and fat-suppressed T1-weighted images and dynamic study must be performed.

Validity of preoperative volumetric analysis of congestion volume in living donor liver transplantation using three-dimensional computed tomography

Reconstruction of middle hepatic vein (MHV) tributaries is controversial in right‐lobe living donor liver transplantation (LDLT). This study aimed to evaluate the appropriateness of reconstructing MHV tributaries by volumetry using 3‐dimensional computed tomography (3D‐CT). Between November 2003 and January 2005, 42 donor livers (right‐lobe graft, n = 25; left‐lobe graft, n = 17) were evaluated using this software. The total congestion volume (CV) associated with the MHV tributaries and the inferior right hepatic vein (IRHV), and graft volume (GV) were calculated. In recipients with right‐lobe grafts, CV/(right liver volume [RLV]) and (GV − CV)/(standard liver volume [SLV]) were compared between 2 groups: with reconstruction (n = 16) and without reconstruction (n = 9). To evaluate the influence of CV on the remnant right lobe in donors, total bilirubin was compared between 2 groups: high CV (CV > 20%, n = 13) or low CV (CV ≤ 20%, n = 4). The mean CV/RLV ratio was 32.3 ± 17.1% (V5, 15.2 ± 9.9%; V8, 9.2 ± 4.1%; and IRHV, 8.5 ± 11.4%) and the maximum ratio was as high as 80.8%. The mean (GV − CV)/SLV ratio before reconstruction in patients with or without reconstruction resulted in 33.5 ± 12.8% and 55.4 ± 12.9%, respectively (P < 0.01). In donors, total bilirubin was significantly high in the high CV group on postoperative day 1 compared with the low CV group (P < 0.05). In conclusion, calculation of CV using 3D‐CT software proved to be very useful. We concluded that this evaluation should be an integral part of procedure planning, especially for right‐lobe LDLT. (Liver Transpl 2005;11:1556–1562.)

Hepatocellular carcinoma with a pseudocapsule on gadolinium-enhanced MR images: correlation with histopathologic findings.

PURPOSE To evaluate the characteristics of hepatocellular carcinoma (HCC) with a pseudocapsule on dynamic magnetic resonance (MR) images. MATERIALS AND METHODS The institutional review board approval was obtained, and the requirements for informed consent were waived for this retrospective study. Dynamic MR studies of surgically resected 106 HCCs in 93 patients were retrospectively reviewed. A false-positive fibrous capsule (FC) on dynamic MR images was considered to be a pseudocapsule. Pathologic specimens of HCCs with a pseudocapsule were reviewed. The differences in size, tumor grade, the degree of liver fibrosis and background liver diseases, and the incidence of vascular invasion were compared between HCCs with a pseudocapsule on MR images and those with FC at histologic examination by using Student t, Kruskal-Wallis, and chi(2) tests. RESULTS The sensitivity, specificity, and accuracy of dynamic MR in the diagnosis of histologic FC were 94.0% (47 of 50), 73.2% (41 of 56), and 83.0% (88 of 106), respectively. There were 15 (14.2%) HCCs with a pseudocapsule. The pathologic specimens suggested possible causes of the pseudocapsule that included prominent sinusoids (n = 6), peritumoral fibrosis mimicking bridging fibrosis (n = 3), and both (n = 5). In one case, the capsulated HCC was surrounded by a well-differentiated HCC component. The mean size of a HCC with a pseudocapsule tended to be smaller than that with histologic FC, although it was not significant (mean +/- standard deviation: 2.8 cm +/- 1.0 vs 3.5 cm +/- 2.0, P = .09). Liver cirrhosis was less frequent in HCCs with a pseudocapsule than in those with a histologic FC (one of 14 [7.1%] vs 20 of 49 [40.8%], P < .05). The tumor grades were not significantly different, and the incidence of vascular invasion after standardizing the tumor size (<or=4 cm) was similar (five of 14 [35.7%] vs 12 of 37 [32.4%]). CONCLUSION Dynamic MR imaging is accurate in depicting FC in HCCs. HCC with a pseudocapsule at MR possibly consists of peritumoral sinusoids and/or fibrosis. The pseudocapsule may be similar to histologic FC in terms of tumor invasiveness.

Arterial Blood Supply of Hepatocellular Carcinoma and Histologic Grading: Radiologic-Pathologic Correlation

OBJECTIVE The objective of our study was to clarify the sequential changes of arterial blood supply during the development of hepatocellular carcinoma (HCC) with an emphasis on its late stage. MATERIALS AND METHODS Sixty HCC nodules were confirmed at pathology in 59 patients who had undergone CT hepatic arteriography and CT during arterioportography (CTAP). Lesions were classified into one of the four groups: group 1, nodules that appeared to show preserved portal perfusion on CTAP and showed hypo- or isoattenuation on CT hepatic arteriography; group 2, very hyperattenuating on CT hepatic arteriography; group 3, hyperattenuating on CT hepatic arteriography; and group 4, hypo- or isoattenuating on CT hepatic arteriography. Groups 2, 3, and 4 showed the portal perfusion defect on CTAP. These hemodynamic patterns were compared among different histologic grades. We also examined the number of unpaired arteries and the Ki-67 labeling index of the tumor pathologically. RESULTS The numbers of lesions in each group were as follows for groups 1, 2, 3, and 4, respectively: 17, one, two, and 0 well-differentiated HCCs; 0, 10, nine, and one moderately differentiated HCC; and 0, three, 12, and five poorly differentiated HCCs. The lesions showed significantly different hemodynamic patterns among different histologic grades (Cramers V = 0.6919, p < 0.0001). The number of unpaired arteries showed a strong correlation with Ki-67 labeling index in well-differentiated HCC and moderately differentiated HCC (rho = 0.673, p < 0.0001) and a moderate inverse correlation with Ki-67 labeling index in poorly differentiated HCC (rho = -0.540, p = 0.0185). CONCLUSION In the late stage of HCC development, the arterial blood supply significantly decreases as the histologic grade progresses.

Diagnostic performance of apparent diffusion coefficient for predicting histological grade of hepatocellular carcinoma

OBJECTIVE To investigate whether the histological grade of hepatocellular carcinoma (HCC) can be predicted using the apparent diffusion coefficient (ADC). MATERIALS AND METHODS This retrospective study group consisted of 80 patients with 85 surgically resected HCCs who underwent preoperative MRI exams including diffusion-weighted imaging. The tumors were histologically classified into five groups as follows: five well (w-), 17 well to moderately (wm-), 37 moderately (m-), 16 moderately to poorly (mp-), and 10 poorly (p-) differentiated HCCs. For ADC measurement of each HCC, the largest possible region of interest was placed on the solid region on the ADC map where ADC was considered to be the lowest. The average ADCs of the five histological grades were compared using Spearmans rank correlation test and Students t-test, and the diagnostic performance of ADC for mp- and p-HCCs was also evaluated using a receiver operating characteristic-based positive test. RESULTS The average ADC of p-HCC (0.76±0.10×10(-3) mm2/s) was significantly lower than those of the other four histological grades. The average ADC of mp-HCCs (0.99±0.20×10(-3) mm2/s) was significantly lower than those of w-, wm- and m-HCCs. The sensitivity, specificity, PPV, NPV, and accuracy, when an ADC of 0.972 or lower was considered an indicator of mp- and p-HCCs, were 73.1%, 72.9%, 54.3%, 86.0% and 72.9%, respectively. CONCLUSION ADCs of mp- and p-HCCs were lower than those of w-, wm- and m-HCCs. ADC can contribute to radiological diagnosis of poorly differentiated components in HCCs.

Short-term intensive treatment for donors with hepatic steatosis in living-donor liver transplantation.

Background. The use of steatotic livers is associated with increased primary nonfunction in liver transplantation. To reduce the risk of liver injury, we applied a short-term combination therapy of diet, exercise and drugs for 11 living-donor liver transplantation (LDLT) candidates with steatosis. Methods. Subjects were treated with a protein-rich (1000 kcal/day) diet, exercise (600 kcal/day), and bezafibrate (400 mg/day) for 2–8 weeks. Results. The treatment significantly improved macrovesicular steatosis (30±4% vs. 12±2% [mean±SEM], P= 0.0028). Body weight and BMI were significantly reduced (73.7±3.2 kg vs. 66.9±2.9 kg, P=0.0033, 26.4±0.7 kg/m2 vs. 24.1±0.8 kg/m2, P=0.0033). The treatment completely normalized liver function tests and lipid metabolism. Seven treated liver grafts (left lobe) were transplanted to the recipients. We compared transplanted graft function and resected liver function of donors using parameters such as peak total bilirubin, prothrombin time at postoperative day 3, and peak alanine aminotransferase between treated liver (n=7) and donor liver without hepatic steotosis (n=37). The transplanted grafts showed good liver functions, and there was no difference between them with respect to functional parameters. The treated donors also showed good liver functions, and no significant differences in functional parameters. Conclusions. The results of this study indicate that our short-term treatment effectively reduced steatosis and contributed to safer LDLT. Our findings also suggest that even severely steatotic livers can be used for LDLT grafting subsequent to our short-term treatment regimen.

MRI of groove pancreatitis.

PURPOSE The purpose of this work is to describe the findings on MRI in patients with groove pancreatitis, a specific form of chronic pancreatitis affecting the groove between the pancreatic head, the duodenum, and the common bile duct. METHOD MR images, including MR cholangiopancreatography, of five patients with groove pancreatitis were reviewed. Three patients underwent pancreatoduodenectomy due to serve duodenal stenosis, and the MR findings were compared to the histologic findings. RESULTS A sheet-like mass was demonstrated between the pancreatic head and the duodenum in all patients. The masses were hypointense relative to pancreatic parenchyma on T1-weighted images and iso- to slightly hyperintense on T2-weighted images. After administration of Gd-DTPA, the masses showed delayed enhancement. Histologically, fibrous scar tissue was detected in the groove. CONCLUSION MR images can clearly demonstrate the fibrous tissue in the groove in groove pancreatitis, and MR cholangiopancreatography can also provide useful information.