M Hori

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (546)2472.27 Total impact

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    ABSTRACT: The objective of this study was to identify features of preoperative computed tomography (CT) scans that can best predict outcomes of primary cytoreductive surgery in ovarian cancer patients. Preoperative CT scans of 98 patients were evaluated retrospectively. Multiple logistic regression analysis was used to develop two models. Although optimal surgical reduction was attempted in 98 patients, 12 had suboptimal results. Having tumor implants on the small or large bowel mesenteries (any size) or at other sites (cutoff index: ≥ 1 cm) was found to be significant (p < 0.001) for predicting a suboptimal cytoreduction outcome. Two predictive models were created using multiple logistic regression analysis; both consider diffuse peritoneal thickening (DPT), infrarenal para-aortic or pelvic lymph node involvement, a bowel encasement tumor (≥ 2 cm), and any tumor implants in the cul-de-sac as significant. Model 1 adds consideration to any tumors in the pelvic or retroperitoneum and has an accuracy of 90.8% for predicting a suboptimal surgery. Model 2 (accuracy of 93.9%) adds to the core of predictors the presence of tumor implants on the bowel mesenteries (≥ 2 cm), omental caking (≥ 2 cm), and ascites fluid. Using specific CT findings from patients with ovarian cancer, we have devised two predictive models that have an accuracy of greater than 90% for predicting whether cytoreductive surgery will completely remove all tumor tissue, which should greatly aid in the differential decision-making as to whether to attempt cytoreductive surgery first, or to advance directly to neoadjuvant chemotherapy.
    Archives of Gynecology 02/2011; 284(6):1501-7. DOI:10.1007/s00404-011-1864-3 · 1.28 Impact Factor
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    ABSTRACT: To demonstrate that positron emission tomography (PET)/magnetic resonance imaging (MRI) fusion was feasible in characterizing pancreatic tumors (PTs), comparing MRI and computed tomography (CT) as mapping images for fusion with PET as well as fused PET/MRI and PET/CT. We retrospectively reviewed 47 sets of (18)F-fluorodeoxyglucose ((18)F -FDG) PET/CT and MRI examinations to evaluate suspected or known pancreatic cancer. To assess the ability of mapping images for fusion with PET, CT (of PET/CT), T1- and T2-weighted (w) MR images (all non-contrast) were graded regarding the visibility of PT (5-point confidence scale). Fused PET/CT, PET/T1-w or T2-w MR images of the upper abdomen were evaluated to determine whether mapping images provided additional diagnostic information to PET alone (3-point scale). The overall quality of PET/CT or PET/MRI sets in diagnosis was also assessed (3-point scale). These PET/MRI-related scores were compared to PET/CT-related scores and the accuracy in characterizing PTs was compared. Forty-three PTs were visualized on CT or MRI, including 30 with abnormal FDG uptake and 13 without. The confidence score for the visibility of PT was significantly higher on T1-w MRI than CT. The scores for additional diagnostic information to PET and overall quality of each image set in diagnosis were significantly higher on the PET/T1-w MRI set than the PET/CT set. The diagnostic accuracy was higher on PET/T1-w or PET/T2-w MRI (93.0 and 90.7%, respectively) than PET/CT (88.4%), but statistical significance was not obtained. PET/MRI fusion, especially PET with T1-w MRI, was demonstrated to be superior to PET/CT in characterizing PTs, offering better mapping and fusion image quality.
    International Journal of Clinical Oncology 02/2011; 16(4):408-15. DOI:10.1007/s10147-011-0202-x · 2.17 Impact Factor
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    ABSTRACT: To investigate the ability of T1 mapping of liver on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging for the estimation of liver function. Local institutional review board approved this study. Ninety-one patients (64 men, 27 women; mean age, 67.4 years) were classified into 4 groups as follows: normal liver function (NLF), n = 16; chronic hepatitis (CH), n = 38; liver cirrhosis with Child-Pugh A (LCA), n = 20; and liver cirrhosis with Child-Pugh B (LCB), n = 17. Look-Locker sequences (single slice multiphase imaging using gradient-echo sequence with inversion recovery pulse) were obtained before and at 3, 8, 13, and 18 minutes after Gd-EOB-DTPA administration. T1 mapping of liver parenchyma was calculated from the Look-Locker sequence. T1 relaxation time of liver and reduction rate of T1 relaxation time between pre- and postcontrast enhancement were measured. The Bonferroni t test was used for comparisons between the 4 groups. Precontrast T1 relaxation times were significantly longer for LCA and LCB than for NLF, and that of LCB was longer than that of chronic hepatitis (P < 0.05). Postcontrast T1 relaxation times were significantly longer for LCB than for other groups at all time points. Those of LCA were longer than those of NLF at all time points. Reduction rates were significantly lower for LCB than for the other groups at ≥8 minutes. Evaluation of hepatic uptake of Gd-EOB-DTPA using T1 mapping of liver parenchyma can help estimate liver function.
    Investigative radiology 02/2011; 46(4):277-83. DOI:10.1097/RLI.0b013e318200f67d · 4.85 Impact Factor
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    ABSTRACT: PURPOSE Although the use of thinner CT slices may improve the accuracy of CT liver volumetry because of reduced partial volume effects, the increased number of images produces a larger workload. No studies have shown systematically a quantitative estimate for the effects of slice thickness on the accuracy of volume calculations and it is unclear how thin CT images should be for optimal use in clinical routines. In this study, we evaluated the relationship between slice thickness and calculated liver volume on CT liver volumetry for living-related liver transplantation. METHOD AND MATERIALS Twenty adult potential liver donors (12 men, 8 women; mean age, 39 years; range, 24-64 years) underwent CT with a 64-channel multidetector-row CT scanner after intravenous injection of 150 mL of contrast material (300 mgI/mL). Four image sets with slice thicknesses of 0.625 mm (isotropic), 2.5 mm, 5 mm, and 10 mm were used. First, we applied our semi-automated liver extraction software to the four sets of portal venous-phase CT images with different slice thicknesses to obtain the initial liver boundaries. An abdominal radiologist reviewed and edited the initial boundaries on all images to optimize accuracy. Finally, liver volumes were determined by counting of the voxels within the liver boundary. Calculated volumes were compared among the four slice thicknesses. RESULTS The mean liver volumes estimated with CT liver volumetry were 1322.5 ± 259.5 cm3 on 0.625-mm, 1313.3 ± 257.8 cm3 on 2.5-mm, 1310.3 ± 260.0 cm3 on 5-mm, and 1268.2 ± 256.8 cm3 on 10-mm images. The volumes calculated for 0.625-mm images were significantly larger than those for thicker images (Dunnett pairwise multiple comparisons t test, P<.0001 for all comparison pairs). CONCLUSION Liver volumes calculated on 2.5-mm or thicker images were significantly smaller than volumes calculated on 0.625-mm-thick 3D isotropic images. However, if a maximum error of 2% in the calculated liver volume is permitted, 5-mm-thick images are acceptable for CT liver volumetry, and 3D isotropic images are not required. CLINICAL RELEVANCE/APPLICATION The accuracy of CT liver volumetry can be improved by using thinner slices. However, if a maximum error of 2% is permitted, 5-mm-thick images are acceptable, and 3D isotropic images are not required.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 12/2010
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    ABSTRACT: PURPOSE Differentiation between benign and malignant liver tumors at CT can be difficult with overlapping imaging features, leading to required biopsy. Our purpose was to develop a CADf scheme to improve the diagnostic accuracy and reduce “unnecessary” biopsies. METHOD AND MATERIALS Our database consisted of 39 tumors, including 15 hepatocellular carcinomas (HCCs) in 11 patients and 24 hemangiomas in 12 patients, selected to cover a wide spectrum of tumor patterns. All lesions were confirmed either pathologically or with follow-up imaging studies over 2 years. Lesion sizes ranged from 8-69 (mean: 23) mm. Scans were acquired with a multi-detector (16 or 64 rows) CT system with 2-5 mm reconstruction slice thickness. We developed CADf for determining the likelihood of malignancy. First, a geodesic active contour model with level-set algorithms segmented the liver accurately. Then, nonlinear gray-scale conversion enhanced both hyper- and hypo-dense tumors in the segmented liver. A gradient magnitude filter followed by a thinning operator determined the precise locations of the tumor boundaries. A watershed algorithm segmented tumors by using the boundary locations for feature analysis. Based on eight morphologic and texture features selected with stepwise feature selection, artificial neural network regression (ANNR) capable of operating on continuous values was trained to distinguish malignant from benign tumors. We transformed the ANNR’s output values to the likelihood of malignancy with a maximum-likelihood estimated binormal model. The performance of our ANNR was compared with linear discriminant analysis (LDA) as reference. RESULTS Our ANNR-based CADf achieved an area under the receiver operating characteristic curve of 0.96 in differentiation between HCCs and hemangiomas in a leave-one-lesion-out cross-validation test, whereas LDA achieved 0.79. The difference was statistically significant (P=.03). Our scheme provided an accurate likelihood of malignancy for “difficult” cases, e.g., a low value (5%) for an HCC-looking hemangioma. At a specific operating point, our scheme correctly characterized 100% (15/15) of HCCs and 92% (22/24) of hemangiomas. CONCLUSION Our CADf was able accurately to differentiate HCC from hemangioma at CT and provided an accurate likelihood of malignancy. CLINICAL RELEVANCE/APPLICATION CADf could be useful for differentiating malignant from benign liver tumors in CT, potentially reducing unnecessary biopsies.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010
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    ABSTRACT: PURPOSE To retrospectively investigate incidence and risk factors for development of hypervascular hepatocellular carcinoma (HCC) from hypo-intense nodules at hepatobiliary phase (HBP) of Gd-EOB-DTPA enhanced MRI (EOB-MRI). METHOD AND MATERIALS In 140 patients (pts) who underwent EOB-MRI for known or suspected HCC at least twice, 50 pts with 50 hepatic nodules (the largest nodule was selected if several nodules existed for each patient) which showed both hypo-intense at HBP and hypovascularity at arterial phase, compared to surrounding liver, were enrolled in this study. Arterial phase and hepatobiliary phase (at 20 min post injection) were obtained after bolus EOB injection (0.1mL/kg, a rate of 2mL/sec) by 1.5 T or 3T MRI at 61 - 477 days (mean 190 days) as interval date. 50 hypo-intense nodules at HBP in 1st EOB-MR examination (baseline) were followed, and outcome was analyzed. Incidence rate of development of hypervascular HCC from hypo-intense nodule at HBP was investigated. We employed the criteria as cut-off size (group A ≥ 15 mm, B < 15mm) of hypo-intense nodule at baseline and growth size (group C ≥ 0.015 mm/day, D < 0.015 mm/day) of hypo-intense nodule compared to previous MR. Incidence of developing hypervascular HCC from hypo-intense nodule was compared between group A and B, group C and D. RESULTS Hypervascular HCCs were confirmed in 5 pts by EOB-MR, 6 pts by dynamic CT and 1 pt by CTHA, and the incidence rate of change from hypo-intense nodule to hypervascular HCC was 24% (12 of 50 pts). Intervals between MR examinations in group A (189+/-104 days) and B (200+/-120 days), or C (185+/-110 days) and D (185+/-114 days) were not significantly different (P=0.94, 0.98, respectively, Mann-Whitney’s test). Incidence rate from hypo-intense nodule to hypervascular HCC in group A (3 of 9 pts; 33%) was higher than that (9 of 41 pts; 22%) of group B (P=0.5), and that of group C (8 of 26 examinations; 31%) was significantly higher than that of group D (4 of 54 examinations; 7%) (P=0.006). CONCLUSION The incidence rate of developing hypervascular HCC from hypo-intense nodule was 24%. We should pay attention in growth size ≥ 0.015 mm/day of hypo-intense nodule at HBP compared to previous EOB-MRI. CLINICAL RELEVANCE/APPLICATION EOB-MRI plays a major role in surveillance for chronic liver disease, and incidence of developing hypervascular HCC from hypo-intense nodules at HBP is 24% (mean interval of 190 days of follow-up MR).
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010
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    ABSTRACT: To compare a three-dimensional (3D) T2-weighted turbo spin-echo (TSE) magnetic resonance (MR) sequence (VISTA; Philips Medical Systems, Best, the Netherlands) with a two-dimensional (2D) T2-weighted TSE sequence in terms of image quality, signal intensity (SI) difference ratios, conspicuity, and staging of uterine tumors. This retrospective study was approved by the institutional review board, and informed consent was waived. Sixty-one women (mean age, 53.0 years ± 13.7 [standard deviation]; range, 30-87 years) with cervical carcinoma (n = 28), endometrial carcinoma (n = 21), or leiomyoma (n = 30) of the uterus were included. Patients underwent T2-weighted MR imaging at 3 T with both 1-mm-thick 3D and 5-mm-thick 2D T2-weighted TSE sequences. Three-dimensional T2-weighted TSE images were reconstructed at 5-mm thickness with the aid of a workstation. Quantitative analyses of signal-to-noise ratio (SNR) and SI difference ratios between tumors and other tissues and qualitative analyses of image quality and tissue conspicuity were performed. Two radiologists independently assessed local-regional staging for carcinomas. Quantitative values, qualitative scores, and tumor staging were analyzed by using the paired t test, Wilcoxon signed rank test, and McNemar test, respectively. Mean myometrial SNR was higher on 3D than 2D images (14.3 vs 9.8; P < .0001). Mean SI difference ratios between cervical (0.45 vs 0.34; P < .0001) or endometrial (0.46 vs 0.40; P = .044) carcinomas and gluteal muscle were higher on 3D images, but those between leiomyoma and myometrium (0.33 vs 0.43; P < .0001) were lower than those on 2D images. Image quality (P = .0004) and carcinoma conspicuity (P < .0005) were superior with the 3D T2-weighted TSE sequence. Although multiplanar reconstruction of 3D T2-weighted TSE images was useful for staging in one case, there were no significant differences between 3D and 2D T2-weighted TSE imaging in accuracy of staging for the two readers for cervical or endometrial carcinoma. The 3D T2-weighted TSE sequence showed certain advantages over the 2D T2-weighted TSE sequence, and it has the potential to improve the performance of MR imaging for the evaluation of uterine carcinoma.
    Radiology 11/2010; 258(1):154-63. DOI:10.1148/radiol.10100866 · 6.21 Impact Factor
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    ABSTRACT: To retrospectively investigate enhancement patterns of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine (Gd-EOB-DTPA)-enhanced MRI in relation to histological grading and portal blood flow. Sixty-nine consecutive patients with 83 histologically proven HCCs and DNs were studied. To assess Gd-EOB-DTPA uptake, we calculated the EOB enhancement ratio, which is the ratio of the relative intensity of tumorous lesion to surrounding nontumorous area on hepatobiliary phase images (post-contrast EOB ratio) to that on unenhanced images (pre-contrast EOB ratio). Portal blood flow was evaluated by CT during arterial portography. Post-contrast EOB ratios significantly decreased as the degree of differentiation declined in DNs (1.00 ± 0.14) and well, moderately and poorly differentiated HCCs (0.79 ± 0.19, 0.60 ± 0.27, 0.49 ± 0.10 respectively). Gd-EOB-DTPA uptake, assessed by EOB enhancement ratios, deceased slightly in DNs and still more in HCCs, while there was no statistical difference in the decrease between different histological grades of HCC. Reductions in portal blood flow were observed less frequently than decreases in Gd-EOB-DTPA uptake in DNs and well-differentiated HCCs. Reduced Gd-EOB-DTPA uptake might be an early event of hepatocarcinogenesis, preceding portal blood flow reduction. The hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI may help estimate histological grading, although difficulties exist in differentiating HCCs from DNs.
    European Radiology 10/2010; 20(10):2405-13. DOI:10.1007/s00330-010-1812-9 · 4.34 Impact Factor
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    Journal of Internal Medicine 10/2010; 268(4):390-4. DOI:10.1111/j.1365-2796.2010.02262.x · 5.79 Impact Factor
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    ABSTRACT: To compare enhancenent patterns of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) between gadoxetate- and ferucarbotran-enhanced MRI. Patients recruited from ultrasound surveillance for HCC in chronic liver diseases were enrolled in this prospective study approved by institutional review board. Thirty-six patients with 37 histologically proven HCC, including 22 well-differentiated HCCs (wHCC), 15 moderately to poorly differentiated HCCs (mpHCCs), and 4 DNs, underwent gadoxetate-enhanced and ferucarbotran-enhanced MRI. We compared hepatobiliary phase image of gadoxetate-enhanced MRI with ferucarbotran-enhanced MR image regarding signal intensity of HCC and DN relative to surrounding liver parenchyma. We calculated contrast ratios between tumor and liver on pre-enhancement, hepatobiliary phase of gadoxetate-enhanced MRI and ferucarbotran-enhanced MRI. On ferucarbotran-enhanced MRI, all mpHCCs showed hyper-intensity, while 14 wHCCs (14/22;63%) showed iso-intensity. On hepatobiliary phase of gadoxetate-enhanced MRI, 13 mpHCCs (13/15;86%) and 20 wHCCs (20/22;91%) showed hypo-intensity. Two DNs and the other two showed iso- and hypo-intensity, respectively, on gadoxetate-enhanced MRI, whereas all DNs revealed iso-intensity on ferucarbotran-enhanced MRI. Gadoxetate-postcontrast ratio was significantly lower than ferucarbotran-postcontrast ratio in wHCC (P = 0.015). The uptake function of hepatocytes that are targeted by gadoxetate is more sensitive than that of Kupffer cells targeted by ferucarbotran in stepwise hepatocarcinogenesis.
    Journal of Magnetic Resonance Imaging 10/2010; 32(4):903-13. DOI:10.1002/jmri.22333 · 2.57 Impact Factor
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    ABSTRACT: A computational framework is presented, based on statistical shape modelling, for construction of race-specific organ models for internal radionuclide dosimetry and other nuclear-medicine applications. This approach was applied to the construction of a Japanese liver phantom, using the liver of the digital Zubal phantom as the template and 35 liver computed tomography (CT) scans of male Japanese individuals as a training set. The first step was the automated object-space registration (to align all the liver surfaces in one orientation), using a coherent-point-drift maximum-likelihood alignment algorithm, of each CT scan-derived manually contoured liver surface and the template Zubal liver phantom. Six landmark points, corresponding to the intersection of the contours of the maximum-area sagittal, transaxial and coronal liver sections were employed to perform the above task. To find correspondence points in livers (i.e. 2000 points for each liver), each liver surface was transformed into a mesh, was mapped for the parameter space of a sphere (parameterisation), yielding spherical harmonics (SPHARMs) shape descriptors. The resulting spherical transforms were then registered by minimising the root-mean-square distance among the SPHARMs coefficients. A mean shape (i.e. liver) and its dispersion (i.e. covariance matrix) were next calculated and analysed by principal components. Leave-one-out-tests using 5-35 principal components (or modes) demonstrated the fidelity of the foregoing statistical analysis. Finally, a voxelisation algorithm and a point-based registration is utilised to convert the SPHARM surfaces into its corresponding voxelised and adjusted the Zubal phantom data, respectively. The proposed technique used to create the race-specific statistical phantom maintains anatomic realism and provides the statistical parameters for application to radionuclide dosimetry.
    Radiation Protection Dosimetry 09/2010; 141(2):140-8. DOI:10.1093/rpd/ncq164 · 0.91 Impact Factor
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    ABSTRACT: Representation and evaluation methods for statistically predicting organ shapes from neighboring organ shapes are described. In order to fully utilize the constraints on interrelations of multiple organ shapes, various extents of sub-shapes of organs are considered based on their proximity instead of just using the whole organ shapes. The prediction power are evaluated for various extents of sub-shapes and enhanced by their integration. Experimental results using shape datasets of several organs in the abdominal domain demonstrate the effective of the proposed methods.
    Software Engineering and Data Mining (SEDM), 2010 2nd International Conference on; 07/2010
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    ABSTRACT: Catheterization is the treatment insert tube which name is catheter from thigh's or wrist's artery and discharge fluid, give medicine to affected area directly etc. Recently this treatment is commonly performed because make only a small hole to the patient body thus patient bears little risks. At the catheterization, expert surgeon's experience and knowledge are needed for making optimal shape of guidewire. There is not enough established objective criterion to decide the shape of guidewire. Therefore this research's goal is to develop semi-automated system for the determination of the optimal shape of guidewire's tip at the vessel bifurcation. In the previous research, we determined the optimal shape of guidewire two-dimensionally to reduce computation time. However, two-dimensionally determination has problem which is not shown real movement of the treatment. In this research, we extend the previous method to determine the optimal shape three-dimensionally and simulate more realistic movement of guidewire. In order to reduce the computation time, we consider the real operation of catheterization and the position of the tip of the catheter in the vessel. We decided position and direction of tip of catheter manually in this research. Moreover, we perform the phantom experiment to validate the proposed method whether the guidewire could reach the target branch vessel using the estimated shape of the guidewire. At the phantom experiment and 3D determination by proposed method, we got same result and it conforms to the real. One of the shapes of the guidewire's tip which is "A" arrive to target branch thus the other shape which is "B" doesn't arrive to target branch.
    Software Engineering and Data Mining (SEDM), 2010 2nd International Conference on; 07/2010
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    ABSTRACT: To investigate the mechanism of enhancement of hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced hepatobiliary phase magnetic resonance (MR) images and to characterize HCC thus enhanced. This retrospective study was approved by the institutional review board, and patient informed consent for research use of the resected specimen was obtained. MR images in 25 patients (20 men, five women; mean age, 68 years; range, 49-82 years) with 27 resected hypervascular HCCs (one well, 13 moderately, 13 poorly differentiated) that demonstrated hepatocyte-selective enhancement on gadoxetic acid-enhanced MR images, were quantitatively studied, and findings were correlated with results of immunohistochemical staining for a sinusoidal transporter, organic anion transporting polypeptide (OATP) 1B1 (OATP1B1) and/or OATP1B3 (OATP1B1 and/or -1B3), and a canalicular transporter, multidrug resistance-associated protein 2 (MRP2), and also with bile accumulation in tumors. Statistical analysis was performed with the Student t test and Scheffé post hoc test. Combined with positive OATP1B1 and/or -1B3 expression (O+), two patterns of MRP2 expression contributed to high enhancement: decreased expression (M-, n = 3) and increased expression at the luminal membrane of pseudoglands (M+[P], n = 3). Nodules without OATP1B1 and/or -1B3 expression (O-, n = 13) and nodules with O+ associated with increased MRP2 expression only at the canaliculi (M+[C], n = 8) induced significantly lower enhancement than those with the two expression patterns described before (O+/M- group vs O- group, P = .002; O+/M- group vs O+/M+[C] group, P = .047; O+/M+[P] group vs O- group, P < .001; O+/M+[P] group vs O+/M+[C] group, P < .001). Nodules with bile pigment (n = 12) showed significantly higher enhancement (P = .004); all five nodules (one well differentiated HCC, four moderately differentiated HCCs), which were enhanced more than adjacent liver parenchyma, contained bile pigment. High hepatocyte-selective enhancement is induced by expression patterns of transporters, which may result in accumulation of gadoxetic acid in cytoplasm of tumor cells or in lumina of pseudoglands. An HCC with gadoxetic acid enhancement is characterized by bile accumulation in tumors.
    Radiology 06/2010; 255(3):824-33. DOI:10.1148/radiol.10091557 · 6.21 Impact Factor
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    ABSTRACT: Methods: The authors developed a computerized liver extraction scheme based on geodesic active contour segmentation coupled with level-set contour evolution. First, an anisotropic diffusion filter was applied to portal-venous-phase CT images for noise reduction while preserving the liver structure, followed by a scale-specific gradient magnitude filter to enhance the liver boundaries. Then, a nonlinear grayscale converter enhanced the contrast of the liver parenchyma. By using the liver-parenchyma-enhanced image as a speed function, a fast-marching level-set algorithm generated an initial contour that roughly estimated the liver shape. A geodesic active contour segmentation algorithm coupled with level-set contour evolution refined the initial contour to define the liver boundaries more precisely. The liver volume was then calculated using these refined boundaries. Hepatic CT scans of 15 prospective liver donors were obtained under a liver transplant protocol with a multidetector CT system. The liver volumes extracted by the computerized scheme were compared to those traced manually by a radiologist, used as "gold standard." Results: The mean liver volume obtained with our scheme was 1504 cc, whereas the mean gold standard manual volume was 1457 cc, resulting in a mean absolute difference of 105 cc (7.2%). The computer-estimated liver volumetrics agreed excellently with the gold-standard manual volumetrics (intraclass correlation coefficient was 0.95) with no statistically significant difference (F=0.77; p(F < f)=0.32). The average accuracy, sensitivity, specificity, and percent volume error were 98.4%, 91.1%, 99.1%, and 7.2%, respectively. Computerized CT liver volumetry would require substantially less completion time (compared to an average of 39 min per case by manual segmentation). Conclusions: The computerized liver extraction scheme provides an efficient and accurate way of measuring liver volumes in CT.
    Medical Physics 05/2010; 37(5):2159-66. DOI:10.1118/1.3395579 · 3.01 Impact Factor
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    ABSTRACT: Kupffer cell imaging is a powerful tool for the detection of liver cancer. This diagnostic procedure depends on the faculty of the reticuloendothelial system (RES) which takes up foreign bodies, including small particles. The current study aimed to develop a novel RES targeting liposomal contrast agent that functionalized with serine or mannose, the moiety specifically binding to a corresponding receptor on phagocytic cells. Liposomes loaded with non-ionic X-ray contrast media, Iohexol, were prepared by supercritical carbon dioxide reverse-phase evaporation method and were intravenously injected to healthy rabbits in order to evaluate the liver parenchymal enhancement in X-ray computed tomography (CT). From 10 to 40 min after injection, the mean enhancement value of the liver parenchyma approached 45 and 34 Hounsfield units (HU) when serine-modified iodinated liposomal contrast agent (ILCA) and mannose-modified ILCA were applied, respectively. The tumor-to-liver contrast values were also evaluated after the administration of the prepared ILCA to rabbits with VX-2 carcinoma. For serine-modified ILCA, tumor-to-liver contrast was 82 HU at 1 min and >24 HU at 10-40 min; for mannose-modified ILCA, the values were 58 HU at 0.5 min and >21 HU at 10-40 min. These vales estimated from the region of intrest and the imaging figures of liver indicate the potential of ILCA for clinical use.
    Contrast Media & Molecular Imaging 03/2010; 5(3):140-6. DOI:10.1002/cmmi.377 · 2.87 Impact Factor
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    ABSTRACT: Automatic liver segmentation on CT images is challenging because the liver often abuts other organs of a similar density. Our purpose was to develop an accurate automated liver segmentation scheme for measuring liver volumes. We developed an automated volumetry scheme for the liver in CT based on a 5 step schema. First, an anisotropic smoothing filter was applied to portal-venous phase CT images to remove noise while preserving the liver structure, followed by an edge enhancer to enhance the liver boundary. By using the boundary-enhanced image as a speed function, a fastmarching algorithm generated an initial surface that roughly estimated the liver shape. A geodesic-active-contour segmentation algorithm coupled with level-set contour-evolution refined the initial surface so as to more precisely fit the liver boundary. The liver volume was calculated based on the refined liver surface. Hepatic CT scans of eighteen prospective liver donors were obtained under a liver transplant protocol with a multi-detector CT system. Automated liver volumes obtained were compared with those manually traced by a radiologist, used as "gold standard." The mean liver volume obtained with our scheme was 1,520 cc, whereas the mean manual volume was 1,486 cc, with the mean absolute difference of 104 cc (7.0%). CT liver volumetrics based on an automated scheme agreed excellently with "goldstandard" manual volumetrics (intra-class correlation coefficient was 0.95) with no statistically significant difference (p(F<=f)=0.32), and required substantially less completion time. Our automated scheme provides an efficient and accurate way of measuring liver volumes.
    Proceedings of SPIE - The International Society for Optical Engineering 03/2010; DOI:10.1117/12.843950 · 0.20 Impact Factor
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    ABSTRACT: To compare the diagnostic performance of magnetic resonance (MR) imaging and multidetector row computed tomography (MDCT) for an anomalous pancreaticobiliary ductal junction (PBJ). This study included 26 patients who underwent MR imaging, MDCT, and endoscopic retrograde cholangiopancreatography. Seventeen of the patients were diagnosed by endoscopic retrograde cholangiopancreatography as having an anomalous PBJ. Three radiologists independently reviewed MR images alone, contrast-enhanced CT images alone, and MR images and CT images combined. Receiver operating characteristic curve analysis was used to compare diagnostic capabilities. The mean area under the receiver operating characteristic curve (Az [95% confidence interval]) was 0.75 (0.73-0.77) for MR imaging alone, 0.79 (0.70-0.89) for CT alone, and 0.84 (0.82-0.86) for the 2 modalities combined. Only between the combination and MR imaging alone was there significant difference in Az value (P < 0.05). The diagnostic performance of MR imaging and MDCT was equivalent for an anomalous PBJ. The addition of MDCT to MR imaging improved the diagnostic performance.
    Journal of computer assisted tomography 01/2010; 34(5):725-31. DOI:10.1097/RCT.0b013e3181e23ff2 · 1.38 Impact Factor
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    ABSTRACT: PURPOSE Our purpose was to evaluate the usefulness of CADe of polyps in improving the sensitivity of expert radiologists in the detection of “difficult” polyps which reporting radiologists initially “missed” in CTC in a multicenter clinical trial or rated “difficult” in our retrospective review. METHOD AND MATERIALS We developed an advanced CADe system consisting of colon segmentation based on anatomy-based extraction and colon-based analysis, detection of polyp candidates based on morphologic analysis of the segmented colon, and a mixture of expert 3D massive-training artificial neural networks for reduction of multiple types of false positives (FPs). We applied our CADe scheme to 30 CTC cases, of which 20 cases had 23 polyps ≥ 6mm (mean: 10 mm) including 14 “missed” and 7 “difficult” polyps and 10 were negative cases. Four board-certified abdominal radiologists including 3 CTC experts participated in our observer performance study. They read 60 supine and prone CTC studies of the 30 patients on a CTC workstation. They were asked, first without and then with CADe, to indicate the location of polyps and their confidence level regarding the presence of the polyps. They were free to use 3D endoluminal or 2D multiplanar views for polyp detection and problem solving. They were blinded to the prevalence of polyps, but told the general performance of our CADe. The diagnostic performance was evaluated by using jackknife alternative free-response receiver-operating characteristic (JAFROC) analysis. RESULTS Our CADe achieved a sensitivity of 74% (17/23) with 3.1 (93/30) FPs per patient. With CADe, the diagnostic performance of radiologists in terms of the average figure of merit (i.e., area under the ROC curve) in the JAFROC analysis was statistically significantly improved from 0.79 to 0.83 (P=.006). The positive predictive value was also improved from 57% to 67% with CADe (P=.098), while the average by-polyp sensitivity of radiologists was improved by 10% at a statistically significant level (P=.037). The average reading time without and with CADe was 12 and 2 min per case, respectively. CONCLUSION Our CADe improved the diagnostic performance of radiologists, including expert readers, and had a great impact in detection of difficult and initially-missed polyps in CTC. CLINICAL RELEVANCE/APPLICATION Observer performance study demonstrated that CADe was effective in improving expert radiologists’ performance in detection of difficult polyps in CTC.
    Proceedings of RSNA Annual Meeting, Chicago, IL; 01/2010
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    ABSTRACT: PURPOSE Liver cancer is the 3rd leading cause of cancer death worldwide. Early detection of hepatocellular carcinoma (HCC), the most common primary malignant tumor of the liver, can be difficult especially when attenuation difference between HCC and normal parenchyma is small. Our purpose was to develop a computer-aided diagnostic (CADe) scheme for early detection of HCC in contrast-enhanced CT. METHOD AND MATERIALS Our CADe scheme consisted of segmentation of the liver, detection of tumor candidates, feature analysis, and classification of the candidates into HCC or non-HCC lesions. Liver segmentation was performed by using a 3D geodesic-active-contour model coupled with a level-set algorithm. A nonlinear gray-scale conversion filter enhanced both hyper- and hypo-dense tumors in the segmented liver. A gradient magnitude filter was then applied, followed by image thresholding and thinning, in order to obtain precise tumor boundaries. A watershed algorithm was employed for segmenting closed-contoured regions as HCC candidates. Eight morphologic and texture features were extracted from the segmented candidates. We used our linear-output artificial neural network (LOANN) for final classification based on these features. We compared its performance with linear discriminant analysis (LDA). Our database consisted of arterial-phase hepatic CT scans of 28 patients acquired with a multi-detector-row CT system with a 16, 40, or 64 channel detector (Brilliance, Philips Medical Systems, Netherlands). Reconstructed CT slices used for CADe were 512x512 pixels in size with 3-5 mm slice thickness. Among 28 cases, 15 HCCs were found in 10 patients. All HCCs were confirmed pathologically. HCC sizes ranged from 15-43 mm with a mean of 22 mm. RESULTS The initial CADe scheme before the classification step detected 100% (15/15) of HCCs with 12.2 (342/28) false positives (FPs) per patient. Our LOANN removed 36% (124/342) of the FPs without any loss of true positive in a leave-one-out cross-validation test; thus, it yielded 100% (15/15) sensitivity with 7.8 (218/28) FPs per patient, whereas LDA yielded 80% (12/15) sensitivity at the same FP rate. CONCLUSION Our CADe scheme achieved 100% sensitivity for detection of HCCs in contrast-enhanced hepatic CT with a reasonable number of FPs. CLINICAL RELEVANCE/APPLICATION CAD could be useful for detecting HCCs in CT; thus, it would potentially improve radiologists’ sensitivity for HCCs.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 11/2009

Publication Stats

14k Citations
2,472.27 Total Impact Points

Institutions

  • 1979–2014
    • Osaka City University
      • • Department of Radiology
      • • Graduate School of Medicine
      • • Department of Cardiology
      Ōsaka, Ōsaka, Japan
  • 1970–2012
    • Osaka University
      • • Department of Radiology
      • • Division of Radiation Biology and Medical Genetics
      • • Department of Internal Medicine
      Suika, Ōsaka, Japan
  • 2011
    • Shimane University
      • Department of Radiology
      Matsue-shi, Shimane-ken, Japan
  • 2009–2011
    • Ritsumeikan University
      • • College of Information Science and Engineering
      • • College of Science and Engineering
      Kioto, Kyōto, Japan
    • University of Chicago
      • Department of Radiology
      Chicago, Illinois, United States
    • University of Tehran
      • School of Electrical and Computer Engineering
      Tehrān, Ostan-e Tehran, Iran
  • 2010
    • Kinki University
      • Department of Radiology
      Ōsaka-shi, Osaka-fu, Japan
    • Tokyo Medical University
      • School of Medicine
      Edo, Tōkyō, Japan
  • 2004–2006
    • Sapienza University of Rome
      Roma, Latium, Italy
    • The American University of Rome
      Roma, Latium, Italy
  • 1992–2005
    • Kyoto Institute of Technology
      • Department of Mechanical and System Engineering
      Kioto, Kyōto, Japan
  • 1988–2005
    • Osaka Police Hospital
      Ōsaka, Ōsaka, Japan
  • 2000
    • National Cerebral and Cardiovascular Center
      • Department of Cardiovascular Medicine
      Ōsaka, Ōsaka, Japan
    • Dallas Zoo
      Dallas, Texas, United States
  • 1999–2000
    • Osaka National Hospital
      Ōsaka, Ōsaka, Japan
    • University Hospitals Birmingham NHS Foundation Trust
      Birmingham, England, United Kingdom
  • 1993–2000
    • Osaka Rosai Hospital
      Ōsaka, Ōsaka, Japan
    • Hokkaido University
      Sapporo, Hokkaidō, Japan
  • 1993–1999
    • Kansai Rosai Hospital
      Itan, Hyōgo, Japan
  • 1995–1998
    • Sakurabashi Watanabe Hospital
      Ōsaka, Ōsaka, Japan
  • 1996
    • Kaizuka Hospital
      Hukuoka, Fukuoka, Japan