Tomoko Hyodo

Kinki University, Ōsaka, Ōsaka, Japan

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Publications (40)46.21 Total impact

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    ABSTRACT: We have encountered occasional equivocal findings when assessing cerebral cortical amyloid retention with (11)C-Pittsburgh compound B (PiB) PET. We investigated the diagnostic significance of equivocal PiB PET findings.
    Annals of Nuclear Medicine 11/2014; · 1.41 Impact Factor
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    ABSTRACT: There is evidence that some cases of patients with dementia with Lewy bodies (DLB) can demonstrate Alzheimer disease (AD) like reduced glucose metabolism without amyloid deposition. The aim of this study was to clarify whether regional hypometabolism is related to amyloid deposits in the DLB brain and measure the degree of regional hypometabolism.
    Annals of Nuclear Medicine 10/2014; · 1.41 Impact Factor
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    ABSTRACT: To investigate optimal flip angle (FA) of three-dimensional fat-suppressed T1-weighted image on Gd-EOB-DTPA-enhanced MRI. Forty-five patients with 35 hepatocellular carcinomas (HCCs) and 16 liver metastases (METs) were investigated. Signal-to-noise ratio (SNR), tumor-to-liver contrast (TLC) of HCC and MET, visual image quality (IQ) and lesion conspicuity (LeCo) were evaluated at hepatobiliary phase with different FAs (FA15°-30°-45°-60° in 13 patients, FA5°-10°-15°-20°-25° in 32 patients). TLC gradually showed better in range from FA15° to FA60° and FA5° to FA25°, but SNRs gradually decreased. SNR and TLC-MET at FA15° were significantly better than those at FA45° and FA60°. SNR at FA10° was significantly higher than at FA5°, FA20°, and FA25°. TLC-HCC and TLC-MET at FA5° were inferior to other FAs. IQs and LeCos at FA15° and FA30° were superior to those at FA45° and FA60°. IQs at FA5° and FA25° were significantly lower than those at FA10°-20°, although LeCos for HCC and MET at FA25° were superior to those at FA5°-20°. FA ranging from 10° to 20° is suitable for hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI, to image HCC and MET.
    Abdominal Imaging 02/2014; · 1.91 Impact Factor
  • Journal of Hepatocellular Carcinoma. 01/2014;
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    ABSTRACT: To compare four imaging approaches in cirrhotic estimation; pre-enhancement T1 relaxation time (T1RT), reduction rate (RR) of T1RT, signal-based liver-to-muscle ratio (L/M ratio) on gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI), and liver stiffness measurement (LSM) of US elastography. Consecutive 58 patients with chronic liver diseases who underwent both Gd-EOB-DTPA-enhanced MRI and FibroScan were analyzed. Four imaging approaches were evaluated by fibrosis score from liver biopsy and receiver operating characteristic (ROC) analysis. RR was found to be inversely correlated with LSM (r = -0.65). RR decreased with degree of fibrosis (F0-F1, 58.5 ± 6.2%, versus F2-F3-F4, 48.8 ± 11.7%, P = 0.010, F0-F1-F2, 58.2 ± 6.2% versus F3-F4, 45.5 ± 12.3%, P = 0.010 and F0-F1, 58.5 ± 6.2%, versus F2-F3, 52.1 ± 12.0%, P = 0.0038). LSM increased with degree of fibrosis (F0-F1, 5.4 ± 2.2 kPa versus F2-F3-F3, 19.3 ± 15.5 kPa, P = 0.0011 and F0-F1-F2, 6.8 ± 3.6 kPa versus F3-F4, 23.8 ± 17.1 kPa, P = 0.0029 and F0-F1, 5.4 ± 2.2 kPa, versus F2-F3, 11.4 ± 7.2 kPa, P = 0.0098). Area under ROC curves were 0.83 (F3-F4), 0.72 (F2-F3-F4), 0.68 (F2-F3) for RR and 0.83 (F3-F4), 0.88 (F2-F3-F4), 0.81 (F2-F3) for LSM in discriminating between patients with fibrosis. The capability by LSM was better than those by RR of T1RT, pre-enhancement T1RT, and L/M ratio to differentiate F ≥ 2, but LSM and RR of T1RT showed the same value to differentiate F ≥ 3.J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 12/2013; · 2.57 Impact Factor
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    ABSTRACT: PURPOSE To examine the optimal monochromatic levels to acquire a highest metastasis-to-liver contrast-to-noise ratio (CNR) on virtual monochromatic spectral (VMS) imaging by dual-energy CT (DECT) and the associations of the optimal monochromatic levels to patient body size METHOD AND MATERIALS 46 hypovascular hepatic metastases of twenty five patients were scanned by DECT in the portal venous phase. The scan was performed with fast kilovoltage switching between 80 and 140 kVp, detector collimation, 0.625 × 64 mm and helical pitch, 1.375. The tube current and rotation speed were adjusted to the computed tomography dose index-volume in a single energy CT acquisition at 120 kVp and Z-axis automatic tube current modulation technique (Noise Index=11). The highest metastasis-to-liver CNRs and the optimal monochromatic levels to acquire the highest metastasis-to-liver CNR on VMS imaging were measured, and their associations to patient body weight and body mass index (BMI) were examined. RESULTS The highest metastasis-to-liver CNR were 6.83±1.6 (range, 3.18-10.83). The optimal monochromatic levels to acquire the highest metastasis-to-liver CNR were 67.91±2.9 (range, 65-74 keV). There was significant positive correlation of the highest metastasis-to-liver CNR to the body weight (r=0.320, p<0.05) and the body mass index (r=0.506, p<0.05). There was a significant positive correlation of the optimal monochromatic level to the body weight (r=0.740, p<0.05) and the body mass index (r=0.637, p<0.05). CONCLUSION A significant positive correlation was observed between the body size and the optimal monochromatic level with regard to the metastasis-to-liver CNR on VMS imaging. Therefore, we consider that it is necessary to adjust an optimal monochromatic level according to the patient size for the evaluation of hepatic metastases on VMS imaging. CLINICAL RELEVANCE/APPLICATION This is the first study demonstrating the associations of the optimal monochromatic level to acquire a highest metastasis-to-liver CNR on virtual monochromatic spectral imaging to patient body size.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE We performed a prospective randomized study using 4 protocols for multiphasic hepatic CT applying a combination of fixed injection duration and patients’ body-weight-tailored dose of contrast material, and to compare the quantitative and qualitative analyses among 4 protocols. METHOD AND MATERIALS This study was approved by the institutional review board. One hundred twenty patients were randomized into 4 groups: Group A (contrast material concentration; 370mgl/mL, fractional dose; 19.2mgI/kg/sec, injection duration; 25sec,and scan timing of arterial, portal, equilibrium phase;35/55/140sec, respectively), Group B (300mgl/mL, 16mgI/kg/sec, 30sec, 40/60/140sec), Group C (300mgl/mL, 15.8mgI/kg/sec, 38sec, 48/70/140sec), and Group D (370mgl/mL, 19.7mgI/kg/sec, 30sec,40/60/140sec). After performing imaging studies for the aorta, hepatic parenchyma, and portal vein, we compared their contrast enhancement among these 4 groups. In addition, we qualitatively evaluated the visualization of the aorta and portal vein. RESULTS The contrast enhancements of the aorta during the arterial phase were Group A/B/C/D=228.8/189.9/236.5/244.4 (HU), and there was no significant difference among Groups A, C, and D; furthermore, there was no difference in visual evaluation. The contrast enhancements of hepatic parenchyma during the portal and equilibrium phase were A/B/C/D= 41.8/42.3/58.7/50.9 (HU) and A/B/C/D= 36.7/34.3/44.9/42.4 (HU), respectively. There were significant differences between Group A and B, as well between as Group C and D, and also there is significant difference of visual evaluation of portal vein and hepatic parenchyma between C and other protocols. CONCLUSION Contrast enhancement of the aorta was dependent on fractional dose, while that of hepatic parenchyma was dependent on iodine dose. Good contrast enhancement of both the aorta and hepatic parenchyma could be achieved by using Group C, which indicated the potential usefulness of this method. CLINICAL RELEVANCE/APPLICATION A new protocol using longer injection duration of 38sec and middle concentration of contrast material may yield satisfactory enhancement.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE The purpose of this study was to investigate the correlation between liver fat volume percentage (LFV%), obtained using a method based on multi-material decomposition (MMD) and histopathologic biopsy score in patients with nonalcoholic fatty liver disease (NAFLD) and alcoholic steatohepatitis. METHOD AND MATERIALS This study included 31 patients who underwent non-contrast (NC) and contrast-enhanced (CE) CT of the upper abdomen with dual energy CT (DECT) within 4 weeks prior to liver biopsy. The scan parameters employed for this study were 80/140kVp, 630mA, 0.6 sec/rot, 5mmTH, and helical mode. For CE studies, a non-ionic contrast agent was used and imaging was performed at the arterial, portal venous, and equilibrium phases. LFV% maps were generated from DECT data using MMD. For NC and CE exams, the measured LFV% was the average of 3 regions-of-interest (ROIs) that were placed in the hepatic parenchyma of the LFV% maps corresponding to the planned biopsy site. LFV% measurements were correlated with histopathologic grade of steatosis by the NAFLD activity (NAS) score. Differences in the mean LFV% for NC and CE data were tested by two-factor analysis of variance (ANOVA) with post hoc Tukey-Kramer test. Spearman rank correlations were calculated between NC LFV% and NAS steatosis score. RESULTS NAS steatosis scores were 0 in 4 patients, 1 in 15 patients, 2 in 12 patients and 3 in 0 patients. The mean LFV% of each NAS steatosis score group was 1.2%, 6.0% and 15.2%, respectively. Two-factor ANOVA results showed a statistically significant difference in LFV% by NAS score (P <0.01), but not by study phases (NC phase and all CE phases). With the Spearman rank test, a significant direct correlation was detected between LFV% and NAS steatosis score (ρ = 0.88, P < 0.01). CONCLUSION MMD-based LFV%, from both NC-CT and CE-CT data, shows statistically significant correlation to histopathologic biopsy grade, implying MMD can be used to accurately LFV% in the liver. Due to the agreement between LFV% across all phases of imaging (NC and CE), MMD can potentially obviate the need for the NC acquisition in DECT imaging of patients with fatty liver disease, which can lead to a significant reduction of radiation dose to patients. CLINICAL RELEVANCE/APPLICATION MMD-based method of LFV using fast-kV switching DECT enables accurate, non-invasive, and rapid measurement of LFV%. MMD may reduce total radiation dose by obviating the need for a NC-CT acquisition.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE The purpose of this study was to retrospectively evaluate diagnostic efficacy of gadoxetic acid-enhanced magnetic resonance (MR) imaging compared with contrast-enhanced CT in the detection of hepatic metastasis in patients with colorectal carcinoma. METHOD AND MATERIALS Consecutive 158 patients with histopathologically confirmed colorectal carcinoma underwent gadoxetic acid-enhanced MR imaging and contrast-enhanced CT. Sixty-eight with 105 histopathological confirmed hepatic metastases by surgery. All MR studies were performed at a 3 T scanner (Magnetom Trio, Siemens Medical Systems, Germany or Achieva 3.0T TX, Philips Medical Solutions, Netherlands ) and CT were performed at 64-detector rows helical CT scanner (Aquilion Multi, Toshiba Medical, Japan). MR examination consisted of T1-weighted 3D-GRE dynamic sequences after bolus-injection of 0.025 mmol gadoxetic acid (Primovist; Bayer Schering Pharma, Japan). Diagnostic analysis was performed by sensitivity and positive predictive value (PPV) for the detection of hepatic metastases in combined arterial- and hepatocyte- phase images compared with contrast-enhanced CT by 2 blinded readers. Sensitivity and PPV for the detection of hepatic metastases were compared using McNemar test. Diagnostic accuracy and sensitivity were evaluated using the alternative-free response receiver operator characteristic (AFROC) method. RESULTS The overall sensitivity of gadoxetic acid-enhanced MR imagings (91.1%) were significantly higher than that of contrast-enhanced CT (78.5%, p<0.001), especially in the sensitivity of gadoxetic acid- enhanced MR imagings was observed in higher sensitivity in smaller size of lesions (76.2% vs 59.3% in the lesions ≤1cm, 97.0% vs 83.5% in the lesions 1 cm< ≤2cm, 98.3% vs 93.5% in the lesions >2cm). The gadoxetic acid-MR imagings showed significantly higher increased area under the ROC curve (Az value = 0.970) compared with contrast-enhanced CT (Az value = 0.899, p<0.01). CONCLUSION The results of this study demonstrated gadoxetic acid-enhanced MR imagings provided higher detectability for hepatic metastases, especially in smaller size of lesion, compared with contrast-enhanced CT in patients with colorectal carcinoma. CLINICAL RELEVANCE/APPLICATION Gadoxetic acid-enhanced MR imaging can detect smaller size of hepatic metastases compared with CT and would provide more feasible therapeutic direction for patients with colorectal carcinoma.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: BACKGROUND AND PURPOSE:Alzheimer disease is the most common neurodegenerative disorder with dementia, and a practical and economic biomarker for diagnosis of Alzheimer disease is needed. Three-dimensional arterial spin-labeling, with its high signal-to-noise ratio, enables measurement of cerebral blood flow precisely without any extrinsic tracers. We evaluated the performance of 3D arterial spin-labeling compared with SPECT, and demonstrated the 3D arterial spin-labeled imaging characteristics in the diagnosis of Alzheimer disease.MATERIALS AND METHODS:This study included 68 patients with clinically suspected Alzheimer disease who underwent both 3D arterial spin-labeling and SPECT imaging. Two readers independently assessed both images. Kendall W coefficients of concordance (K) were computed, and receiver operating characteristic analyses were performed for each reader. The differences between the images in regional perfusion distribution were evaluated by means of statistical parametric mapping, and the incidence of hypoperfusion of the cerebral watershed area, referred to as "borderzone sign" in the 3D arterial spin-labeled images, was determined.RESULTS:Readers showed K = 0.82/0.73 for SPECT/3D arterial spin-labeled imaging, and the respective areas under the receiver operating characteristic curve were 0.82/0.69 for reader 1 and 0.80/0.69 for reader 2. Statistical parametric mapping showed that the perisylvian and medial parieto-occipital perfusion in the arterial spin-labeled images was significantly higher than that in the SPECT images. Borderzone sign was observed on 3D arterial spin-labeling in 70% of patients misdiagnosed with Alzheimer disease.CONCLUSIONS:The diagnostic performance of 3D arterial spin-labeling and SPECT for Alzheimer disease was almost equivalent. Three-dimensional arterial spin-labeled imaging was more influenced by hemodynamic factors than was SPECT imaging.
    American Journal of Neuroradiology 11/2013; · 3.17 Impact Factor
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    ABSTRACT: Background and study aims: Pancreatic ductal adenocarcinomas (PDAC) sometimes arise in patients with intraductal papillary mucinous neoplasms (IPMNs). This study examined the incidence of PDACs concomitant to or derived from branch duct IPMNs. The usefulness of endoscopic ultrasonography (EUS) relative to other imaging methods for detecting these tumors was also assessed. Patients and methods: This retrospective study used data from clinical records and imaging studies that were collected prospectively. During 2001 - 2009, 167 consecutive patients with IPMNs underwent EUS, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The 102 patients whose branch duct IPMNs lacked mural nodules/symptoms and thus did not qualify for resection were followed up by semiannual EUS and annual ultrasonography, CT, and MRI. The sensitivity and specificity with which the four modalities detected IPMN-derived and -concomitant PDACs at the first examination and throughout the study period were evaluated. The rate of PDAC development during follow-up was analyzed by the Kaplan-Meier method. Results: A total of 17 IPMN-derived and 11 IPMN-concomitant PDACs were diagnosed at the first examination. Lesions that did not qualify for resection or chemotherapy were followed up for a median of 42 months. Seven IPMN-concomitant PDACs and no IPMN-derived PDACs were detected during follow-up. The 3- and 5-year rates of IPMN-concomitant PDAC development were 4.0 % and 8.8 %, respectively. At the first examination, EUS was superior to other imaging modalities in terms of IPMN-derived and -concomitant PDAC detection. Throughout the study period, including follow-up, EUS was significantly better at detecting IPMN-concomitant PDACs than the other modalities. Conclusions: IPMN-concomitant PDACs are quite often found at diagnosis and during follow-up. EUS examination of the whole pancreas plays an important role in the management of IPMNs as it allows the early detection of these small invasive carcinomas.
    Endoscopy 11/2013; · 5.74 Impact Factor
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    ABSTRACT: The aim of this study was to investigate the prevalence of intravertebral pneumatocyst (IVP) of the cervical spine by age group, compared with that of intradiscal vacuum (IDV). We investigated 500 consecutive patients who underwent cervical computed tomography (CT) from May 2012 to May2013 for various indications. CT datasets were assessed for the presence of IVPs and IDVs with stratification by age. IVPs of the cervical spine were detected in 8 % (7 of 86 subjects) of patients in their forties or below, 30 % (23 of 75) in their fifties, 49 % (67 of 136) in their sixties, 55 % (76 of 137) in their seventies, and 60 % (40 of 66) in their eighties or over. IDVs of the cervical spine were detected in 6, 25, 48, 54, and 57 %, respectively. Coexistence of both phenomena was identified in 4, 17, 33, 40, and 43 %, respectively. IVPs of the cervical spine are a common incidental finding, increasing in prevalence with age and more common than IDV in all age groups.
    Neuroradiology 10/2013; · 2.70 Impact Factor
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    ABSTRACT: Purpose: To identify patient characteristics and magnetic resonance (MR) imaging findings associated with subsequent hypervascularization in hypovascular nodules that show hypointensity on hepatobiliary phase gadoxetic acid-enhanced MR images in patients with chronic liver diseases. Materials and Methods: Institutional review board approval was obtained, and informed consent was waived. At multiple follow-up gadoxetic acid-enhanced MR imaging examinations of 68 patients, 160 hypovascular nodules were retrospectively reviewed. A Cox regression model for hypervascularization was developed to explore the association of baseline characteristics, including patient factors (Child-Pugh classification, etiology of liver disease, history of local therapy for hepatocellular carcinoma [HCC], and coexistence of hypervascular HCC) and MR imaging findings (fat content, signal intensity on T2-weighted images, and nodule size). In addition, the growth rate was calculated as the reciprocal of tumor volume doubling time to investigate its relationship with subsequent hypervascularization by using receiver operating characteristic and Kaplan-Meier analyses. Results: The prevalence of subsequent hypervascularization was 31% (50 of 160 nodules). Independent Cox multivariable predictors of increased risk of hypervascularization were hyperintensity on T2-weighted images (hazard ratio [HR] = 8.7; 95% confidence interval [CI]: 3.6, 20.8), previous local therapy for hypervascular HCC (HR = 5.0; 95% CI: 1.8, 13.6), Child-Pugh B cirrhosis (HR = 3.6; 95% CI: 1.4, 9.5) and coexistence of hypervascular HCC (HR = 2.0; 95% CI: 1.0, 3.8). The mean growth rate was significantly higher in nodules that showed subsequent hypervascularization than in those without hypervascularization. Kaplan-Meier analysis based on the receiver operating characteristic cutoff level (1.8 × 10(-3)/day [tumor volume doubling time, 542 days]) showed that nodules with a higher growth rate had a significantly higher incidence of hypervascularization (P = 5.2 × 10(-8), log-rank test). Conclusion: Hyperintensity on T2-weighted images is an independent and strong risk factor at baseline for subsequent hypervascularization in hypovascular nodules in patients with chronic liver disease. Tumor volume doubling time of less than 542 days was associated with a high rate of subsequent hypervascularization. © RSNA, 2013.
    Radiology 02/2013; 266(2):480-90. · 6.34 Impact Factor
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    ABSTRACT: Purpose To investigate whether low-dose dynamic CT of the liver with iterative reconstruction can reduce both the radiation dose and the amount of contrast medium. Materials and methods This study was approved by our institutional review board. 113 patients were randomly assigned to one of two groups. Group A/group B (fifty-eight/fifty-five patients) underwent liver dynamic CT at 120/100 kV, with 0/40% adaptive statistical iterative reconstruction (ASIR), with a contrast dose of 600/480 mgI/kg, respectively. Radiation exposure was estimated based on the manufacturer's phantom data. The enhancement value of the hepatic parenchyma, vessels and the tumor-to-liver contrast of hepatocellular carcinomas (HCCs) were compared between two groups. Two readers independently assessed the CT images of the hepatic parenchyma and HCCs. Results The mean CT dose indices: 6.38/4.04 mGy, the dose–length products: 194.54/124.57 mGy.cm, for group A/group B. The mean enhancement value of the hepatic parenchyma and the tumor-to-liver contrast of HCCs with diameters greater than 1 cm in the post-contrast all phases did not differ significantly between two groups (P>0.05). The enhancement values of vessels in group B were significantly higher than that in group A in the delayed phases (P<0.05). Two reader's confidence levels for the hepatic parenchyma in the delayed phases and HCCs did not differ significantly between the groups (P>0.05). Conclusions Low-dose dynamic CT with ASIR can reduce both the radiation dose and the amount of contrast medium without image quality degradation, compared to conventional dynamic CT without ASIR.
    European journal of radiology 01/2013; · 2.65 Impact Factor
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    ABSTRACT: Objective: We aimed to investigate the natural outcome of nonhypervascular lesions detected in the hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI by performing a longitudinal study retrospectively enrolled in a nationwide manner. Methods: Between February 2008 and March 2011, 224 patients with 504 nodules that were diagnosed as nonhypervascular by imaging were recruited from institutions that participated in the present study. We examined the natural outcome of nonhypervascular lesions and evaluated the risk factors. Results: Of the 504 nodules, 173 (34.3%) showed hypervascular transformation. The overall cumulative incidence of hypervascular transformation was 14.9% at 12 months and 45.8% at 24 months. Multivariate analysis using the Cox regression model revealed previous treatment history for hepatocellular carcinoma (HCC; relative risk = 1.498; p = 0.036, 95% CI 1.03-2.19) and hyperintensity on T2-weighted images (relative risk = 1.724; p = 0.015, 95% CI 1.11-2.67) were identified as independent factors for hypervascular transformation. Conclusions: Patients who have a previous treatment history for HCC and with hypointense nodules showing hyperintensity on T2-weighted images need careful follow-up because of the high incidence of hypervascular transformation. © 2013 S. Karger AG, Basel.
    Digestive Diseases 01/2013; 31(5-6):472-9. · 2.73 Impact Factor
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    ABSTRACT: PURPOSE To describe a pharmacokinetic analysis to quantify the hepatocyte-specific uptake and hepatobiliary excretion of gadoxetic acid, and to evaluate the correlation of the results and hepatobiliary function in patients with chronic liver disease. METHOD AND MATERIALS Thirty six patients with chronic hepatitis or cirrhosis were enrolled. All patients underwent gadoxetic acid-enhanced MRI using the Look-Locker turbo-field echo (LL-TFE) sequence before and at 1.5, 3, 8, 13 and 18 min after gadoxetic acid injection (0.025 mmol/kg bw; 2.0ml/sec). T1 fitting tool was employed for measurement of T1 value using data from LL-TFE. T1 values of the liver parenchyma and the aorta were obtained from the regions of interest (ROIs; 50-60 pixels) on each time series T1 mapping image. The R1 (1/T1)-time curves of ROIs were generated.In three-compartment model simulation, hepatic uptake rate (Ku) and hepatobiliary excretion rate (Ke) were calculated. The patients were classified into 2 groups for hepatobiliary function as follows: patients with chronic hepatitis or Child-Pugh A cirrhosis (group 1, n = 19); and patients with Child-Pugh B or C cirrhosis (group 2, n = 17).For each Ku and Ke, Student's t-test was used to determine a significant difference between the two groups. Receiver operating characteristic (ROC) analysis was used to evaluate the ability of Ku and Ke to discriminate between two groups. RESULTS Both Ku and Ke of group 1 were significantly higher (p =6.09 x10-4, 1.02 x 10-3) than those of group 2. Areas under ROC curves for the Ku and Ke were 0.89 and 0.78, respectively. For Ku, cut-off point of 0.16 showed a balanced sensitivity of 84% (16/19) and a specificity of 88% (15/17). For Ke, cut-off point of 0.044 shows a sensitivity/specificity (58% [11/19] and 94% [16/17], respectively). CONCLUSION Ku and Ke may be useful indices for evaluating the hepatobiliary function. The pharmacokinetic analysis based on three compartment model is promising approach for assessing the hepatobiliary function using gadoxetic acid-enhanced MRI. CLINICAL RELEVANCE/APPLICATION Using this approach, gadoxetic acid-enhanced MRI may be useful modality for evaluating the function reserve capacity of the liver in patients considering liver transplantation.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE CT value (HU) of objects with single-energy CT (SECT) is influenced by patient body size due to beam hardening (BH) effect. Thus we have to increase the volume of contrast medicine for large patients. The purpose of this study is to assess whether virtual monochromatic image (VMI) with dual-energy CT (DECT) can reduce BH effect and maintain the CT value of large objects. METHOD AND MATERIALS We made cylindrical phantoms having soft tissue-equivalent materials (density 1.018g/cm3, effective atomic number 7.444) to simulate X-ray attenuation coefficient of human body. A diameter of each phantom was 10cm, 20cm, 30cm. Five vials filled with degrees diluted solutions (0, 3, 6, 9,12mgI/cc) of iodine were inserted into center of cylindrical phantoms. Each vials with/without phantom were scanned with SECT mode (120kVp) and DECT mode using DECT (Discovery CT750 HD, GE Healthcare), respectively. SECT images and VMI (60keV-80keV, interval of 5keV) were reconstructed and CT value was measured by using the average measurement in three regions-of-interest (ROI). CT value of each vial was compared SECT images as basis with VMI about amount of change of CT value. RESULTS As size of phantom became large, CT value decreased in average as follows; 69.9% in SECT, 88.5% in 60keV, 90.7% in 65keV, 93.2% in 70keV, 96.2% in 75keV and 99.8% in 80keV. The change of the maximum CT value in each VMI compared on the basis of the maximum CT value of SECT image without cylindrical phantom was as follows; 119.7% in 60kev, 98.0% in 65keV, 80.9% in 70keV, 67.1% in 75keV and 56.0% in 80keV. CT value did not decrease due to increase of phantom size in use of higher keV VMI. On the other hand, overall CT value decreased in use of high keV VMI. 65keV VMI showed the same maximum CT value approximately as CT value of SECT without phantom, and there was little degradation of CT value due to increase of phantom size. BH effect can be effectively reduced by 65keV VMI. CONCLUSION VMI with DECT has the ability to reduce BH effect in contrast-enhance study. VMI with appropriate energy (keV) can maintain CT value of contrast medicine without increasing amount of contrast medicine with large patients. CLINICAL RELEVANCE/APPLICATION Use of VMI at appropriate energy (keV) with DECT in contrast-enhanced study, it is possible to reduce BH effect. It may be possible not to increase amount of contrast medicine with larger patients.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: Excretion of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) in the bile may be related to liver function, because of elimination from the liver after preferential uptake by hepatocytes. The purpose of this study was to investigate the relation between liver and biliary enhancement in patients with or without liver dysfunction, and to compare the tumor-to-liver contrast in these patients. Forty patients [group 1: normal liver and Child-Pugh class A in 20 patients, group 2: Child-Pugh class B in 18 patients and Child-Pugh C in 2] were evaluated. All patients underwent MR imaging of the liver using a 1.5-Tesla system. T1-weighted 3D images were obtained at 5, 10, 15 and 20 minutes after Gd-EOB-DTPA injection. The relation between group 3 (total bilirubin <1.8 mg/dL) and group 4 (total bilirubin ≥1.8 mg/dL) was investigated at 20 minutes. Liver and biliary signals were measured, and compared between groups 1 and 2 or groups 3 and 4. Tumor-to-liver ratio was also evaluated between groups 1 and 2. Scheffe's post-hoc test after two-way repeated-measures ANOVA and Pearson's correlation test were used for statistical analysis. Liver enhancement showed significant difference at all time points between groups 1 and 2. Biliary enhancement did not show a significant difference between groups 1 and 2 at 5 minutes, but did at 10, 15 and 20 minutes. At 20 minutes, significant differences between groups 3 and 4 were seen for liver and biliary enhancement. At all time points, liver enhancement correlated with biliary enhancement in both groups. At 5 minutes and 20 minutes, statistical differences between groups 1 and 2 were seen for tumor-to-liver ratio. The degree of biliary enhancement has a close correlation to that of liver enhancement. It is especially important that insufficient liver enhancement causes lower tumor-to-liver contrast in the hepatobiliary phase of Gd-EOB-DTPA.
    Hepatobiliary & pancreatic diseases international: HBPD INT 06/2012; 11(3):307-13. · 1.26 Impact Factor
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    ABSTRACT: We aimed to evaluate gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the detection of hepatocellular carcinomas (HCCs) and dysplastic nodules (DNs) compared with dynamic multi-detector row computed tomography (MDCT), and to discriminate between HCCs and DNs. Eighty-six nodules diagnosed as HCC or DNs were retrospectively investigated. Gd-EOB-DTPA-enhanced MRI and dynamic MDCT were compared with respect to their diagnostic ability for hypervascular HCCs and detection sensitivity for hypovascular tumors. The ability of hepatobiliary images of Gd-EOB-DTPA-enhanced MRI to discriminate between these nodules was assessed. We also calculated the EOB enhancement ratio of the tumors. For hypervascular HCCs, the diagnostic ability of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of MDCT for tumors less than 2 cm (p = 0.048). There was no difference in the detection of hypervascular HCCs between hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI (43/45: 96%) and dynamic MDCT (40/45: 89%), whereas the detection sensitivity of hypovascular tumors by Gd-EOB-DTPA-enhanced MRI was significantly higher than that by dynamic MDCT (39/41: 95% vs. 25/41: 61%, p = 0.001). EOB enhancement ratios were decreased in parallel with the degree of differentiation in DNs and HCCs, although there was no difference between DNs and hypovascular well-differentiated HCCs. The diagnostic ability of Gd-EOB-DTPA-enhanced MRI for hypervascular HCCs less than 2 cm was significantly higher than that of MDCT. For hypovascular tumors, the detection sensitivity of hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of dynamic Gd-EOB-DTPA-enhanced MRI and dynamic MDCT. It was difficult to distinguish between DNs and hypovascular well-differentiated HCCs based on the EOB enhancement ratio.
    Journal of Gastroenterology 04/2012; 47(9):1036-47. · 3.79 Impact Factor
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    ABSTRACT: Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.
    The British journal of radiology 03/2012; 85(1015):887-96. · 2.11 Impact Factor

Publication Stats

66 Citations
46.21 Total Impact Points

Institutions

  • 2011–2014
    • Kinki University
      • • Department of Radiology
      • • Department of Internal Medicine
      Ōsaka, Ōsaka, Japan
  • 2009
    • Ehime University
      • Department of Urology
      Matuyama, Ehime, Japan