Akira Yamamoto

Kyoto University, Kioto, Kyoto, Japan

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Publications (110)221.67 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives: The aims of this study were to optimize parameters for Nesterov algorithm (NESTA) in reconstruction of 3-dimensional time-of-flight (TOF) magnetic resonance angiography (MRA) at 3 T by performing an exhaustive search and to validate the performance of compressed sensing (CS) by applying it to data from cerebral aneurysms and evaluating diagnostic quality. Materials and methods: Three-dimensional TOF-MRA was obtained using a 3 T MR system with a 32-channel head coil for both healthy volunteers and 10 patients (11 aneurysms). No undersampling was applied for imaging parameters, including parallel imaging or other partial Fourier sampling. In the first step, the experimental setup was for healthy subjects to optimize CS parameters of NESTA and the undersampling mask pattern, so 24,696 different reconstruction conditions were surveyed for sampling rates of 8.0X and 5.0X. Mean square error (MSE) was calculated for each image reconstructed with the undersampling pattern and CS parameter sets. Evaluation was by normalized MSE, edge sharpness for MRA reconstructed using fully sampled data (MRA-full), zero-filled MRA (ZF-MRA) with Poisson disk undersampling mask, and CS-MRA (5.0X and 8.0X) with iterations of 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50. CS-MRA (5.0X and 8.0X) with 5, 10, and 50 iterations of the sampling pattern and CS parameter set with the lowest MSE were visually inspected by 2 neuroradiologists to check the diagnostic quality. Results: The sampling pattern and CS parameter set with the lowest MSE were identical for both CS-MRA 5.0X and CS-MRA 8.0X. At the initial 5 to 15 iterations, MSE of both sampling rates greatly decreased from that of ZF-MRA. For subsequent iterations, the decrease in MSE was relatively small. For CS-MRA, sharpness greatly increased from that of ZF-MRA within the initial 5 to 15 iterations, followed by slight increases with further iterations. Two neuroradiologists graded most aneurysms as excellent, with the exception of 1 to 4 aneurysms recognized as good by 1 observer in CS-MRA (8.0X). Conclusions: Optimization of NESTA in the reconstruction of 3-dimensional TOF-MRA was conducted, and the parameters and undersampling mask with the lowest MSE were determined. Caliber measurement should be performed with CS (5.0X) with 25 or 30 iterations. Most cerebral aneurysms were sufficiently recognized using CS-MRA (5.0X) or CS-MRA (8.0X) with 10 iterations.
    Investigative radiology 11/2015; DOI:10.1097/RLI.0000000000000226 · 4.44 Impact Factor
  • Noah Nakanishi · Taro Shimono · Akira Yamamoto · Yukio Miki ·
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    ABSTRACT: Purpose: Delayed colonic perforation after acute pancreatitis (AP) is a potentially lethal complication. This study investigated the frequency and predictors of delayed colonic perforation (DCP) following AP by reviewing the earliest laboratory data and computed tomography (CT) examination findings after pancreatitis onset. Materials and methods: This retrospective study examined 75 consecutive cases of AP treated between April 2009 and April 2014. Laboratory data after onset and imaging features from earliest CT examinations (Balthazar grade, CT Severity Index) were reviewed. To clarify relationships between these data and DCP, univariate analyses were undertaken between perforated and nonperforated groups. Results: Delayed colonic perforation occurred in four of the 75 patients (5.3 %). Median duration to perforation after onset was 13 days (range 6-47). All four patients with DCP showed grade E according to Balthazar grade (≥2 peripancreatic collections and/or gas bubbles in or adjacent to pancreas). Univariate analyses identified Balthazar grade E as a risk factor for DCP (p = 0.0087). Conclusion: Delayed colonic perforation is not uncommon and can occur a week or more after AP. Balthazar grade E on earliest CT after onset represents a risk factor for DCP.
    Japanese journal of radiology 10/2015; DOI:10.1007/s11604-015-0491-5 · 0.84 Impact Factor
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    ABSTRACT: Background: Focal stenosis or occlusion of the infrarenal aorta is rare, and treatment is usually conventional bypass or endarterectomy. However, endovascular treatment has advanced in recent years. The purpose of this retrospective study is to report the results of primary stenting for focal infrarenal aortic occlusive disease and clarify the usefulness of endovascular treatment. Methods: This study includes 6 consecutive patients (3 men, 3 women; mean age, 59.3 years) with infrarenal aortic stenosis or occlusion who underwent endovascular intervention at our hospital between April 2009 and February 2014. All patients had bilateral intermittent claudication. The mean preoperative ankle-brachial index (ABI) showed a slight to moderate decrease: right 0.668 and left 0.636. The mean lesion site length was 12.5 mm, the percent stenosis was 90.7%, and calcification was present in 3 patients. Primary stenting was performed in all patients. The stent selected was generally a self-expanding stent (SES). For patients with severe calcification, the stent selected was a balloon-expandable stent (BES). Results: Four patients received an SES and two patients received a BES. The technical success rate was 100%, no complications occurred, and the mean pressure gradient disappeared or decreased. Symptoms resolved in all patients and the postoperative ABI improved: right 0.923 and left 0.968. During a mean follow-up period of 27 months, there were no recurrent symptoms and no restenosis on CT angiography. Conclusions: Endovascular treatment should be considered as a first line treatment for focal infrarenal aortic stenosis and occlusion.
    Osaka city medical journal 10/2015; 61(1):1-8.
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    ABSTRACT: There is no established second-line treatment for steroid-resistant acute graft-versus-host disease (GVHD). We prospectively assessed the safety and efficacy of intra-arterial steroid infusions (IASI) for steroid-resistant acute gastrointestinal (GI) GVHD and compared the outcomes with those of historical controls at our institution. Nineteen consecutive, allogeneic hematopoietic stem cell transplantation subjects aged 31-67 years (median 52) were enrolled between October 2008 and November 2012. Acute GVHD was confirmed by biopsy in all cases. The enrolled patients were treated with infusions of methylprednisolone into the mesenteric arteries and/or gastroduodenal and left gastric arteries. Fourteen consecutive patients who developed steroid-resistant acute GI GVHD between 2001 and 2008 were used as controls. For the primary endpoint at day 28, the overall and complete responses in the IASI group trended higher (79% vs. 42%, p=.066) and were significantly higher (63% vs. 21%, p=.033) than those in the control group. Although not statistically significant due to the small population, the crude day 180-non-relapse mortality rate was about 20 percent lower and the day 180-overall survival rate tended to be higher than the control (11% versus 29%, p=.222; 79% versus 50%, p=.109, respectively). There were no serious IASI-related complications. Our results suggest that IASI can safely provide excellent efficacy for refractory acute GI GVHD without increasing infection-related complications and may improve prognosis. Copyright © 2015 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.
    Experimental hematology 08/2015; DOI:10.1016/j.exphem.2015.08.002 · 2.48 Impact Factor
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    ABSTRACT: To compare magnetization-prepared two rapid acquisition gradient echoes (MP2RAGE) imaging with conventional MPRAGE imaging for deep gray matter (GM) segmentation, reproducibility, contrast ratio (CR) and contrast-to-noise ratio (CNR), and to evaluate reproducibility of T1 maps derived from MP2RAGE. MP2RAGE and MPRAGE imaging were conducted twice for each of 20 volunteers on a 3 Tesla MRI scanner. Images were normalized and segmented using SPM12 with the DARTEL algorithm. Reproducibility of segmentation was evaluated using coefficients of variation (COVs) of deep GM probability maps between first and second scans, which was compared between MP2RAGE and MPRAGE. Differences in deep GM probability were compared voxel-wise. CR and CNR analyses were conducted using regions of interest. COVs of T1 maps were also evaluated. Comparison of GM probability maps demonstrated that putamen, caudate nucleus and thalamus were segmented significantly larger in MP2RAGE than in MPRAGE, and MP2RAGE was inferior only at some areas of globus pallidus and lateral thalamus (P < 0.05; false discovery rate, FDR). CRs of deep GM structures were significantly better in MP2RAGE (P < 0.0001). COVs of deep GM probability maps were significantly higher at large areas of the deep GM in MPRAGE (P < 0.05, FDR). COVs ranged from 0.50 to 3.31% in MP2RAGE and from 0.62 to 4.12% in MPRAGE. COVs of the T1 map were around 2%. MP2RAGE yields greater reproducibility and better tissue contrast than MPRAGE in deep GM. T1 maps derived from MP2RAGE were highly reliable. MP2RAGE is useful for measurement and analysis of deep GM.J. Magn. Reson. Imaging 2015. © 2015 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 06/2015; DOI:10.1002/jmri.24960 · 3.21 Impact Factor
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    ABSTRACT: The aim of this study was to assess the consistency and reproducibility of quantitative susceptibility mapping (QSM) at 3-T and 1.5-T magnetic resonance (MR) scanners. This study was approved by institutional ethics committee, and written informed consent was obtained. Twenty-two healthy volunteers underwent 2 examinations on different days. Each examination consisted of MR imaging on both 3-T and 1.5-T MR scanners. The data from both scanners and examination days were obtained, and QSM was calculated with STI Suite using 2 different algorithms-harmonic phase removal using laplacian operator (HARPERELLA) and a sophisticated harmonic artifact reduction for phase data (SHARP) method with a variable radius of the spherical kernel at the brain boundary (V-SHARP). We evaluated consistency of QSM between 3 T and 1.5 T and the reproducibility between the first and second examinations using 2-phase processing methods (HARPERELLA and V-SHARP). Susceptibility values of regions of interests at 3 T were highly correlated with those at 1.5 T with good agreement (HARPERELLA, R = 0.838; V-SHARP, R = 0.898) (average difference, ±1.96 SD; HARPERELLA, -0.012 ± 0.046; V-SHARP, -0.002 ± 0.034). Reproducibility analysis demonstrated excellent correlation between the first and second examination at both 3 T and 1.5 T for both algorithms (HARPERELLA at 3 T, R = 0.921; 1.5 T, R = 0.891; V-SHARP at 3 T, R = 0.937; 1.5 T, R = 0.926). Bland-Altman analysis showed excellent reproducibility for HARPERELLA (3 T, -0.003 ± 0.032; 1.5 T, -0.003 ± 0.038) and V-SHARP (3 T, -0.003 ± 0.027; 1.5 T, -0.003 ± 0.029). Susceptibility values of these 2 algorithms were highly correlated with good agreement (3T, R = 0.961; 1.5 T, R = 0.931) (3 T, 0.009 ± 0.023; 1.5 T, -0.003 ± 0.049). Quantitative susceptibility mapping with HARPERELLA and V-SHARP demonstrated good reproducibility at 3 T and 1.5 T, and QSM with V-SHARP demonstrated good consistency at 3 T and 1.5 T.
    Investigative radiology 04/2015; Publish Ahead of Print(8). DOI:10.1097/RLI.0000000000000159 · 4.44 Impact Factor
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    ABSTRACT: Pancreatic cancer (PC) with arterial invasion is currently a contraindication to resection and has a miserable prognosis. Seventeen patients with locally advanced PC involving the celiac axis and/or common hepatic artery (CHA) who received chemoradiotherapy (CRT) composed of gemcitabine, S-1, and external beam irradiation over the last 2 years were investigated. Thirteen patients underwent pancreatectomy with major arterial resection: 6 distal pancreatectomies with resection of the celiac axis, 4 total pancreatectomies with resection of both the celiac axis and the CHA, and 3 pancreatoduodenectomies with resection of the CHA. Preoperative arterial embolization and/or arterial reconstruction to prevent ischemic gastropathy and hepatopathy was performed in 7 of the 13 patients. Distant metastases were found in 3 patients after CRT. One patient did not consent to operation after CRT. The morbidity rate of the 13 patients who underwent surgery was 62% (8/13), but no deaths occurred. Although there were no responders on CT, >90% of tumor cells were necrotic on histopathology in 5 of 13 tumors after CRT. Invasion of the celiac axis remained in 5 tumors, and extrapancreatic plexus invasion remained in 8 tumors, but an R0 resection was achieved in 12 of 13 tumors. Lymph node metastases were found in 3 of 13 cases. The overall 1-year survival rate from commencement of CRT and resection was 12 of 13 patients. Neoadjuvant CRT containing gemcitabine and S-1 and subsequent pancreatectomy with major arterial resection for patients with locally advanced PC with arterial invasion were carried out safely with an acceptable R0 resection acceptable morbidity and mortality, and encouraging survival (12 of 13) at 1 year postoperatively. Copyright © 2015 Elsevier Inc. All rights reserved.
    Surgery 04/2015; 158(1). DOI:10.1016/j.surg.2015.02.016 · 3.38 Impact Factor
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    ABSTRACT: To evaluate prevalence of subcutaneous fluid collection (SFC) in infectious thoracolumbar spondylodiscitis (SD) compared with control patients and to investigate correlation between volume changes of SFC and treatment response of SD. This retrospective study was approved by our institutional review board. From April 2011 to March 2012, 49 patients (24 SD and 25 non-SD patients) were enrolled. Prevalence of SFC was evaluated respectively for SD and non-SD patients using magnetic resonance imaging (MRI) on the sagittal short tau inversion recovery (STIR) imaging or fat-saturated T2-weighted imaging (T2WI), and compared. In SD patients with SFC, correlation was investigated between SFC volume on the 1st MRI and initial clinical status. The same analysis was conducted also for SFC volume changes from the 1st to 2nd or last MRI. SFC was found in 20 patients with SD (83.3%) and 3 non-SD patients (12%) with significant difference (p<.001). In 20 SD patients with SFC, 17 patients had follow-up MRI. For the 1st MRI, no significant correlation was found between volume of SFC and initial status of patients, including body weight, body mass index (BMI), white blood cell (WBC), and erythrocyte sedimentation rate (ESR). However, significant positive correlations were found between changes of C-reactive protein (CRP) and SFC volume from the 1st to 2nd as well as from the 1st to the last MRI (each p<.05). SD patients had significantly higher prevalence of SFC than non-SD patients. Volume changes of SFC had significant correlation with changes of CRP, which can be used as an imaging marker for treatment response of SD on MRI. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    European Journal of Radiology 04/2015; 84(7). DOI:10.1016/j.ejrad.2015.03.027 · 2.37 Impact Factor
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    ABSTRACT: There is no consensus guidelines for treating duodenal variceal bleeding, which is a rare and life-threatening complication of portal hypertension. Here we report an exceedingly unusual case in a 9-year-old boy who had developed left-sided portal hypertension after surgical treatment for pancreatoblastoma followed by a duodenal variceal bleeding with massive melena, severe anemia (hemoglobin 4.5 g/dL) and hypovolemic shock. Emergency partial splenic arterial embolization (PSE) provided a reduction of variceal bleeding and improved blood pressure. Endoscopic injection sclerotherapy (EIS) was subsequently performed and stopped the duodenal variceal bleeding without the complication of portal vein thrombosis caused by injected sclerosant under hepatopetal flow. Our case demonstrates that emergency combined therapy with PSE and EIS can be considered as the therapeutic option for the management of left-sided portal hypertension-induced ectopic variceal bleedings in order to avoid the complication of portal embolization by EIS and provide effective hematostasis.
    Clinical Journal of Gastroenterology 04/2015; 8(3). DOI:10.1007/s12328-015-0563-1
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    ABSTRACT: Background. Previous studies have shown that intratumoral hemorrhage is a common finding in glioblastoma multi-forme, but is rarely observed in primary central nervous system lymphoma. Our aim was to reevaluate whether intratumoral hemorrhage observed on T2-weighted imaging (T2WI) as gross intratumoral hemorrhage and on susceptibility-weighted imaging as intratumoral susceptibility signal can differentiate primary central nervous system lymphoma from glioblastoma multiforme. Patients and methods. A retrospective cohort of brain tumors from August 2008 to March 2013 was searched, and 58 patients (19 with primary central nervous system lymphoma, 39 with glioblastoma multiforme) satisfied the inclusion criteria. Absence of gross intratumoral hemorrhage was examined on T2WI, and an intratumoral susceptibility signal was graded using a 3-point scale on susceptibility-weighted imaging. Results were compared between primary central nervous system lymphoma and glioblastoma multiforme, and values of P < 0.05 were considered significant. Results. Gross intratumoral hemorrhage on T2WI was absent in 15 patients (79%) with primary central nervous system lymphoma and 23 patients (59%) with glioblastoma multiforme. Absence of gross intratumoral hemorrhage could not differentiate between the two disorders (P = 0.20). However, intratumoral susceptibility signal grade 1 or 2 was diagnostic of primary central nervous system lymphoma with 78.9% sensitivity and 66.7% specificity (P < 0.001), irrespective of gross intratumoral hemorrhage. Conclusions. Low intratumoral susceptibility signal grades can differentiate primary central nervous system lymphoma from glioblastoma multiforme. However, specificity in this study was relatively low, and primary central nervous system lymphoma cannot be excluded based solely on the presence of an intratumoral susceptibility signal.
    Radiology and Oncology 03/2015; 49(2):128-134. DOI:10.1515/raon-2015-0007 · 1.91 Impact Factor
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    ABSTRACT: The purpose was to compare capability of fluorine-18 fluorodeoxyglucose (FDG)-PET and thallium-201 (Tl)-SPECT for grading meningioma.This retrospective study was conducted as a case-control study under approval by the institutional review board. In the hospital information system, 67 patients (22 men and 45 women) who had both FDG-PET and Tl-SPECT preoperative examinations were found with histopathologic diagnosis of meningioma. The maximum FDG uptake values of the tumors were measured, and they were standardized to the whole body (SUVmax) and normalized as gray matter ratio (SUVRmax). Mean and maximum Tl uptake ratios (TURmean and TURmax, respectively) of the tumors were measured and normalized as ratios to those of the contralateral normal brain. Receiver-operating characteristic curve analyses of the 4 indexes were conducted for differentiation between low- and high-grade meningiomas, and areas under the curves (AUCs) were compared. Correlation coefficients were calculated between these indexes and Ki-67.Fifty-six meningiomas were classified as grade I (low grade), and 11 were grade II or III (high grade). In all 4 indexes, a significant difference was observed between low- and high-grade meningiomas (P < 0.05). AUCs were 0.817 (SUVmax), 0.781 (SUVRmax), 0.810 (TURmean), and 0.831 (TURmax), and no significant difference was observed among the indexes. Their sensitivity and specificity were 72.7% to 90.9% and 71.4% to 87.5%, respectively. Correlation of the 4 indexes to Ki-67 was statistically significant, but coefficients were relatively low (0.273-0.355).Tl-SPECT, which can be used at hospitals without a cyclotron or an FDG distribution network, has high diagnostic capability of meningioma grades comparable to FDG-PET.
    Medicine 02/2015; 94(6):e549. DOI:10.1097/MD.0000000000000549 · 5.72 Impact Factor
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    ABSTRACT: Amide proton transfer (APT) magnetic resonance imaging is gaining attention for its capability for grading glial tumors. Usually, a representative slice is analyzed. Different definitions of tumor areas have been employed in previous studies. We hypothesized that the accuracy of APT imaging for brain tumor grading may depend upon the analytical methodology used, such as selection of regions of interest (ROIs), single or multiple tumor slices, and whether or not there is normalization to the contralateral white matter. This study was approved by the institutional review board, and written informed consent was waived. Twenty-six patients with histologically proven glial tumors underwent preoperative APT imaging with a three-dimensional gradient-echo sequence. Two neuroradiologists independently analyzed APT asymmetry (APTasym) images by placing ROIs on both a single representative slice (RS) and all slices including tumor (i.e. whole tumor: WT). ROIs indicating tumor extent were separately defined on both FLAIR and, if applicable, contrast-enhanced T1-weighted images (CE-T1WI), yielding four mean APTasym values (RS-FLAIR, WT-FLAIR, RS-CE-T1WI, and WT-CE-T1WI). The maximum values were also measured using small ROIs, and their differences among grades were evaluated. Receiver operating characteristic (ROC) curve analysis was also conducted on mean and maximum values. Intra-class correlation coefficients for inter-observer agreement were excellent. Significant differences were observed between high- and low-grade gliomas for all five methods (P < 0.01). ROC curve analysis found no statistically significant difference among them. This study clarifies that single-slice APT analysis is robust despite tumor heterogeneity, and can grade glial tumors with or without the use of contrast material.
    Journal of Neuro-Oncology 01/2015; 122(2). DOI:10.1007/s11060-014-1715-8 · 3.07 Impact Factor
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    ABSTRACT: The objective was to evaluate diagnostic performance of dynamic susceptibility-contrast perfusion-weighted imaging, diffusion-weighted imaging, and (18)F-fluorodeoxyglucose positron emission tomography in differentiating primary central nervous system lymphoma (PCNSL) and glioblastoma. Twenty-three glioblastomas and 11 PCNSLs were analyzed with uncorrected cerebral blood volume (CBV) ratio, fifth percentile value of cumulative apparent diffusion coefficient histogram (ADC5%), and maximum standardized uptake value (SUVmax) using regions of interest created semiautomatically on enhancing areas. Uncorrected CBV ratio was highly capable of differentiating PCNSL from glioblastoma, as well as SUVmax and ADC5%. Uncorrected CBV ratio demonstrates high diagnostic performance comparable to SUVmax. Copyright © 2014 Elsevier Inc. All rights reserved.
    Clinical Imaging 12/2014; 39(3). DOI:10.1016/j.clinimag.2014.12.002 · 0.81 Impact Factor
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    ABSTRACT: Background We present a case series of a palliative radiofrequency ablation (RFA) for the tumors that lead to the resolution of pain and motor function disorders. RFA is widely used on tumors in various organs and often reported in good outcome. There are some reports that RFA was performed as a palliative treatment but a few reports of RFA that performed for lung tumor as a palliative treatment. This case series includes two cases, palliative RFA for a sacrum and a lung tumor. The results of this case series presented that a palliative RFA is effective in improving the symptoms of patients. Case presentation Case 1. A 64-year-old Japanese woman with a chordoma at her sacrum presented with pain in her left leg and claudication. Though operations, radiation therapy and GS-TAE (gelatin sponge–transarterial embolization, via the L5 lumbar artery) were performed, the size of the tumor leading pain and claudication increased. RFA was performed for the sacral tumor, and these symptoms resolved one year after the procedure. Case 2. A 68-year-old Japanese man with a leiomyosarcoma at the apex of left lung presented with pain and motor function disorders of the left upper limb. Dissemination in the pleura was appeared after the operation for a leiomyosarcoma at the mediastinum. Though radiation therapy and a second operation were performed, the tumor at the apex of the left lung increased and pain and numbness of the left upper limb were appeared after the second operation. RFA was performed for the left lung tumor, and the symptoms resolved 3 months after RFA. Conclusion RFA is effective as a palliative treatment and has a potential to salvage the patients from the symptoms of the tumors when conventional palliative treatments such as surgery, radiation therapy, and chemotherapy are difficult or contraindicated.
    BMC Research Notes 10/2014; 7(1):765. DOI:10.1186/1756-0500-7-765
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    ABSTRACT: To evaluate whether the combination of radiofrequency (RF) ablation and local injection of the immunostimulant Mycobacterium bovis bacillus Calmette-Guérin (BCG) induces systemic antitumor immunity. Japanese White rabbits with lung and auricle VX2 tumors were randomized into three groups: control (n = 8; no treatment), RF ablation only (n = 8; RF ablation to the lung tumor), and RF ablation with local BCG injection into the lung tumor (n = 8). Treatments were performed 1 week after tumor implantation. Survival was evaluated with Kaplan-Meier method and log-rank test. Weekly mean volume and specific growth rate (SGR) of auricle tumors were calculated, and comparisons were made by Mann-Whitney test. Median survival of control, RF-only, and RF/BCG groups were 23, 41.5, and 103.5 days, respectively. Survival was significantly prolonged in the RF-only and RF/BCG groups compared with the control group (P = .034 and P =.003, respectively), but no significant difference was found between the RF-only and RF/BCG groups (P = .279). Only in the RF/BCG group was mean auricle tumor volume decreased 5 weeks after implantation. No significant difference in SGR was found between the control and RF-only groups (P = .959), but SGR in the RF/BCG group was significantly lower than in the control group (P = .005). The combination of RF ablation and local injection of BCG resulted in distant tumor suppression compared with the control group, whereas RF ablation alone did not produce this effect. Therefore, the combination of RF ablation and local injection of BCG may induce systemic antitumor immunity. Copyright © 2014 SIR. Published by Elsevier Inc. All rights reserved.
    Journal of vascular and interventional radiology: JVIR 10/2014; 26(2). DOI:10.1016/j.jvir.2014.09.002 · 2.41 Impact Factor
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    ABSTRACT: Introduction: The aim of this study is to investigate the relationship between abnormal retropharyngeal lymph nodes (RPLNs) and sinonasal malignancies among adults. Methods: Magnetic resonance and computed tomography images from 89 patients over 20 years old who were all histopathologically confirmed to have sinonasal malignancies from September 2001 to April 2014 were assessed retrospectively. Abnormal RPLNs were determined as those >5 mm in shortest axis or showing heterogeneous enhancement on axial images. Locations of sinonasal malignancies were categorized using the anterior border of the pterygopalatine fossa as a boundary: (a) anterior lesions, only present anterior to the boundary, or (b) posterior lesions, present or extending posterior to the boundary. Fisher's exact test was used for the analysis of the relationship between frequency of abnormal RPLNs and lesion location. Results: Abnormal RPLNs were present in 13 of 89 patients (15%), including 6 of 41 squamous cell carcinomas (15%), 4 of 24 malignant lymphomas (17%), 3 of 5 olfactory neuroblastomas (60%), and 0 of 19 others (0%). Four of the 39 patients (10%) with anterior lesions showed abnormal RPLNs, compared to 9 of 50 patients (18%) with posterior lesions. No significant difference in frequency of abnormal RPLNs was apparent between anterior and posterior lesions (P = 0.37). Conclusions: In primary sinonasal malignancies among adults, the highest incidence of abnormal RPLNs was seen with olfactory neuroblastoma. The frequency of abnormal RPLNs was unaffected by the location of sinonasal malignancies among adults.
    Neuroradiology 09/2014; 56(12). DOI:10.1007/s00234-014-1428-x · 2.49 Impact Factor

  • International Congress of Radiology ICR2014, Dubai, UAE; 09/2014
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    ABSTRACT: To evaluate the feasibility of gastric variceal (GV) volumetry using computed tomography (CT) images taken before balloon-occluded retrograde transvenous obliteration (B-RTO) and to assess its correlation with the actual amount of 5% ethanolamine oleate and iodinated contrast medium (EOI) injected in B-RTO. Forty-seven consecutive patients with GV underwent B-RTO of the gastrorenal shunt. GV volume was measured with preoperative CT images by three radiologists. Statistical significance was examined by intraclass correlation coefficient (ICC) for concordance among three radiologists and by Pearson correlation test for correlation between GV volume and the amount of 5% EOI injected. GV volumes measured by three radiologists significantly correlated with each other (ICC=0.959). Combining all patients and all measurements, the mean GV volume and the mean amount of 5% EOI were 27.02±16.67cm3 and 28.72±17.72mL, respectively. There was a significant correlation between GV volume, calculated as a mean of the three values measured by the three radiologists, and the amount of EOI (r2=0.706, p<0.001). GV volume measured on CT showed a significant correlation with the amount of 5% EOI injected. CT volumetry of GV has the potential to determine an amount of the sclerosing agent to be injected in B-RTO.
    Hepato-gastroenterology 09/2014; 61(134):1806-11. DOI:10.5754/hge14474 · 0.93 Impact Factor
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    ABSTRACT: Objective: We qualitatively evaluated the differences among susceptibility-weighted (SWI), magnitude (MAG), and high pass filtered phase (PHA) images in depicting interlobar differences in the appearance of the signal of the corticomedullary junction (CMJ). We conducted quantitative evaluation to validate the qualitative results. Materials and methods: We obtained SWI images from 25 preoperative brain tumor patients (12 men, 13 women, aged 19 to 82 years, mean, 52 years). Two trained neuroradiologists evaluated MAG, PHA, and SWI images. Qualitative evaluation of the CMJ signal and quantitative calculation of the relative signal ratio (RSR) percentages between the CMJ and deep white matter (WM) were conducted at 3 different slice levels of the brain independently for 4 different lobes (frontal, parietal, temporal, and occipital) and compared among MAG, PHA, and SWI. The extent of the area of the CMJ signal was graded on a 4-point scale (Grade 3, >75%; Grade 2, 50 to 75%; Grade 1, 25 to 50%; Grade 0, <25%). Data were statistically analyzed using a nonparametric Friedman test. Results: The Kappa coefficients between the qualitative and quantitative grades were 0.002 for MAG, 0.0047 for PHA, and 0.050 for SWI. Qualitatively, on the PHA images and SWI, grades of the occipital lobes were significantly higher than those of the other lobes (P < 0.005). Quantitatively, PHA images showed statistically significant interlobar differences in RSR percentage values of the CMJ (P = 0.025). Conclusion: Qualitatively, the appearance of the CMJ differed significantly among the different lobes of the brain on SWI and underlying PHA images but not on MAG images. Quantitatively, only PHA images showed significant interlobar differences in the RSR. PHA images are most sensitive to the CMJ signal contrast due to local paramagnetic iron content.
    Magnetic Resonance in Medical Sciences 08/2014; 13(4). DOI:10.2463/mrms.2013-0108 · 1.48 Impact Factor
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    ABSTRACT: Objectives: To evaluate the validity of 3D dynamic pituitary MR imaging with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA), with special emphasis on demarcation of pituitary posterior lobe and stalk. Methods: Participants comprised 32 patients who underwent dynamic pituitary MR imaging due to pituitary or parasellar lesions. 3D dynamic MR with CAIPIRINHA was performed at 3T with 20-s-interval, precontrast, 1st to 5th dynamic images. Normalized values and enhanced ratios (dynamic postcontrast image values divided by precontrast ones) were compared between 3D and 2D dynamic MR imaging for patients with visual identification of posterior lobe and stalk. Results: In 3D, stalk was identified in 29 patients and unidentified in 3, and posterior lobe was identified in 28 and unidentified in 4. In 2D, stalk was identified in 26 patients and unidentified in 6 patients, and posterior lobe was identified in 15 and unidentified in 17. Normalized values of pituitary posterior lobe and stalk were higher in 3D than 2D (P<0.001). No significant difference in enhancement ratio was seen between 3D and 2D. Conclusions: 3D dynamic pituitary MR provided better identification and higher normalized values of pituitary posterior lobe and stalk than 2D.
    European Journal of Radiology 07/2014; 83(10). DOI:10.1016/j.ejrad.2014.06.018 · 2.37 Impact Factor

Publication Stats

882 Citations
221.67 Total Impact Points


  • 2005-2015
    • Kyoto University
      • Department of Diagnostic Imaging and Nuclear Medicine
      Kioto, Kyoto, Japan
  • 2006-2014
    • Osaka City University
      • • Department of Radiology
      • • Graduate School of Medicine
      Ōsaka, Ōsaka, Japan
  • 2011
    • Johns Hopkins University
      • Department of Radiology
      Baltimore, Maryland, United States
  • 2009
    • Kyoto City Hospital
      Kioto, Kyōto, Japan