Yasuo Amano

Nippon Medical School, Edo, Tōkyō, Japan

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Publications (121)158.85 Total impact

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    ABSTRACT: Dilated cardiomyopathy (DCM) is often associated with progressive heart failure or ventricular arrhythmia. Look-Locker magnetic resonance imaging (MRI) allows quantitative evaluation of interstitial fibrosis by measuring the myocardial T1 value, and delayed enhancement (DE) MRI visualizes myocardial scar. To determine the relationship of postcontrast myocardial T1 value or DE to reduced cardiac function or sustained ventricular tachycardia (SVT) in DCM patients with a left ventricular ejection fraction (LVEF) <35%. We enrolled 41 patients with DCM. Correlations between the cardiac function parameters and postcontrast myocardial T1 value or extent of DE were evaluated. The relationship between SVT and the T1 values or extent of DE was assessed. The correlation between the extent of DE and the T1 value was also examined. The postcontrast myocardial T1 value was significantly correlated with the LVEF (P < 0.05; r = 0.31) and end-diastolic volume (P < 0.01; r = -0.40) in 40 patients with LVEF <35%. DE was not correlated with the cardiac function, but provided a high negative predictive value of 94.7% for SVT. No correlation was found between the myocardial T1 value and extent of DE. In DCM patients with LVEF <35%, the postcontrast myocardial T1 value correlated with the severity of cardiac dysfunction, and the absence of DE indicated the low risk of SVT. Both MRI parameters should be estimated because they may reflect discrete forms of myocardial damages in patients with DCM. © The Foundation Acta Radiologica 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
    Acta Radiologica 04/2015; DOI:10.1177/0284185115580840 · 1.35 Impact Factor
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    ABSTRACT: Purpose: We investigated whether corticomedullary differentiation (CMD) increased to a pseudonormal appearance on T1-weighted magnetic resonance (MR) images in patients with chronic kidney disease (CKD) with cirrhosis compared with patients with CKD without chronic liver disease.Methods: We assessed CMD on T1-weighted MR images of 32 patients with CKD with liver cirrhosis and 32 age-matched patients with CKD without liver cirrhosis, grading CMD visualization as good, moderate, or poor. We calculated quantitative CMD by the ratio of the signal intensity of the cortex to that of the medulla.Results: The proportions of patients in each of the good, moderate, and poor groups differed significantly between those with and without liver cirrhosis (P = 0.048). In patients with CKD with liver cirrhosis, the estimated glomerular filtration rate (eGFR) differed between those with poor CMD and those with good or moderate CMD (P < 0.01) but not between those with good and those with moderate CMD. In patients with CKD without cirrhosis, the eGFR differed significantly among the good, moderate, and poor CMD groups (P < 0.05). We observed no significant correlation between CMD and eGFR in patients with and without cirrhosis (P < 0.05, r = 0.62).Conclusion: CMD of the kidney had a pseudonormal appearance on T1-weighted MR imaging in patients with CKD with cirrhosis.
    Magnetic Resonance in Medical Sciences 02/2015; DOI:10.2463/mrms.2014-0044 · 1.04 Impact Factor
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    ABSTRACT: The clinical significance of microvascular obstruction (MO) in hypertrophic cardiomyopathy (HOCM) after percutaneous transluminal septal myocardial ablation (PTSMA) remains unknown. To assess the relationship between the location of MO and the improvement in symptoms and pressure gradient after PTSMA in patients with HOCM. Twenty-three patients with HOCM underwent MRI within 24 weeks after PTSMA. The MO was defined visually as the hypointense region adjacent to the left or right ventricular cavity, which was surrounded by myocardial infarction. The location of MO and improvement in clinical symptoms and pressure gradient at 3-6 months follow-up were assessed. MO was observed in 16 patients who underwent MRI within 7 weeks after PTSMA. Left-sided MO was observed in 12 patients, and right-sided MO was observed in four patients. Improvement in clinical symptoms and reduction in the pressure gradient were not sufficient in the patients with right-sided MO, while PTSMA was effective in the patients with the left-sided MO. The location of MO identified by MRI may be related to the effectiveness of PTSMA at the short-term follow-up. The left-sided MO is related to complete improvement in clinical symptoms and pressure gradients. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
    Acta Radiologica 11/2014; DOI:10.1177/0284185114559871 · 1.35 Impact Factor
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    ABSTRACT: Purpose. To investigate the liver volume change and the potential of early evaluation by contrast-enhanced magnetic resonance imaging (MRI) using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) after portal vein embolization (PVE). Materials and Methods. Retrospective evaluations of computed tomography (CT) volumetry of total liver and nonembolized areas were performed before and 3 weeks after PVE in 37 cases. The percentage of future liver remnant (%FLR) and the change ratio of %FLR (%FLR ratio) were calculated. Prospective evaluation of signal intensities (SIs) was performed to estimate the role of Gd-EOB-DTPA-enhanced MRI as a predictor of hypertrophy in 16 cases. The SI contrast between embolized and nonembolized areas was calculated 1 week after PVE. The change in SI contrast before and after PVE (SI ratio) was also calculated in 11 cases. Results. %FLR ratio significantly increased, and SI ratio significantly decreased (both P < 0.01). There were significant negative correlations between %FLR and SI contrast and between %FLR and SI ratio (both P < 0.01). Conclusion. Hypertrophy in the nonembolized area after PVE was indicated by CT volumetry, and measurement of SI contrast and SI ratio in Gd-EOB-DTPA-enhanced MRI early after PVE may be useful to predict the potential for hepatic hypertrophy.
    BioMed Research International 09/2014; 2014. DOI:10.1155/2014/684754 · 2.71 Impact Factor
  • The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques 09/2014; 41(5):656-8. DOI:10.1017/cjn.2014.6 · 1.60 Impact Factor
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    ABSTRACT: PurposeTo evaluate the distribution and extent of myocardial fibrosis identified by either contrast-enhanced Look–Locker or late gadolinium enhancement magnetic resonance imaging (LGE MRI) and their relationships between ventricular tachyarrhythmia or risk factors in apical hypertrophic cardiomyopathy (APH). Materials and Methods Twenty-five APH patients were examined using a 3.0 T or 1.5 T instrument. We used MRI to evaluate myocardial T1 values and scar. We compared the myocardial fibrosis assessed by contrast-enhanced Look–Locker or LGE MRI with ventricular tachyarrhythmia or risk factors for hypertrophic cardiomyopathy. ResultsMyocardial scar was present in 17 of the 25 patients with APH. Myocardial scar was distributed predominantly in the apical myocardium (P < 0.01), whereas myocardial T1 values did not differ between the apical, midventricular, and basal septum. The extent of myocardial scar according to 16-segment model and ejection fraction were related to ventricular tachyarrhythmia or risk factors in APH (P < 0.05 for both). The myocardial T1 value was not associated with the tachyarrhythmia or risk factors. Conclusion In APH, the extent of myocardial scar on LGE MRI is associated with ventricular tachyarrhythmia and risk factors. Quantification of the myocardial T1 value is not necessary for its risk stratification.J. Magn. Reson. Imaging 2013; © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 08/2014; 40(2). DOI:10.1002/jmri.24357 · 2.79 Impact Factor
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    ABSTRACT: Purpose: A drawback of time-resolved 3-dimensional phase contrast magnetic resonance (4D Flow MR) imaging is its lengthy scan time for clinical application in the brain. We assessed the feasibility for flow measurement and visualization of 4D Flow MR imaging using Cartesian y-z radial sampling and that using k-t sensitivity encoding (k-t SENSE) by comparison with the standard scan using SENSE.Materials and Methods: Sixteen volunteers underwent 3 types of 4D Flow MR imaging of the brain using a 3.0-tesla scanner. As the standard scan, 4D Flow MR imaging with SENSE was performed first and then followed by 2 types of acceleration scan-with Cartesian y-z radial sampling and with k-t SENSE. We measured peak systolic velocity (PSV) and blood flow volume (BFV) in 9 arteries, and the percentage of particles arriving from the emitter plane at the target plane in 3 arteries, visually graded image quality in 9 arteries, and compared these quantitative and visual data between the standard scan and each acceleration scan.Results: 4D Flow MR imaging examinations were completed in all but one volunteer, who did not undergo the last examination because of headache. Each acceleration scan reduced scan time by 50% compared with the standard scan. The k-t SENSE imaging underestimated PSV and BFV (P < 0.05). There were significant correlations for PSV and BFV between the standard scan and each acceleration scan (P < 0.01). The percentage of particles reaching the target plane did not differ between the standard scan and each acceleration scan. For visual assessment, y-z radial sampling deteriorated the image quality of the 3 arteries.Conclusion: Cartesian y-z radial sampling is feasible for measuring flow, and k-t SENSE offers sufficient flow visualization; both allow acquisition of 4D Flow MR imaging with shorter scan time.
    Magnetic Resonance in Medical Sciences 01/2014; 13(1). DOI:10.2463/mrms.2013-0008 · 1.04 Impact Factor
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    ABSTRACT: This study aimed to determine the relationship between delayed enhancement magnetic resonance imaging (DE MRI) and ventricular tachyarrhythmia in patients with hypertrophic cardiomyopathy (HCM) with basal septal hypertrophy and preserved ejection fraction (EF). One hundred seven patients with HCM with basal septal hypertrophy and EF greater than 50% underwent cine and DE MRI. Myocardial scar was identified with DE MRI. We assessed whether patient,s background, cine MRI findings, presence of myocardial scar, or number of scarred myocardial segments was related to the occurrence of ventricular tachyarrhythmia. Patient,s age, family history of HCM, and number of scarred segments differed between the patients with and without the arrhythmia. A family history of HCM and number of scarred segments were significantly related to ventricular tachyarrhythmia (P < 0.01). The number of scarred segments is the significant DE MRI parameter related to ventricular tachyarrhythmia in HCM with basal septal hypertrophy and preserved EF.
    Journal of computer assisted tomography 12/2013; 38(1). DOI:10.1097/RCT.0b013e3182a2fb01 · 1.60 Impact Factor
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    ABSTRACT: Our aim was to evaluate the long-term efficacy and safety of percutaneous transhepatic obliteration (PTO) alone and combined with balloon-occluded retrograde transvenous obliteration (BRTO) for gastroesophageal varices refractory to BRTO alone. Between July 1999 and December 2010, 13 patients with gastroesophageal varices refractory to BRTO were treated with PTO (n = 6) or a combination of PTO and BRTO (n = 7). We retrospectively investigated the rates of survival, recurrence, or worsening of the varices; hepatic function before and after the procedure; and complications. The procedure achieved complete obliteration or significant reduction of the varices in all 13 patients without major complications. During follow-up, the varices had recurred in 2 patients, of which one had hepatocellular carcinoma, and the other died suddenly from variceal rebleeding 7 years after PTO. The remaining 11 patients did not experience worsening of the varices and showed significant improvements in the serum ammonia levels and prothrombin time. The mean follow-up period was 90 months, and the cumulative survival rate at 1, 3, and 5 years was 92.9%, 85.7%, and 85.7%, respectively. Both PTO and combined PTO and BRTO seem as safe and effective procedures for the treatment of gastroesophageal varices refractory to BRTO alone.
    The Scientific World Journal 12/2013; 2013:498535. DOI:10.1155/2013/498535 · 1.73 Impact Factor
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    ABSTRACT: CONCLUSION The hemodynamics after EC-IC bypass is assessed by 4D Flow comprehensively. BACKGROUND Extracranial-intracranial (EC-IC) bypass is performed to maintain blood flow in the brain of patients with internal carotid artery (ICA) occlusion. However, hemodynamics after EC-IC bypass is not well known. The aim of this study was to comprehensively assess the hemodynamics in patients after EC-IC bypass using time-resolved 3D phase contrast MRI (4D Flow). EVALUATION 4D Flow was performed in 19 patients (12 men; mean 66 years) who had undergone EC-IC bypass. Ten of the 19 patients received radial artery graft (RAG) bypass surgery after ICA ligation for aneurysm, and the other 9 received superficial temporal artery (STA) bypass for ICA occlusion. The velocity data and pressure gradient map were generated using a dedicated software. As the parameters related to hemodynamics, we evaluated the following ones: 1, Flow direction of M1 which was classified to anterograde and retrograde, compared to that of the native M1; 2, Blood flow volume (BFV) of ICA, basilar artery (BA) and the bypass; 3, BFV difference (ΔBFV) as {(BFV of contralateral ICA + BA)- (BFV of bypass)); 4, Pressure gradient at the M1 (ΔP), from the MCA origin to the M1-M2 segment. Thereafter, we evaluated the relationship between the type of bypass graft and flow direction of M1 or BFV of the bypass and the correlation between ΔP and ΔBFV in patients who had no early bifurcation at M1. The retrograde flow at M1 was observed more frequently after RAG bypass surgery (n = 8 / 10) than after STA bypass (n = 2 / 9, p < 0.05). The BFV was higher in RAG bypass in STA bypass (3.41 ± 0.95 ml/s vs. 1.90 ± 1.02 ml/s, p < 0.01). ΔP was calculated in 11 patients. The 5 patients with anterograde flow of the M1 showed positive ΔP (18.4 ± 14.4Pa), whereas the other 6 with retrograde flow of the M1 showed negative ΔP (-38.1 ± 13.8Pa). ΔP significantly correlated with ΔBFV (p < 0.01, r = 0.742). DISCUSSION 4D Flow shows that the type of bypass affects flow direction and BFV, and that ΔP correlates with ΔBFV. 4D Flow can quantify BFV and ΔP after EC-IC bypass as well as visualize flow direction.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE Time resolved 3D phase-contrast (4D-flow) MRI is a promising tool for blood flow evaluation in cerebrovascular disease. The purpose of this study is to demonstrate the clinical feasibility of 4D-flow MRI in the evaluation of hemodynamics in patients after both ICA ligation for Aneurysm and extracranial/intracranial (EC/IC) bypass surgery using a radial artery graft. METHOD AND MATERIALS Seven patients (6 females and one male, mean age; 68 years) with 6 giant aneurysms (size; 15-30mm, mean 21mm) and one carotid cavernous fistula were treated with ICA ligation and EC/IC bypass surgery using a radial artery graft. We performed CT Angiography (CTA) and CT perfusion (CTP) using 64-slice multi-detector (MD)-CT, TOF-MRA and 4D-flow MRI at 3T after surgery. The date of 4D flow MRI was transported to another personal computer with 4D flow visualization software (GT-Flow; GyroTools). Time-resolved 3D-flow mapping images of EC/IC bypass graft and cerebral artery were generated. The patency, stenosis and bending of radial artery graft were evaluated independently on CTA, TOF-MRA and 4D-flow MRA. 4D-flow MRI and CTP were evaluated for the perfusion of MCA territory. RESULTS Bypass surgery was successful in all patients. The acquisition time of 4D-flow MRI data was about less than 10 minutes. 4D-flow MRI visualized the arterial flow from radial artery graft to MCA successfully. TOF-MRA demonstrated narrowing of graft-side MCA in all patients and stenosis of 5 locations (severe; 1, moderate; 2, mild; 2) of graft in 4 patients. 4D-flow MRI showed stenosis of 5 locations (severe; 0, moderate; 1, mild; 4). CTA showed stenosis of 4 locations (severe; 0, moderate; 0, mild; 4). CTP demonstrated symmetrical perfusion of MCA territory in all patients. On the other side, 4D-flow MRI demonstrated of flow delay of MCA M1 portion in 6 patients and could not depict flow of M1 by the artifact of aneurismal clip in one patient. CONCLUSION 4D-flow MRI is a promising tool that visualizes graft flow and intracranial arterial hemodynamic in patients after IC ligation for aneurysm and EC/IC bypass surgery. CLINICAL RELEVANCE/APPLICATION Time resolved 3D phase-contrast (4D-flow) MRI is a promising tool that visualizes cerebral blood flow and graft patency after both ICA ligation for giant aneurysm and high flow EC/IC bypass surgery.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: To assess relationship between nonscarred myocardial T1 value measured using contrast-enhanced Look-Locker MRI and cardiac function in dilated cardiomyopathy (DCM) at 1.5 Tesla (T) and 3.0T MRI. Contrast-enhanced Look-Locker MRI was performed in 35 DCM patients. Nonscarred myocardial and blood T1 values were calculated from the signal intensity values and the delay time obtained on Look-Locker MRI. We assessed the correlation between the myocardial T1 value or myocardial T1 minus blood T1 value and cardiac function estimated using cine MRI (e.g., end-diastolic volume: EDV, left ventricular ejection fraction: LVEF) or brain natriuretic peptide (BNP). With 1.5T MRI (n = 16), the myocardial T1 value correlated negatively with the EDV(r = -0.66) and end-systolic volume (ESV; r = -0.68), and positively with the LVEF (r = 0.51); the myocardial T1 minus blood T1 value correlated inversely with EDV (r = -0.70), ESV (r = -0.62), and brain natriuretic peptide (BNP; r = -0.56). With 3.0T MRI (n = 17), the myocardial T1 value correlated negatively with ESV (r = -0.44), septal thickness (r = -0.60), and BNP (r = -0.51), and positively with LVEF (r = 0.61); the myocardial T1 minus blood T1 value negatively correlated with BNP (r = -0.50) and positively with LVEF (r = 0.54). The nonscarred myocardial T1 value measured with either 1.5T or 3.0T contrast-enhanced Look-Locker MRI is significantly related to cardiac dysfunction in DCM. J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.
    Journal of Magnetic Resonance Imaging 12/2013; 38(6). DOI:10.1002/jmri.24131 · 2.79 Impact Factor
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    ABSTRACT: Replacement of aneurysm clips or temporary parent artery occlusion during aneurysm clipping (AC) carries the risk of inducing postoperative neurologic deficits. When studying the risk of surgical complications associated with cerebral aneurysms, patients with similar conditions should be compared to eliminate the influence of rupture and location of aneurysm. MATERIAL and We used 3.0-Tesla (3.0T) magnetic resonance diffusion-weighted imaging (DWI) and magnetic resonance angiography (MRA) to analyze surgical complications after AC. A total of 42 AC procedures for 40 unruptured and 2 delayed-phase ruptured MCA aneurysms were evaluated. In six patients, temporary parent artery occlusion was performed. Asymptomatic hyperintensities were observed on DWI of three patients. In one patient, an asymptomatic lesion was most likely caused by a small contusion that occurred during dissection of an aneurysm attached to the brain surface. In two patients, asymptomatic cortical lesions were caused by brain surface contusions due to lacerations of the open dura. No symptomatic hyperintensities on DWI were observed after surgery. No fixed ischaemic neurologic deficits resulted from AC. Although some postoperative abnormalities were observed with 3.0T DWI, we found clipping of MCA aneurysms to be a safe procedure with a low risk of ischaemic complications.
    Turkish neurosurgery 11/2013; 23(6):772-7. DOI:10.5137/1019-5149.JTN.7886-13.1 · 0.53 Impact Factor
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    ABSTRACT: To evaluate the capability of MRI to differentiate cardiac amyloidosis (CA), end-stage hypertrophic cardiomyopathy (HCM), and hypertensive heart disease (HHD), which are important etiologies of left ventricular hypertrophy (LVH) and heart failure. We enrolled 26 patients presenting with both LVH and heart failure: six with CA, nine with end-stage HCM, and 11 with HHD. Cardiac function, presence of pericardial or pleural effusion, and the extent and patterns of late gadolinium enhancement (LGE) were compared among the three diseases. Myocardial LGE was observed in all six CA patients, eight end-stage HCM patients, and six HHD patients. The number of LGE segments was significantly greater in CA than in HCM or HHD (p = 0.02 for both), and all patients with CA showed a global endocardial pattern of LGE. There were significant differences among CA, HCM, and HHD in ejection fraction and end-diastolic and end-systolic volume indices (p < 0.05 for all). Pericardial effusion was observed more frequently in CA than in HCM or HHD (p = 0.04 or 0.01, respectively). MRI is valuable for distinguishing among CA, end-stage HCM, and HHD, all of which present with LVH and heart failure.
    Japanese journal of radiology 08/2013; 31(10). DOI:10.1007/s11604-013-0238-0 · 0.74 Impact Factor
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    ABSTRACT: Cardiac magnetic resonance (CMR) imaging is an established method of detecting myocardial fibrosis related to prognosis in patients with dilated cardiomyopathy (DCM). Recent studies have found that (99m)Tc-methoxy-isobutyl-isonitrile (MIBI) and (123)I-15-(p-iodophenyl)-3(R,S)-methylpentadecanoic acid (BMIPP) dual single-photon-emission computerized tomography (MIBI-BMIPP dual SPECT) can detect perfusion-metabolism mismatches. We compared MIBI-BMIPP dual SPECT with CMR findings and assessed their prognostic abilities to determine the significance of abnormal metabolism in patients with DCM. Fifty inpatients with DCM (age 58 ± 12 y; 14 female) were assessed with the use of MIBI-BMIPP dual SPECT and CMR. Perfusion-metabolism mismatches were identified mainly at the left ventricular free wall, whereas late gadolinium enhancement (LGE) was evident mostly at the septal wall. During a median follow-up of 33 months, 9 patients developed cardiac events including death, heart failure, and fatal arrhythmia. Event-free survival rates were significantly lower for patients with LGE plus a mismatch than with other abnormalities (P = .001). Among clinical and imaging variables, LGE plus a mismatch was significantly associated with cardiac events (hazard ratio 7.9, 95% confidence interval 1.8-35.6; P = .007). Coexisting LGE and a perfusion-metabolism mismatch accurately predict future cardiac events in patients with DCM.
    Journal of cardiac failure 07/2013; 19(7):445-53. DOI:10.1016/j.cardfail.2013.05.009 · 3.07 Impact Factor
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    ABSTRACT: BACKGROUND: The aim of the present study is to quantify the degree of the error as a function of the left ventricular (LV) wall thickness, in calculation of the ejection fraction (EF) using gated single-photon emission computed tomography (SPECT). The essential error of quantitative gated SPECT (QGS) software in patients with myocardial hypertrophy has not been quantitatively estimated. METHODS: Forty-six patients with known or suspected hypertrophic cardiomyopathy underwent gated myocardial perfusion SPECT and cardiac magnetic resonance (MR) imaging. The EF value was automatically calculated from gated SPECT using the QGS software. Twelve points of regional LV wall thickness and the EF value were estimated from MR images. RESULTS: Only a fair correlation was found between the QGS-EF and the MR-EF values (r = 0.48, y = 0.49x + 26.80, p < 0.01), and the QGS-EF was underestimated (r = 0.25, y = 0.90x) in 30 patients with myocardial hypertrophy (mean wall thickness > 12 mm). The magnitude of the error of the EF quantification from gated SPECT showed a significant negative correlation with the mean 12-point LV wall thickness in all 46 patients (r = -0.67, y = -4.12x + 40.44, p < 0.0001). The degree of the error of the ESV and that of the EDV showed positive correlation with the mean LV wall thickness (r = 0.55, y = 5.46x - 56.13, p < 0.0001; r = 0.31, y = 4.20x - 55.28, p < 0.05, respectively). CONCLUSIONS: The underestimation of EF increases with the degree of myocardial hypertrophy, because of the overestimation of the LV cavity especially in the end-systolic phase.
    Annals of Nuclear Medicine 03/2013; 27(6). DOI:10.1007/s12149-013-0713-9 · 1.51 Impact Factor
  • Journal of Nippon Medical School 01/2013; 80(1):2-3. DOI:10.1272/jnms.80.2 · 0.59 Impact Factor
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    ABSTRACT: PURPOSE Dynamic MRI is useful to detect pituitary microadenoma, whereas it is not easy to adjust the slice of dynamic scanning to micro-lesion. The aim of this study is to evaluate the clinical feasibility of high-resolution (HR) dynamic MRI using a volume isotropic turbo spin-echo acquisition (VISTA) at 3-Tesla for the detection of pituitary microadenoma. METHOD AND MATERIALS Before clinical application of the HR dynamic MRI, we compared 3D-VISTA with conventional 2D-TSE using phantom. After then, we investigated 17 patients (mean age, 40 years) with endocrine and/or clinical symptoms and clinically suspected pituitary microadenomas. All patients underwent pre-contrast MRI. The HR dynamic MRI was done during a bolus injection of contrast material. The voxel size was 0.63 x 0.70 x 2 mm3. The data acquisition time of the HR dynamic MRI was 30 sec / phase, and five phases were acquired. Thereafter, post-contrast MRI was obtained. We compared pre- and post-contrast and HR dynamic MRI and final diagnosis for the tumor detection. RESULTS The phantom study demonstrated 3D-VISTA provided 40% improvement in SNR in comparison with 2D-TSE. HR dynamic MRI identified 14 microadenomas in 14 of the 17 patients, whereas pre- and post-contrast MRI identified 5 and 10 tumors. The size of 14 microadenomas ranged from 3 to 10 mm (mean, 5.9mm). In 10 of the 14 patients, trans-sphenoidal surgery was performed and the microadenomas were proven histologically. Surgical findings showed coincidence with HR dynamic MRI findings in 9 patients. In only one adenoma (ACTH- secreting tumor), HR dynamic MRI demonstrated tiny nodule at left side, whereas surgical finding showed tiny microadenoma at right side. The remaining 4 microadenomas were diagnosed by the laboratory tests and treated medically. In 3 of the 17 patients, any MRI scans did not detect pituitary adenoma. The laboratory tests excluded pituitary adenoma in 2 of the 3 patients, but the other patient presented with a high value of ACTH. The sensitivity, positive predictive value, and accuracy of the HR dynamic MRI were 93%, 93%, and 88%, respectively. CONCLUSION The HR dynamic MRI using 3D VISTA may be useful for the detection of pituitary microadenoma and determination of surgical procedures. CLINICAL RELEVANCE/APPLICATION Dynamic MRI using 3D VISTA with 3-Tesla identifies pituitary microadenoma with the high spatial and contrast resolutions and multiplanar reconstruction capability.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: Cerebral revascularization surgery (CRS) is increasingly recognized as an important component in the treatment of complex cerebral vascular disease and tumors. CRS requires that the incidence of perioperative neurological complications should be minimized, because CRS for ischemic disease is often not the goal of treatment, but rather a prophylactic surgery. CRS carries the risk of focal postoperative neurological deficits. Little has been established concerning mechanisms of post-CRS ischemia. We used 3.0-T diffusion-weighted magnetic resonance imaging (DWI) and magnetic resonance angiography (MRA) to analyze the incidence and mechanism of ischemic lesions.
    Clinical neurology and neurosurgery 11/2012; 115(7). DOI:10.1016/j.clineuro.2012.10.021 · 1.25 Impact Factor
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    Yasuo Amano · Masaki Tachi · Shinichiro Kumita
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    ABSTRACT: Background Two-dimensional (2D) Look-Locker MRI technique can identify myocardial fibrosis, but cannot cover the whole left ventricle during a single scan.PurposeTo develop breath-hold three-dimensional (3D) Look-Locker MRI for the evaluation of postcontrast myocardial and blood T1 values and myocardial scarring in the left ventricle.Material and MethodsA phantom and 24 patients with myocardial diseases underwent gadolinium-enhanced 2D and 3D Look-Locker MRI using a 1.5-T unit. We compared the T1 value of the phantom and the values of the myocardium and blood in the patients between the two Look-Locker MRI sequences. In the patient study, the scan ordering of the two Look-Locker MRI was selected randomly. We also assessed the ability of the 3D imaging to detect myocardial scarring that was confirmed by late gadolinium enhancement MRI.ResultsThe phantom study showed a good agreement for the T1 value between 2D and 3D Look-Locker MRI. There were no significant differences in the myocardial T1 values after contrast between 2D and 3D Look-Locker MRI or in the T1 values between the two imaging slices on the 3D Look-Locker MRI (P > 0.10). A better agreement for the myocardial T1 values was found when the 3D Look-Locker imaging was performed first. The T1 values for blood were affected by the scan order (P < 0.05). The 3D Look-Locker MRI showed myocardial scarring with a shorter T1 value (290.4 ± 62.7 ms) than those for unscarred myocardium (360.8 ± 30.3 ms).Conclusion Three-dimensional Look-Locker MRI may precisely estimate the postcontrast myocardial and blood T1 values for the entire left ventricle during a single scan.
    Acta Radiologica 11/2012; 54(1). DOI:10.1258/ar.2012.120378 · 1.35 Impact Factor