Publications (26)166.33 Total impact
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Article: Reduction of Visceral Fat Correlates with the Decrease in the Number of Obesity-Related Cardiovascular Risk Factors in Japanese with Abdominal Obesity (VACATION-J Study).
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ABSTRACT: Aim: Visceral fat accumulation is associated with obesity-related cardiovascular risk factor accumulation and atherosclerosis. The present study investigated whether one-year reduction of the visceral fat area (VFA) correlates with a decrease in the number of such factors in Japanese with or without visceral fat accumulation.Methods: The study subjects comprised 5,347 Japanese, who underwent health check-ups in 2007 and 2008, including measurements of VFA and subcutaneous fat area (SFA) by computed tomography at 9 centers in Japan. Subjects with one or more such factor(s) were categorized into tertiles based on the one-year change in VFA. We investigated the multivariate age, sex, and one-year change in SFA-adjusted odds ratios (ORs) and 95% confidence intervals (CI) for reductions in the number of risk factors in each of the three categories based on the one-year change in VFA, in subjects with one or more such factors (n= 3,648).Results: In the entire group (n=3,648), the OR and 95%CI for reductions in the number of risk factors in the first tertile were 0.804 (0.673-0.962, p=0.0172), compared with the second tertile set at 1.0. Subjects with VFA <100cm(2) showed no reduction in the number of risk factors. In subjects with VFA .100 cm(2), OR in the first tertile was 0.788 (0.639-0.972, p=0.0257) relative to the second tertile set at 1.0.Conclusions: In subjects with multiple cardiovascular risk factors, visceral fat reduction correlated with a decrease in the number of such factors in subjects with VFA≥100cm(2), but not in those with VFA<100cm(2).Journal of atherosclerosis and thrombosis 07/2012; · 2.69 Impact Factor -
Article: Absolute value of visceral fat area measured on computed tomography scans and obesity-related cardiovascular risk factors in large-scale Japanese general population (the VACATION-J study).
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ABSTRACT: The management of cardiovascular risk factors is important for prevention of atherosclerotic cardiovascular diseases (ACVD). Visceral fat accumulation plays an important role in the clustering of cardiovascular risk factors, leading to ACVD. The present study investigated the gender- and age-specific relationship between obesity-related cardiovascular risk factor accumulation and computed tomography (CT)-measured fat distribution in a large-scale Japanese general population. Fat distribution was measured on CT scans in 12,443 subjects (males/females = 10,080/2,363), who underwent medical health check-up at 9 centers in Japan. The investigated obesity-related cardiovascular risk factors were hyperglycemia, dyslipidemia, and elevated blood pressure. Visceral fat area (VFA) for all males and old females showed almost symmetric distribution, while that of young females showed skewed distribution with a marked left shift. Only a small proportion of young females had large visceral fat and cardiovascular risk accumulation. The mean number of risk factors exceeded 1.0 at around 100 cm(2) for VFA in all groups, irrespective of gender, age (cut-off age 55), and BMI (cut-off BMI 25 kg/m(2)). In this large-scale Japan-wide general population study, an absolute VFA value of about 100 cm(2) equated with obesity-related cardiovascular risk factor accumulation, irrespective of gender, age, and BMI.Annals of medicine 10/2010; 44(1):82-92. · 3.52 Impact Factor -
Article: Carotid magnetic resonance imaging. A window to study atherosclerosis and identify high-risk plaques.
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ABSTRACT: Despite recent advances in the understanding and etiology of cardiovascular disease, it remains the leading cause of morbidity and mortality worldwide. A great deal of research has been dedicated to investigating and identifying plaque instability: the so-called "vulnerable plaque". A reliable, in vivo, imaging method capable of identifying plaque characteristics associated with high-risk plaque will be immensely useful for evaluating plaque status and predicting future events. With excellent soft-tissue contrast and resolution, magnetic resonance imaging (MRI) has the ability to visualize features of vulnerable plaques, as well as perform longitudinal studies on the etiology, progression, and regression of atherosclerotic plaque. This review will cover the current state-of-the-art and new developments in carotid MRI to characterize atherosclerosis and its use in clinical diagnoses and longitudinal studies to understand mechanisms of lesion progression and regression.Circulation Journal 10/2009; 73(10):1765-73. · 3.77 Impact Factor -
Article: Relationship between coronary artery wall thickness measured by 64-slice multidetector computed tomography and cardiovascular risk factors.
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ABSTRACT: Recent studies have demonstrated the quantitative ability of contrast-enhanced multidetector computed tomography (MDCT) to evaluate not only the vessel lumen but also coronary plaque. The aim of this study was to assess the association between coronary wall thickness quantified by 64-slice MDCT and cardiovascular risk factors. A total of 149 subjects with suspected coronary artery disease were scanned by contrast-enhanced 64-slice MDCT. The maximum coronary wall thickness of each proximal segment was measured and associations with baseline coronary risk factors were analyzed. The mean maximum wall thickness of all 149 patients was 0.7+/-0.3 mm and there was a significant positive correlation with age (P<0.001) and hemoglobin (Hb) A1c (P=0.001). Patients with hypertension (0.8+/-0.3 vs 0.7+/-0.3 mm, P=0.024) and diabetes (0.9+/-0.4 vs 0.7+/-0.3 mm, P=0.002) had thicker walls than those without. Multivariate linear regression analysis demonstrated that both risk factors were independently correlated with mean maximum wall thickness. Coronary wall thickness measured by 64-slice MDCT is associated with age and HbA1c, so may add useful information to cardiovascular risk stratification.Circulation Journal 02/2009; 73(4):681-5. · 3.77 Impact Factor -
Article: Rationale and design of the carotid plaque in human for all evaluations with aggressive rosuvastatin therapy (CHALLENGER trial): evaluation by magnetic resonance imaging.
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ABSTRACT: Intensive lipid-lowering therapy with statins reduces levels of low-density lipoprotein (LDL)-cholesterol (C) and improves plaque volume and composition in patients with cardiovascular disease. Furthermore, rosuvastatin ameliorated carotid stenosis in the ASTEROID study, and altered the composition of plaques in a predominantly Caucasian study population in the ORION study. However, it is not known whether statin therapy achieves similar quantitative improvement in carotid artery plaque in other ethnic groups. Fifty patients with hypercholesterolemia (LDL-C >or=120 mg/dl) and a maximum carotid intima-media thickness >or=1.8 mm will be enrolled and treated with rosuvastatin at a dose of 5 mg/day for 96 weeks. The primary endpoints will be the percent change of carotid plaque volume and the change in plaque composition after 96 weeks of treatment, as evaluated by magnetic resonance imaging. The CHALLENGER study will provide a noninvasive assessment of the changes in carotid plaque volume and composition achieved by reduction of LDL levels in Japanese patients with carotid stenosis on long-term rosuvastatin therapy.Circulation Journal 01/2009; 73(1):111-5. · 3.77 Impact Factor -
Article: Prevalence of American Heart Association type VI carotid atherosclerotic lesions identified by magnetic resonance imaging for different levels of stenosis as measured by duplex ultrasound.
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ABSTRACT: Via magnetic resonance imaging (MRI), we sought to determine the prevalence of atherosclerotic American Heart Association type VI lesions (AHA-LT6) (lesions with luminal surface defect, hemorrhage/thrombus, or calcified nodule) in carotid arteries that represented all categories of stenosis as measured by duplex ultrasound. Arterial stenosis alone has been shown to be a poor predictor of cardiovascular events. Autopsy studies suggest that features associated with AHA-LT6 lesions, rather than the degree of luminal narrowing, characterize the high-risk plaque. A total of 192 subjects underwent bilateral carotid artery magnetic resonance imaging (MRI) scans at 1.5T after evaluation with ultrasound to determine stenosis. After excluding arteries with a previous endarterectomy, poor image quality, or missing ultrasound data, there were 175 patients with 260 arteries available for analysis. The AHA lesion type was determined by the consensus opinion of 2 experienced carotid MRI reviewers. In total, 96 of 260 (37.0%) arteries had >or=1 location with AHA-LT6. Of the arteries with AHA-LT6, 84.4% had hemorrhage, 45.8% had a ruptured fibrous cap, and 14.6% showed other type of complications. Prevalence of AHA-LT6 was an increasing sequence of 8.1% in the 37 arteries with 1% to 15% stenosis, 21.7% in the 60 arteries with 16% to 49% stenosis, 36.8% in the 114 arteries with 50% to 79% stenosis, and 77.6% in the 49 arteries with 80% to 99% stenosis. Complicated AHA-LT6 are frequently found in arteries with <or=50% stenosis. These findings indicate that complex lesions develop in a substantial number of arteries in the absence of high-grade stenosis. Ongoing prospective studies will determine the predictive value of vulnerable plaque features, as visualized by MRI, for risk of subsequent ischemic events.Journal of the American College of Cardiology 04/2008; 51(10):1014-21. · 14.16 Impact Factor -
Article: Effect of rosuvastatin therapy on carotid plaque morphology and composition in moderately hypercholesterolemic patients: a high-resolution magnetic resonance imaging trial.
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ABSTRACT: Magnetic resonance imaging (MRI) can noninvasively assess changes in atherosclerotic plaque morphology and composition. The ORION trial assessed the effects of rosuvastatin on carotid plaque volume and composition. The randomized, double-blind ORION trial used 1.5-T MRI to image carotid atherosclerotic plaques at baseline and after 24 months of treatment. Forty-three patients with fasting low-density lipoprotein cholesterol > or = 100 and < 250 mg/dL and 16% to 79% carotid stenosis by duplex ultrasound were randomized to receive either a low (5 mg) or high (40/80 mg) dose of rosuvastatin. After 24 months, 33 patients had matched serial MRI scans to compare by reviewers blinded to clinical data, dosage, and temporal sequence of scans. Low-density lipoprotein cholesterol was significantly reduced from baseline in both the low- and high-dose groups (38.2% and 59.9%, respectively, both P < .001). At 24 months, there were no significant changes in carotid plaque volume for either dosage group. In all patients with a lipid-rich necrotic core (LRNC) at baseline, the mean proportion of the vessel wall composed of LRNC (%LRNC) decreased by 41.4% (P = .005). In patients with moderate hypercholesterolemia, both low- and high-dose rosuvastatin were effective in reducing low-density lipoprotein cholesterol. Furthermore, rosuvastatin was associated with a reduction in %LRNC, whereas the overall plaque burden remained unchanged over the course of 2 years of treatment. These findings provide evidence that statin therapy may have a beneficial effect on plaque volume and composition, as assessed by noninvasive MRI.American heart journal 03/2008; 155(3):584.e1-8. · 4.65 Impact Factor -
Article: Differences in carotid arterial morphology and composition between individuals with and without obstructive coronary artery disease: A cardiovascular magnetic resonance study
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ABSTRACT: Abstract Objective We sought to determine differences with cardiovascular magnetic resonance (CMR) in the morphology and composition of the carotid arteries between individuals with angiographically-defined obstructive coronary artery disease (CAD, ≥ 50% stenosis, cases) and those with angiographically normal coronaries (no lumen irregularities, controls). Methods and results 191 participants (50.3% female; 50.8% CAD cases) were imaged with a multi-sequence, carotid CMR protocol at 1.5T. For each segment of the carotid, lumen area, wall area, total vessel area (lumen area + wall area), mean wall thickness and the presence or absence of calcification and lipid-rich necrotic core were recorded bilaterally. In male CAD cases compared to male controls, the distal bulb had a significantly smaller lumen area (60.0 ± 3.1 vs. 79.7 ± 3.2 mm<sup>2</sup>, p < 0.001) and total vessel area (99.6 ± 4.0 vs. 119.8 ± 4.1 mm<sup>2</sup>; p < 0.001), and larger mean wall thickness (1.25 ± 0.03 vs. 1.11 ± 0.03 mm; p = 0.002). Similarly, the internal carotid had a smaller lumen area (37.5 ± 1.8 vs. 44.6 ± 1.8 mm<sup>2</sup>; p = 0.006) and smaller total vessel area (64.0 ± 2.3 vs. 70.9 ± 2.4 mm<sup>2</sup>; p = 0.04). These metrics were not significantly different between female groups in the distal bulb and internal carotid or for either gender in the common carotid. Male CAD cases had an increased prevalence of lipid-rich necrotic core (49.0% vs. 19.6%; p = 0.003), while calcification was more prevalent in both male (46.9% vs. 17.4%; p = 0.002) and female (33.3% vs. 14.6%; p = 0.031) CAD cases compared to controls. Conclusion Males with obstructive CAD compared to male controls had carotid bulbs and internal carotid arteries with smaller total vessel and lumen areas, and an increased prevalence of lipid-rich necrotic core. Carotid calcification was related to CAD status in both males and females. Carotid CMR identifies distinct morphological and compositional differences in the carotid arteries between individuals with and without angiographically-defined obstructive CAD.Journal of Cardiovascular Magnetic Resonance. 01/2008; -
Article: Predictors of carotid atherosclerotic plaque progression as measured by noninvasive magnetic resonance imaging.
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ABSTRACT: The purpose of this in vivo MRI study was to quantify changes in atherosclerotic plaque morphology prospectively and to identify factors that may alter the rate of progression in plaque burden. Sixty-eight asymptomatic subjects with >or=50% stenosis, underwent serial carotid MRI examinations over an 18-month period. Clinical risk factors for atherosclerosis, and medications were documented prospectively. The wall and total vessel areas, matched across time-points, were measured from cross-sectional images. The normalized wall index (NWI=wall area/total vessel area), as a marker of disease severity, was documented at baseline and at 18 months. Multiple regression analysis was used to correlate risk factors and morphological features of the plaque with the rate of progression/regression. On average, the wall area increased by 2.2% per year (P=0.001). Multiple regression analysis demonstrated that statin therapy (P=0.01) and a normalized wall index >0.64 (P=0.001) were associated with a significantly reduced rate of progression in mean wall area. All other documented risk factors were not significantly associated with changes in wall area. Findings from this study suggest that increased normalized wall index and the use of statin therapy are associated with reduced rates of plaque progression amongst individuals with advanced, asymptomatic carotid atherosclerosis.Atherosclerosis 11/2007; 194(2):e34-42. · 3.79 Impact Factor -
Article: Magnetic resonance imaging of carotid atherosclerosis: plaque analysis.
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ABSTRACT: The Computer-Aided System for CArdiovascular Disease Evaluation (CASCADE) has been developed for streamlined, automated analysis of carotid artery magnetic resonance imaging to measure atherosclerotic plaque burden and composition in vivo. The purpose of this investigation was to assess the performance of CASCADE compared with manual outlining. Magnetic resonance images were obtained from 26 subjects with 16% to 79% carotid artery stenosis by duplex ultrasound who were imaged twice in a 2-week period with a multiple-slice, multiple-contrast magnetic resonance imaging protocol as part of the Outcome of Rosuvastatin treatment on carotid artery atheroma: a magnetic resonance Imaging ObservatioN trial. Manual outlining was used to identify the boundaries of the lumen, wall, necrotic core (NC), and calcifications. After 6 months, the analysis was repeated using CASCADE. For each data set, the contours were used to compute the maximal normalized wall index (NWI; wall area divided by total vessel area), maximal wall thickness (WT), and the average NC and calcified (CA) areas per slice. Agreement between manual and automated reviews and the scan-scan measurement reproducibilities were evaluated. Pearson correlation between manual and automated analyses was 0.94 for maximal NWI, 0.86 for maximal WT, 0.84 for NC, and 0.96 for CA. Intraclass correlation coefficients for manual and automated analyses were 0.90 and 0.97 for maximal NWI, 0.89 and 0.95 for maximal WT, 0.95 and 0.87 for NC, and 0.96 and 0.94 for CA, respectively. Automated analysis tools are capable of providing accurate and reproducible measurements of carotid atherosclerotic burden and composition when compared with manually outlined results.Topics in Magnetic Resonance Imaging 11/2007; 18(5):371-8. -
Article: The vulnerable, or high-risk, atherosclerotic plaque: noninvasive MR imaging for characterization and assessment.
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ABSTRACT: "Vulnerable" plaques are atherosclerotic plaques that have a high likelihood to cause thrombotic complications, such as myocardial infarction or stroke. Plaques that tend to progress rapidly are also considered to be vulnerable. Besides luminal stenosis, plaque composition and morphology are key determinants of the likelihood that a plaque will cause cardiovascular events. Noninvasive magnetic resonance (MR) imaging has great potential to enable characterization of atherosclerotic plaque composition and morphology and thus to help assess plaque vulnerability. A classification for clinical, as well as pathologic, evaluation of vulnerable plaques was recently put forward in which five major and five minor criteria to define vulnerable plaques were proposed. The purpose of this review is to summarize the status of MR imaging with regard to depiction of the criteria that define vulnerable plaques by using existing MR techniques. The use of MR imaging in animal models and in human disease in various vascular beds, particularly the carotid arteries, is presented.Radiology 08/2007; 244(1):64-77. · 5.73 Impact Factor -
Article: Reader and platform reproducibility for quantitative assessment of carotid atherosclerotic plaque using 1.5T Siemens, Philips, and General Electric scanners.
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ABSTRACT: To evaluate the platform and reader reproducibility of quantitative carotid plaque measurements. A total of 32 individuals with >or=15% carotid stenosis by duplex ultrasound were each imaged once by a 1.5T General Electric (GE) whole body scanner and twice by either a 1.5T Philips scanner or a 1.5T Siemens scanner. A standardized multisequence protocol and identical phased-array carotid coils were used. Expert readers, blinded to subject information, scanner type, and time point, measured the lumen, wall, and total vessel areas and determined the modified American Heart Association lesion type (AHA-LT) on the cross-sectional images. AHA-LT was consistently identified across the same (kappa = 0.75) and different scan platforms (kappa = 0.75). Furthermore, scan-rescan coefficients of variation (CV) of wall area measurements on Siemens and Philips scanners ranged from 6.3% to 7.5%. However, wall area measurements differed between Philips and GE (P = 0.003) and between Siemens and GE (P = 0.05). In general, intrareader reproducibility was higher than interreader reproducibility for AHA-LT identification as well as for quantitative measurements. All three scanners produced images that allowed AHA-LT to be consistently identified. Reproducibility of quantitative measurements by Siemens and Philips scanners were comparable to previous studies using 1.5T GE scanners. However, bias was introduced with each scanner and the use of different readers substantially increased variability. We therefore recommend using the same platform and the same reader for scans of individual subjects undergoing serial assessment of carotid atherosclerosis.Journal of Magnetic Resonance Imaging 08/2007; 26(2):344-52. · 2.70 Impact Factor -
Article: MRI of atherosclerosis in clinical trials.
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ABSTRACT: Magnetic resonance imaging (MRI) of the arterial wall has emerged as a viable technology for characterizing atherosclerotic lesions in vivo, especially within carotid arteries and other large vessels. This capability has facilitated the use of carotid MRI in clinical trials to evaluate therapeutic effects on atherosclerotic lesions themselves. MRI is specifically able to characterize three important aspects of the lesion: size, composition and biological activity. Lesion size, expressed as a total wall volume, may be more sensitive than maximal vessel narrowing (stenosis) as a measure of therapeutic effects, as it reflects changes along the entire length of the lesion and accounts for vessel remodeling. Lesion composition (e.g. lipid, fibrous and calcified content) may reflect therapeutic effects that do not alter lesion size or stenosis, but cause a transition from a vulnerable plaque composition to a more stable one. Biological activity, most notably inflammation, is an emerging target for imaging that is thought to destabilize plaque and which may be a systemic marker of vulnerability. The ability of MRI to characterize each of these features in carotid atherosclerotic lesions gives it the potential, under certain circumstances, to replace traditional trials involving large numbers of subjects and hard end-points--heart attacks and strokes--with smaller, shorter trials involving imaging end-points. In this review, the state of the art in MRI of atherosclerosis is presented in terms of hardware, image acquisition protocols and post-processing. Also, the results of validation studies for measuring lesion size, composition and inflammation will be summarized. Finally, the status of several clinical trials involving MRI of atherosclerosis will be reviewed.NMR in Biomedicine 11/2006; 19(6):636-54. · 3.21 Impact Factor -
Article: Response to Letter by Moody et al.
Stroke 07/2006; · 5.73 Impact Factor -
Article: Intra- and interreader reproducibility of magnetic resonance imaging for quantifying the lipid-rich necrotic core is improved with gadolinium contrast enhancement.
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ABSTRACT: To test the hypothesis that intra- and interreader reproducibility for measuring the lipid-rich necrotic core (LR-NC) size is significantly improved with gadolinium (Gd) contrast-enhanced magnetic resonance imaging (CEMRI) compared to non-CEMRI. Thirty-seven individuals with >50% carotid artery stenosis underwent carotid MRI at 1.5T (pre- and postcontrast T1-weighted (T1W), T2-weighted (T2W), proton density-weighted (PDW), and three-dimensional time-of-flight (TOF) sequences). Two independent readers measured the mean area of the LR-NC from the precontrast images only, followed by a second measurement using the additional postcontrast images. One reader repeated the measurements after an interval of five months. Intra- and interreader reproducibility was analyzed by means of the intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard deviation (SD). The CV decreased from 33.7% to 8.8% for intrareader measurements of the LR-NC, and from 33.5% to 17.6% for interreader measurements. The SD was significantly smaller with CEMRI than with non-CEMRI (P = 0.003 and P = 0.006, respectively). The ICC increased from 0.94 to 0.99 and from 0.85 to 0.93 for the intra- and interreader measurements, respectively. Reader reproducibility for in vivo MRI quantification of LR-NC size is significantly improved by the addition of Gd contrast in individuals with >50% carotid stenosis.Journal of Magnetic Resonance Imaging 07/2006; 24(1):203-10. · 2.70 Impact Factor -
Article: Multicontrast black-blood MRI of carotid arteries: comparison between 1.5 and 3 tesla magnetic field strengths.
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ABSTRACT: To compare black-blood multicontrast carotid imaging at 3T and 1.5T and assess compatibility between morphological measurements of carotid arteries at 1.5T and 3T. Five healthy subjects and two atherosclerosis patients were scanned in 1.5T and 3T scanners with a similar protocol providing transverse T1-, T2-, and proton density (PD)-weighted black-blood images using a fast spin-echo sequence with single- (T1-weighted) or multislice (PD-/T2-weighted) double inversion recovery (DIR) preparation. Wall and lumen signal-to-noise ratio (SNR) and wall/lumen contrast-to-noise ratio (CNR) were compared in 44 artery cross-sections by paired t-test. Interscanner variability of the lumen area (LA), wall area (WA), and mean wall thickness (MWT) was assessed using Bland-Altman analysis. Wall SNR and lumen/wall CNR significantly increased (P < 0.0001) at 3T with a 1.5-fold gain for T1-weighted images and a 1.7/1.8-fold gain for PD-/T2-weighted images. Lumen SNR did not differ for single-slice DIR T1-weighted images (P = 0.2), but was larger at 3T for multislice DIR PD-/T2-weighted images (P = 0.01/0.03). The LA, WA, and MWT demonstrated good agreement with no significant bias (P 0.5), a coefficient of variation (CV) of < 10%, and intraclass correlation coefficient (ICC) of > 0.95. This study demonstrated significant improvement in SNR, CNR, and image quality for high- resolution black-blood imaging of carotid arteries at 3T. Morphologic measurements are compatible between 1.5T and 3T.Journal of Magnetic Resonance Imaging 05/2006; 23(5):691-8. · 2.70 Impact Factor -
Article: Images in cardiovascular medicine. Serial high-spatial-resolution, multisequence magnetic resonance imaging studies identify fibrous cap rupture and penetrating ulcer into carotid atherosclerotic plaque.
Circulation 04/2006; 113(12):e660-1. · 14.74 Impact Factor -
Article: Automated in vivo segmentation of carotid plaque MRI with Morphology-Enhanced probability maps.
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ABSTRACT: MRI is a promising noninvasive technique for characterizing atherosclerotic plaque composition in vivo, with an end-goal of assessing plaque vulnerability. Because of limitations arising from acquisition time, achievable resolution, contrast-to-noise ratio, patient motion, and the effects of blood flow, automatically identifying plaque composition remains a challenging task in vivo. In this article, a segmentation method using maximum a posteriori probability Bayesian theory is presented that divides axial, multi-contrast-weighted images into regions of necrotic core, calcification, loose matrix, and fibrous tissue. Key advantages of the method are that it utilizes morphologic information, such as local wall thickness, and coupled active contours to limit the impact from noise and artifacts associated with in vivo imaging. In experiments involving 142 sets of multi-contrast images from 26 subjects undergoing carotid endarterectomy, segmented areas of each of these tissues per slice agreed with histologically confirmed areas with correlations (R(2)) of 0.78, 0.83, 0.41, and 0.82, respectively. In comparison, manually identifying areas blinded to histology yielded correlations of 0.71, 0.76, 0.33, and 0.78, respectively. These results show that in vivo automatic segmentation of carotid MRI is feasible and comparable to or possibly more accurate than manual review for quantifying plaque composition.Magnetic Resonance in Medicine 03/2006; 55(3):659-68. · 2.96 Impact Factor -
Article: Association between carotid plaque characteristics and subsequent ischemic cerebrovascular events: a prospective assessment with MRI--initial results.
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ABSTRACT: MRI is able to quantify carotid plaque size and composition with good accuracy and reproducibility and provides an opportunity to prospectively examine the relationship between plaque features and subsequent cerebrovascular events. We tested the hypothesis that the characteristics of carotid plaque, as assessed by MRI, are possible predictors of future ipsilateral cerebrovascular events. A total of 154 consecutive subjects who initially had an asymptomatic 50% to 79% carotid stenosis by ultrasound with > or =12 months of follow-up were included in this study. Multicontrast-weighted carotid MRIs were performed at baseline, and participants were followed clinically every 3 months to identify symptoms of cerebrovascular events. Over a mean follow-up period of 38.2 months, 12 carotid cerebrovascular events occurred ipsilateral to the index carotid artery. Cox regression analysis demonstrated a significant association between baseline MRI identification of the following plaque characteristics and subsequent symptoms during follow-up: presence of a thin or ruptured fibrous cap (hazard ratio, 17.0; P< or =0.001), intraplaque hemorrhage (hazard ratio, 5.2; P=0.005), larger mean intraplaque hemorrhage area (hazard ratio for 10 mm2 increase, 2.6; P=0.006), larger maximum %lipid-rich/necrotic core (hazard ratio for 10% increase, 1.6; P=0.004), and larger maximum wall thickness (hazard ratio for a 1-mm increase, 1.6; P=0.008). Among patients who initially had an asymptomatic 50% to 79% carotid stenosis, arteries with thinned or ruptured fibrous caps, intraplaque hemorrhage, larger maximum %lipid-rich/necrotic cores, and larger maximum wall thickness by MRI were associated with the occurrence of subsequent cerebrovascular events. Findings from this prospective study provide a basis for larger multicenter studies to assess the risk of plaque features for subsequent ischemic events.Stroke 03/2006; 37(3):818-23. · 5.73 Impact Factor -
Article: Platelets activated by collagen through the immunoreceptor tyrosine-based activation motif in the Fc receptor gamma-chain play a pivotal role in the development of myocardial ischemia-reperfusion injury.
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ABSTRACT: Platelet activation and the formation of platelet microaggregates in coronary vessels play pivotal roles in myocardial ischemia and reperfusion injury. The Fc receptor gamma-chain (FcR gamma) is coexpressed with glycoprotein (GP) VI, forming a platelet collagen receptor, and the activation of platelets by collagen is closely coupled with tyrosine phosphorylation of the FcRgamma. To examine the functional significance of platelet FcR gamma/GPVI complex in the early phase of myocardial ischemia and reperfusion injury in mice, we performed coronary occlusion and reperfusion experiments using wild type mice and FcRgamma-deficient (FcRgamma(-/-)) mice that lack GPVI. The infarct size was significantly smaller in FcRgamma(-/-) mice subjected to occlusion and reperfusion of the coronary artery than in control FcR gamma(+/+) mice. Twenty-four hours after the reperfusion, electron microscopy of the injured tissue showed substantially more platelet aggregation and occlusive platelet microthrombi in the capillaries of the damaged areas of the wild type mice than in those of the FcR gamma(-/-) mice. Platelet Syk was scarcely activated in the FcR gamma(-/-) mice after myocardial ischemia and reperfusion, but significantly activated in the FcR gamma(+/+) mice. CD11b expression on neutrophils was elevated after myocardial ischemia and reperfusion in both mouse groups, whereas myeloperoxidase activity in the injured areas was significantly lower in the FcRgamma(-/-) mice than in the FcRgamma(+/+) mice. These results suggest that the collagen-induced activation of platelets through the FcR gamma plays a pivotal role in the extension of myocardial ischemia-reperfusion injury. FcRgamma and GPVI may be important therapeutic targets for myocardial ischemia-reperfusion injury.Journal of Molecular and Cellular Cardiology 01/2006; 39(6):856-64. · 5.17 Impact Factor
Top co-authors
Top Journals
Institutions
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2002–2009
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Juntendo University
- • Department of Cardiovascular Medicine
- • Department of Cardiology
Tokyo, Tokyo-to, Japan
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2005–2008
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University of Washington Seattle
- Department of Radiology
Seattle, WA, USA
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