T J Brady

Harvard Medical School, Boston, Massachusetts, United States

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Publications (437)1699.11 Total impact

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    ABSTRACT: Artifacts caused by head motion present a major challenge in brain positron emission tomography (PET) imaging. The authors investigated the feasibility of using wired active MR microcoils to track head motion and incorporate the measured rigid motion fields into iterative PET reconstruction. Several wired active MR microcoils and a dedicated MR coil-tracking sequence were developed. The microcoils were attached to the outer surface of an anthropomorphic(18)F-filled Hoffman phantom to mimic a brain PET scan. Complex rotation/translation motion of the phantom was induced by a balloon, which was connected to a ventilator. PET list-mode and MR tracking data were acquired simultaneously on a PET-MR scanner. The acquired dynamic PET data were reconstructed iteratively with and without motion correction. Additionally, static phantom data were acquired and used as the gold standard. Motion artifacts in PET images were effectively removed by wired active MR microcoil based motion correction. Motion correction yielded an activity concentration bias ranging from -0.6% to 3.4% as compared to a bias ranging from -25.0% to 16.6% if no motion correction was applied. The contrast recovery values were improved by 37%-156% with motion correction as compared to no motion correction. The image correlation (mean ± standard deviation) between the motion corrected (uncorrected) images of 20 independent noise realizations and static reference was R(2) = 0.978 ± 0.007 (0.588 ± 0.010, respectively). Wired active MR microcoil based motion correction significantly improves brain PET quantitative accuracy and image contrast.
    Medical Physics 04/2014; 41(4):041910. · 2.91 Impact Factor
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    ABSTRACT: Coronary atherosclerotic plaque rupture is the main cause of myocardial infarction and the leading killer in the US. Inflammation is a known bio-marker of plaque vulnerability and can be assessed non-invasively using fluorodeoxyglucose-positron emission tomography imaging (FDG-PET). However, cardiac and respiratory motion of the heart makes PET detection of coronary plaque very challenging. Fat surrounding coronary arteries allows the use of MRI to track plaque motion during simultaneous PET-MR examination. In this study, we proposed and assessed the performance of a fat-MR based coronary motion correction technique for improved FDG-PET coronary plaque imaging in simultaneous PET-MR. The proposed methods were evaluated in a realistic four-dimensional PET-MR simulation study obtained by combining patient water-fat separated MRI and XCAT anthropomorphic phantom. Five small lesions were digitally inserted inside the patients coronary vessels to mimic coronary atherosclerotic plaques. The heart of the XCAT phantom was digitally replaced with the patient's heart. Motion-dependent activity distributions, attenuation maps, and fat-MR volumes of the heart, were generated using the XCAT cardiac and respiratory motion fields. A full Monte Carlo simulation using Siemens mMR's geometry was performed for each motion phase. Cardiac/respiratory motion fields were estimated using non-rigid registration of the transformed fat-MR volumes and incorporated directly into the system matrix of PET reconstruction along with motion-dependent attenuation maps. The proposed motion correction method was compared to conventional PET reconstruction techniques such as no motion correction, cardiac gating, and dual cardiac-respiratory gating. Compared to uncorrected reconstructions, fat-MR based motion compensation yielded an average improvement of plaque-to-background contrast of 29.6%, 43.7%, 57.2%, and 70.6% for true plaque-to-blood ratios of 10, 15, 20 and 25:1, respectively. Channelized Hotelling observer (CHO) signal-to-noise ratio (SNR) was used to quantify plaque detectability. CHO-SNR improvement ranged from 105% to 128% for fat-MR-based motion correction as compared to no motion correction. Likewise, CHO-SNR improvement ranged from 348% to 396% as compared to both cardiac and dual cardiac-respiratory gating approaches. Based on this study, our approach, a fat-MR based motion correction for coronary plaque PET imaging using simultaneous PET-MR, offers great potential for clinical practice. The ultimate performance and limitation of our approach, however, must be fully evaluated in patient studies.
    Physics in Medicine and Biology 03/2014; 59(5):1203-22. · 2.70 Impact Factor
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    ABSTRACT: -The contribution of plaque extent to predict cardiovascular (CV) events among patients with non-obstructive and obstructive coronary artery disease (CAD) is not well defined. Our objective was to evaluate the prognostic value of plaque extent detected by coronary computed tomography (CTA). -All consecutive patients without prior CAD referred for coronary CTA to evaluate for CAD were included. Exam findings were classified as normal, non-obstructive (<50% stenosis) or obstructive (≥50%). Based on the number of segments with disease, extent of CAD was classified as non-extensive (≤4 segments) or extensive (>4 segments). The cohort included 3242 patients followed for the primary outcome of cardiovascular (CV) death or myocardial infarction (MI) for a median of 3.6 (2.1 - 5.0) years. In a multivariable analysis, the presence of extensive non-obstructive CAD (HR 3.1, 95% confidence interval (CI):1.5-6.4); non-extensive obstructive (HR 3.0, 95%CI: 1.3-6.9) and extensive obstructive CAD (HR:3.9, 95%CI:2.2-7.2) were associated with an increased rate of events, while non-extensive non-obstructive CAD was not. The addition of plaque extent to a model that included clinical probability as well as the presence and severity of CAD improved risk prediction. -Among patients with non-obstructive CAD, those with extensive plaque experienced a higher rate CV death or MI, comparable to those who have non-extensive obstructive disease. Even among patients with obstructive CAD, greater extent of non-obstructive plaque was associated with higher event rate. Our findings suggest that regardless whether obstructive or non-obstructive disease is present, the extent of plaque detected by coronary CTA enhances risk assessment.
    Circulation Cardiovascular Imaging 02/2014; · 5.80 Impact Factor
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    ABSTRACT: Brain PET scanning plays an important role in the diagnosis, prognostication and monitoring of many brain diseases. Motion artifacts from head motion are one of the major hurdles in brain PET. In this work, we propose to use wireless MR active markers to track head motion in real time during a simultaneous PET-MR brain scan and incorporate the motion measured by the markers in the listmode PET reconstruction. Several wireless MR active markers and a dedicated fast MR tracking pulse sequence module were built. Data were acquired on an ACR Flangeless PET phantom with multiple spheres and a non-human primate with and without motion. Motions of the phantom and monkey's head were measured with the wireless markers using a dedicated MR tracking sequence module. The motion PET data were reconstructed using list-mode reconstruction with and without motion correction. Static reference was used as gold standard for quantitative analysis. The motion artifacts, which were prominent on the images without motion correction, were eliminated by the wireless marker based motion correction in both the phantom and monkey experiments. Quantitative analysis was performed on the phantom motion data from 24 independent noise realizations. The reduction of bias of sphere-to-background PET contrast by active marker based motion correction ranges from 26% to 64% and 17% to 25% for hot (i.e., radioactive) and cold (i.e., non-radioactive) spheres, respectively. The motion correction improved the channelized Hotelling observer signal-to-noise ratio of the spheres by 1.2 to 6.9 depending on their locations and sizes. The proposed wireless MR active marker based motion correction technique removes the motion artifacts in the reconstructed PET images and yields accurate quantitative values.
    NeuroImage 01/2014; · 6.25 Impact Factor
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    ABSTRACT: Objective To evaluate the prognostic value and test characteristics of coronary artery calcium (CAC) score for the identification of obstructive coronary artery disease (CAD) in comparison with coronary computed tomography angiography (CCTA) among symptomatic patients. Methods Retrospective cohort study at two large hospitals, including all symptomatic patients without prior CAC who underwent both CCTA and CAC. Accuracy of CAC for the identification of ≥50% and ≥70% stenosis by CCTA was evaluated. Prognostic value of CAC and CCTA were compared for prediction of major adverse cardiovascular events (MACE, defined as non-fatal myocardial infarction, cardiovascular death, late coronary revascularization (>90 days), and unstable angina requiring hospitalization). Results Among 1145 included patients, the mean age was 55±12 years and median follow up 2.4 (IQR: 1.5 – 3.5) years. Overall, 406 (35%) CCTA were normal, 454 (40%) had <50% stenosis, and 285 (25%) had ≥50% stenosis. The prevalence of ≥70% stenosis was 16%. Among 483 (42%) patients with CAC zero, 395 (82%) had normal CCTA, 81 (17%) <50% stenosis, and 7 (1.5%) ≥ 50% stenosis. 2 (0.4%) patients had ≥70% stenosis. For diagnosis of ≥50% stenosis, CAC had a sensitivity of 98% and specificity of 55%. The negative predictive value (NPV) for CAC was 99% for ≥50% stenosis and 99.6% for ≥70% stenosis by CCTA. There were no adverse events among the 7 patients with zero calcium and ≥50% CAD. For prediction of MACE, the c-statistic for clinical risk factors of 0.62 increased to 0.73 (p<0.001) with CAC versus 0.77 (p=0.02) with CCTA. Conclusion Among symptomatic patients with CAC zero, a 1-2% prevalence of potentially obstructive CAD occurs, although this finding was not associated with future coronary revascularization or adverse prognosis within 2 years.
    Atherosclerosis 01/2014; 233(1):190-195. · 3.71 Impact Factor
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    ABSTRACT: Fluorine-18 labeled 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([(18) F]T807) is a potent and selective agent for imaging paired helical filaments of tau and is among the most promising PET radiopharmaceuticals for this target in early clinical trials. The present study reports a simplified one-step method for the synthesis of [(18) F]T807 that is broadly applicable for routine clinical production using a GE TRACERlab™ FXFN radiosynthesis module. Key facets of our optimized radiosynthesis include development and use of a more soluble protected precursor, tert-butyl 7-(6-nitropyridin-3-yl)-5H-pyrido[4,3-b]indole-5-carboxylate, as well as new HPLC separation conditions that enable a facile one-step synthesis. During the nucleophilic fluorinating reaction with potassium cryptand [(18) F]fluoride (K[(18) F]/K222 ) in DMSO at 130 °C over 10 min the precursor is concurrently deprotected. Formulated [(18) F]T807 was prepared in an uncorrected radiochemical yield of 14 ± 3%, with a specific activity of 216 ± 60 GBq/µmol (5837 ± 1621 mCi/µmol) at the end of synthesis (60 min; n = 3) and validated for human use. This methodology offers the advantage of faster synthesis in fewer steps, with simpler automation that we anticipate will facilitate widespread clinical use of [(18) F]T807. Copyright © 2013 John Wiley & Sons, Ltd.
    Journal of Labelled Compounds 12/2013; 56(14):736-40.
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    ABSTRACT: This study sought to determine whether arterial inflammation measured by (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) improves prediction of cardiovascular disease (CVD) beyond traditional risk factors. It is unknown whether arterial (18)F-FDG uptake measured with routine PET imaging provides incremental value for predicting CVD events beyond Framingham risk score (FRS). We consecutively identified 513 individuals from 6,088 patients who underwent (18)F-FDG-PET and computed tomography (CT) imaging at Massachusetts General Hospital between 2005 and 2008 and who met additional inclusion criteria: ≥30 years of age, no prior CVD, and free of cancer. CVD events were independently adjudicated, while blinded to clinical data, using medical records to determine incident stroke, transient ischemic attack, acute coronary syndrome, revascularization, new-onset angina, peripheral arterial disease, heart failure, or CVD death. FDG uptake was measured in the ascending aorta (as target-to-background-ratio [TBR]), while blinded to clinical data. During follow-up (median 4.2 years), 44 participants developed CVD (2 per 100 person-years at risk). TBR strongly predicted subsequent CVD independent of traditional risk factors (hazard ratio: 4.71; 95% confidence interval [CI]: 1.98 to 11.2; p < 0.001) and (hazard ratio: 4.13; 95% CI: 1.59 to 10.76; p = 0.004) after further adjustment for coronary calcium score. Addition of arterial PET measurement to FRS scores improved the C-statistic (mean ± standard error 0.62 ± 0.03 vs. 0.66 ± 0.03). Further, incorporation of TBR into a model with FRS variables resulted in an integrated discrimination of 5% (95% CI: 0.36 to 9.87). Net reclassification improvements were 27.48% (95% CI: 16.27 to 39.92) and 22.3% (95% CI: 11.54 to 35.42) for the 10% and 6% intermediate-risk cut points, respectively. Moreover, TBR was inversely associated with the timing of CVD (beta -0.096; p < 0.0001). Arterial FDG uptake, measured from routinely obtained PET/CT images, substantially improved incident CVD prediction beyond FRS among individuals undergoing cancer surveillance and provided information on the potential timing of such events.
    JACC. Cardiovascular imaging 10/2013; · 14.29 Impact Factor
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    ABSTRACT: Objective Our purpose was to evaluate coronary artery disease (CAD) prevalence and prognosis according to cardiometabolic (CM) risk.Research Design and Methods Registry of all patients without prior CAD referred for coronary computed tomography angiography (CCTA). Patients were stratified by groups of increasing CM risk factors (hypertension, low HDL, hypertriglyceridemia, obesity, and dysglycemia) as: patients without type 2 diabetes mellitus (T2DM) with <3 or ≥3 CM risk factors, patients with T2DM not requiring insulin or those with T2DM requiring insulin. Patients were followed for a primary endpoint of major adverse cardiovascular events (MACE) composed of unstable angina, late coronary revascularization, myocardial infarction, and cardiovascular mortality.ResultsAmong 1118 patients (mean age 57±13 years) followed for a mean 3.1 years, there were 21 (1.9%) cardiovascular deaths and 13(1.2%) myocardial infarctions. There was a stepwise increase in the prevalence of obstructive CAD with increasing CM risk, from 15% in those without diabetes and <3 CM risk factors to as high as 46% in patients with type 2 diabetes requiring insulin (p<0.001). Insulin exposure was associated with the highest adjusted hazard of MACE (HR = 3.29, 95% CI 1.28-8.45, p=0.01), while both T2DM without insulin (HR=1.35, p=0.3) and ≥3 CM risk factors without T2DM (HR=1.48, p=0.3) were associated with a similar rate of MACE.Conclusion Patients without diabetes who have multiple metabolic risk factors have a similar prognosis and burden of CAD as those with T2DM not requiring insulin. Among patients with diabetes, the need for insulin therapy is associated with greater burden of CAD as well as worse prognosis.
    Diabetes care 10/2013; · 7.74 Impact Factor
  • Journal of the American College of Radiology: JACR 08/2013;
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    ABSTRACT: Numerous protocols have been developed to reduce cardiac computed tomography angiography (cCTA) radiation dose while maintaining image quality. However, cCTA practice is highly dependent on physician and technologist experience and education. In this study, we sought to evaluate the incremental value of real-time feedback via weekly dose reports on a busy cCTA service. This time series analysis consisted of 450 consecutive patients whom underwent physician-supervised cCTA for clinically indicated native coronary evaluation between April 2011 and January 2013, with 150 patients before the initiation of weekly dose report (preintervention period: April-September 2011) and 150 patients after the initiation (postintervention period: September 2011-February 2012). To assess whether overall dose reductions were maintained over time, results were compared to a late control group consisting of 150 consecutive cCTA exams, which were performed after the study (September 2012-January 2013). Patient characteristics and effective radiation were recorded and compared. Total radiation dose was significantly lower in the postintervention period (3.4 mSv [1.7-5.7] and in the late control group (3.3 mSv [2.0-5.3] versus the preintervention period (4.1 mSv [2.1-6.6] (P = .005). The proportion of high-dose outliers was also decreased in the postintervention period and late control period (exams <10 mSv were 88.0% preintervention vs. 97.3% postintervention vs. 95.3% late control; exams <15 mSv were 98.0% preintervention vs. 100.0% postintervention vs. 98.7% late control; exams <20.0 mSv were 98.7% preintervention vs. 100.0% postintervention vs. 100.0% late control). Weekly dose report feedback of site radiation doses to patients undergoing physician-supervised cCTA resulted in significant overall dose reduction and reduction of high-dose outliers. Overall dose reductions were maintained beyond the initial study period.
    Academic radiology 08/2013; 20(8):1015-23. · 2.09 Impact Factor
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    ABSTRACT: Cardiac CT angiography (cCTA) has become an established method for the assessment of congenital heart disease. However, the potential harmful effects of ionizing radiation must be considered, particularly in younger, more radiosensitive patients. In this study, we sought to assess the temporal change in radiation doses from pediatric cCTA during an 8-year period at a tertiary medical center. This retrospective study included all patients ≤18 years old who were referred to electrocardiography (ECG)-gated cCTA for the assessment of congenital heart disease or inflammatory disease (Kawasaki disease) from November 2004 to September 2012. During the study period, 95 patients were scanned using 3 different scanner models-64-slice multidetector CT (64-MDCT) and first- (64-DSCT) and second-generation (128-DSCT) dual-source CT-and 3 scan protocols-retrospective ECG-gated helical scanning (RG), prospective ECG-triggered axial scanning (PT), or prospective ECG-triggered high-pitch helical scanning (HPH). Effective dose (ED) was calculated with the dose length product method with a conversion factor (k) adjusted for age. ED was then compared among scan protocols. Image quality was extracted from clinical cCTA reports when available. Overall, 94 % of scans were diagnostic (80 % for 64-slice MDCT, 93 % for 64-slice DSCT, and 97 % for 128-slice DSCT).With 128-DSCT, median ED (1.0 [range 0.6-2.0] mSv) decreased by 85.8 % and 66.8 % compared with 64-MDCT (6.8 [range 2.9-13.6] mSv) and 64-DSCT (2.9 [range 0.9-4.1] mSv), respectively. With HPH, median ED (0.9 [range 0.6-1.8] mSv) decreased by 59.4 % and 85.4 % compared with PT (2.2 [range 0.9-3.4] mSv) and RG (6.1 [range 2.5-10.6] mSv). cCTA can now be obtained at very low radiation doses in pediatric patients using the latest dual-source CT technology in combination with prospective ECG-triggered HPH acquisition.
    Pediatric Cardiology 07/2013; · 1.20 Impact Factor
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    ABSTRACT: -Arterial calcium (Ca) deposition has been identified as an active inflammatory process. We sought to test the hypothesis that local vascular inflammation predisposes to subsequent arterial calcium deposition in humans. -From a hospital database, we identified 137 patients (age=61±13, 48.1% Male) patients who underwent serial PET/CT (1 to 5 years apart). Focal arterial inflammation was prospectively determined by measuring FDG uptake (using baseline PET) within pre-determined locations of the thoracic aortic wall, and reported as a standardized uptake value (SUV). A separate, blinded investigator evaluated calcium deposition (on the baseline and follow-up CT scans) along the same, standardized sections of the aorta. New calcification was prospectively defined using square root transformed difference of calcium volume score (CVS), with a cut-off value of 2.5. Accordingly, vascular segment were classified as either with- or without- "subsequent calcification". Overall, 67(9%) of aortic segments demonstrated subsequent calcification. Baseline median (IQR) SUV was higher in segments with- vs. without subsequent calcification (2.09[1.84, 2.44] vs. 1.92[1.72, 2.20], p=0.002). This was also true in the subset of segments with Ca present at baseline (2.08 [1.81, 2.40] vs. 1.86[1.66, 2.09], p=0.02), as well as those without (2.17[1.87, 2.51] vs. 1.93[1.73, 2.20], p=0.04). Moreover, across all patients, subsequent Ca deposition was associated with the underlying FDG uptake (inflammatory signal), measured as SUV [OR (95%CI) = 2.94 (1.27 - 6.89), p =0.01] or TBR [2.59 (1.18 - 5.70), p=0.02], after adjusting for traditional cardiovascular risk factors. -Here we provide first in-man evidence that arterial inflammation precedes subsequent Ca deposition, a marker of plaque progression, within the underlying location in the artery wall.
    Circulation Cardiovascular Imaging 07/2013; · 5.80 Impact Factor
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    ABSTRACT: BACKGROUND: HIV-infected patients are at increased risk of coronary artery disease (CAD). We evaluated the cost-effectiveness of cardiac screening for HIV-positive men at intermediate or greater CAD risk. DESIGN: We developed a lifetime microsimulation model of CAD incidence and progression in HIV-infected men. METHODS: Input parameters were derived from two HIV cohort studies and the literature. We compared no CAD screening with stress testing and coronary computed tomography angiography (CCTA)-based strategies. Patients with test results indicating 3-vessel/left main CAD underwent invasive coronary angiography (ICA) and received coronary artery bypass graft surgery. In the stress testing + medication and CCTA + medication strategies, patients with 1-2-vessel CAD results received lifetime medical treatment without further diagnostics whereas in the stress testing + intervention and CCTA + intervention strategies, patients with these results underwent ICA and received percutaneous coronary intervention. RESULTS: Compared to no screening, the stress testing + medication, stress testing + intervention, CCTA + medication, and CCTA + intervention strategies resulted in 14, 11, 19, and 14 quality-adjusted life days per patient and incremental cost-effectiveness ratios of 49,261, 57,817, 34,887 and 56,518 Euros per quality-adjusted life year (QALY), respectively. Screening only at higher CAD risk thresholds was more cost-effective. Repeated screening was clinically beneficial compared to one-time screening, but only stress testing + medication every 5 years remained cost-effective. At a willingness-to-pay threshold of 83,000 €/QALY (∼100,000 US$/QALY), implementing any CAD screening was cost-effective with a probability of 75-95%. CONCLUSIONS: Screening HIV-positive men for CAD would be clinically beneficial and comes at a cost-effectiveness ratio comparable to other accepted interventions in HIV care.
    European journal of preventive cardiology. 03/2013;
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    ABSTRACT: In this study, we sought to evaluate the image quality and effective radiation dose of prospectively ECG-triggered adaptive systolic (PTA-systolic) dual-source CTA versus prospectively triggered adaptive diastolic (PTA-diastolic) dual-source CTA in patients of unselected heart rate and rhythm. This retrospective cohort study consisted of 41 PTA-systolic and 41 matched PTA-diastolic CTA patients whom underwent clinically indicated 128-slice dual source CTA between December 2010 to June 2012. Image quality and motion artifact score (both on a Likert scale 1-4 with 4 being the best), effective dose, and CTDIvol were compared. The effect of heart rate (HR) and heart rate variability [HRV] on image motion artifact score and CTDIvol was analyzed with Pearson's correlation coefficient. All 82 exams were considered diagnostic with 0 non-diagnostic segments. PTA-systolic CTA patients had a higher maximum HR, wider HRV, were less likely to be in sinus rhythm, and received less beta-blocker vs. PTA-diastolic CTA patients. No difference in effective dose was observed (PTA-systolic vs. PTA-diastolic CTA: 2.9 vs. 2.2 mSv, p = 0.26). Image quality score (3.3 vs. 3.5, p < 0.05) and motion artifact score (3.5 vs. 3.8, p < 0.05) were lower in PTA-systolic CTAs than in PTA-diastolic CTAs. For PTA-systolic CTAs, an increase in HR was not associated with a negative impact on motion artifact score nor CTDIvol. For PTA-diastolic CTA, an increase in HR was associated with increased motion artifacts and CTDIvol. HRV demonstrated no correlation with motion artifact and CTDIvol for both PTA-systolic and PTA-diastolic CTAs. In conclusion, both PTA-diastolic CTA and PTA-systolic CTA yielded diagnostic examinations at unselected heart rates and rhythms with similar effective radiation, but PTA-systolic CTA resulted in more consistent radiation exposure and image quality across a wide range of rates and rhythms.
    The international journal of cardiovascular imaging 03/2013; · 2.15 Impact Factor
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    ABSTRACT: BACKGROUND: Bronchial asthma is a chronic inflammatory condition associated with increased cardiovascular (CV) events. Here, we assess arterial inflammation, using 18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging (FDG-PET/CT), in patients with bronchial asthma and low to intermediate Framingham risk scores (FRS). METHODS: A total of 102 patients underwent FDG-PET/CT imaging for clinical indications. Thirty-four patients (mean age 54.9 ± 16.1) with mild asthma and no known atherosclerotic disease were compared to 2 non-asthmatic groups. The first control group (n = 34) were matched by age, gender, and FRS. The second control group (n = 34) had clinical atherosclerosis and were matched by gender. Thereafter, arterial FDG uptake on PET images was determined, while blinded to patient identifiers. RESULTS: Target-to-background-ratio (TBR) in the aorta was higher in asthmatics vs non-asthmatic FRS-matched controls (1.96 ± 0.26 vs 1.76 ± 0.20; P < .001). The aortic TBR remained elevated in asthmatics vs non-asthmatic controls after adjusting traditional CV risk factors (P < .001). An inverse correlation was observed between FDG uptake and lung function, FEV1 (P = .02) and peak flow (P = .03). CONCLUSIONS: Bronchial asthma is associated with increased arterial inflammation beyond that estimated by current risk stratification tools. Further studies are required to evaluate whether attenuation of systemic inflammation will decrease CV events.
    Journal of Nuclear Cardiology 03/2013; · 2.85 Impact Factor
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    ABSTRACT: BACKGROUND: Myocardial delayed enhancement (MDE) by gadolinium-enhanced cardiac MRI is well established for myocardial scar assessment in ischemic and non-ischemic heart disease. The role of MDE by cardiac CT (CT-MDE) is not yet defined. FINDINGS: We reviewed all clinical cases of CT-MDE at a tertiary referral center to present the cases as a case series. All clinical cardiac CT exams which utilized CT-MDE imaging between January 1, 2005 and October 1, 2010 were collected as a series and their findings were also compared with available myocardial imaging to assess for myocardial abnormalities, including echocardiography (wall motion, morphology), cardiac MRI (delayed enhancement, morphology), SPECT MPI (perfusion defects). 5,860 clinical cardiac CT exams were performed during the study period. CT-MDE was obtained in 18 patients and was reported to be present in 9 patients. The indications for CT-MDE included ischemic and non-ischemic heart diseases. In segments positive for CT-MDE, there was excellent agreement of CT with other modalities: echocardiography (n=8) demonstrated abnormal morphology and wall motion (k=1.0 and k=0.82 respectively); prior MRI (n=2) demonstrated abnormal delayed enhancement (MR-MDE) (k=1.0); SPECT MPI (n=1) demonstrated fixed perfusion defects (k=1.0). In the subset of patients without CT-MDE, no abnormal segments were identified by echocardiography (n=8), MRI (n=1) and nuclear MPI (n=0). CONCLUSIONS: CT-MDE was performed in rare clinical situations. The indications included both ischemic and non-ischemic heart disease and there was an excellent agreement between CT-MDE and abnormal myocardium by echocardiography, cardiac MRI, and nuclear MPI.
    BMC Research Notes 01/2013; 6(1):2.
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    ABSTRACT: The objective was to determine the association of four clinical risk scores and coronary plaque burden as detected by computed tomography (CT) with the outcome of acute coronary syndrome (ACS) in patients with acute chest pain. The hypothesis was that the combination of risk scores and plaque burden improved the discriminatory capacity for the diagnosis of ACS. The study was a subanalysis of the Rule Out Myocardial Infarction Using Computer-Assisted Tomography (ROMICAT) trial-a prospective observational cohort study. The authors enrolled patients presenting to the emergency department (ED) with a chief complaint of acute chest pain, inconclusive initial evaluation (negative biomarkers, nondiagnostic electrocardiogram [ECG]), and no history of coronary artery disease (CAD). Patients underwent contrast-enhanced 64-multidetector-row cardiac CT and received standard clinical care (serial ECG, cardiac biomarkers, and subsequent diagnostic testing, such as exercise treadmill testing, nuclear stress perfusion imaging, and/or invasive coronary angiography), as deemed clinically appropriate. The clinical providers were blinded to CT results. The chest pain score was calculated and the results were dichotomized to ≥10 (high-risk) and <10 (low-risk). Three risk scores were calculated, Goldman, Sanchis, and Thrombolysis in Myocardial Infarction (TIMI), and each patient was assigned to a low-, intermediate-, or high-risk category. Because of the low number of subjects in the high-risk group, the intermediate- and high-risk groups were combined into one. CT images were evaluated for the presence of plaque in 17 coronary segments. Plaque burden was stratified into none, intermediate, and high (zero, one to four, and more than four segments with plaque). An outcome panel of two physicians (blinded to CT findings) established the primary outcome of ACS (defined as either an acute myocardial infarction or unstable angina) during the index hospitalization (from the presentation to the ED to the discharge from the hospital). Logistic regression modeling was performed to examine the association of risk scores and coronary plaque burden to the outcome of ACS. Unadjusted models were individually fitted for the coronary plaque burden and for Goldman, Sanchis, TIMI, and chest pain scores. In adjusted analyses, the authors tested whether the association between risk scores and ACS persisted after controlling for the coronary plaque burden. The prognostic discriminatory capacity of the risk scores and plaque burden for ACS was assessed using c-statistics. The differences in area under the receiver-operating characteristic curve (AUC) and c-statistics were tested by performing the -2 log likelihood ratio test of nested models. A p value <0.05 was considered statistically significant. Among 368 subjects, 31 (8%) subjects were diagnosed with ACS. Goldman (AUC = 0.61), Sanchis (AUC = 0.71), and TIMI (AUC = 0.63) had modest discriminatory capacity for the diagnosis of ACS. Plaque burden was the strongest predictor of ACS (AUC = 0.86; p < 0.05 for all comparisons with individual risk scores). The combination of plaque burden and risk scores improved prediction of ACS (plaque + Goldman AUC = 0.88, plaque + Sanchis AUC = 0.90, plaque + TIMI AUC = 0.88; p < 0.01 for all comparisons with coronary plaque burden alone). Risk scores (Goldman, Sanchis, TIMI) have modest discriminatory capacity and coronary plaque burden has good discriminatory capacity for the diagnosis of ACS in patients with acute chest pain. The combined information of risk scores and plaque burden significantly improves the discriminatory capacity for the diagnosis of ACS.
    Academic Emergency Medicine 07/2012; 19(8):934-42. · 1.76 Impact Factor
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    ABSTRACT: PURPOSE:: Automatic exposure control (AEC) algorithms are widely available in coronary computed tomography angiography (CTA) and have been shown to reduce radiation doses by adjusting tube current to patient size. However, the effects of anthropometry-based automatic potential selection (APS) on image quality and radiation dose are unknown. We sought to investigate the effect of an APS algorithm on coronary CTA radiation dose and image quality. MATERIALS AND METHODS:: For this retrospective case-control study we selected 38 patients who had undergone coronary CTA for coronary artery assessment in whom tube potential and tube current were selected automatically by a combined automatic tube potential and tube current selection algorithm (APS-AEC) and compared them with 38 controls for whom tube voltage was selected according to standard body mass index (BMI) cutoffs and tube current was selected using automatic exposure control (BMI-AEC). Controls were matched for BMI, heart rate, heart rhythm, sex, acquisition mode, and indication for cardiac CTA. Image quality was assessed as contrast-to-noise ratio and signal-to-noise ratio in the proximal coronary arteries. Subjective reader assessment was also made. Total radiation dose (volume-weighted computed tomography dose index) was measured and compared between the 2 groups. In the study group, comparison was made with conventional BMI-guided prior protocols (site protocols and Society of Cardiovascular Computed Tomography recommendations) through disagreement analysis. RESULTS:: The APS-AEC cases received 29.8% lower overall radiation dose compared with controls (P=not significant). APS-AEC resulted in a significantly higher signal-to-noise ratio of the proximal coronary arteries (P<0.01) and contrast-to-noise ratio of the left main (P=0.01). In the study cases, the APS resulted in a change in tube potential versus site protocols and Society of Cardiovascular Computed Tomography recommendations in 45% (n=17) and 50% (n=19) of patients, respectively. CONCLUSION:: Automated tube potential selection software resulted in significantly improved objective image quality versus standard BMI-based methods of tube potential selection, without increased radiation doses.
    Journal of thoracic imaging 07/2012; · 1.42 Impact Factor
  • Maros Ferencik, Thomas J Brady, Udo Hoffmann
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    ABSTRACT: Cardiac allograft vasculopathy (CAV) is the main cause of morbidity and mortality beyond 1 year after heart transplantation. Ischemic symptoms are usually not present because of the denervated allograft and diffuse nature of the disease. Patients present with heart failure, ventricular arrhythmia, or sudden cardiac death as a result of advanced CAV. Therefore, clinical evaluation includes routine annual invasive coronary angiography (ICA) and transthoracic echocardiography to screen for CAV. Noninvasive imaging methods for the detection of CAV have not been widely adopted. Computed tomography (CT) permits detection of coronary stenoses and plaque in the nontransplant population. The strength of CT is its high negative predictive value. These attributes predispose CT to a role of a gatekeeper for further invasive testing in heart transplant recipients. We reviewed the available literature on CT evaluation of CAV. Technical challenges (eg, high heart rates, need for contrast and radiation, image quality) specific for patients who have received a heart transplant are emphasized, and solutions, including appropriate protocols and advances through the new CT technology, are summarized. We systematically analyze the results of studies that report the diagnostic performance of cardiac CT for the detection of coronary stenoses compared with ICA. Similar analysis is performed for the comparison between CT and intravascular ultrasound scanning for the detection of nonobstructive CAV. Finally, we suggest future directions in cardiac CT imaging research of CAV.
    Journal of cardiovascular computed tomography 07/2012; 6(4):223-31. · 2.55 Impact Factor
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    ABSTRACT: We aimed to assess the temporal change in radiation doses from coronary computed tomography angiography (CCTA) during a 6-year period. High CCTA radiation doses have been reduced by multiple technologies that, if used appropriately, can decrease exposures significantly. A total of 1277 examinations performed from 2005 to 2010 were included. Univariate and multivariable regression analysis of patient- and scan-related variables was performed with estimated radiation dose as the main outcome measure. Median doses decreased by 74.8% (P<.001), from 13.1 millisieverts (mSv) (interquartile range 9.3-14.7) in period 1 to 3.3 mSv (1.8-6.7) in period 4. Factors associated with greatest dose reductions (P<.001) were all most frequently applied in period 4: axial-sequential acquisition (univariate: -8.0 mSv [-9.7 to -7.9]), high-pitch helical acquisition (univariate: -8.8 mSv [-9.3 to -7.9]), reduced tube voltage (100 vs 120 kV) (univariate: -6.4 mSv [-7.4 to -5.4]), and use of automatic exposure control (univariate: -5.3 mSv [-6.2 to -4.4]). CCTA radiation doses were reduced 74.8% through increasing use of dose-saving measures and evolving scanner technology.
    The American journal of medicine 06/2012; 125(8):764-72. · 4.47 Impact Factor

Publication Stats

14k Citations
1,699.11 Total Impact Points


  • 1983–2014
    • Harvard Medical School
      • • Department of Radiology
      • • Department of Medicine
      Boston, Massachusetts, United States
  • 1982–2014
    • Massachusetts General Hospital
      • • Division of Nuclear Medicine and Molecular Imaging
      • • Division of Cardiology
      • • Department of Radiology
      • • Hospital Medicine Unit
      • • Department of Medicine
      Boston, Massachusetts, United States
  • 2013
    • Beverly Hospital, Boston MA
      Beverly, Massachusetts, United States
  • 2012
    • Brigham and Women's Hospital
      • Division of Cardiovascular Medicine
      Boston, MA, United States
  • 2011
    • Boston Children's Hospital
      • Department of Radiology
      Boston, MA, United States
  • 2008
    • St Vincent's University Hospital
      Dublin, Leinster, Ireland
    • Cardiocentro Ticino
      • Cardiac Surgery
      Lugano, Ticino, Switzerland
  • 2007–2008
    • Boston University
      • Department of Electrical and Computer Engineering
      Boston, MA, United States
  • 2006
    • Beneficência Portuguesa Hospital of São Paulo
      Potengy, Rio Grande do Norte, Brazil
  • 2005
    • Hannover Medical School
      Hanover, Lower Saxony, Germany
  • 2001
    • Johns Hopkins Medicine
      Baltimore, Maryland, United States
  • 1993
    • University of Münster
      • Department of Clinical Radiology
      Münster, North Rhine-Westphalia, Germany
  • 1990
    • Beth Israel Deaconess Medical Center
      • Department of Radiology
      Boston, MA, United States
  • 1988
    • Sharp Grossmont Hospital
      La Mesa, California, United States
  • 1987
    • University of Massachusetts Boston
      Boston, Massachusetts, United States