Publications (31)150.79 Total impact
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Article: Aligning Coronary Anatomy and Myocardial Perfusion Territories: An Algorithm for the CORE320 Multicenter Study.
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ABSTRACT: Background- Appropriate clinical decisions concerning diagnosis and treatment of coronary artery disease rely on correct integration of data on coronary anatomy and myocardial perfusion. The purpose of this article is to introduce a new left ventricular segmentation model for improved alignment of coronary arterial segments and myocardial perfusion territories, designed for the CORE320 study. Methods and Results- CORE320 is a prospective, multicenter study with a primary objective to evaluate the diagnostic accuracy of 320-row detector computed tomography (CT) to detect coronary artery luminal stenosis and corresponding myocardial perfusion deficits in patients with suspected coronary artery disease compared with the gold standard of conventional coronary angiography and single-photon emission CT myocardial perfusion imaging. We describe a 19-coronary segment and 13-myocardial territory alignment model, its application in both standard and CT image data sets, and the adjudication process of the initial cohort of patients recruited for the CORE320 study. Adjudication committees reviewed the images of the first 101 gold standard and 107 CT data sets. On the basis of the presented model and rules, all cases for adjudication were correctly identified. During image review, 6 (5.9%) gold standard and 9 (8.4%) CT data sets needed further realignment not triggered by the algorithm. Conclusions- We present a vascular territory distribution model developed for the CORE320 multicenter study, which accounts for variability in coronary anatomy and potential myocardial perfusion territory overlap. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00934037.Circulation Cardiovascular Imaging 08/2012; 5(5):587-95. · 5.94 Impact Factor -
Article: Influence of image acquisition settings on radiation dose and image quality in coronary angiography by 320-detector volume computed tomography: the CORE320 pilot experience.
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ABSTRACT: The objective of this study was to investigate the impact of image acquisition settings and patients' characteristics on image quality and radiation dose for coronary angiography by 320-row computed tomography (CT). CORE320 is a prospective study to investigate the diagnostic performance of 320-detector CT for detecting coronary artery disease and associated myocardial ischemia. A run-in phase in 65 subjects was conducted to test the adequacy of the computed tomography angiography (CTA) acquisition protocol. Tube current, exposure window, and number of cardiac beats per acquisition were adjusted according to subjects' gender, heart rate, and body mass index (BMI). Main outcome measures were image quality, assessed by contrast/noise measurements and qualitatively on a 4-point scale, and radiation dose, estimated by the dose-length-product. Average heart rate at image acquisition was 55.0±7.3 bpm. Median Agatston calcium score was 27.0 (interquartile range 1-330). All scans were prospectively triggered. Single heart beat image acquisition was obtained in 61 of 65 studies (94%). Sixty-one studies (94%) and 437 of 455 arterial segments (96%) were of diagnostic image quality. Estimated radiation dose was significantly greater in obese (5.3±0.4 mSv) than normal weight (4.6±0.3 mSv) or overweight (4.7±0.3 mSv) subjects (P<0.001). BMI was the strongest factor influencing image quality (odds ratio=1.457, P=0.005). The CORE320 CTA image acquisition protocol achieved a good balance between image quality and radiation dose for a 320-detector CT system. However, image quality in obese subjects was reduced compared to normal weight subjects, possibly due to tube voltage/current restrictions mandated by the study protocol.Heart International 06/2012; 7(2):e11. -
Article: Added value of CT myocardial perfusion imaging
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ABSTRACT: Multidetector CT angiography (MDCTA) has become an accurate, noninvasive test for the diagnosis of coronary atherosclerosis. Studies have established a good sensitivity and an excellent negative predictive value for the diagnosis of coronary stenoses of 50% or greater severity. However, MDCTA is more limited in patients with disease with a lower specificity and positive predictive value for predicting atherosclerosis causing myocardial ischemia. Although radionuclide myocardial perfusion imaging (MPI) has been the mainstay for evaluating the presence of myocardial ischemia and scar in patients at risk for coronary artery disease, contrast-enhanced multidetector CT (MDCT) alone, with or without vasodilator stress, has the potential to provide both anatomical and functional information on coronary atherosclerosis and its impact on myocardial perfusion. We review the current status of MDCT MPI, including its advantages, limitations, and pitfalls.Current Cardiovascular Imaging Reports 04/2012; 1(2):96-104. -
Article: Computed tomography myocardial perfusion imaging with 320-row detector computed tomography accurately detects myocardial ischemia in patients with obstructive coronary artery disease.
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ABSTRACT: Computed tomography coronary angiography (CTA) has been shown to be accurate in detecting anatomic coronary arterial obstruction, but is limited for the detection of myocardial ischemia. The primary aim of this study was to assess the accuracy of 320-row computed tomography perfusion imaging (CTP) to detect atherosclerosis causing myocardial ischemia. Fifty symptomatic patients with recent single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) underwent a comprehensive cardiac computed tomography (CT) protocol that included 320-CTA, followed by adenosine stress CTP. CTP images were analyzed quantitatively for the presence of subendocardial perfusion deficits. All analyses were blinded to imaging and clinical results. CTA alone was a limited predictor of myocardial ischemia compared with SPECT, with a sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of 56%, 75%, 56%, and 75%, and the area under the receiver operator characteristic curve (AUC) was 0.65 (95% CI, 0.51-0.78, P=0.07). CTP was a better predictor of myocardial ischemia, with a sensitivity, specificity, PPV, and NPV of 72%, 91%, 81%, and 85%, with an AUC of 0.81 (95% CI, 0.68-0.91, P<0.001), and was an excellent predictor of myocardial ischemia on SPECT-MPI in the presence of stenosis (≥50% on CTA), with a sensitivity, specificity, PPV, and NPV of 100%, 81%, 50%, and 100%, with an AUC of 0.92 (95% CI, 0.80-0.97, P<0.001). The radiation dose for the comprehensive cardiac CT protocol and SPECT were 13.8±2.9 and 13.1±1.7; respectively (P=0.15). Computed tomography perfusion imaging with rest and adenosine stress 320-row CT is accurate in detecting obstructive atherosclerosis causing myocardial ischemia.Circulation Cardiovascular Imaging 03/2012; 5(3):333-40. · 5.94 Impact Factor -
Article: Myocardial perfusion by CT versus hybrid imaging.
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ABSTRACT: Coronary computed tomography angiography (CTA) is a reliable diagnostic test for the anatomic diagnosis of obstructive coronary artery disease (CAD). Although coronary CTA shows high sensitivity and negative predictive value for detecting stenosis greater than or equal to 50% diameter, it is limited in its ability to diagnose myocardial ischemia. Advances in computed tomography (CT) technology alone and technology that hybridizes CT with single-photon emission CT and positron emission tomography allow for the combined anatomic and physiologic diagnosis of CAD. This article summarizes these combined technologies, emphasizing the merits and limitations of each technology and their clinical implications.Cardiology clinics 02/2012; 30(1):135-46. · 1.25 Impact Factor -
Article: Patterns of myocardial perfusion in humans evaluated with contrast-enhanced 320 multidetector computed tomography.
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ABSTRACT: Left ventricular (LV) myocardial contrast enhancement can be recorded using 320 multi detector computed tomography (MDCT). We aimed to (1) assess patterns of regional myocardial perfusion at rest and compare them with NH(3) positron emission tomography (PET) (2) and to assess the effect of intravenous adenosine infusion on regional myocardial perfusion. To evaluate myocardial perfusion patterns at rest, we scanned 14 healthy subjects with PET and 14 age and gender matched subjects with 320 MDCT. To evaluate the effect of adenosine stress on relative perfusion patterns 14 subjects with near-normal epicardial coronary arteries were studied at rest and during adenosine stress. Relative perfusion was assessed as attenuation density (AD) in 16 segments of the LV, and each segment was divided into 3 layers: endo-, mid- and epi-cardial. During rest the relative AD by MDCT was lower in the lateral wall compared with the remainder of the LV (P < 0.002). A similar pattern was found by PET-imaging. LV endocardial AD was higher than mid- and epicardial AD (P < 0.05). At rest the endocardial/epicardial ratio in the septum was 0.99 compared with 1.23 in non-septal segments (P < 0.001). During adenosine infusion transmural AD increased due to significant increases in the mid- and epicardium and the endocardial/epicardial ratio decreased by 18% in non-septal segments (from 1.23 to 1.05 P < 0.001). Relative perfusion at rest is lower in the lateral wall of the LV with both PET and MDCT compared to the remainder of the myocardium. During adenosine stress endocardial/epicardial ratio decrease significantly.The international journal of cardiovascular imaging 12/2011; 28(7):1739-47. · 2.15 Impact Factor -
Article: CT for evaluation of myocardial cell therapy in heart failure: a comparison with CMR imaging.
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ABSTRACT: The aim of this study was to use multidetector computed tomography (MDCT) to assess therapeutic effects of myocardial regenerative cell therapies. Cell transplantation is being widely investigated as a potential therapy in heart failure. Noninvasive imaging techniques are frequently used to investigate therapeutic effects of cell therapies in the preclinical and clinical settings. Previous studies have shown that cardiac MDCT can accurately quantify myocardial scar tissue and determine left ventricular (LV) volumes and ejection fraction (LVEF). Twenty-two minipigs were randomized to intramyocardial injection of phosphate-buffered saline (placebo, n = 9) or 200 million mesenchymal stem cells (MSC, n = 13) 12 weeks after myocardial infarction (MI). Cardiac magnetic resonance and MDCT acquisitions were performed before randomization (12 weeks after MI induction) and at the study endpoint 24 weeks after MI induction. None of the animals received medication to control the intrinsic heart rate during first-pass acquisitions for assessment of LV volumes and LVEF. Delayed-enhancement MDCT imaging was performed 10 min after contrast delivery. Two blinded observers analyzed MDCT acquisitions. MDCT demonstrated that MSC therapy resulted in a reduction of infarct size from 14.3 ± 1.2% to 10.3 ± 1.5% of LV mass (p = 0.005), whereas infarct size increased in nontreated animals (from 13.8 ± 1.3% to 16.5 ± 1.5%; p = 0.02) (placebo vs. MSC; p = 0.003). Both observers had excellent agreement for infarct size (r = 0.96; p < 0.001). LVEF increased from 32.6 ± 2.2% to 36.9 ± 2.7% in MSC-treated animals (p = 0.03) and decreased in placebo animals (from 33.3 ± 1.4% to 29.1 ± 1.5%; p = 0.01; at week 24: placebo vs. MSC; p = 0.02). Infarct size, end-diastolic LV volume, and LVEF assessed by MDCT compared favorably with those assessed by cardiac magnetic resonance acquisitions (r = 0.70, r = 0.82, and r = 0.902, respectively; p < 0.001). This study demonstrated that cardiac MDCT can be used to evaluate infarct size, LV volumes, and LVEF after intramyocardial-delivered MSC therapy. These findings support the use of cardiac MDCT in preclinical and clinical studies for novel myocardial therapies.JACC. Cardiovascular imaging 12/2011; 4(12):1284-93. · 14.29 Impact Factor -
Article: Diagnostic performance of combined noninvasive coronary angiography and myocardial perfusion imaging using 320 row detector computed tomography: design and implementation of the CORE320 multicenter, multinational diagnostic study.
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ABSTRACT: Multidetector coronary computed tomography angiography (CTA) is a promising modality for widespread clinical application because of its noninvasive nature and high diagnostic accuracy as found in previous studies using 64 to 320 simultaneous detector rows. It is, however, limited in its ability to detect myocardial ischemia. In this article, we describe the design of the CORE320 study ("Combined coronary atherosclerosis and myocardial perfusion evaluation using 320 detector row computed tomography"). This prospective, multicenter, multinational study is unique in that it is designed to assess the diagnostic performance of combined 320-row CTA and myocardial CT perfusion imaging (CTP) in comparison with the combination of invasive coronary angiography and single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI). The trial is being performed at 16 medical centers located in 8 countries worldwide. CT has the potential to assess both anatomy and physiology in a single imaging session. The co-primary aim of the CORE320 study is to define the per-patient diagnostic accuracy of the combination of coronary CTA and myocardial CTP to detect physiologically significant coronary artery disease compared with (1) the combination of conventional coronary angiography and SPECT-MPI and (2) conventional coronary angiography alone. If successful, the technology could revolutionize the management of patients with symptomatic CAD.Journal of cardiovascular computed tomography 11/2011; 5(6):370-81. -
Article: A stepwise approach to the visual interpretation of CT-based myocardial perfusion.
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ABSTRACT: Cardiovascular anatomic and functional testing have been longstanding and key components of cardiac risk assessment. As part of that strategy, CT-based imaging has made steady progress, with coronary computed tomography angiography (CTA) now established as the most sensitive noninvasive strategy for assessment of significant coronary artery disease. Myocardial CT perfusion imaging (CTP), as the functional equivalent of coronary CTA, is being tested in currently ongoing multicenter trials and is proposed to enhance the accuracy of coronary CTA alone. However, unlike coronary CTA that has published guidelines for interpretation and is rapidly gaining applicability in the noninvasive risk assessment paradigms, myocardial CTP is rapidly evolving, and guidance on a standard approach to its interpretation is lacking. In this article we describe a practical stepwise approach for interpretation of myocardial CTP that should add to the clinical applicability of this modality. These steps include (1) coronary CTA interpretation for potentially obstructive atherosclerosis, (2) reconstruction and preprocessing of myocardial CTP images, (3) image quality assessment and the identification of potentially confounding artifacts, (4) rest and stress image interpretation for enhancement patterns and areas of hypoattenuation, and (5) correlation of coronary anatomy and myocardial perfusion deficits. This systematic review uses already published methods from multiple clinical studies and is intended for general usage, independent of the platform used for image acquisition.Journal of cardiovascular computed tomography 11/2011; 5(6):357-69. -
Article: Diagnostic performance of combined noninvasive coronary angiography and myocardial perfusion imaging using 320-MDCT: the CT angiography and perfusion methods of the CORE320 multicenter multinational diagnostic study.
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ABSTRACT: OBJECTIVE: Coronary MDCT angiography has been shown to be an accurate noninvasive tool for the diagnosis of obstructive coronary artery disease (CAD). Its sensitivity and negative predictive value for diagnosing percentage of stenosis are unsurpassed compared with those of other noninvasive testing methods. However, in its current form, it provides no information regarding the physiologic impact of CAD and is a poor predictor of myocardial ischemia. CORE320 is a multicenter multinational diagnostic study with the primary objective to evaluate the diagnostic accuracy of 320-MDCT for detecting coronary artery luminal stenosis and corresponding myocardial perfusion deficits in patients with suspected CAD compared with the reference standard of conventional coronary angiography and SPECT myocardial perfusion imaging. CONCLUSION: We aim to describe the CT acquisition, reconstruction, and analysis methods of the CORE320 study.American Journal of Roentgenology 10/2011; 197(4):829-37. · 2.78 Impact Factor -
Article: CT-based myocardial perfusion imaging-practical considerations: acquisition, image analysis, interpretation, and challenges.
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ABSTRACT: Methods for non-invasive, cardiac risk assessment have historically relied on exercise stress testing with or without echocardiography or radionuclide imaging and pharmacological stress testing when appropriate. More recently, CT-based modalities like CT angiography (CTA) have been shown to reliably differentiate low from high-risk coronary disease. The advent of newer CT technology now allows for CT-based myocardial perfusion imaging (CTP) that provides functional information, that when analyzed with anatomic data from CTA, can provide a comprehensive risk assessment strategy. In this review, we discuss the research and implementation; as well as the quantitative, semiquantitative, and qualitative methods of image analysis of CT-based perfusion. We also discuss the present state of technology and challenges associated with the methodology. In each section, when appropriate, we provide some information regarding the translation of these methods being utilized in the international, multicenter CORE320 study that is evaluating the combined CT-based imaging (CTA and CTP) strategy of risk assessment in comparison to the combined reference standard of radionuclide myocardial perfusion imaging and invasive angiography.Journal of Cardiovascular Translational Research 06/2011; 4(4):437-48. · 2.61 Impact Factor -
Article: CT perfusion: ready for prime time.
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ABSTRACT: Advancements in computed tomography (CT) technology have revolutionized clinical practice, particularly regarding the noninvasive assessment of coronary artery disease (CAD). The versatility of cardiac CT has rendered multiple applications including assessment of cardiac structure and function, myocardial viability, and coronary anatomy. The merits of cardiac computed tomography angiography (CTA) have been proven for the detection, and particularly the exclusion, of CAD. However, CTA becomes limited in the presence of significant CAD. Its inability to consistently identify lesion-associated ischemia may necessitate additional radionuclide myocardial perfusion imaging. Myocardial computed tomography perfusion imaging (CTP) has emerged as a useful and convenient method to immediately assess myocardial ischemia. In this review, we discuss the current state of CTP including available technology, its performance to date from current literature, and future challenges to this field.Current Cardiology Reports 11/2010; 13(1):57-66. -
Article: Quantitative and qualitative analysis and interpretation of CT perfusion imaging.
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ABSTRACT: Coronary artery disease (CAD) remains the leading cause of death in the United States. Rest and stress myocardial perfusion imaging has an important role in the non-invasive risk stratification of patients with CAD. However, diagnostic accuracies have been limited, which has led to the development of several myocardial perfusion imaging techniques. Among them, myocardial computed tomography perfusion imaging (CTP) is especially interesting as it has the unique capability of providing anatomic- as well as coronary stenosis-related functional data when combined with computed tomography angiography (CTA). The primary aim of this article is to review the qualitative, semi-quantitative, and quantitative analysis approaches to CTP imaging. In doing so, we will describe the image data required for each analysis and discuss the advantages and disadvantages of each approach.Journal of Nuclear Cardiology 10/2010; 17(6):1091-100. · 2.67 Impact Factor -
Article: Assessment of coronary blood flow with computed tomography and magnetic resonance imaging.
Journal of Nuclear Cardiology 08/2010; 17(4):582-90. · 2.67 Impact Factor -
Article: Coronary flow reserve by CT perfusion.
Journal of Nuclear Cardiology 08/2010; 17(4):540-3. · 2.67 Impact Factor -
Article: Characterization and correction of beam-hardening artifacts during dynamic volume CT assessment of myocardial perfusion.
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ABSTRACT: To fully characterize beam-hardening effects caused by iodinated contrast medium in the left ventricular (LV) cavity and aorta in the assessment of myocardial perfusion at computed tomography (CT) and to validate a beam-hardening artifact correction algorithm that considers fluid-filled vessels and chambers important sources of beam hardening. The Johns Hopkins University animal care and use committee approved all procedures. An anatomically correct LV and myocardial phantom to characterize beam-hardening artifacts was designed. Following validation in the phantom, the beam-hardening correction (BHC) algorithm was applied to 256-detector row dynamic volume CT images in a canine ischemia model (n = 5) during adenosine stress, and the effect of beam hardening was determined by comparing regional dynamic volume CT perfusion metrics (myocardial upslope normalized by maximum LV blood pool attenuation) with microsphere-derived myocardial blood flow (MBF). A paired Student t test was used to compare continuous variables from the same subject but under different conditions, while linear regression analysis was performed to estimate the slope and statistical significance of the relationship between CT-derived perfusion metrics and microsphere-derived MBF. Beam-hardening artifacts were successfully reproduced in phantom studies and were eliminated with the BHC algorithm. The correlation coefficient of CT-derived perfusion metrics and microsphere-derived MBF improved from 0.60 to 0.74 (P > .05) following correction in the animal model. Beam-hardening artifacts confound dynamic volume CT assessment of myocardial perfusion. Application of the BHC algorithm is helpful for improving accuracy of myocardial perfusion at dynamic volume CT.Radiology 07/2010; 256(1):111-8. · 5.73 Impact Factor -
Article: A method for reconstructing the arterial input function during helical CT: implications for myocardial perfusion distribution imaging.
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ABSTRACT: To determine if a multidetector computed tomographic (CT) image acquisition and analysis method can enable accurate measurement of the arterial input function (AIF) during first-pass adenosine stress helical multidetector CT angiography and to test the effect of using this method on the semiquantitative assessment of myocardial perfusion distribution. The animal care and use committee of Johns Hopkins University approved the use of all procedures. The AIF was reconstructed by using a combination of bolus-tracking and time-registered helical multidetector CT data. After the AIF reconstruction method was validated in healthy animals, coronary stenosis was induced in seven dogs and contrast material-enhanced multidetector CT was performed during adenosine infusion (0.14-0.21 mg per kilogram of body weight per minute). Myocardial attenuation density (AD) parameters normalized to portions of the AIF were compared with microsphere myocardial blood flow (MBF) measurements at linear regression analysis. There was no significant difference between the area under the curve (AUC) for dynamic multidetector CT-derived AIF (3108 + or - 1250 [standard deviation]) and that for combined bolus-tracking and time-registered multidetector helical CT-derived AIF (3086 + or - 941) (P = .90). When AIF analysis was applied to helical multidetector CT myocardial perfusion measurements, the correlation between MBF and mean myocardial AD normalized to the AUC for the entire AIF was significant (R(2) = 0.82, P <.001). Myocardial AD normalized to the AUC for the AIF measured during helical multidetector CT correlated best with MBF (R(2) = 0.86, P <.001). The combination of bolus tracking and time-registered helical imaging enables reconstruction of the AIF during multidetector CT perfusion imaging. The helical CT AIF can be used to improve the semiquantitative assessment of myocardial perfusion distribution.Radiology 03/2010; 255(2):396-404. · 5.73 Impact Factor -
Article: Left ventricular function, myocardial perfusion and viability.
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ABSTRACT: Cardiac computed tomography is now poised to revolutionize the practice of cardiology. Multi-detector row CT (MDCT) has the potential to evaluate cardiac function, myocardial perfusion, and viability. These capabilities, combined with the robust ability of MDCT to noninvasively image the coronary arteries, makes MDCT a comprehensive tool for the evaluation of coronary artery disease and its anatomic and physiologic impact on the myocardium. Recent technologic advances in MDCT technology in regards to detector coverage, and spatial and temporal resolution promise to improve the capabilities of cardiac CT in the assessment of cardiac function, perfusion, and viability.Cardiology clinics 11/2009; 27(4):645-54. · 1.25 Impact Factor -
Article: Applications of cardiac multidetector CT beyond coronary angiography.
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ABSTRACT: Noninvasive imaging of the coronary arteries using multidetector CT (MDCT) represents one of the most promising diagnostic imaging advances in contemporary cardiology. This challenging application has driven a rapid and impressive advancement in CT technology over the past 10 years; leading to increased spatial and temporal resolution, decreased scan times and substantial reductions in radiation dose. Recent technological improvements have not only improved the status of CT coronary angiography but have also enabled new functional myocardial applications that are gaining a foothold in clinical practice as adjuncts or replacements for conventional coronary angiographic studies. Wide-detector CT designs along with prospective ECG-triggered protocols have opened the possibility of performing multiple complementary myocardial measurements during a coronary CT exam with acceptable radiation and contrast exposure. In this Review, we discuss recent technical developments in cardiac MDCT and outline newly enabled noncoronary cardiac applications including viability assessment, myocardial perfusion and molecular imaging.Nature Reviews Cardiology 11/2009; 6(11):699-710. · 8.83 Impact Factor -
Article: Newer methods for noninvasive assessment of myocardial perfusion: cardiac magnetic resonance or cardiac computed tomography?
JACC. Cardiovascular imaging 06/2009; 2(5):656-60. · 14.29 Impact Factor
Top co-authors
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2006–2012
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Johns Hopkins University
- • Division of Cardiology
- • Department of Medicine
Baltimore, MD, USA
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2010
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Johns Hopkins Medicine
- Department of Medicine
Baltimore, MD, USA
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