Assessment of coronary endothelial function using PET

Assessment of the Dimensions of Coronary Arteries for the Manifestation of Coronary Artery Disease

INTRODUCTION

The size of the coronary artery influences the effective outcome of therapeutic measures like coronary artery bypass graft (CABG) surgery, percutaneous coronary interventions (PCI), and diagnosis of coronary artery disease. Patients' age, gender, BMI, anatomical variations, and increased left ventricular size all have an effect on coronary artery parameters.

OBJECTIVE

This study aims to compare the average size of the coronary arteries of the Pakistani population in both sexes for manifestation of coronary artery disease.

METHODOLOGY

For the analysis of the coronary arteries, 100 patients of both sexes, male and female, were taken. X-ray angiography was performed for two-dimensional images of coronary arteries. For diameter measurement, images were visualized on quantitative coronary angiography (QCA) in different views (caudal and cranial views). The diameters of the left main coronary artery (left main stem/LMS), left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) were measured on angiograms. Data about the dimensions of the coronary artery was gathered through quantitative angiography. Data analysis was done through SPSS version 26 (IBM Corp., Armonk, NY).

RESULTS

 There is a notable distinction in the average diameters among the proximal LAD (3.12), mid-LAD (2.40), and distal LAD (1.29). A statistically significant difference is evident among mid-LCx, distal LCx, and proximal LCx (p-value < 0.001). Likewise, the average diameter of the distal RCA (1.89) was smaller when compared to the mid-RCA (3.19) and proximal RCA (3.78). However, there was no significant difference in the average diameter among mid-LMS, distal LMS, and proximal LMS (p-value = 0.09).

CONCLUSION

The average diameter of distal RCA was smaller when compared to mid-RCA and proximal RCA. The average size of proximal LAD and proximal LCx was comparatively larger than mid- and distal LAD and LCx. The findings of current research will be beneficial for the diagnosis and management of coronary artery disease patients.

Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive imaging assessment

The microvasculature serves an imperative function in regulating perfusion and nutrient exchange throughout the body, adaptively altering blood flow to preserve hemodynamic and metabolic homeostasis. Its normal functioning is vital to tissue health, whereas its dysfunction is present in many chronic conditions, including diabetes, heart disease, and cognitive decline. As microvascular dysfunction often appears early in disease progression, its detection can offer early diagnostic information. To detect microvascular dysfunction, one uses imaging to probe the microvasculature's ability to react to a stimulus, also known as microvascular reactivity (MVR). An assessment of MVR requires an integrated understanding of vascular physiology, techniques for stimulating reactivity, and available imaging methods to capture the dynamic response. Practical considerations, including compatibility between the selected stimulus and imaging approach, likewise require attention. In this review, we provide a comprehensive foundation necessary for informed imaging of MVR, with a particular focus on the challenging endeavor of assessing microvascular function in deep tissues.

Absolute quantification of myocardial blood flow

With the increasing availability of positron emission tomography (PET) myocardial perfusion imaging, the absolute quantification of myocardial blood flow (MBF) has become popular in clinical settings. Quantitative MBF provides an important additional diagnostic or prognostic information over conventional visual assessment. The success of MBF quantification using PET/computed tomography (CT) has increased the demand for this quantitative diagnostic approach to be more accessible. In this regard, MBF quantification approaches have been developed using several other diagnostic imaging modalities including single-photon emission computed tomography, CT, and cardiac magnetic resonance. This review will address the clinical aspects of PET MBF quantification and the new approaches to MBF quantification.

Comparison of rest and adenosine stress quantitative and semi-quantitative myocardial perfusion using magnetic resonance in patients with ischemic heart disease

The aim was to compare absolute quantified myocardial perfusion (MP) to semi-quantitative measurements of MP using MRI for detection of ischemia. Twenty-nine patients underwent rest and stress MP imaging obtained by 1.5T MRI and analyzed using own developed software and by commercial available software. Linear regression analysis demonstrated that absolute quantitative data correlated stronger to maxSI (rest: r=0.296, p=.193; stress: r=0.583, p=0.011; myocardial perfusion reserve (MPR): r=0.789, p<0.001; and Δ myocardial blood flow (Δ MBF: r=0.683, p=0.004) than to upslope (rest: r=0.420, p=0.058; stress: r=0.096, p=0.704; MPR: r=0.682, p=0.004; and Δ MBF: r=0.055, p=0.804). Absolute quantified MP was able to distinguish between ischemic and non-ischemic territories at rest (left anterior descending artery (LAD): 103.1±11.3mL/100g/min vs. 206.3±98.5mL/100g/min; p=0.001, right coronary artery (RCA): 124.1±45.2mL/100g/min vs. 241.3±81.7mL/100g/min; p<0.001, and left circumflex artery (LCX): 132.8±53.8mL/100g/min vs. 181.2±56.6mL/100g/min; p=0.060) and at stress (LAD: 148.1±47.2mL/100g/min vs. 296.6±111.6mL/100g/min; p=0.012, RCA: 173.4±63.7mL/100g/min vs. 290.2±100.6mL/100g/min; p=0.008, and LCX: 206.6±105.1mL/100g/min vs. 273.8±78.0mL/100g/min; p=0.186). The correlation between global maxSI and positron emission tomography data was non-significant at rest and borderline significant at stress (r=0.265, p=0.382 and r=0.601, p=0.050, respectively). Quantified MP may be useful in patients for detection of ischemia.

Overweight status is associated with extensive signs of microvascular dysfunction and cardiovascular risk

The aim of this present study was to investigate if overweight individuals exhibit signs of vascular dysfunction associated with a high risk for cardiovascular disease (CVD). One hundred lean and 100 overweight participants were recruited for the present study. Retinal microvascular function was assessed using the Dynamic Retinal Vessel Analyser (DVA), and systemic macrovascular function by means of flow-mediated dilation (FMD). Investigations also included body composition, carotid intimal-media thickness (c-IMT), ambulatory blood pressure monitoring (BP), fasting plasma glucose, triglycerides (TG), cholesterol levels (HDL-C and LDL-C), and plasma von Willebrand factor (vWF). Overweight individuals presented with higher right and left c-IMT (p = 0.005 and p = 0.002, respectively), average 24-h BP values (all p < 0.001), plasma glucose (p = 0.008), TG (p = 0.003), TG: HDL-C ratio (p = 0.010), and vWF levels (p = 0.004). Moreover, overweight individuals showed lower retinal arterial microvascular dilation (p = 0.039) and baseline-corrected flicker (bFR) responses (p = 0.022), as well as, prolonged dilation reaction time (RT, p = 0.047). These observations emphasise the importance of vascular screening and consideration of preventive interventions to decrease vascular risk in all individuals with adiposity above normal range.

Anatomical and Functional Estimations of Brachial Artery Diameter and Elasticity Using Oscillometric Measurements with a Quantitative Approach

Noninvasive vascular function measurement plays an important role in detecting early stages of atherosclerosis and in evaluating therapeutic responses. In this regard, recently, new vascular function measurements have been developed. These new measurements have been used to evaluate vascular function in coronary arteries, large aortic arteries, or peripheral arteries. Increasing vascular diameter represents vascular remodeling related to atherosclerosis. Attenuated vascular elasticity may be a reliable marker for atherosclerotic risk assessment. However, previous measurements for vascular diameter and vascular elasticity have been complex, operator-dependent, or invasive. Therefore, simple and reliable approaches have been sought. We recently developed a new automated oscillometric method to measure the estimated area (eA) of a brachial artery and its volume elastic modulus (VE). In this review, we further report on this new measurement and other vascular measurements. We report on the reliability of the new automated oscillometric measurement of eA and VE. Based on our findings, this measurement technique should be a reliable approach, and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings. In this review, we report the characteristics of our new oscillometric measurements and other related vascular function measurements.

Pulmonary Hypertension and Indicators of Right Ventricular Function

Pulmonary hypertension (PH) is a rare disease, whose underlying mechanisms are not fully understood. It is characterized by pulmonary arterial vasoconstriction and vessels wall thickening, mainly intimal and medial layers. Several molecular pathways have been studied, but their respective roles remain unknown. Cardiac repercussions of PH are hypertrophy, dilation, and progressive right ventricular dysfunction. Multiple echocardiographic parameters are being used, in order to assess anatomy and cardiac function, but there are no guidelines edited about their usefulness. Thus, it is now recommended to associate the best-known parameters, such as atrial and ventricular diameters or tricuspid annular plane systolic excursion. Cardiac catheterization remains necessary to establish the diagnosis of PH and to assess pulmonary hemodynamic state. Concerning energetic metabolism, free fatty acids, normally used to provide energy for myocardial contraction, are replaced by glucose uptake. These abnormalities are illustrated by increased (18)F-fluorodeoxyglucose ((18)F-FDG) uptake on positron emission tomography/computed tomography, which seems to be correlated with echocardiographic and hemodynamic parameters.

The prognostic value of non-perfusion variables obtained during vasodilator stress myocardial perfusion imaging

Myocardial perfusion imaging (MPI) is an established diagnostic test that provides useful prognostic data in patients with known or suspected coronary artery disease. In more than half of the patients referred for stress testing, vasodilator stress is used in lieu of exercise. Unlike exercise, vasodilator stress does not provide information on exercise and functional capacity, heart rate recovery, and chronotropy, and ECG changes are less frequent. These non-perfusion data provide important prognostic and patient management information. Further, event rates in patients undergoing vasodilator MPI are higher than in those undergoing exercise MPI and even in those with normal images probably due to higher pretest risk. However, there are a number of non-perfusion variables that are obtained during vasodilator stress testing, which have prognostic relevance but their use has not been well emphasized. The purpose of this review is to summarize the prognostic values of these non-perfusion data obtained during vasodilator MPI.

Comprehensive assessment of impaired peripheral and coronary artery endothelial functions in smokers using brachial artery ultrasound and oxygen-15-labeled water PET

BACKGROUND

Comprehensive evaluation of endothelium-dependent and endothelium-independent vascular functions in peripheral arteries and coronary arteries in smokers has never been performed previously. Through the use of brachial artery ultrasound and oxygen-15-labeled water positron emission tomography (PET), we sought to investigate peripheral and coronary vascular dysfunctions in smokers.

METHODS AND RESULTS

Eight smokers and 10 healthy individuals underwent brachial artery ultrasound at rest, during reactive hyperemia [250mmHg cuff occlusion (flow-mediated dilatation (FMD)], and following sublingual nitroglycerin (NTG) administration. Myocardial blood flow (MBF) was assessed through O-15-labeled water PET at rest, during adenosine triphosphate (ATP) administration, and during a cold pressor test (CPT). Through ultrasound, smokers were shown to have significantly reduced %FMD compared to controls (6.62±2.28% vs. 11.29±2.75%, p=0.0014). As assessed by O-15-labeled water PET, smokers were shown to have a significantly lower CPT response than were controls (21.1±9.5% vs. 50.9±16.9%, p=0.0004). There was no relationship between %FMD and CPT response (r=0.40, p=0.097). Endothelium-independent vascular dilatation was similar for both groups in terms of coronary flow reserve with PET (p=0.19). Smokers tended to have lower %NTG in the brachial artery (p=0.055).

CONCLUSIONS

Smokers exhibited impaired coronary endothelial function as well as peripheral brachial artery endothelial function. In addition, there was no correlation between PET and ultrasound measurements, possibly implying that while smokers may have systemic vascular endothelial dysfunction, the characteristics of that dysfunction may be different in peripheral arteries and coronary arteries.

Endothelial Dysfunction: Clinical Implications in Cardiovascular Disease and Therapeutic Approaches

Atherosclerosis is a chronic progressive vascular disease. It starts early in life, has a long asymptomatic phase, and a progression accelerated by various cardiovascular risk factors. The endothelium is an active inner layer of the blood vessel. It generates many factors that regulate vascular tone, the adhesion of circulating blood cells, smooth muscle proliferation, and inflammation, which are the key mechanisms of atherosclerosis and can contribute to the development of cardiovascular events. There is growing evidence that functional impairment of the endothelium is one of the first recognizable signs of development of atherosclerosis and is present long before the occurrence of atherosclerotic cardiovascular disease. Therefore, understanding the endothelium's central role provides not only insights into pathophysiology, but also a possible clinical opportunity to detect early disease, stratify cardiovascular risk, and assess response to treatments. In the present review, we will discuss the clinical implications of endothelial function as well as the therapeutic issues for endothelial dysfunction in cardiovascular disease as primary and secondary endothelial therapy.

Current and future trends in multimodality imaging of coronary artery disease

Nowadays, there is a wide array of imaging studies available for the evaluation of coronary artery disease, each with its particular indications and strengths. Cardiac single photon emission tomography is mostly used to evaluate myocardial perfusion, having experienced recent marked improvements in image acquisition. Cardiac PET has its main utility in perfusion imaging, atherosclerosis and endothelial function evaluation, and viability assessment. Cardiovascular computed tomography has long been used as a reference test for non-invasive evaluation of coronary lesions and anatomic characterization. Cardiovascular magnetic resonance is currently the reference standard for non-invasive ventricular function evaluation and myocardial scarring delineation. These specific strengths have been enhanced with the advent of hybrid equipment, offering a true integration of different imaging modalities into a single, simultaneous and comprehensive study.

Accurate quantitative measurements of brachial artery cross-sectional vascular area and vascular volume elastic modulus using automated oscillometric measurements: comparison with brachial artery ultrasound

Increasing vascular diameter and attenuated vascular elasticity may be reliable markers for atherosclerotic risk assessment. However, previous measurements have been complex, operator-dependent or invasive. Recently, we developed a new automated oscillometric method to measure a brachial artery's estimated area (eA) and volume elastic modulus (V_E). The aim of this study was to investigate the reliability of new automated oscillometric measurement of eA and V_E. Rest eA and V_E were measured using the recently developed automated detector with the oscillometric method. eA was estimated using pressure/volume curves and V_E was defined as follows (V_E=Δ pressure/ (100 × Δ area/area) mm Hg/%). Sixteen volunteers (age 35.2±13.1 years) underwent the oscillometric measurements and brachial ultrasound at rest and under nitroglycerin (NTG) administration. Oscillometric measurement was performed twice on different days. The rest eA correlated with ultrasound-measured brachial artery area (r=0.77, P<0.001). Rest eA and V_E measurement showed good reproducibility (eA: intraclass correlation coefficient (ICC)=0.88, V_E: ICC=0.78). Under NTG stress, eA was significantly increased (12.3±3.0 vs. 17.1±4.6 mm², P<0.001), and this was similar to the case with ultrasound evaluation (4.46±0.72 vs. 4.73±0.75 mm, P<0.001). V_E was also decreased (0.81±0.16 vs. 0.65±0.11 mm Hg/%, P<0.001) after NTG. Cross-sectional vascular area calculated using this automated oscillometric measurement correlated with ultrasound measurement and showed good reproducibility. Therefore, this is a reliable approach and this modality may have practical application to automatically assess muscular artery diameter and elasticity in clinical or epidemiological settings.

Cardiac rehabilitation improves coronary endothelial function in patients with heart failure due to dilated cardiomyopathy: A positron emission tomography study

BACKGROUND

Endothelial dysfunction is common in patients with heart failure and is associated with poor clinical outcome. Cardiac rehabilitation is able to enhance peripheral endothelial function but its impact on coronary vasomotion remains unknown. We aimed to evaluate the effect of cardiac rehabilitation on coronary vasomotion in patients with heart failure.

METHOD

We prospectively enrolled 29 clinically stable heart failure patients from non-ischaemic dilated cardiomyopathy and without coronary risk factors. Myocardial blood flow was quantified using (15)-O water positron emission tomography at rest and during a cold pressor test, before and after 12 weeks of cardiac rehabilitation and optimization of medical therapy.

RESULTS

Rest myocardial blood flow was significantly improved after the completion of rehabilitation compared to baseline (1.31 ± 0.38 mL/min/g vs. 1.16 ± 0.41 mL/min/g, p = 0.04). The endothelium-related change in myocardial blood flow from rest to cold pressor test and the percentage of myocardial blood flow increase during the cold pressor test were both significantly improved after cardiac rehabilitation (respectively from -0.03 ± 0.22 mL/min/g to 0.19 ± 0.22 mL/min/g, p < 0.001 and from 101.5 ± 16.5% to 118.3 ± 24.4%, p < 0.001). Left ventricular ejection fraction, plasma levels of brain natriuretic peptide, maximal oxygen consumption and the Minnesota Living with Heart Failure Questionnaire score were also significantly improved. The improvement was not related to uptitration of medical therapy.

CONCLUSIONS

Coronary endothelial function is altered in patients with heart failure due to non-ischaemic dilated cardiomyopathy. In these patients, cardiac rehabilitation significantly improves coronary vasomotion.

Quantification of myocardial blood flow using PET to improve the management of patients with stable ischemic coronary artery disease

ABSTRACT 

Cardiac PET has been evolving over the past 30 years. Today, it is accepted as a valuable imaging modality for the noninvasive assessment of coronary artery disease. PET has demonstrated superior diagnostic accuracy for the detection of coronary artery disease compared with single-photon emission computed tomography, and also has a well-established prognostic value. The routine addition of absolute quantification of myocardial blood flow increases the diagnostic accuracy for three-vessel disease and provides incremental functional and prognostic information. Moreover, the characterization of the vasodilator capacity of the coronary circulation may guide proper decision-making and monitor the effects of lifestyle changes, exercise training, risk factor modification or medical therapy for improving regional and global myocardial blood flow. This type of image-guided approach to individualized patient therapy is now attainable with the routine use of cardiac PET flow reserve imaging.

Positron emission tomography imaging of atherosclerosis

Atherosclerosis-related cardiovascular events are the leading causes of death in the industrialized world. Atherosclerosis develops insidiously and the initial manifestation is usually sudden cardiac death, stroke, or myocardial infarction. Molecular imaging is a valuable tool to identify the disease at an early stage before fatal manifestations occur. Among the various molecular imaging techniques, this review mainly focuses on positron emission tomography (PET) imaging of atherosclerosis. The targets and pathways that have been investigated to date for PET imaging of atherosclerosis include: glycolysis, cell membrane metabolism (phosphatidylcholine synthesis), integrin α_vβ_3, low density lipoprotein (LDL) receptors (LDLr), natriuretic peptide clearance receptors (NPCRs), fatty acid synthesis, vascular cell adhesion molecule-1 (VCAM-1), macrophages, platelets, etc. Many PET tracers have been investigated clinically for imaging of atherosclerosis. Early diagnosis of atherosclerotic lesions by PET imaging can help to prevent the premature death caused by atherosclerosis, and smooth translation of promising PET tracers into the clinic is critical to the benefit of patients.

Using advanced noninvasive imaging techniques to probe the links between regional coronary artery endothelial dysfunction and atherosclerosis

Cardiovascular disease remains the number one cause of death in the US annually. The development in recent years of imaging strategies that can identify coronary endothelial dysfunction noninvasively provides new information about the early presence and local spatial heterogeneity of endothelial function in patients with, and those at risk for, coronary artery disease. In this article, we will briefly review the mechanisms relating endothelial function and atherosclerosis, contemporary imaging strategies now able to quantify coronary endothelial function noninvasively, and recent insights on human coronary endothelial function.

Assessment of myocardial perfusion and viability by positron emission tomography

An important evolution has taken place recently in the field of cardiovascular Positron Emission Tomography (PET) imaging. Being originally a highly versatile research tool that has contributed significantly to advance our understanding of cardiovascular physiology and pathophysiology, PET has gradually been incorporated into the clinical cardiac imaging portfolio contributing to diagnosis and management of patients investigated for coronary artery disease (CAD). PET myocardial perfusion imaging (MPI) has an average sensitivity and specificity around 90% for the detection of angiographically significant CAD and it is also a very accurate technique for prognostication of patients with suspected or known CAD. In clinical practice, Rubidium-82 ((82)Rb) is the most widely used radiopharmaceutical for MPI that affords also accurate and reproducible quantification in absolute terms (ml/min/g) comparable to that obtained by cyclotron produced tracers such as Nitrogen-13 ammonia ((13)N-ammonia) and Oxygen-15 labeled water ((15)O-water). Quantification increases sensitivity for detection of multivessel CAD and it may also be helpful for detection of early stages of atherosclerosis or microvascular dysfunction. PET imaging combining perfusion with myocardial metabolism using (18)F-Fluorodeoxyglucose ((18)F FDG), a glucose analog, is an accurate standard for assessment of myocardial hibernation and risk stratification of patients with left ventricular dysfunction of ischemic etiology. It is helpful for guiding management decisions regarding revascularization or medical treatment and predicting improvement of symptoms, exercise capacity and quality of life post-revascularization. The strengths of PET can be increased further with the introduction of hybrid scanners, which combine PET with computed tomography (PET/CT) or with magnetic resonance imaging (PET/MRI) offering integrated morphological, biological and physiological information and hence, comprehensive evaluation of the consequences of atherosclerosis in the coronary arteries and the myocardium.

Nuclear perfusion imaging for functional evaluation of patients with known or suspected coronary artery disease: the future is now

Nuclear imaging, with both single-photon emission computed tomography and PET, has a well-established role in the assessment of patients with known or suspected coronary artery disease. There is a large body of evidence regarding the diagnostic accuracy and prognostic value of these modalities, however, they continue to evolve rapidly with advances in camera and tracer technology, as well as changes in imaging protocols to increase lab efficiency, improve image quality and to decrease radiation exposure to patients. Nuclear imaging also provides insights into atherogenesis at a molecular level and can be combined with other imaging modalities, providing both functional and structural data and complimentary information on the presence of coronary disease and its functional implications.

Quantification of myocardial blood flow with 82Rb positron emission tomography: clinical validation with 15O-water

Purpose

Quantification of myocardial blood flow (MBF) with generator-produced ⁸²Rb is an attractive alternative for centres without an on-site cyclotron. Our aim was to validate ⁸²Rb-measured MBF in relation to that measured using ¹⁵O-water, as a tracer 100% of which can be extracted from the circulation even at high flow rates, in healthy control subject and patients with mild coronary artery disease (CAD).

Methods

MBF was measured at rest and during adenosine-induced hyperaemia with ⁸²Rb and ¹⁵O-water PET in 33 participants (22 control subjects, aged 30 ± 13 years; 11 CAD patients without transmural infarction, aged 60 ± 13 years). A one-tissue compartment ⁸²Rb model with ventricular spillover correction was used. The ⁸²Rb flow-dependent extraction rate was derived from ¹⁵O-water measurements in a subset of 11 control subjects. Myocardial flow reserve (MFR) was defined as the hyperaemic/rest MBF. Pearson’s correlation r, Bland-Altman 95% limits of agreement (LoA), and Lin’s concordance correlation ρ_c (measuring both precision and accuracy) were used.

Results

Over the entire MBF range (0.66–4.7 ml/min/g), concordance was excellent for MBF (r = 0.90, [⁸²Rb–¹⁵O-water] mean difference ± SD = 0.04 ± 0.66 ml/min/g, LoA = −1.26 to 1.33 ml/min/g, ρ_c = 0.88) and MFR (range 1.79–5.81, r = 0.83, mean difference = 0.14 ± 0.58, LoA = −0.99 to 1.28, ρ_c = 0.82). Hyperaemic MBF was reduced in CAD patients compared with the subset of 11 control subjects (2.53 ± 0.74 vs. 3.62 ± 0.68 ml/min/g, p = 0.002, for ¹⁵O-water; 2.53 ± 1.01 vs. 3.82 ± 1.21 ml/min/g, p = 0.013, for ⁸²Rb) and this was paralleled by a lower MFR (2.65 ± 0.62 vs. 3.79 ± 0.98, p = 0.004, for ¹⁵O-water; 2.85 ± 0.91 vs. 3.88 ± 0.91, p = 0.012, for ⁸²Rb). Myocardial perfusion was homogeneous in 1,114 of 1,122 segments (99.3%) and there were no differences in MBF among the coronary artery territories (p > 0.31).

Conclusion

Quantification of MBF with ⁸²Rb with a newly derived correction for the nonlinear extraction function was validated against MBF measured using ¹⁵O-water in control subjects and patients with mild CAD, where it was found to be accurate at high flow rates. ⁸²Rb-derived MBF estimates seem robust for clinical research, advancing a step further towards its implementation in clinical routine.

Assessment of coronary vasoreactivity by multidetector computed tomography: feasibility study with rubidium-82 cardiac positron emission tomography

BACKGROUND

Positron emission tomography (PET) during the cold pressor test (CPT) has been used to assess endothelium-dependent coronary vasoreactivity, a surrogate marker of cardiovascular events. However, its use remains limited by cardiac PET availability. As multidetector computed tomography (MDCT) is more widely available, we aimed to develop a measurement of endothelium-dependent coronary vasoreactivity with MDCT and similar radiation burden as with PET.

METHODS AND RESULTS

A study group of 18 participants without known cardiovascular risk factor (9F/9M; age 60±6 years) underwent cardiac PET with (82)Rb and unenhanced ECG-gated MDCT within 4h, each time at rest and during CPT. The relation between absolute myocardial blood flow (MBF) response to CPT by PET (ml·min(-1)·g(1)) and relative changes in MDCT-measured coronary artery surface were assessed using linear regression analysis and Spearman's correlation. MDCT and PET/CT were analyzed in all participants. Hemodynamic conditions during CPT at MDCT and PET were similar (P>0.3). Relative changes in coronary artery surface because of CPT (2.0-21.2%) correlated to changes in MBF (-0.10-0.52ml·min(-1)·g(1)) (ρ=0.68, P=0.02). Effective dose was 1.3±0.2mSv for MDCT and 3.1mSv for PET/CT.

CONCLUSIONS

Assessment of endothelium-dependent coronary vasoreactivity using MDCT CPT appears feasible. Because of its wider availability, shorter examination time and similar radiation burden, MDCT could be attractive in clinical research for coronary status assessment.