Coronary risk factors and myocardial blood flow in patients evaluated for coronary artery disease: a quantitative [15O]H2O PET/CT study

Abstract

BackgroundThere has been increasing interest in quantitative myocardial blood flow (MBF) imaging over the last years and it is expected to become a routinely used technique in clinical practice. Positron emission tomography (PET) using [15O]H2O is the established gold standard for quantification of MBF in vivo. A fundamental issue when performing quantitative MBF imaging is to define the limits of MBF in a clinically suitable population. The aims of the present study were to determine the limits of MBF and to determine the relationship among coronary artery disease (CAD) risk factors, gender and MBF in a predominantly symptomatic patient cohort without significant CAD.MethodsA total of 128 patients (mean age 54 ± 10 years, 50 men) with a low to intermediate pretest likelihood of CAD were referred for noninvasive evaluation of CAD using a hybrid PET/computed tomography (PET/CT) scanner. MBF was quantified with [15O]H2O at rest and during adenosine-induced hyperaemia. Obstructive CAD was excluded in these patients by means of invasive or CT-based coronary angiography.ResultsGlobal average baseline MBF values were 0.91 ± 0.34 and 1.09 ± 0.30 ml·min−1·g−1 (range 0.54–2.35 and 0.59–2.75 ml·min−1·g−1) in men and women, respectively (p < 0.01). However, no gender-dependent difference in baseline MBF was seen following correction for rate–pressure product (0.98 ± 0.45 and 1.09 ± 0.30 ml·min−1·g−1 in men and women, respectively; p = 0.08). Global average hyperaemic MBF values were 3.44 ± 1.20 ml·min−1·g−1 in the whole study population, and 2.90 ± 0.85 and 3.78 ± 1.27 ml·min−1·g−1 (range 1.52–5.22 and 1.72–8.15 ml·min−1·g−1) in men and women, respectively (p < 0.001). Multivariate analysis identified male gender, age and body mass index as having an independently negative impact on hyperaemic MBF.ConclusionGender, age and body mass index substantially influence reference values and should be corrected for when interpreting hyperaemic MBF values.

Hybrid Imaging Using Quantitative H215O PET and CT-Based Coronary Angiography for the Detection of Coronary Artery Disease

“…Although methodologic considerations between imaging protocols and patient selection may account for some of these discrepancies, the selection of an optimal threshold to reproduce such a high diagnostic yield may prove difficult in clinical practice. Studies in patients without CAD have clearly demonstrated that the reference range of hyperemic MBF is relatively broad because of physiologic variation in minimal coronary microvascular resistance, which is related to patient characteristics such as age, sex, and CAD risk factors (11,(18)(19)(20). Because hyperemic MBF is governed by the (potential) presence of an epicardial coronary lesion and microvascular resistance, a cutoff value to identify an obstructive coronary lesion will vary according to the conductance capacity of the microvascular bed in each individual patient.…”

“…Patients with a stable heart rate below 65 bpm (either spontaneous or after the administration of oral or intravenous metoprolol) underwent a CT scan for calcium scoring and CTCA as previously described (11). All CT scans were analyzed with a 3-dimensional workstation (Brilliance, Philips) by an experienced radiologist and cardiologist who were masked to the ICA results.…”

“…The PET sequence has been described in detail previously (10,11). Parametric MBF images, showing MBF on the voxel level, were generated, and quantitative analysis was performed using Cardiac VUer software developed in-house (12).…”

Quantitative myocardial blood flow imaging: not all flow is equal

“…Upon exclusion of patients with atherosclerosis, gender-related differences in coronary microvascular function remained substantial. Last year, a comparable study by Danad et al was published in this journal [6]. Although both studies linked a number of traditional cardiovascular risk factors to coronary microvascular dysfunction, the most prominent similarity between them is the impact of gender.…”

Diagnostic Accuracy of Endocardial-to-Epicardial Myocardial Blood Flow Ratio for the Detection of Significant Coronary Artery Disease With Dynamic Myocardial Perfusion Dual-Source Computed Tomography

“…4, 5 Previous CTP studies used absolute MBF thresholds in mL/100 g/min to discriminate flow-limiting CAD, 6-10 but the absolute MBF can vary because of factors other than the degree of coronary artery stenosis. 11- 14 Patients with extensive non-obstructive CAD may show GOTO Y et al…”