Journal Article

177 High resolution free-breathing automated quantitative myocardial perfusion by cardiovascular magnetic resonance can detect functionally significant coronary artery disease

Milidonis, Xenios, Chiribiri, Amedeo, Scannell, Cian, Plein, Sven, Crawley, Richard, Kunze, Karl P, Alskaf, Ebraham

2024

Overview

BackgroundAssessment of myocardial ischaemia from stress perfusion cardiovascular magnetic resonance (SP-CMR) is largely dependent on visual interpretation, with high level operator experience necessary for accurate assessment. Automated SP-CMR perfusion mapping techniques can provide estimation of myocardial blood flow (MBF). This study investigated the use of novel high spatial-resolution free-breathing SP-CMR with automated quantitative mapping in the diagnosis of coronary artery disease (CAD). Diagnostic performance was evaluated against invasive coronary angiography (ICA) with fractional flow reserve (FFR) measurement.MethodsSeven-hundred and three patients were recruited for SP-CMR using the research sequence at 3 Tesla. Of those receiving ICA within 6 months, 60 patients had FFR measurement. Those with FFR value ≤ 0.80 were classified as having functionally significant CAD. All patients were imaged during vasodilatory hyperaemia in 3 ventricular slices (basal, mid, apical) with dual-sequence acquisition to calculate the arterial input function. Myocardial blood flow (MBF) maps were automatically generated in-line on the scanner following image acquisition at hyperaemic stress and rest, allowing myocardial perfusion reserve (MPR) calculation. MBF maps were analysed using 600 data points per slice, allowing analysis of the endocardial (inner 50%) and epicardial (outer 50%) myocardial layers. Non-parametric statistical analysis was performed using Mann-Whitney U testing and ROC analysis.ResultsSeventy-five coronary vessels assessed by FFR were evaluated at both segmental and coronary territory level. The baseline demographics are shown in table 1. Coronary territory stress MBF and MPR were reduced in FFR-positive (≤ 0.80) regions (median stress MBF: 1.74 [0.90–2.17] ml/min/g; MPR: 1.67 [1.10–1.89]) compared with FFR-negative (> 0.80) regions (stress MBF: 2.50 [2.15–2.95] ml/min/g; MPR 2.35 [2.06–2.54] p < 0.001 for both) [figure 1]. When only analysing the lowest 2 segments of each coronary territory, perfusion values were lower in FFR-positive territories (FFR ≤ 0.80: stress MBF 1.53 [0.79–1.90] ml/min/g, MPR 1.42 [0.99–1.78]; FFR > 0.80: stress MBF 2.08 [1.87–2.52] ml/min/g, MPR 2.11 [1.86–2.45], p < 0.001 for both). A similar pattern is seen when assessing the endocardial layers of each coronary territory (FFR ≤ 0.80: stress MBF 1.63 [0.86–2.03] ml/min/g, MPR 1.63 [1.08–1.87]; FFR > 0.80: stress MBF 2.32 [2.00–2.92] ml/min/g, MPR 2.14 [1.92–2.49], p < 0.001 for both).Considering whole territory analysis, stress MBF ≤ 1.94 ml/min/g and MPR ≤ 1.97 accurately detected FFR-positive CAD on a per-vessel basis (area under the curve: 0.85 and 0.96 respectively; p < 0.001 for both). For whole territory analysis: stress MBF sensitivity 70.0%, specificity 90.8%; MPR sensitivity 90.0%, specificity 84.9%. Similar diagnostic performance is seen for both ‘lowest 2 segments’ and ‘endocardial’ assessment methods, with higher sensitivity and lower specificity seen for both alternative analyses [figure 2].ConclusionScanner-integrated high-resolution free-breathing SP-CMR with automated in-line perfusion mapping can accurately detect functionally significant CAD. High-resolution MBF maps allow assessment of both transmural myocardial segments and the endocardial layers within each coronary territory.Abstract 177 Table 1Baseline characteristics at the time of CMR scan. PCI = Percutaneous coronary intervention; CABG = Coronary artery bypass grafting. Continuous variables displayed as group mean ± standard deviation; discrete variables displayed as frequency (group%). Age 61.3 ± 10.5 Sex Male 31 (51.7) Stress agent Adenosine 56 (93.3) Left ventricular ejection fraction 58.3 ± 9.1 Cardiac rhythm Sinus rhythm 58 (96.7) Atrial fibrillation 2 (3.3) History of CAD 24 (40.0) Previous coronary intervention None 48 (80.0) PCI 11 (18.3) CABG 1 (1.7) Diabetes mellitus 19 (31.7) Hypercholesterolemia 40 (66.7) Hypertension 34 (56.7) Smoking history None 36 (60.0) Ex-smoker 20 (33.3) Current smoker 4 (6.7) Presence of LGE (any myocardial segment) 22 (36.7) Abstract 177 Figure 1Box plots highlighting the differences in both stress MBF (A) and MPR (B) values seen between FFR-negative (> 0.80) and FFR-positive (≤ 0.80) lesions. Similar differences are seen for whole territory, lowest 2 segments and endocardial assessment strategiesAbstract 177 Figure 2ROC curves demonstrating diagnostic performance of whole territory (A), lowest 2 segment (B) and endocardial (C) analysis in the assessment of functionally significant coronary disease as defined by FFRConflict of InterestNone

• Publisher: BMJ Publishing Group Ltd and British Cardiovascular Society,BMJ Publishing Group LTD
• Subject: Automation / Cardiovascular disease / Cardiovascular magnetic resonance / Coronary artery disease / Coronary vessels / Imaging / Quantitative perfusion / Vein & artery diseases