Objectives: To establish the regional delay of contrast arrival in magnetic resonance perfusion imaging (MRPI) for the detection of collateral-dependent myocardium in patients with coronary artery disease.
Design and Setting: observational study, case series; single center, university hospital.
Patients: 30 patients with coronary artery disease and collateral-dependent myocardium and 17 healthy volunteers.
Methods: Resting and hyperemic (adenosine) MRPI was used to determine delay time (Δtd) of contrast arrival between the left ventricle and collateral-dependent or antegradely-perfused myocardium, and myocardial perfusion (MP, ml/g/min).
Results: In healthy volunteers Δtd at rest and during hyperemia were 0.8±0.4 and 0.3±0.3 sec., and MP was 1.14±0.21 and 4.23±1.12 ml/min/g. Δtd in antegradely-perfused vs. collateraldependent
myocardium was 0.9±0.7 vs. 1.7±1.0 sec. at rest (p<0.001) and 0.4±0.3 vs. 1.1±0.6
sec (p<0.001) during hyperemia. MP was 1.12±0.11 and 0.98±0.28 ml/min/g (p = n.s.) at rest and 2.46±0.85 vs. 1.86±0.91 ml/min/g (p<0.01) during hyperemia. ROC analysis showed best sensitivity and specificity of 90% and 83% for hyperemic Δtd of >0.6 sec (AUC=0.89) to detect collateral-dependent myocardium, while resting Δtd (AUC= 0.77) or perfusion (AUC = 0.69 at rest or 0.70 during hyperemia) were less accurate.
Conclusions: MRPI derived hyperemic delay of contrast arrival detects collateral-dependent
myocardium with high sensitivity and specificity. Perfusion was less sensitive, emphasizing the clinical role of Δtd for non-invasive detection of collateral-dependent myocardium.