13 Accelerated CMR perfusion for the detection of functionally significant coronary artery disease: a prospective randomised diagnostic accuracy study

<h3>Introduction</h3> In patients with suspected coronary artery disease (CAD), the diagnostic and prognostic roles of stress-perfusion cardiovascular magnetic resonance (CMR) are well established. To meet increasing demand, there is a strong impetus to improve the time efficiency of existing CMR protocols. Newly developed sequences may enable faster acquisition and shorter examination times. This prospective, randomised study evaluated the accuracy of an accelerated CMR protocol in identifying functionally significant CAD, as determined by (1) invasive fractional flow reserve (FFR_inv) assessment and (2) standard stress-perfusion CMR. <h3>Materials and Methods</h3> Patients with suspected stable CAD referred for clinically-indicated invasive coronary angiography underwent two 3-Tesla CMR scans (standard and accelerated protocols), performed on separate days and in random order. Accelerated CMR comprised: (1) stress-perfusion assessment [dual-sequence T1-weighted saturation-recovery gradient echo sequence] following intravenous adenosine (3–4 minutes, 140–210 mcg/kg/min) and 0.075 mmol/kg gadolinium bolus injection); (2) volumetric assessment [non-breath-hold, steady-state free precession (SSFP) multi-slice real-time cine sequence]; and (3) late gadolinium enhancement (LGE) [non-breath-hold, single-shot segmented inversion-recovery gradient echo sequence] following 0.025 mmol/kg gadolinium top up. The standard scan comprised standard SSFP cine, stress/rest perfusion (0.075 mmol/kg each acquisition) and LGE sequences. CMR images were analysed by two experienced observers acting in consensus (following two independent reads), blinded to clinical/angiographic data, and results from the other CMR protocol. Significant CAD was defined invasively by FFR_inv ≤0.80 in any vessel ≥2 mm in diameter. <h3>Results</h3> A total of 149 patients with paired scans were studied (mean age 65±9 years, 73% male, CAD prevalence 51%, ejection fraction 60±10%). The median interval between the two scans was 2 days. The mean scan duration of the accelerated protocol was 19±5 minutes. On a per-patient basis, using FFR_inv as the reference standard, the accelerated protocol achieved diagnostic accuracy 87%, sensitivity 78% and specificity 96%. With standard CMR as the reference standard, accelerated CMR achieved diagnostic accuracy 87%, sensitivity 84% and specificity 89%. Interobserver agreement for the accelerated protocol was excellent (Kappa 0.83). <h3>Conclusion</h3> A 20-minute accelerated CMR protocol achieves favourable diagnostic accuracy in identifying functionally significant CAD, as determined by both invasive and non-invasive reference standards. Accelerated CMR may prove effective in the clinical evaluation of patients with suspected CAD.