Quantitative stress perfusion cardiovascular magnetic resonance: clinical implications for patients with suspected myocardial ischemia.

Introduction: Recent technical advances in stress perfusion cardiovascular magnetic resonance (CMR) imaging allow for myocardial blood flow (MBF) quantification (quantitative perfusion CMR [QP CMR]). However, clinical utility of QP CMR, as compared with conventional grayscale qualitative assessment (QA), is unknown.

Objectives: The study aimed to compare the clinical conclusions on ischemia detection derived from QA of conventional grayscale stress perfusion CMR images and QP CMR in a real‑world population of patients with suspected myocardial ischemia.

Patients and methods: This study retrospectively analyzed 101 patients with suspected myocardial ischemia referred for adenosine stress perfusion CMR imaging. QA of grayscale first‑pass perfusion CMR was performed by level 3 CMR experts. In QP assessment, stress and rest MBF (ml/g/min) were calculated for automatically determined myocardial segments. Each patient and coronary territory were classified by both QA and QP mapping, in a blind manner, as either ischemic or nonischemic.

Results: QP assessment classified more coronary territories as ischemic than QA (46% vs 17%; P <0.001). In the per‑patient analysis, QP analysis identified myocardial ischemia in 64 patients (63%), and QA in 40 (40%; P <0.001). Ischemia was diagnosed by QA but not by QP analysis in 7% of the patients (QA+/QP-). In 31% of the patients, QP assessment established a new diagnosis of myocardial ischemia (QA-/QP+).

Conclusion: QP CMR detects more ischemic coronary territories than QA and holds promise for identifying cases of myocardial ischemia that may be overlooked by QA alone in a real‑world patient population.