Abstract 618: Measurement of Absolute Myocardial Perfusion in Healthy Volunteers Using 3 Tesla Cardiac Magnetic Resonance: Validation Against Positron Emission Tomography
Objective: To assess the feasibility of measuring myocardial blood flow (MBF) with 3T CMR at rest and during hyperemia in healthy volunteers, and validate these measurements against PET as the gold standard.
Methods: Ten healthy subjects underwent PET scanning using oxygen 15-labeled water (H2150) and CMR scanning at 3T. MBF was assessed at rest and during adenosine stress. Three short-axis images were acquired at every heartbeat using a saturation recovery fast-gradient echo sequence and 0.04 mmol/kg Gd-DTPA bolus. CMR images were co-registered with PET images using anatomical land marks in a 16 segment model. CMR MBF was determined by model independent deconvolution. Blood pool signal was corrected for saturation using calibration curves.
Results: Mean (±SD) resting MBF was 1.0 ±0.3 ml/min/g by PET and 0.8 ±0.2 ml/min/g by CMR. Hyperemic MBF was 3.6 ±1.0 ml/min/g by PET and 2.5 ±0.9 ml/min/g by CMR. There was no significant difference in rest and stress rate pressure product during PET and CMR scanning. Agreement between the two methods was tested by Bland Altman plots. Resting mean difference was 0.2 ml/min/g (limits of agreement −0.3 to 0.8). Hyperemic mean difference was 1.1 ml/min/g (limits of agreement of −1.6 to 3.8).
Conclusion: MBF quantification at 3T is feasible. Myocardial contrast enhancement (CE) saturation at 3T with a 0.04 mmol/kg dosage may result in an underestimate of blood flow, which is more noticeable during stress with higher myocardial peak CE than at rest. Any CE saturation is most likely during the early vascular phase of myocardial CE and correcting for this suggests the need for compartmental modeling.