MEASUREMENT OF CORONARY BLOOD-FLOW AND FLOW RESERVE USING MAGNETIC-RESONANCE-IMAGING

Purpose: It was the purpose of this study to demonstrate the feasibili ty of performing coronary artery flow and coronary flow reserve (CFR) measurements in normal human volunteers using a magnetic resonance (MR ) phase contrast technique. Materials and Methods: Coronary flow rate, flow velocity, peak flow and CFR were determined at rest and during p harmacologically induced hyperemia in 10 healthy volunteers, The flow measurements were obtained during a single breath-hold by using a fast , prospectively gated, segmented k-space gradient-echo phase contrast acquisition with view sharing (FASTCARD PC) that was modified to impro ve sampling of the diastolic flow. Data were processed using the stand ard phase difference (PD) processing techniques as well as a new compl ex difference (CD) flow measurement method intended to improve the acc uracy of flow measurements in small vessels. Results: Mean hyperemic f low velocity (40 +/- 16 cm/s) and blood flow (3.9 +/- 1.5 ml/s) rates differed significantly from resting velocity (13 +/- 6.6 cm/s) and flo w (1.1 +/- 0.4 ml/s) measurements (p < 0.0001), PD methods consistentl y measured larger flow rates at rest (24% larger, p < 0.0005) and stre ss (29% larger, p < 0.0001), CFR, calculated as the ratio of the mean PD flows (4.7 +/- 2.8), was higher than CFR calculated as the ratio of mean CD flows (4.2 +/- 1.8); however, the differences did not reach s tatistical significance (p = 0.07). Flow measurements performed in adj acent slices of the same vessel correlated well (r = 0.88). Conclusion s: Coronary flow and CFR measurements using the MR techniques are feas ible and are similar to those reported in the literature for healthy v olunteers.