Detection of coronary arterial microvascular disorders using (99m)Tc-tetrofosmin uptake increase during exercise and coronary blood flow velocity patterns obtained by magnetic resonance imaging.

Abstract

This study reports an evaluation of coronary arterial blood flow patterns in patients with diabetes mellitus and healthy subjects using magnetic resonance coronary angiography (MRCA). Twenty patients with diabetes mellitus (DM group) and 20 healthy subjects (N group) were studied using MRCA and myocardial SPECT images using (99m)Tc-tetrofosmin (TF). The rate of change in myocardial TF uptake was measured during a 1-day protocol of exercise and rest. Initial and delayed exercise single photon emission computed tomography (SPECT) images were acquired 30 min and 3 h after injection (370 MBq of TF) (TF1 and TF2, respectively). Thereafter, 740 MBq of TF was administered intravenously, again, and resting SPECT images (TF3) were acquired 30 min later. The myocardial counts of these three points of acquisition were defined, and the rate of change of myocardial TF uptake between exercise and rest was determined. The % increase in uptake was significantly lower in the DM group than in the N group in all myocardial segments. The average coronary arterial diastolic velocity determined using MRCA was slightly lower in the DM group than in the N group, and the average systolic peak velocity (ASPV) was slightly greater in the DM group than in the N group, although these values were not statistically significant. The diastolic/systolic velocity ratio (DSVR) in the DM group was significantly lower than that in the N group ( P < 0.05). There was a significant correlation between DSVR and % uptake increase ( r = 0.605, P < 0.05). These results indicate that the measurements made using MRCA and the % uptake increase measured using TF myocardial scintigraphy represent a potentially useful noninvasive method for diagnosing microvascular dysfunction in diabetic patients.