Abstract 4207: Comparison of 1st-Pass Myocardial Perfusion Imaging by 64-slice CT and by MRI
The purpose of this study was to compare the signal intensity (SI) and image characteristics of 1st-pass (FP) CT imaging vs. MR FP in an animal model of resting myocardial blood flow (MBF). Pigs (n=5) were scanned at rest using FP MRI perfusion imaging. Gd-DTPA was injected IV at 5cc/sec at 0.04mmol/kg. FP MR was acquired at 3T with 3 axial slices 3mm thick per R-R interval during bolus injection using a saturation recovery gradient echo sequence. ECG gated FP CT was performed immediately thereafter on a 64-slice scanner in axial mode with 10 2.5mm thick slices during bolus injection (5cc/sec) of 40% dilution of iopamidol 370. MBF was measured at rest using fluorescent microspheres between studies. SI was measured for baseline and peak myocardial enhancement phases. Contrast enhancement (CE)= (peak-baseline) SI/baseline SI X 100. Rest MBF was 0.60±0.15 ml/min/g. Temporal resolution was similar by technique but more slices were imaged by CT per R-R interval (10 vs 3) and spatial resolution was superior for FP CT. Image characteristics are shown in the table⇓. Baseline (top) and peak enhancement (bottom) images for FP CT and MRI are shown in the figure⇓. Results were similar when undiluted contrast was used for each modality. Despite similar absolute change in SI, CE during FP CT is markedly reduced compared to FP MR due to a more than 20-fold higher baseline SI of the myocardium.