Abstract 4176: Quantification of Myocardial Blood Flow Reserve by 1st-Pass CT Imaging
The accurate assessment of myocardial blood flow (MBF) is a potential adjunct to the anatomy of CT coronary angiography. To compare quantitative parameters from 1st-pass CT (FP CT) imaging with absolute measures of MBF in an animal model of altered MBF. A pig model of intracoronary adenosine (n=9) was used during FP CT. This produces a zone with hyperemic MBF and a control zone within a slice. Fluorescent microspheres (Mcsp) were injected into the left atrium with to determine absolute MBF concurrent with CT imaging. Pigs were placed in a 64-slice (Philips) CT with acquisition performed during IC adenosine. A 40% dilution of Iopamidol 370 (1ml/Kg) was injected IV at 5ml/sec. CT acquisition was ECG gated over 40 cardiac phases with the following parameters: 180° axial mode (pitch=0), field of view=250mmsq, 512×512 matrix, slice thickness=2.5 mm × 10 slices, temporal resolution=210ms, 120KV, 495ma. Mcsp were injected immediately following CT imaging. The heart was sectioned into 2.5mm slices to match the CT images and segmented. Time intensity curves (TIC) were generated from CT in adenosine and control zones based on Mcsp values. Mcsp coronary flow reserve (CFR) = hyperemic/control MBF, and CT CFR was derived from hyperemic/control area under curve from baseline corrected TIC (Klocke, Circ. 2001). MBF control=0.65±0.25, MBF adenosine=2.6±0.7 ml/min/g (p<0.0001). CFR=4.5±1.05, CT CFR=4.4±1.5 (p=NS). There was a significant (r=0.93, p<0.0001) correlation between CFR and CT CFR (figure⇓). FP CT myocardial perfusion imaging is feasible at clinically relevant radiation dosimetry and provides reasonable estimates of CFR during hyperemia.