Anesthetized dogs were scanned in the dynamic spatial re-constructor, a fast multislice computed tomographic scanner. In one group of eight dogs, four differently radiolabeled microspheres (15 μm diameter) were injected into the left atrium, with each label corresponding to a different hemodynamic condition. The image data collected from this group of dogs were used to develop the algorithm for estimating regional myocardial perfusion from the CT image data. In an additional 11 dogs three differently radiolabeled microspheres were also injected during different hemodynamic conditions. The image data collected from this second group of dogs were used to prospectively evaluate the accuracy of the algorithm developed from data in the first group of dogs. In all dogs scans of 0.127 second duration were recorded for each cardiac cycle before, during, and after a bolus injection of 32 ml Iohexol into the aortic root. Dye dilution curves were generated from brightness values measured from images of 2 mm thick transaxial slices. In all dogs images were reconstructed at the same phase of each cardiac cycle and were analyzed to obtain estimates of myocardial perfusion FDSR. After the scans were completed, the hearts were sectioned and microsphere-based estimates of myocardial perfusion (FMS) were obtained. In the group of eight dogs the resulting value was expressed in flow per gram of muscle within the sampled volume of myocardium so that FDSR = 0.996 FMS + 0.49, r = 0.972. A similar linear relationship was also demonstrated in four quadrants and three transmural layers. In the group of 11 dogs FDSR = 0.98 FMS + 0.16, r = 0.95. The contrast clearance data were also used to deduce the ratio of intramyocardial blood volume to total myocardial volume. At flows greater than 7 ml/g/min, this ratio exceeded 20 percent, and at 1 ml/g/min was approximately 7 percent.
ASJC Scopus subject areas
- Radiological and Ultrasound Technology
- Computer Science Applications
- Electrical and Electronic Engineering