748-2 Tomographic Myocardial Perfusion Studies in the Intensive Care Unit Using a Mobile Gamma Camera System

A tomographic technique called Ectomography has been developed to enable bedside evaluation of myocardial perfusion during the acute phase of a myocardial infarction or immediately following coronary by-pass surgery (CABG). Ectomography can be implemented on a mobile gamma camera system using a rotating slant hole collimator, which allows three-dimensional periusion studies within the intensive care unit. A prototype mobile system has been designed and built in our departments. This system is currently undergoing clinical evaluation at the Karolinska hospital. During the first eight months of operation, more than 150 periusion studies have been performed. Currently, a second generation prototype, comparable in size to a modern mobile x-ray cart, is being developed and built. Results from the following three studies will be presented: 1) In an initial comparative study using Tc-99m Cardiolite® and a two day protocol, 19 patients with suspected coronary artery disease were imaged under the same conditions with SPECT and Ectomography. In a blind evaluation of short axis view sections and polar tomograms, the diagnosis were in agreement in 90% of the patients. 2) In an animal study using Tc-99m Myoview ® , 10 pigs were imaged before, during and after occlusion of the left anterior descending artery (LAD); staining and autoradiography were also periormed. Regions of reduced perfusion in Ectomographic section images corresponded well to areas of ischemia and infarction as shown by staining and autoradiogram. 3) The dynamics of reversible myocardial perfusion defects after CABG were studied in 12 patients using Tc-99m Cardiolite ® and adenosine provocation the day before, immediately after and one week after CABG. CABG surgery eliminated coronary steal revealed preoperatively with Ectomography and restored flow reserve in all patients immediately postoperatively, but reversible uptake defects remained after one week in half of the patients. In conclusion, results from studies performed show that a mobile gamma camera system based on Ectomography is an important research instrument and potential clinical tool for the objective evaluation of the effects of intervention on myocardial perfusion.