Kinetics of rubidium-82 after coronary occlusion and reperfusion. Assessment of patency and viability in open-chested dogs.
- R A Goldstein
- The Journal of clinical investigation
At the end of 1988, Karla Harby asked in the SNM Newsline in Journal of Nuclear Medicine if it was "time to take the plunge?" into clinical PET (Harby 1988). In that paper several people involved in obtaining PET in their hospitals commented on the status of clinical PET. It was concluded that it will take some time, but clinical PET will soon be used. Now, more than a year later, we would like briefly to review the status of PET in clinical cardiology. In this editorial we will not discuss the cardiac research performed in large, fully equipped PET research centres, but will concentrate on the application of 82Rb for clinical myocardial perfusion studies. The potassium analogue, rubidium 82 (SZRb) is a positron-emitting isotope with a very short half-life of only 78 s. The parent isotope of 8aRb is strontium 82 (82SR), with a physical half-life of 25 days. The generator can be used for 4-6 weeks, Due to the short half-life of BaRb, it can be applied in repetitive studies of the myocardial blood flow of patients within 8-10 min, e.g. before and after an intervention. Absorbed radiation doses for the whole body, heart and kidneys in a 4.4 GBq patient study (e. g. 2 x 2.2 GBq, during exercise and rest) are comparable with or somewhat smaller than those in a 75 MBq a°lT1 study (Williams 1989a). Partially extracted radiotracers like S2Rb can be applied for in vivo measurements of the regional blood flow (Klocke 1976). However, flow and extraction fraction (ExF) are inversely and nonlinearly related. Accurate measurement of the regional ExF of a diffusible radiopharmaceutical is essential for quantifying the regional blood flow. Measurements of ExF of 82Rb from the coronary blood in animal studies sampled from the myocardial wall have been shown to be independent of regional blood flow at rates up to five times the resting blood-flow rate. Moreover, blood flow can be accurately determined in this range and was found to show a linear