Estimates of myocardial perfusion with PET using kinetic models require faithful recording of radioactivity content in blood and myocardium. Typically the arterial time-activity curve is obtained by placing a region of interest (ROIs) within the left atrial or left ventricular cavity. However, curves generated from these regions appear earlier in time than tissue time-activity curves obtained from ROIs within the myocardial tissue, and such time discrepancies can lead to errors in flow estimates. Methods: The magnitude of these time discrepancies and their effect on estimates of regional myocardial perfusion using oxygen-15-water were measured in 30 normal subjects evaluated at rest and again after administration of dipyridamole. Results: Under baseline conditions, the left atrial curve appeared 0.97 ± 0.67 (s.d.) before the ascending aorta input curve (p < 0.05) and estimated perfusion decreased from 1.28 ± 0.28 ml/g/min using the left atrial curve uncorrected for time to 0.98 ± 0.27 ml/g/min after correction (p < 0.05). After dipyridamole, the left atrial curve appeared 0.68 ± 0.72 sec before the ascending aorta curve (p < 0.05) and estimated perfusion decreased from 3.60 ± 1.40 ml/g/min using the left atrial curve uncorrected for time to 3.24 ± 1.26 ml/g/min using the time-corrected curve (p < 0.05). Because the magnitude of time discrepancies between the left ventricular and ascending aortic curves was less (0.25 ± 0.34 and 0.19 ± 0.23 sec at rest and after dipyridamole, respectively), effects on flow estimates were more modest. Conclusions: The results of this study demonstrate that time discrepancies between input and tissue time-activity curves can affect estimates of myocardial flow. Correction for this potential source of error is proposed.
|Number of pages||9|
|Journal||Journal of Nuclear Medicine|
|State||Published - Jan 1 1994|
- myocardial perfusion imaging