ASSESSMENT OF LEFT-VENTRICULAR REGIONAL FUNCTION BY RADIONUCLIDE ANGIOGRAPHY - EFFECTS OF NUMBER OF SECTORS ON REPEATABILITY

Twenty patients were studied by equilibrium radionuclide angiography ( RNA) twice in the same day in order to assess the repeatability of qua ntitative measurements of left ventricular (LV) regional function by u sing a sector analysis method. RNA was performed in the best septal 45 degrees left anterior oblique projection, acquiring 150,000 counts/fr ame, at 20 msec/frame with 5% gate tolerance. LV regional analysis was performed using a computer algorithm written by the authors running o n Digital PDP 11/34 machine. The algorithm after having identified the center of gravity of the LV, divided it into 4, 5 and 6 equiangular s ectors. In the 5, and 6 sector analysis, the region including the mitr al and aortic valves was excluded from subsequent analysis. In each se ctor Ejection Fraction (EF) and Peak Filling Rate (PFR) were computed. In addition, the Time to End Systole (TES) and Time to Peak Filling R ate were also assessed for each region. The coefficient of variation o f the regional values of TES (CV-TES) and regional TPFR (CV-TPFR) were then computed and considered as indices of LV systolic (CV-TES) and d iastolic (CV-TPFR) asynchrony. Repeatability was firstly assessed by l inear regression analysis between the 2 RNA studies. Our data show a h igh correlation coefficient on regional values of EF and PFR (R: > 0.9 2). Moreover, the differences in a given parameter between the 2 studi es were plotted against their mean value, and the coefficient of repea tability (CR) was calculated as twice the standard deviation of the di fferences. No significant differences were found between EF and PFR re gional Values in the 2 RNA studies (EF coefficient of repeatability: < 0.18; PFR coefficient of repeatability: < 0.8). A low value of coeffic ient of repeatability was found also for CV-TES (<17) and for CV-TPFR (<18). In conclusion LV regional analysis is a repeatable method of an alysis, and the number of regions does not affect the repeatability.