title: Nuclear ejection fraction measurements with a small crystal detector: methodological investigations.
abstract: A series of studies were performed with a single crystal detector system, nuclear stethoscope (N.S.) (Bios) used for measuring left ventricular function (ejection fraction [EF]). Counting capacity, validity, reproducibility, effect of repositioning of the instrument and of different operators were investigated. Counting capacity was found to be approximately linear up to a count rate of 40.000 cps. Validity was studied by comparing measurements in the same subject using the N.S. with those obtained by a gamma-camera computer system with software using a background subtraction similar to that in the N.S. The mean difference in EF (0.01) was not significant. Maximum emptying and filling velocity measurements with the two instruments were also compared r = 0.86 and r = 0.89, respectively, and a coefficient of variation of 18.1% and 17.9%. Reproducibility was determined from duplicate determinations under identical conditions. The standard error of a single determination was 5%. Repositioning by the same operator increased the variation to 9.1% without any systematic difference. Comparison between two operators did not increase the coefficient of variation (8.8%). There was a systematic difference between measurements using the two acquisition modes, ventricular function mode and position monitor mode. Beat-to-beat variation of EF values during 12 s in 25 patients with coronary heart disease studied under standardized resting conditions was 11.9%.
mesh_terms: D000328:Adult; D000368:Aged; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011875:Radionuclide Angiography / Q000295:instrumentation* / Q000379:methods; D013318:Stroke Volume