Repeatability and Reproducibility of Thallium-201 Gated SPECT for the Measurement of Left Ventricular Function

Received 10/11/2004; revised 11/8/2004; accepted 11/12/2004. For correspondence or reprints contact: Guang-Uei Hung, M.D., Department of Nuclear Medicine, Changhua Christian Hospital, 135 Nan-Shiao Street, Changhua 500, Taiwan. Tel: (886)4-7238595 ext. 3091, Fax: (886)4-7232942, E-mail: [email protected] Background: Gated myocardial perfusion single photon emission computed tomography (SPECT) has also been suggested applicable by using thallium-201(Tl) as the tracer in the evaluation of left ventricular function. However, some investigators found that the repeatability of Tl gated SPECT was suboptimal. In this study, the imaging protocol of Tl gated SPECT was modified from those of previous studies and we reevaluated the repeatability and reproducibility of Tl gated SPECT for the measurements of left ventricular ejection fracture (LVEF), end-diastolic volume (EDV) and end-systolic volume (ESV). Methods: Seventeen patients referred for routine dipyridamole-stress/redistribution Tl myocardial perfusion imaging were included. Gated SPECT was applied for every patient and automated quantitative gated SPECT (QGS) software was used for measurement of LVEF, EDV and ESV. Delayed 4-h redistribution imaging was sequentially repeated within 30 min for assessment of repeatability. The same raw data were processed by two different operators and were processed twice by an operator for assessment of interobserver and intraobserver reproducibility. Results: The repeatability study showed that the 2 standard deviations of the absolute difference between two sequential measurements for LVEF, EDV and ESV were 6.4%, 16.8 ml and 8.6 ml, respectively. The results were better than previous studies. The interobserver and intraobserver reproducibility were both excellent as previous studies (all r = 0.96 ~ 0.99, and all P < 0.0001). Conclusion: Our study suggests that the Tl gated SPECT processed with QGS software has good repeatability and excellent reproducibility in the measurement of left ventricular function with our imaging protocol. The results may imply that the evaluation of functional changes between post-stress and rest imaging in a patient by Tl gated SPECT is feasible.