Intra-patient reproducibility of myocardial SPECT imaging with 201Tl

Abstract

BackgroundTo define the physical and clinical reproducibility of 201Tl myocardial perfusion SPECT (MPS), this study assesses the variation between two repeated rest 201Tl MPS with repositioning only, with a two-hour time interval and with phantom measurements as a reference. MethodsThree anthropomorphic thorax phantoms were filled with 201Tl. For each phantom five repeated 201Tl MPS were obtained. In addition, in 20 patients repeated 201Tl rest-MPS and in 26 patients early and delayed 201Tl rest-MPS were performed. Quantitative analysis was done using MunichHeart. Statistical methods were used to calculate variability. Visual analysis was performed by 2 independent observers. ResultsThe average variation between repeated phantom MPS was 0.5% (95% confidence interval (CI): −0.4% to 1.4%). For patient scans this was −5.0% (95% CI: −2.5% to −7.5%) and between early and delayed 201Tl MPS −15.5% (95% CI: −11.7% to −19.3%). Visual assessment revealed no clinical significant differences between rest 201Tl and repeated or delayed 201Tl MPS. ConclusionsRepositioning in phantom 201Tl MPS does not cause significant variation. Repeated 201Tl MPS in patients shows 5.0% decrease of 201Tl in 30 minutes, which increases to 15% during a two-hour time interval without quantitative or visual regional differences. This decrease indicates a time-related washout of 201Tl, but does not change clinical diagnosis.