Comparison of extent and severity of quantitative perfusion defects on rest Tl-201 and rest Tc-99m sestamibi myocardial perfusion SPECT

Abstract

Background: Rest Tl-201 (Tl) myocardial perfusion SPECT (MPS) has been widely used alone or in dual isotope MPS, but the direct comparison of quantitative perfusion defect (PD) on rest Tl and rest sestamibi (MIBI) MPS has not been evaluated in depth. Methods: 162 pts in a randomized clinical trial with known or suspected CAD ( ≥4/20 segments with reversible defects, age 40–76, 34 F) underwent same day rest Tl followed immediately by rest MIBI injection and MPS 1 hr later. The same protocol was repeated in 56 pts of the placebo group (with no clinical changes or coronary interventions) at day 60. Reconstruction using Butterworth filtered backprojection, cutoff /order 0.55 / 5.00 for MIBI and 0.50 / 10.00 for Tl, sex and isotope specific normal limits were used. PD extent (% of pixels abnormal) and severity (mean number of standard deviations by which counts of abnormal pixels fell below normal profile) were determined by QPS. Correlation and regression analysis were performed. Results: The linear correlation between rest Tl and rest MIBI showed high agreement as follows: N = 162 R 2 Rt MSE Regression Extent MIBI-TI 0.93;*> 2.91 MIBI ext = 1.03 TI ext + 1.32 Severity MIBI-TI 0.90;*> 0.20 MIBI sev = 1.04 TI sev + 0.06 Repeated scans at day 60 showed similar results for MIBI and Tl agreement, and good inter scan reproducibility (MIBI day 0 vs day 60). * N = 56 R 2 Rt MSE Interscan R 2-MIBI Rt MSE Extent MIBI-TI 0.96 * 2.42 Extent 0.94 * 2.69 Severity MIBI-TI 0.92 * 0.18 Severity 0.94 * 0.16 * (p < 0.0001) Conclusion: Quantitative analysis of perfusion defect extent and severity on same day rest Tl and rest MIBI MPS shows excellent correlation which is as high as the reproducibility of day 0 vs day 60 MIBI. These findings indicate that a rest Tl / rest MIBI protocol may be useful in same day assessment of changes in myocardial perfusion with therapeutic interventions.