Abstract 12183: Multi-Center Evaluation of Inter-Site Variability in SPECT Myocardial Blood Flow Measurement

Abstract

Introduction: Myocardial blood flow (MBF) imaging with SPECT is possible using cardiac-specific cameras. Single-center studies have shown that SPECT MBF is accurate compared with PET MBF and angiography. Clinical implementation requires consistency of SPECT MBF measurements across multiple sites. This study is the first multi-center evaluation of the inter-site processing variability of SPECT MBF. Objective: To compare SPECT MBF obtained locally to MBF calculated at the core lab in Ottawa, Canada. Methods: Six sites (2 in Canada and one each from Japan, Singapore, Italy, and Germany) each acquired 25 rest/stress MBF studies using Tc99m-tetrofosmin (377 MBq at rest; 1060 MBq at stress) on a pinhole-collimated cadmium-zinc-telluride(CZT)-based cardiac SPECT camera. Patients had intermediate to high pre-test probability of coronary artery disease. MBF was analyzed locally and at a core lab using commercially available software. The time that a room was occupied for a MBF study was compared to that for a standard rest/stress myocardial perfusion study. Results: Preliminary results from 4 sites showed a correlation in MBF between the core lab and the local site of an average of 0.96 (range 0.95 to 0.97) at rest and 0.89 (range 0.77 to 0.96) at stress. From Bland-Altman analysis, the mean bias from zero in global MBF between local and core-lab analysis was 3.3% +/- 13.4% at rest and 3.0 % +/- 18.6% at stress. Between the 4 sites, the bias ranged from -4.1% to 9.9% at rest and from -6.3% to 12.8% at stress; the standard deviation (SD) ranged from 10.5% to 14.0% at rest and from 12.0% to 24.5% at stress. There was no significant difference between sites in the SD. The SD of the local-to-core-lab MBF differences is less than the SD of the test-retest difference of 30%, measured in a previous single-center study. The average additional time to perform a MBF study acquisition varied between sites from 45 to 76 min. This additional time includes the time needed to pharmacologically stress the patient which is normally done outside the camera room. Conclusions: This multi-center evaluation supports the feasibility of consistently measuring MBF using CZT-based cardiac SPECT cameras, as has been suggested from previous single-center studies.