Prospective validation of an automatic alignment tool to improve repeatability of left ventricular dyssynchrony measurement in serial gated myocardial perfusion SPECT studies

Objectives An automatic alignment tool has been developed to reduce variability of left ventricular (LV) dyssynchrony measurement in serial gated SPECT myocardial perfusion imaging (MPI) studies due to inconsistent oblique reorientation and basal slice selection. The purpose of this study is to prospectively validate this tool.

Methods Twenty-eight patients, who had serial gated SPECT MPI, were prospectively enrolled. For each patient, the two datasets were first processed blinded from each other by the same technologist in different weeks. These processed data were then re-aligned by the automatic tool, and manual side-by-side processing. All processing methods used standard iterative reconstruction and Butterworth filtering. The Emory Cardiac Toolbox was used to measure the LV dyssynchrony parameters - phase standard deviation (PSD) and phase histogram bandwidth (PHB).

Results The automatic tool failed in one patient, who had a large, severe scar at the apex. In the remaining 27 patients, the mean difference and standard deviation of difference in the LV dyssynchrony parameters between the serial studies were calculated and are listed in the following table. The repeatability of these parameters after automatic alignment was significantly improved from blinded processing (p<0.01 by f test) and comparable to manual re-alignment (p=NS by f test).

Conclusions The automatic alignment tool can be an alternative method to manual re-alignment to improve repeatability of LV dyssynchrony parameters in serial gated SPECT MPI.

Research Support This study was supported in part by an NIH grant (1R01HL094438, PI: Ji Chen, PhD)

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