Left Ventricular Strain from Myocardial Perfusion PET Imaging: Method Development and Comparison to 2-Dimensional Echocardiography

Abstract

This study aimed to develop a measure of longitudinal, radial, and circumferential myocardial strain at rest and regadenoson during pharmacologic stress using 82 Rb PET electrocardiography-gated myocardial perfusion imaging (MPI). Methods: We retrospectively identified 80 patients who underwent rest and regadenoson-stress CT attenuationcorrected 82 Rb PET and had a standard resting transthoracic echocardiogram (TTE) with global longitudinal strain (GLS) analysis within 3 mo. A method was developed to compute longitudinal, radial, and circumferential strain from PET MPI at stress and rest. PET MPI-derived strain and left ventricular function were compared with resting TTE measures as the clinical reference standard. Interobserver agreement of PET MPI strain and left ventricular ejection fraction processing was reported. Results: Longitudinal strain assessed with resting TTE GLS showed good correlation with PET MPI at stress (r 5 0.68, P , 0.001) and rest (r 5 0.58, P , 0.001). Resting TTE GLS also correlated with PET MPI radial strain at stress (r 5 20.70, P , 0.001) and rest (r 5 20.59, P , 0.001) and circumferential strain at stress (r 5 0.67, P , 0.001) and rest (r 5 0.69, P , 0.001). The left ventricular ejection fraction showed good correlation between resting TTE and PET MPI at stress (r 5 0.83, P , 0.001) and rest (r 5 0.80, P , 0.001). Bland-Altman analysis indicated positive bias of TTE GLS compared with PET MPI longitudinal strain at stress (mean difference 5 5.1%, 95% CI 5 [22.5, 12.7]) and rest (mean difference 5 4.2%, 95% CI 5 [24.3, 12.8]). Reproducibility of PET MPI longitudinal strain showed good agreement at stress (concordance correlation coefficient 5 0.73, P , 0.001) and rest (concordance correlation coefficient 5 0.74, P , 0.001), with Bland-Altman analysis showing a small bias in the longitudinal direction at stress (mean difference 5 20.2%) and rest (mean difference 5 21.0%). Conclusion:Strain measured with PET MPI using an automated technique correlated well with resting GLS strain obtained by TTE, and the measure is reproducible. Strain from PET MPI should be investigated further to establish reference ranges and assess its value in routine clinical practice.

Myocardial perfusion imaging-derived left ventricular strain: Regional abnormalities associated with transthyretin cardiac amyloidosis

“…Aside from cardiac MRI, there is limited data to assess myocardial strain derived from other non-invasive cardiac imaging modalities. Our group recently developed a method to measure left ventricular strain from gated myocardial perfusion images and showed that it correlates well with TTE-derived strain [ 5 ]. Apical strain index (ASI), apex-to-base ratio (ABR), and ejection fraction to global strain are three parameters that have been used to distinguish cardiac amyloidosis from other causes of left ventricular hypertrophy (LVH) [ [6] , [7] , [8] ].…”