Novel analysis for endocardial wall strain with N-13 ammonia PET feature tracking -Comparison with CMR-feature tracking using integrated PETMR system-

Introduction: This study was aimed to clarify the clinical feasibility of novel endocardial strain analysis with PET feature tracking (PETFT). We compared PETFT to cardiac magnetic resonance derived FT (CMRFT) which has been established as a robust technique for myocardial strain analysis.

Methods: Consecutive 30 patients who underwent rest ¹³N ammonia PETMR were enrolled (mean 66ys, male 24). Perfusion defect was assessed as summed defect score by visual grading. ECG gated PET cine images were obtained from list-mode acquisition with free-breathing, followed by breath-hold cine CMR. PETFT derived global longitudinal, and short-axis circumferential strain (LS and CS) were calculated using semi-automatic endocardium contour tracking. The strain values were compared to those of CMRFT.

Results: Twelve patients showed perfusion defects (summed rest score > 3). PETFT and CMRFT showed a significant correlation (r=0.8, 0.5, p<0.0001, and p=0.007 for CS and LS, respectively). Bland-Altman plot showed a good agreement, while a systematic error was observed (Limit of agreement was -4.0 to 18.1, -7.7 to 13.8; bias 7.1, 3.1 for CS and LS, respectively). In comparison for patients with perfusion defects, CS showed a significant correlation, while LS did not (r=0.6, 0.5, p=0.03, and 0.06 for CS and LS, respectively).

Conclusions: In comparison with CMR, endocardial strain analysis by PETFT was feasible technique, while appeared to be less accurate in patients with perfusion defect.

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