Evaluation of Volumetric Reference Ranges for SPECT MPI Parameters and the Predictive Power of Dyssynchrony Parameters: A Cross-Sectional Study

Introduction: This study aims to evaluate reference ranges for SPECT Myocardial Perfusion Imaging (MPI) parameters using Myoview® (tetrofosmin) radiopharmaceutical and Myovation® processing software. This study also aims to provide a reference range for future MPI quantitative studies in patients with suspected heart disease and to identify significant variables associated with an abnormal left ventricular ejection fraction. Methods: Data were retrospectively collected from 1,100 MPI studies (2017-2024) with 932 participants included after excluding poor-quality images. Imaging was performed using a GE SPECT/CT Optima NM/CT640 camera, and images were reconstructed using the OSEM algorithm (Myovation®). Volumetric and quantitative parameters were extracted for analysis (e.g., Left Ventricular Ejection Fraction (LVEF), End-Systolic Volume (ESV), End-Diastolic Volume (EDV), Stroke Volume (SV), and dyssynchrony parameters). Reference ranges were derived using descriptive statistics, and comparative analyses examined how parameters varied by sex and age. Regression analysis and Receiver Operating Characteristic (ROC) curves were used to assess the relationship between abnormal LVEF and dyssynchrony indices. Results: The study analysed 932 participants under stress and 462 at rest, yielding adequate statistical power. Average LVEF was 68% in both conditions. At stress, mean EDV was 95.1 mL and mean ESV was 34.7 mL; corresponding values at rest were 104.8 mL and 40.1 mL. Diagnosis significantly influenced all volumetric and dyssynchrony parameters at rest and during stress (all p < 0.001), showing progressive ventricular dilation, reduced LVEF, and increased dyssynchrony from the normal to the ischemic and infarcted groups. Sex significantly affected LVEF and ventricular volumes, with females exhibiting higher LVEF and smaller volumes, while age had minimal effects. Resting dyssynchrony indices correlated strongly with stress LVEF, particularly in diseased groups. Logistic regression demonstrated good discrimination (AUC = 0.80) and calibration, identifying resting volumetric and clinical factors as independent predictors of abnormal stress LVEF. Discussion: This study defines sex- and age-specific reference ranges for gated SPECT MPI–derived ventricular function in a Kuwaiti population. Ventricular volumes, systolic function, and dyssynchrony varied significantly by sex and diagnosis, with progressive impairment across disease groups. Logistic regression analysis with multiple variables identified resting volumetric indices and demographic characteristics, rather than dyssynchrony measures, as the primary independent predictors of abnormal left ventricular function during stress. The model demonstrated good discriminatory ability and calibration. Conclusion: Sex- and age-specific reference ranges for gated SPECT MPI reveal clinically meaningful variation in ventricular function and dyssynchrony by diagnosis. Logistic regression findings indicate that conventional ventricular volumes and patient characteristics primarily drive stress systolic impairment, while dyssynchrony indices offer complementary but not independent prognostic value.