Interventricular Asynchrony Determination by Equilibrium RadioIsotope Ventriculography Image analisis

Interventricular cardiac asynchrony determination and assessment is very important in the evaluation of patients as candidates for Cardiac Resynchronization Therapy (CRT). In the present work, image and Fourier analysis of images obtained by Equilibrium Radioisotope Ventriculography Imaging (ERVI) allows for the evaluation of ventricular asynchrony including temporal parameters that describe the ventricular function, for the systolic and diastolic phases. Up to 16 ERV images including the complete cardiac cycle were acquired for 17 female patients with an average age >50 years. At the filtered ERV image for the systolic phase a ROI is selected manually within the ventricle region and other near its apex, to correct for background activity. Image segmentation proceeds by histogram thresholding with Opsu’s method throughout the whole set of frames, and Time-Activity Curves (TAC) were obtained. Fourier analysis is performed upon by fitting a Fourier series up to the fourth harmonic to measured TACs, obtaining the Ventricular Ejection Fraction (VEF) and ventricular volume parameters. Results indicate an average ventricular contraction time of 371 ± 41 ms for the left ventricle and 355 ± 45 ms for the right ventricle, 70.6 % of the total population exhibit a VEF for the left ventricle superior to 50 % and the average initial contraction time for the left ventricle was 39.9 ± 36 ms compared to the time for the right ventricle of 49.18 ± 40 ms, which indicates a ventricular asynchrony of 9.7 ± 16 ms. Also the method analyzes the whole image set allowing for a more precise determination of ventricular parameters than conventional methods. Further research work is under development to extend the use of the proposed method as a general practice of equilibrium radioisotope ventriculography.