Correction for partial volume effect in myocardial PET: A model fitting method

    MA Xingª²Rong, Hinako Toyama, ZHANG Hong

    1Department of Nuclear Medicine, Xijing Hospital, Xi¬ðan 710033, 2National Institute of Radiological Sciences, Chiba, Japan, 3Electric Engineering and Electronics Teachingª²experiment Center, Xi¬ðan Jiaotong University, Xi¬ðan 710049, China

    ¡¾Abstract¡¿ AIM: To correct partial volume effect (PVE) by using a model fitting method, in which the best model parameters were calculated in the sense of least square. METHODS: Two types of myocardial models were developed: two oneª²dimensional (1D) models and one twoª²dimensional (2D) model. Four parameters (counts, background, wall position and wall thickness) were used and optimized for both 1D model and 2D model. The spatial resolution of the detector system was used in one 1D model as the fifth parameter. 1D models were calculated by two rectangular pulses convoluted with a Gaussian function and the 2D model was calculated by pulses convoluted with a twoª²dimensional Gaussian function, for the effect of areas in perpendicular direction was included. This method needed nonª²linear fitting, which could only be solved by iterative process. Computer simulated myocardial images, PET images of two phantoms and some patient¬ðs myocardial PET images were used to evaluate the method. RESULTS: For the simulated images, the corrected recovery coefficient (RC) was between 0.97 and 1.10 for the 2D model even when the thickness of myocardium was as small as 0.25 times of the system spatial resolution. For the 1D models, the RC was about 0.9 only when the thickness was 1.5 times more than the system¬ðs spatial resolution. When the 2D model was applied to PET phantom images, the RC was 1.0 for different thickness of the myocardium. The 2D model could also correct the thinner area of the patients¬ð PET images. The iterating process converged for a relatively wide range of myocardium thickness and different noise levels. CONCLUSION: The 2D model corrects partial volume effect in myocardial PET, even for very thin wall thickness. ......