Optimization and evaluation of reconstruction-based compensation methods in myocardial perfusion SPECT using the channelized hotelling observer

In this study we have applied the channelized Hotelling observer (CHO) using a defect detection task to the optimization and evaluation of iterative reconstruction compensation for myocardial perfusion SPECT. We used a population of 24 mathematical cardiac-torso (MCAT) phantoms that realistically model the activity and attenuation distribution in three classes of patients: females and males with flat and raised diaphragms. Defects were placed at 6 positions along myocardium. Projection data were generated and subsequently reconstructed using methods based on the ordered-subsets expectation-maximization (OSEM) algorithm. The methods evaluated included iterative reconstruction compensation for attenuation, detector response blurring and scatter in various combinations. We applied the CHO to find the optimal number of iterations and cutoff frequency of a post-reconstruction filter that gave the highest value of the area under the receiver operating characteristics (ROC) curve (AUC). We investigated from 1 to 12 iterations with 16 subsets per iteration and an order 8 Butterworth post-reconstruction filter with cutoff frequencies of 0.04 to 0.34 pixel 1. For the optimal reconstruction parameters, attenuation with either detector response or scatter compensation gave statistically significant increases in the AUC compared to attenuation compensation alone. The greatest increase in the AUC occurred when all three compensations were applied.