PET attenuation correction using mean attenuation coefficients: a simulation study

It is desirable to use mean population attenuation coefficients to reduce the statistical fluctuations in measured attenuation maps. In addition, the use of mean attenuation coefficients is also expected to facilitate algorithmic approaches to attenuation correction. Because of the large variation in lung attenuation coefficients both within and among individuals, there is concern about the errors using mean attenuation might create. To test the magnitude of this problem, myocardial metabolic studies were simulated. Attenuated projections were generated from 20 emission and transmission distributions spanning the heart volume. The projections were corrected with both the actual attenuation map and with a mean attenuation map. Quantitative comparisons of the reconstructed images demonstrate no significant differences in the myocardial distributions. However, errors in the lung field exceeded 300% in some regions.