An image reconstruction that preserves the regional physiological variation of radioactivity concentration

Regularization of PET reconstruction is needed to suppress noise in images, but the level of smoothness is difficult to choose. The proper amount of image variation should be close to the one that arises from physiology, for example local differences in glucose uptake. However, this small natural variation is mixed with the large noise component. We present a method which estimates and cancels the amount of statistical reconstruction noise and reveals the true regional variation of PET image pixels. This information can then be used as a simple stopping rule for Maximum Likelihood reconstruction, resulting in image whose pixel values contain the true, natural amount of variation. The performance of the method was tested for phantoms with different ROI sizes and sinogram count levels. We demonstrated the working limits where the error is significant before the correction, and where the method is sufficiently robust.