Correcting for residual activity at PET scan reconstruction

摘要

A method of correcting for residual activity due to an earlier tracer from a later PET image at reconstruction, thereby generating a residual free image. The method comprises the steps of estimating the residual activity from first frame by detecting a time of injection from count-rate curve of listmode data, representing the residual activity in a sinogram and separating the residual activity from the true counts during iterative reconstruction of the scan image. The first frame of residual activity data may be aligned with a later image frame to compensate for patient motion. The time of injection may be detected by a derivative threshold method or by a phase method wherein the head curve is decomposed into structure and contrast information and the time of injection identified by identifying an up-step in the structure information. The sonogram representation of residual activity may be done by identifying listmode data acquired prior to the time of tracer injection and reconstructing that data into a residual activity only frame R(0) and generating a residual only sinogram R_S(0) from R(0) by forward projection.