Elastic motion correction for continuous bed motion whole-body PET/CT

The Continuous Bed Motion (CBM) acquisition mode in PET imaging, recently introduced commercially by Siemens and marketed as FlowMotion, has the potential advantages compared to the conventional step and shoot (S&S) mode. With CBM, the image quality at different axial regions of interest can be adjusted based on clinical need by using variable bed speed acquisitions. This flexibility cannot be accommodated by S&S mode since discrete bed positions are acquired. The respiratory motion in wholebody PET studies degrades image quality, introduces bias and partial volume artifacts, which are critical considerations for obtaining quantitative imaging with high resolution scanners. Elastic motion correction is needed to correct for respiratory motion artifacts. Elastic Motion DeBlurring (EMDB) was previously introduced by the authors. It was shown that it does not depend on the number of gates. Instead, a Mass Preservation Optical Flow (MPOF) algorithm was used to calculate a blurring kernel between the reference gate and the static (motion blurred) image. This approach reduces the processing time and hardware requirements for an iterative EMC reconstruction. In this work, EMDB is applied to CBM PET studies acquired with variable bed speed.