Motion modulated sensitivity gating (MMSG) using internal signal for quantitative PET

Nuclear imaging modalities such as PET and SPECT are used as quantification tools for tumor staging, planning, and response evaluation. The imaging findings of these modalities are largely affected by respiratory motion [1]. Common approach to motion management is to acquire and reconstruct the data in relation to externally recorded signal by motion detection systems. Currently available respiratory motion detection systems typically account for the surrogate structures. However, the surrogate structures can be an inaccurate representation of internal motion [2]. Therefore, a respiratory motion management technique that entirely relies on external breathing motion detection system could lead to potentially significant errors in quantification. We hypothesize that for a given PET bed position, the temporal pattern of cumulative counts within a predefined time bin can provide a direct measurement of internal organ motion and thus lead to more accurate quantification of images being acquired. Therefore, instead of using approximately one third of total counts for image reconstruction of all bed position in a whole body scan, different percentage of total counts depending on the magnitude of motion occurred within the FOV of each bed acquisition can be used for image reconstruction.