Dynamic PET image reconstruction integrating temporal regularization associated with respiratory motion correction for applications in oncology.

Dynamic PET image reconstruction integrating temporal regularization associated with respiratory motion correction for applications in oncology.

Phys Med Biol. 2018 Jan 17;:

Authors: Merlin T, Visvikis D, Fernandez P, Lamare F

Abstract
Respiratory motion reduces both the qualitative and quantitative accuracy of PET images in oncology. This impact is more significant for quantitative applications based on kinetic modeling, where dynamic acquisitions are associated with limited statistics due to the necessity of enhanced temporal resolution. The aim of this study is to address these drawbacks by combining within a unique reconstruction algorithm in dynamic PET imaging, a respiratory motion correction approach, as well as a temporal regularization. Elastic transformation parameters for the motion correction are estimated from the non-attenuation corrected PET images. The derived displacement matrices are subsequently used in a list-mode based OSEM reconstruction algorithm integrating a temporal regularization between the 3D dynamic PET frames based on temporal basis functions. These functions are simultaneously estimated at each iteration along with their relative coefficients for each image voxel. Quantitative evaluation was performed using dynamic FDG PET/CT acquisitions of lung cancer patients acquired on a GE DRX system. The proposed method was compared with the performance of a standard multi-frame OSEM reconstruction algorithm. The proposed method achieved substancial improvements in terms of noise reduction while accounting for loss of contrast due to respiratory motion. Results on simulated data showed that the proposed 4D algorithms led to bias reduction values up to 40\% in both tumor and blood regions for similar standard deviation levels in comparison with a standard 3D reconstruction. Patlak parameters estimations on reconstructed images with the proposed reconstruction methods resulted in 30% and 40% bias reduction in the tumor and lung region respectively for the Patlak slope, and a 30% bias reduction for the intercept in the tumor region (a similar Patlak intercept was achieved in the lung area). Incorporation of the respiratory motion correction using an elastic model along with a temporal regularization in the reconstruction process of the PET dynamic series led to substancial quantitative improvements and motion artifacts' reduction. Future work will include the integration of a linear FDG kinetic model in order to directly reconstruct parametric images.

PMID: 29339575 [PubMed - as supplied by publisher]

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