Impact of motion compensation and partial volume correction for¹⁸F-NaF PET/CT imaging of coronary plaque

Abstract

Recent studies have suggested that <sup>18</sup>F-NaF-PET enables visualization and quantification of plaque micro-calcification in the coronary tree. However, PET imaging of plaque calcification in the coronary arteries is challenging because of the respiratory and cardiac motion as well as partial volume effects. The objective of this work is to implement an image reconstruction framework, which incorporates compensation for respiratory as well as cardiac motion (MoCo) and partial volume correction (PVC), for cardiac <sup>18</sup>F-NaF PET imaging in PET/CT. We evaluated the effect of MoCo and PVC on the quantification of vulnerable plaques in the coronary arteries. Realistic simulations (Biograph TPTV, Biograph mCT) and phantom acquisitions (Biograph mCT) were used for these evaluations. Different uptake values in the calcified plaques were evaluated in the simulations, while three "plaque-type" lesions of 36, 31 and 18 mm<sup>3</sup> were included in the phantom experiments. After validation, the MoCo and PVC methods were applied in four pilot NaF-PET patient studies. In all cases, the MoCo-based image reconstruction was performed using the STIR software. The PVC was obtained from a local projection (LP) method, previously evaluated in preclinical and clinical PET. The results obtained show a significant increase of the measured lesion-to-background ratios (LBR) in the MoCo+PVC images. These ratios were further enhanced when using directly the tissue-activities from the LP method, making this approach more suitable for the quantitative evaluation of coronary plaques. When using the LP method on the MoCo images, LBR increased between 200% and 1119% in the simulated data, between 212% and 614% in the phantom experiments and between 46% and 373% in the plaques with positive uptake observed in the pilot patients. In conclusion, we have built and validated a STIR framework incorporating MoCo and PVC for <sup>18</sup>F-NaF PET imaging of coronary plaques. First results indicate an improved quantification of plaque-type lesions.

Hybrid Imaging: Instrumentation and Data Processing

“…More advanced methods, that use the synergistic information derived from the simultaneous PET and MR data acquisition, have been proposed to estimate [198] and to correct for motion in both PET and MR images [189]. Other attempts focused on the implementation of joint MoCo and PVC approaches to further improve the PET quantification of small lesions in regions that are susceptible to motion [199,200].…”

Atherosclerosis imaging with 18F-sodium fluoride PET: state-of-the-art review

“…A more in-depth discussion of quantification methods is beyond the scope of this article. Instead, readers are referred to articles dealing with such topic [16,[26][27][28][29][52][53][54][55][56][57].…”

Cardiac motion and spillover correction for quantitative PET imaging using dynamic MRI

“…which uses expectation‐maximization during reconstruction; or Wang et al . and Cal‐Gonzalez et al . that utilize motion fields to generate a single motion corrected image preserving the count statistics, would possibly be the most efficient way to account for cardiac and respiratory motion.…”

“…Advanced reconstruction methods, such as the work by Karakatsanis et al 24 which uses expectation-maximization during reconstruction; or Wang et al 6 and Cal-Gonzalez et al 25 that utilize motion fields to generate a single motion corrected image preserving the count statistics, would possibly be the most efficient way to account for cardiac and respiratory motion. However, these methods would involve the development of a dedicated reconstruction algorithm as no such reconstruction method is readily available for commercial scanners.…”