Cardiac atrial metabolism quantitative assessment with analog and digital time of flight-PET/computed tomography.

BACKGROUND: Evaluation of left atrium (LA) remodeling is becoming increasingly relevant in understanding several pathological cardiac conditions. 18F-FDG-PET/computed tomography (CT), the current gold standard for metabolic evaluation of the left ventricle, could be extended to LA using the latest PET technologies. We sought to perform a phantom study to optimize the reconstruction algorithm in this context.

METHODS: The liver, heart cavity and walls of an anthropomorphic phantom were filled with typical patient 18F-FDG activity concentrations. Acquisitions were performed on an analog and on a digital TOF-PET/CT, and reconstructed with and without resolution recovery (RR). The Richardson-Lucy RR method was used, either through a third-party software or through the PET/CT manufacturer algorithm. Activity recoveries in the atria and ventricles and signal-to-noise ratios were evaluated to identify the best reconstruction and RR parameters. The same methodology was applied on a patient cardiac study.

RESULTS: Analog PET/CT with the third-party RR cannot improve the activity recovery without markedly degrading the image quality. For the digital PET/CT, the optimal algorithm was the manufacturer RR reconstruction using four iterations and 15 subsets combined with five RR iterations. This reconstruction improved the LA activity recovery from 58% to 70% while preserving images of diagnostic quality. Similar results were obtained for the patient study.

CONCLUSION: The digital TOF-PET/CT with the identified optimal reconstruction can be used to quantitatively analyze the LA uptake in 18F-FDG cardiac studies while still preserving image reading quality. This may lead to more precise cardiovascular disease status evaluation, especially when atria are concerned.