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

Abstract

Background Evaluation of left atrium (LA) remodeling is becoming increasingly relevant in understanding several pathological cardiac conditions. 18 F-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. MethodsThe liver, heart cavity and walls of an anthropomorphic phantom were filled with typical patient 18 F-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. ResultsAnalog 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. ConclusionThe digital TOF-PET/CT with the identified optimal reconstruction can be used to quantitatively analyze the LA uptake in 18 F-FDG cardiac studies while still preserving image reading quality. This may lead to more precise cardiovascular disease status evaluation, especially when atria are concerned. Nucl Med Commun

Left Atrial Glucose Metabolism Evaluation by 18F-FDG-PET in Persistent Atrial Fibrillation and in Sinus Rhythm

“…Recent improvements in PET technology have enabled higher spatial resolution and improved image quality, thereby allowing for the acquisition of high-quality PET images of the atria without influence of partial volume effect. 5 Our study is novel in that it prospectively used this technique to explore the metabolic changes in the atria of patients with persistent AF in comparison with those with restored SR. Although some previous studies have reported increased FDG uptake in atria of patients with AF, 6 , 7 , 8 , 9 , 10 the type of AF (ie, paroxysmal vs persistent varied); importantly, these studies were not performed under well-standardized metabolic conditions, but usually only after fasting.…”

“…FDG PET/CT was performed using a high-resolution digital 64 slice PET/CT system (Vereos TOF- Philips Healthcare) using a previously optimized protocol to enable the reconstruction of high-resolution atrial PET images. 5 Patients were studied after overnight fasting and received a nicotinic acid derivative (acipimox 250 mg) to maximally stimulate myocardial glucose uptake. Before tracer injection levels of fasting glucose, insulin, and free fatty acids were measured in venous blood samples.…”

“…Indeed, through recent improvements in digital PET camera technologies, it is now also possible to quantitatively analyze the FDG uptake in the LA. 5 Although a few prior studies have described increased atrial FDG uptake in patients with AF, 6 , 7 , 8 , 9 , 10 this was not done under standardized metabolic conditions, which is critical, because glucose uptake is not only dependent on the rate of glucose use of the heart, but also on substrate availability. Oral administration of a nicotinic acid derivative (acipimox) inhibits peripheral lipolysis decreasing plasma levels of free fatty acids and stimulates preferential glucose use by cardiac myocytes.…”