Abstract
BackgroundCurrent 18F-NaF assessments of aortic valve microcalcification using 18F-NaF PET/CT are based on evaluations of end-diastolic or cardiac motion-corrected (ECG-MC) images, which are affected by both patient and respiratory motion. We aimed to test the impact of employing a triple motion correction technique (3 × MC), including cardiorespiratory and gross patient motion, on quantitative and qualitative measurements.Materials and methodsFourteen patients with aortic stenosis underwent two repeat 30-min PET aortic valve scans within (29 ± 24) days. We considered three different image reconstruction protocols; an end-diastolic reconstruction protocol (standard) utilizing 25% of the acquired data, an ECG-gated (four ECG gates) reconstruction (ECG-MC), and a triple motion-corrected (3 × MC) dataset which corrects for both cardiorespiratory and patient motion. All datasets were compared to aortic valve calcification scores (AVCS), using the Agatston method, obtained from CT scans using correlation plots. We report SUVmax values measured in the aortic valve and maximum target-to-background ratios (TBRmax) values after correcting for blood pool activity.ResultsCompared to standard and ECG-MC reconstructions, increases in both SUVmax and TBRmax were observed following 3 × MC (SUVmax: Standard = 2.8 ± 0.7, ECG-MC = 2.6 ± 0.6, and 3 × MC = 3.3 ± 0.9; TBRmax: Standard = 2.7 ± 0.7, ECG-MC = 2.5 ± 0.6, and 3 × MC = 3.3 ± 1.2, all p values ≤ 0.05). 3 × MC had improved correlations (R2 value) to the AVCS when compared to the standard methods (SUVmax: Standard = 0.10, ECG-MC = 0.10, and 3 × MC = 0.20; TBRmax: Standard = 0.20, ECG-MC = 0.28, and 3 × MC = 0.46).Conclusion3 × MC improves the correlation between the AVCS and SUVmax and TBRmax and should be considered in PET studies of aortic valves using 18F-NaF.
Highlights
Current 18F-NaF assessments of aortic valve microcalcification using 18F-NaF Positron emission tomography (PET)/CT are based on evaluations of end-diastolic or cardiac motion-corrected (ECG-Triple motion-corrected (MC)) images, which are affected by both patient and respiratory motion
We evaluated the use of a novel 3 × MC PET reconstruction technique tested for the first time in PET imaging of aortic valves, including cardiorespiratory and gross patient motion correction
The impact of the 3 × MC protocol was evaluated on five criteria assessing the quantitative and qualitative assessments of the images: S UVmax, Maximum target-to-background ratio (TBRmax), signal -to-noise ratio (SNR), the test–retest repeatability, and the correlation between the quantitative measures and aortic valve calcification scores (AVCS)
Summary
Current 18F-NaF assessments of aortic valve microcalcification using 18F-NaF PET/CT are based on evaluations of end-diastolic or cardiac motion-corrected (ECG-MC) images, which are affected by both patient and respiratory motion. Cardiac 18F-NaF PET imaging is affected by motion (cardiac and respiratory [cardiorespiratory] and patient) and by technical challenges associated with the current acquisition protocols for 18F-NaF PET, which can last for up to 30 min. Patient motion during imaging protocols with long acquisition times degrades the image quality of the scans [10] and reduces the quantitative accuracy and the test–retest repeatability [11, 12]. Best possible image quality and spatial resolution are of critical importance in studies of microcalcification in native valves to understand the pathophysiology of aortic stenosis, and in studies of bioprosthetic valves where accurate localization of 18F-NaF uptake is essential
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