Abstract
Background18F-Fluoride uptake denotes calcification activity in aortic stenosis and atherosclerosis. While PET/MR has several advantages over PET/CT, attenuation correction of PET/MR data is challenging, limiting cardiovascular application. We compared PET/MR and PET/CT assessments of 18F-fluoride uptake in the aortic valve and coronary arteries. Methods and results18 patients with aortic stenosis or recent myocardial infarction underwent 18F-fluoride PET/CT followed immediately by PET/MR. Valve and coronary 18F-fluoride uptake were evaluated independently. Both standard (Dixon) and novel radial GRE) MR attenuation correction (AC) maps were validated against PET/CT with results expressed as tissue-to-background ratios (TBRs). Visually, aortic valve 18F-fluoride uptake was similar on PET/CT and PET/MR. TBRMAX values were comparable with radial GRE AC (PET/CT 1.55±0.33 vs. PET/MR 1.58 ± 0.34, P = 0.66; 95% limits of agreement − 27% to + 25%) but performed less well with Dixon AC (1.38 ± 0.44, P = 0.06; bias (−)14%; 95% limits of agreement − 25% to + 53%). In native coronaries, 18F-fluoride uptake was similar on PET/MR to PET/CT regardless of AC approach. PET/MR identified 28/29 plaques identified on PET/CT; however, stents caused artifact on PET/MR making assessment of 18F-fluoride uptake challenging. ConclusionCardiovascular PET/MR demonstrates good visual and quantitative agreement with PET/CT. However, PET/MR is hampered by stent-related artifacts currently limiting clinical application.
Highlights
Calcification is a key pathological process in both aortic stenosis and coronary atherosclerosis
Cardiac studies investigating the uptake of 18F-fluoride have predominantly employed hybrid PET/ CT, but interest has recently developed in Positron Emission Tomography/Magnetic Resonance (PET/MR) platforms
There was no difference in net PET counts on the 30 minutes PET/CT compared to the 50 minutes PET/MR (P = 0.66)
Summary
Calcification is a key pathological process in both aortic stenosis and coronary atherosclerosis. PET/MR provides several potential advantages compared to PET/CT including reduced radiation exposure, integrated functional assessment, improved soft tissue characterisation and motion correction.[1] While PET/MR has already shown promise in the assessment of aortic stenosis,[2] coronary atherosclerosis,[3] cardiac amyloidosis and sarcoidosis,[4,5] it remains unclear how the pattern and intensity of tracer uptake compares with the current gold-standard of PET/CT. This is of particular importance given concerns regarding the optimal method for attenuation correction on PET/MR. We compared PET/MR and PET/CT assessments of 18F-fluoride uptake in the aortic valve and coronary arteries
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