Quantifying microcalcification activity in the thoracic aorta

Abstract

Background Standard methods for quantifying positron emission tomography (PET) uptake in the aorta are time consuming and may not reflect overall vessel activity. We describe aortic microcalcification activity (AMA), a novel method for quantifying 18F-sodium fluoride (18F-NaF) uptake in the thoracic aorta. Methods Twenty patients underwent two hybrid 18F-NaF PET and computed tomography (CT) scans of the thoracic aorta less than three weeks apart. AMA, as well as maximum (TBRmax) and mean (TBRmean) tissue to background ratios, were calculated by two trained operators. Intra-observer repeatability, inter-observer repeatability and scan-rescan reproducibility were assessed. Each 18F-NaF quantification method was compared to validated cardiovascular risk scores. Results Aortic microcalcification activity demonstrated excellent intra-observer (intraclass correlation coefficient 0.98) and inter-observer (intraclass correlation coefficient 0.97) repeatability with very good scan-rescan reproducibility (intraclass correlation coefficient 0.86) which were similar to previously described TBRmean and TBRmax methods. AMA analysis was much quicker to perform than standard TBR assessment (3.4min versus 15.1min, P<0.0001). AMA was correlated with Framingham stroke risk scores and Framingham risk score for hard cononary heart disease. Conclusions AMA is a simple, rapid and reproducible method of quantifying global 18F-NaF uptake across the ascending aorta and aortic arch that correlates with cardiovascular risk scores.

[18F]FDG and [18F]NaF as PET markers of systemic atherosclerosis progression: A longitudinal descriptive imaging study in patients with type 2 diabetes mellitus

“…5,12 HbA1 c increased significantly over five years (46 [42-48] vs 52 [44-56] mmolÁmol (P = .012). After five-year follow-up, CPscore had increased significantly (16.0 [5.0-19.5] vs 20 [7.5-24.5] (P = .007), with a CPscore %change of 24% [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], whereas PWV remained stable (7.98 [6.95-9.29] vs 8.65 [7.79-9.70] mÁs (P = .203), with a PWV %change of 7.2% [-9.0 to 27] as did other parameters (SBP, BMI, lipids, C-reactive protein, and kidney function (estimated glomerular filtration rate, albumin-creatinin ratio)). Baseline age correlated significantly with mean TBR[ 18 F]NaF and PWV (r = 0.746, P = .013, and r = 0.654, P = .040, respectively).…”

18F-fluorodeoxyglucose and 18F-sodium fluoride for imaging atherosclerotic plaque activity

“…Additionally, 18 F-sodium fluoride and 18 F-fluorodeoxyglucose uptake were expressed as single SUVmax or TBRmax measured within a relatively large volume of interest (such as the entire ascending aorta and the aortic arch)-yet it was recently proposed that measures of uptake which consider both the extent and intensity of uptake might be superior to characterize atherosclerotic disease activity in the great vessels. 15 On the molecular level, the association between osteogenesis and inflammation in atherosclerosis was widely reported, and the study by Reijrink et al supports these findings at a non-invasive imaging level. 16,17 This association was also explored in histological assessment of carotid endarterectomy specimens and preclinical models.…”

Aortic 18F-sodium fluoride imaging

“…In the study by Fiz et al, the mean TBR was used within a manually drawn cylindric volume-of-interest, encompassing the whole lumen of the infrarenal aorta. An alternative approach for characterizing activity within the ascending aorta was recently proposed by Fletcher et al 20 The aortic microcalcification activity (AMA), incorporates both voxel intensity and volume. Compared to tedious averaging of SUV or TBR values, AMA was highly reproducible and more time-efficient than the previous approaches.…”