Positron emission tomography imaging for vascular inflammation evaluation in elderly subjects with different risk factors for cardiovascular diseases

Abstract

This study was aimed to investigate the usefulness of (18)F-FDG-PET to differentiate vascular inflammation and to determine the effect of rosuvastatin. Eight subjects were recruited and were divided according to their health status in three groups; 3 healthy subjects, 3 patients with hypercholesterolemia and 2 patients with stable angina pectoris. Hypercholesterolemic patients were submitted immediately after their recruitment to rosuvastatin treatment (20 mg/d). Two PET/CT measurements were made throughout the course of the study, one at baseline and the second 12 months later. Our results showed that the ratio of calcified arteries to total analyzed arteries segments were 23%, 36% and 44% for healthy, hypercholesterolemic and stable angina patients respectively. Healthy subjects present, at baseline, a high level of vascular inflammation as measured by (18)F-FDG uptake in both calcified and non-calcified segments of the arteries. This vascular inflammation increases as a function of the cardiovascular risk factors. After the 12-month follow-up period, non-calcified arteries showed a significant increase of (18)F-FDG uptake in both healthy, hypercholesterolemic and stable angina patients. However, the highest increase was noted for the healthy subjects; (50% increase, p<0.0001), while hypercholesterolemic patients under rosuvastatin showed only 25% increase of (18)F-FDG uptake (p<0.0001). This study confirms the usefulness of (18)F-FDG measurement to localize and quantify arterial inflammation in each artery segments and as a function of the CVD risk factors. Rosuvastatin may have a protective effect against arterial inflammation however; other studies with higher rosuvastatin doses (>20 mg/d) are needed to confirm this beneficial effect.

Keywords: 18F-FDG; Atherosclerosis; aging; positron emission tomography; rosuvastatin; vascular inflammation.

Figure 1

Coronal and transaxial PET-CT images at T0 (A, C) and at T12 (B, D). Arrows indicate calcified segments of the aorta. Fusion of PET and CT shows that ¹⁸F-FDG uptake is mostly located in the calcified segments of the arteries suggesting inflammation in the atherosclerotic plaque. (A) Coronal fused PET-CT at T0, (B) Coronal fused PET-CT at T12, (C) Transaxial fused PET-CT at T0 and (D) Transaxial fused PET-CT at T12.

Figure 2

Comparison of the SUV values of calcified and non-calcified segments of arteries of healthy, hypercholesterolemic and stable angina patients. SUV values were determined at baseline (T0) for the three groups. Panels A-C correspond to healthy, hypercholesterolemic and stable angina patients respectively. The data were obtained from transaxial image slices. Student-t test was used to determine whether there is a significant difference between the means. P<0.05 was considered significant. n: represents the number of arteries segments evaluated for ¹⁸F-FDG uptake.

Figure 3

Comparison of the SUV of non-calcified arteries between baseline and after 12 months of follow-up of healthy, hypercholesterolemic and stable angina patients SUV values were determined at baseline and after 12 months for non-calcified segments of the arteries of the same patient in each group. The data were obtained from transaxial image slices. Statistical analyses were performed using GraphPad Prism. A student-t test was used to compare values at T0 and T12. P<0.05 was considered significant. n: represents the number of arteries segments evaluated for ¹⁸F-FDG uptakes.

Figure 4

Measurement of SUV of non-calcified segments of the arteries of healthy, hypercholesterolemic and stable angina patients at baseline (A) and after 12 months (B). SUV values were determined at baseline and after 12 months for non-calcified segments of the arteries of the same patient in each group. The data were obtained from transaxial image slices. Statistical analyses were performed using GraphPad Prism. A one-way analysis of variance (ANOVA) was used for multiple comparisons, followed by Bonferonni’s multiple comparison tests. P<0.05 was considered significant. n: represents the number of arteries segments evaluated for ¹⁸F-FDG uptake. Non-significant statistical differences between the groups are not indicated in the figure.