Increased 18F-fluorodeoxyglucose uptake in abdominal aortic aneurysms in positron emission/computed tomography is associated with inflammation, aortic wall instability, and acute symptoms

An 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography of abdominal aortic aneurysm (AAA) vessel wall at maximum focal FDG uptake in a 66-year-old woman with a symptomatic AAA (maximum diameter, 50 mm; maximum standard uptake value, 9.1). Panel a, coronal section. Panel b, transversal section; arrow, effusive aortic FDG uptake with spillover effect.

Average maximum standard uptake values (SUV_max) of the control group compared with patients with asymptomatic and symptomatic abdominal aortic aneurysms (AAAs). Both, asymptomatic and symptomatic patients showed significant increase in uptake values compared with controls, with highest SUV_max levels in the symptomatic AAAs.

Histologic results to the corresponding 18F-fluorodeoxyglucose uptake of positron emission tomography/computed tomography from Fig 1. Panel a, Hematoxylin and eosin staining; arrow, inflammatory infiltrates. Panel b, Elastin von Gieson staining; arrows, collagen (red) and elastin (black) fibers in the tunica media; Panel c, CD68 antibody staining (brown); arrow designates CD68-positive cells with dens transmural infiltration; Panel d, CD3 antibody staining (brown); arrow designates CD3-positive cells; Panels e and f, Matrix metalloproteinase (MMP) -2, MMP-9 antibody staining (brown); arrow designates positive cells); Panel g, Smooth muscle actin antibody staining (red); arrow designates rarified smooth muscle actin–positive cells. Original magnification, 50×.

Scatter plot of maximum standard values (SUV_max) of fluorodeoxyglucose F18 uptake compared with (A) inflammatory cell infiltrate, (B) matrix metalloproteinase (MMP)-2 and -9 activities, and (C) content of elastin, collagen, and vascular smooth muscle cells (VSMC) in the corresponding area of abdominal aortic aneurysm (AAA) vessel wall. Cell densities were semiquantitatively determined and scored from 0 to 6+. Increasing SUV_max correlated significantly with higher densities of (A) inflammatory infiltrates and (B) MMP-2 or MMP-9. C, Negative correlation was found for collagen and VSMCs but not for elastin.