¹⁸F-Sodium Fluoride Positron Emission Tomography and Computed Tomography in Acute Aortic Syndrome

Acute aortic syndrome is associated with aortic medial degeneration. ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) detects microscopic tissue calcification as a marker of disease activity.

In a proof-of-concept study, this investigation aimed to establish whether ¹⁸F-NaF PET combined with computed tomography (CT) angiography could identify aortic medial disease activity in patients with acute aortic syndrome.

Patients with aortic dissection or intramural hematomas and control subjects underwent ¹⁸F-NaF PET/CT angiography of the aorta. Aortic ¹⁸F-NaF uptake was measured at the most diseased segment, and the maximum value was corrected for background blood pool activity (maximum tissue-to-background ratio [TBR_max]). Radiotracer uptake was compared with change in aortic size and major adverse aortic events (aortic rupture, aorta-related death, or aortic repair) over 45 ± 13 months.

Aortic ¹⁸F-NaF uptake co-localized with histologically defined regions of microcalcification and elastin disruption. Compared with control subjects, patients with acute aortic syndrome had increased ¹⁸F-NaF uptake (TBR_max: 1.36 ± 0.39 [n = 20] vs 2.02 ± 0.42 [n = 47] respectively; P < 0.001) with enhanced uptake at the site of intimal disruption (+27.5%; P < 0.001). ¹⁸F-NaF uptake in the false lumen was associated with aortic growth (+7.1 mm/year; P = 0.011), and uptake in the outer aortic wall was associated with major adverse aortic events (HR: 8.5 [95% CI: 1.4-50.4]; P = 0.019).

In patients with acute aortic syndrome, ¹⁸F-NaF uptake was enhanced at sites of disease activity and was associated with aortic growth and clinical events. ¹⁸F-NaF PET/CT holds promise as a noninvasive marker of disease severity and future risk in patients with acute aortic syndrome. (¹⁸F Sodium Fluoride PET/CT in Acute Aortic Syndrome [FAASt]; NCT03647566).