The relationship between metabolic syndrome and its components with thoracic aorta calcification-related parameters using [¹⁸F]-NaF PET/CT in patients with coronary artery disease

Objectives: Metabolic syndrome is known to be associated with thoracic aorta calcification which increases the risk of cardiovascular disease. In this study, we investigated a relationship between metabolic syndrome and vascular calcifying activity, vascular calcification metabolic burden and vascular calcium burden of descending thoracic aorta in population with suspected coronary artery disease.

Methods: Patients with suspected coronary artery disease who underwent [¹⁸F]-NaF PET/CT before invasive coronary angiography were enrolled. All vascular calcification-related [¹⁸F]-NaF PET/CT parameters, clinical characteristics, biochemistry parameters related to metabolic syndrome, and estimated 10-year cardiovascular disease risk score were analyzed. Patients who had history of other cardiovascular disease were excluded.[¹⁸F]-NaF uptake and CT calcium burden were quantified on descending thoracic aorta using PET and co-registered CT images in fixed number of transaxial slices covering aortic length 102mm. The vascular calcifying activity was estimated as follow: maximum SUV obtained per ROI on arterial wall were averaged and subsequently divided (target-to-background ratio, TBR) or subtracted (corrected uptake per lesion, CUL) by mediastinal blood pool activity. Vascular calcifying metabolic burden was determined as follows: mean SUV and target volume above threshold activity on VOI were multiplied and subsequently divided by blood pool activity (total lesion uptake ratio, TLUR). The detection threshold was 150% times of blood pool activity. The CT calcium burden of descending thoracic aorta (total lesion calcium, TLC) was determined by integration of Hounsfield units multiplied by each voxel volume with detection threshold >130HU on VOI.

Results: Forty subjects (33 male, mean age 62, range 44-79 years) were included in this study. Overall, [¹⁸F]-NaF parameters increased in diabetic patients, but not in non-diabetic (TBR, CUL, and TLUR, p <0.05). Aortic TBR (rho=0.433, p <0.01), CUL (rho=0.433, p <0.01) and TLUR (rho=0.344 at detection threshold 150%, p <0.05) showed significant correlation with glycated hemoglobin level. Patients with hypertension had significantly higher TLC than patients without hypertension (p <0.001). Hyperlipidemia was not significantly related to both [¹⁸F]-NaF PET and CT parameters (p >0.05). There was significant difference of CT calcium burden but not on [¹⁸F]-NaF parameters among cardiovascular risk categories (p <0.05, Kruskall-Wallis test). Framingham risk score (rho=0.637, p <0.0001), BMI (rho=0.655, p <0.0001), and systolic blood pressure (rho=0.376, p <0.05) positively correlated with TLC. CT calcium burden was increased in patients with metabolic syndrome (n=19, p <0.01), but [¹⁸F]-NaF parameter was not.

Conclusions: Diabetes and glycated hemoglobin were associated with increased descending thoracic aorta [¹⁸F]-NaF uptake in patients with suspected coronary artery disease. CT calcium burden was associated with hypertension and metabolic syndrome.