Sodium Fluoride PET/CT Imaging as a Promising Tool for the Assessment of Coronary Plaque Deposition

298 Objectives: Cardiovascular diseases (CVD’s) are a broad category of conditions characterized by degeneration and impaired function of the human vasculature. CVD is most commonly associated with a process known as atherosclerosis, in which plaque is deposited within the blood vessels of the body causing narrowing of the lumen as well as the potential for thrombus formation leading to downstream ischemia and tissue death (1). On a global scale, it is estimated that deaths attributed to ischemic heart disease total nearly 7 million annually (2,3). Computed Tomography (CT) calcium score is a current clinical standard in the assessment of atherosclerosis, but is only effective once appreciable amounts of plaque have formed. The ability to identify and assess early-stage plaque build-up within human vasculature through non-invasive imaging techniques is crucial in order to stratify risk and initiate treatment for patients suffering from atherosclerosis (4,5). PET/CT imaging incorporating a sodium fluoride (NaF) radiotracer provides a supported biochemical pathway in which the quantity of radiotracer adsorption is directly correlated with the extent of plaque formation in the human vasculature (3). We aimed to develop a clinically feasible methodology for the quantification of atherosclerotic plaque build up in the coronary vasculature to increase the utility of NaF PET/CT in this field. This technique was applied to a patient cohort with a history of cardiovascular symptoms and matched control subjects. Methods: 68 female (ages 21-75, BMI 18-37 kg/m²) and 68 male patients (ages 23-75 years, BMI 18-43 kg/m2) were intravenously injected with a dose of NaF that was controlled for each individual’s body weight (2.2MBq/Kg of body weight). The PET/CT images were then conducted 90 minutes following the injections. The scans were conducted under the same condition for all individuals (GE Discovery STE, VCT, RX, and 690/710). CT images (140kV, 30-110 mA, noise index 25, 0.8 seconds per rotation, slice thickness 3.75 mm) were corrected for anatomic orientation. Likewise, PET images were corrected for attenuation due to scattering, and random coincidence. An operator guided computer software, PMOD (PMOD Technologies LLC, Switzerland), was used to carry out the segmentation of the coronary vasculature, as well as to perform standard uptake value (SUV) calculations. Regions of interest (ROI’s) were created using coronal CT images that defined the entire heart. These ROI’s, which encompassed exclusively vascular tissue, were then stacked to created three dimensional volumes of interest (VOI’s). Individuals within the patient cohort had been referred for coronary CT-angiography due to persistent chest pain and were matched with controls on the basis of gender, height, weight, radiotracer dosage, and age. Results: Patients displaying cardiovascular symptoms showed significantly higher SUV values compared to matched controls (p = 0.006) (Figure 1). CT calcium score did not differ between these cohorts (Figure 2). SUV was correlated with age and BMI after adjusting for covariates (p &lt 0.001). SUV was found to increase by 5.88% percent per decade of life for female subjects ( p &lt 0.001) and 8.75% per decade of life for male subjects (p &lt 0.001). Conclusions: These results support the assertion that NaF PET/CT is an effective imaging modality with respect to the detection and quantification of atherosclerotic plaque deposition of the coronary vasculature.