FDG PET/CT in Assessing the Association Between Myocardial Glucose Metabolism and Blood Pressure

Objectives: High blood pressure can cause the left ventricular (LV) myocardium to undergo certain adaptive changes such as LV hypertrophy that may ultimately lead to heart failure. We aimed to assess the association between blood pressure and LV myocardial uptake of FDG hypothesizing that subjects with raised blood pressure would have higher FDG uptake in response to the increased external work load.

Methods: We analyzed 86 healthy controls (40 women and 46 men, mean age 46 ± 13.5 between 21-66 years) who underwent PET/CT imaging 180 minutes following the injection of FDG (4 MBq/Kg) by using a GE Discovery STE, VCT, R, or 690/710 system. CT imaging (140 kV, 30-110 mA, noise index 25, 0.8 seconds per rotation, slice thickness 3.75 mm) was performed for attenuation correction and anatomic referencing with PET images. PET images were corrected for attenuation, scatter, scanner dead time, and random coincidence. LV myocardial analysis was performed on axial sections using standard operator guided computer software (OsiriX MD software, version 9.0.02). The average LV myocardial SUVmean (MSUVmean) was calculated for each subject. Blood pressure was measured under standardized conditions, and the average of the last two of three consecutive recordings was used. Subjects were categorized based on their systolic and diastolic blood pressure (SBP and DBP) according to the 2017 ACC/AHA guidelines for high blood pressure in adults: Normal SBP <120 and DBP <80 mmHg, elevated SBP = 120-129, stage I systolic hypertension = 130-139, stage II systolic hypertension = ≥140 mmHg; stage I diastolic hypertension = 80-89, stage II diastolic hypertension ≥90 mmHg. Mean arterial blood pressure (MABP) was calculated as DBP plus 1/3 SBP amplitude. Univariate and multivariate regression models were used to determine the association of MSUVmean with SBP, DBP, and MABP. ANOVA analysis was employed to assess differences between MSUVmean and blood pressures.

Results: MSUVmean was found to be higher in subjects with elevated BP compared to those with normal BP. The association of MSUVmean was more pronounced with DBP (r=0.32, p=0.002) than with SBP (r=0.27, p=0.009); its interrelationship with MABP was comparable (r=0.32, p=0.002). Correlations of MSUVmean with categorized BPs were: normal SBP (r=0.27, p=0.01), elevated SBP (r=0.28, p=0.009), stage 1 SBP (r=0.27, p=0.01), stage 2 SBP (r=0.28, p=0.008); normal DBP (r=0.33, p=0.001), stage 1 DBP (r=0.34, p=0.001), stage 2 DBP (r=0.35, p=0.001). Multivariate analysis demonstrated significance with DBP (p=0.006), MABP (p=0.007), and SBP (0.02). ANOVA analysis showed significant difference of MSUVmean in SBP (p=0.04) and DBP (p=0.03).

Conclusions: LV myocardial FDG uptake was higher in subjects with elevated blood pressure and correlated positively with SBP and in particular DBP and MABP. This data provides evidence for a potential new role of FDG PET/CT in identifying subtle changes in LV myocardial metabolism prior to the onset of structural changes related to hypertension.