Semiquantitative evaluation of ⁶⁸Ga-DOTANOC uptake in the normal myocardium: establishment of reference values

Background: To ascertain presence of physiological uptake and derive standardized uptake values (SUV) of ⁶⁸Ga-DOTANOC in normal myocardium and establish reference values.

Methods and results: Dedicated cardiac ⁶⁸Ga-DOTANOC PET/CT studies of patients referred for evaluation of cardiac sarcoidosis (CS) or myocarditis and found to be normal on visual assessment and on cardiac MRI were analyzed semiquantitatively. The studies were acquired 45-60 minutes after intravenous injection of 111-185 MBq of ⁶⁸Ga-DOTANOC. Myocardial SUV_max normalized to lean body mass (SUV_{max_}lbm) values for septum, anterior wall, proximal lateral wall, distal lateral wall, inferior wall, and apical region were 1.12 ± .39, 1.09 ± .42, 1.26 ± .49, 1.16 ± .40, 1.23 ± .39, and 1.05 ± .40, respectively. Myocardial SUV_{max_}lbm-to-blood pool SUV_mean_lbm ratios were calculated for each region and 95th percentile values of these ratios were considered the upper limit of normal. 95th percentile values of myocardial SUV_{max_}lbm-to-blood pool SUV_mean_lbm ratio for the corresponding regions were 1.70, 1.70, 2.00 1.95, 2.05, and 1.70, respectively.

Conclusion: There can be physiological uptake of ⁶⁸Ga-DOTANOC in normal myocardium and the reference values of semiquantitative parameters established in this study may be employed as a corroborative tool for visual assessment in patients undergoing ⁶⁸Ga-DOTANOC PET/CT for suspected CS or myocarditis.