RT Journal Article SR Electronic T1 Evaluation of DOTA as a marker for myocardial blood flow using 68Ga-DOTA and 15O-water PET JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 3391 OP 3391 VO 63 IS supplement 2 A1 Mark Lubberink A1 Irina Velikyan A1 Sofia Kvernby A1 Elin Lindström A1 Keivan Azarbar A1 Christoph Rischpler A1 Jens Sörensen A1 Tanja Kero YR 2022 UL http://jnm.snmjournals.org/content/63/supplement_2/3391.abstract AB 3391 Introduction: Gd-DOTA (DOTAREM) and similar MRI contrast agents are often suggested as markers for myocardial blood flow (MBF). Accurate quantification of MBF with MR contrast agents requires correct conversion of the MR signal to Gd concentration which is challenging; analysis with an appropriate kinetic model; and correction for the limited extraction of Gd-DOTA using the relationship between the uptake rate of the contrast agent and true MBF. Contrary to MRI, the PET signal is directly proportional to radioactivity concentrations and hence a PET analogue, 68Ga-DOTA, could be used to assess the kinetics of DOTA without the challenges of measuring Gd concentration with MRI. The aim of the present work was to assess the kinetics of DOTA by comparing 68Ga-DOTA to the gold standard for non-invasive measurement of MBF, 15O-water PET.Methods: Nine patients underwent 4 min dynamic 15O-water-PET followed by 10 min dynamic 68Ga-DOTA-PET during rest and pharmacological stress on a Signa PET/MR scanner. 15O-water PET was analysed automatically using aQuant software, and volumes of interest were transferred to the co-registered 68Ga-DOTA-PET images. 68Ga-DOTA-PET was analysed using single- and two-tissue irreversible compartment models and the uptake rate constant K1 of 68Ga-DOTA was compared to that of 15O-water. Permeability-surface area product for 68Ga-DOTA was estimated using the Renkin-Crone equation.Results: Kinetics of 68Ga-DOTA was well described by a single-tissue compartment model. Correlation between 68Ga-DOTA and 15O-water K1 values was moderate (Spearman rho 0.82 at the global and 0.72 at the regional level, P < 0.005). Extraction of 68Ga-DOTA was low with average whole myocardium 68Ga-DOTA K1 values ranging between 0.28 and 0.88 mL/cm3/min compared to 0.72 and 4.2 mL/cm3/min for 15O-water. The permeability surface area product of 68Ga-DOTA was 0.38 mL/cm3/min. Regional 68Ga-DOTA K1 versus 15O-water MBF values, as well as 68Ga-DOTA MBF values after applying the Renkin-Crone equation, are shown in the Figure below.Conclusions: Extraction of DOTA is low, and much lower than for e.g., 82Rb or even 99mTc-sestamibi, resulting in a high uncertainty in hyperemic MBF and coronary flow reserve values. Based on these results, and even when Gd-DOTA concentration can be accurately quantified using MRI, DOTA cannot be considered a suitable agent for accurate measurement of MBF.