Sex differences in brain perfusion during adenosine stress as measured using total-body positron emission tomography

Introduction Novel total-body positron emission tomography (PET) scanners offer a unique possibility to simultaneously measure various organ functions in the body. Adenosine is routinely used as a pharmacological vasodilator in myocardial perfusion imaging. Purpose The study aimed to investigate sex differences in brain perfusion at rest and during adenosine stress. Methods A total of 130 patients with suspected coronary artery disease and without prior stroke were prospectively recruited to undergo total-body [15O]H2O PET perfusion imaging at rest and during adenosine stress. The brain and the heart were analysed using organ-specific models. K1-derived absolute perfusion for different brain regions was measured using a single-tissue-compartment model. Comparison of regional brain perfusion between sexes was adjusted with the volume of the regions of interest. k2-derived absolute myocardial perfusion was measured for the heart. Results Myocardial perfusion was significantly lower in males (rest median 0.84 [25th-75th percentiles 0.75–0.94] mL/min/g and stress 2.54 [2.15–2.95] mL/min/g) compared with females (rest 1.13 [0.96–1.30] mL/min/g and stress 3.44 [2.75–3.81] mL/min/g) both at rest (p<0.0001) and during adenosine stress (p<0.0001). In males, global brain perfusion was mean 0.42 (SD 0.07) mL/min/mL at rest and 0.30 (0.05) mL/min/mL during adenosine stress (p<0.0001). In females global brain perfusion was 0.46 (0.07) mL/min/mL at rest and 0.34 (0.06) mL/min/mL during adenosine stress (p<0.0001). Volume-adjusted global brain perfusion was significantly higher in females compared to males during adenosine stress (p=0.013), but did not differ between sexes at rest (p=0.7). In the grey matter cortex, brain perfusion during adenosine stress was also significantly lower in males than in females (0.30 (0.05) mL/min/mL vs 0.34 (0.05) mL/min/mL, p=0.03). No difference was observed in white matter at rest (p=0.11) or during adenosine stress (p=0.11). Conclusions Adenosine decreases brain perfusion in both sexes as compared with the resting state. Brain perfusion differs between sexes during adenosine stress. Males appear to have lower volume-adjusted global brain perfusion than females during adenosine stress. Males also had lower brain perfusion during adenosine stress in the grey matter cortex compared to females. The clinical significance of sex differences in brain perfusion warrants further study.