Rapid quantitative CBF and CMRO2 measurements from a single PET scan with sequential administration of dual 15O-labeled tracers

Positron emission tomography (PET) with ¹⁵O tracers provides essential information in patients with cerebral vascular disorders, such as cerebral blood flow (CBF), oxygen extraction fraction (OEF), and metabolic rate of oxygen (CMRO₂). However, most of techniques require an additional C¹⁵O scan for compensating cerebral blood volume (CBV). We aimed to establish a technique to calculate all functional images only from a single dynamic PET scan, without losing accuracy or statistical certainties. The technique was an extension of previous dual-tracer autoradiography (DARG) approach, but based on the basis function method (DBFM), thus estimating all functional parametric images from a single session of dynamic scan acquired during the sequential administration of H₂¹⁵O and ¹⁵O₂. Validity was tested on six monkeys by comparing global OEF by PET with those by arteriovenous blood sampling, and tested feasibility on young healthy subjects. The mean DBFM-derived global OEF was 0.57±0.06 in monkeys, in an agreement with that by the arteriovenous method (0.54±0.06). Image quality was similar and no significant differences were seen from DARG; 3.57%±6.44% and 3.84%±3.42% for CBF, and ?2.79%±11.2% and ?6.68%±10.5% for CMRO₂. A simulation study demonstrated similar error propagation between DBFM and DARG. The DBFM method enables accurate assessment of CBF and CMRO₂ without additional CBV scan within significantly shortened examination period, in clinical settings.