Detection of B-CSF permeability barrier for 99mTc-sestamibi in vivo in human and rat. (A) Coronal human brain SPECT image 90 min after intravenous injection of 99mTc-sestamibi (Right); a gadolinium-chelate contrast-enhanced T1-weighted coronal head MRI (Left); and coregistered image (Center) of a human volunteer. Arrowheads on the MRI demarcate CP visualized bilaterally within the lateral ventricles. Note the radioactive drug localized to the CP. (B) In anesthetized rats, microdialysate samples from a cannulated lateral ventricle (○, ●) and concurrent blood samples from the periorbital plexus (□, ■) were collected at the indicated times after tail-vein injection of 99mTc-sestamibi in the absence (○, □) or presence of 250 mg/kg GF120918 (●, ■) and then counted for γ-activity. In the absence of GF120918, there is a 100-fold lower drug concentration in CSF compared with blood. Data represent a typical experiment from three independent experiments under each condition.