Kinetic analysis of CSF to brain tracer exchange in the pig brain under different anesthetic regimes
Introduction: Anesthesia is known to modulate glymphatic clearance and cerebrospinal fluid (CSF) transport in rodents, but how these effects translate to a larger, gyrencephalic brain is unknown. With its anatomical similarity to the human brain, the pig offers a valuable translational model for examining anesthesia-dependent CSF-to-brain transport. Methods: We used dynamic in vivo SPECT/CT…
Anesthesia's impact on the movement of cerebrospinal fluid (CSF) into the brain of pigs has been studied using advanced imaging techniques. The research, conducted on six-hour intervals following injection of [99mTc]-DTPA into the cisterna magna, compared two anesthesia regimens: ketamine/dexmedetomidine (K/D) and propofol (PRO). The pigs were divided into two groups, with five in each, and their brain and CSF spaces were identified using a sophisticated data-driven analysis.
The study revealed that brain tracer accumulation could be reliably estimated within two hours after injection. Two distinct kinetically different components within the brain parenchyma were identified, with one located near the surface and the other situated deeper and laterally. Similar to findings in rodents, pigs anesthetized with K/D had 62% more tracer accumulation in their brains than those under PRO anesthesia (p=0.002).
Despite similar brain influx rates (p=0.047), K/D-anesthetized pigs exhibited a 52% higher cumulative CSF tracer concentration (p=0.047). This greater CSF retention is believed to be responsible for the majority of the difference, providing more tracer availability for entry into the brain. The findings emphasize the importance of quantifying dynamic CSF tracer concentrations when evaluating CSF-to-brain influx, suggesting that future glymphatic studies should consider this factor.
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