Propofol allows precise quantitative arterial spin labelling functional magnetic resonance imaging in the rat

Area of Science:

• Neuroscience
• Medical Imaging
• Physiology

Background:

• Functional magnetic resonance imaging (fMRI) studies in animals face challenges with anesthesia-induced blood flow changes and measurement reproducibility.
• Quantitative measurements of cerebral blood flow are crucial for understanding brain activity but are difficult to achieve accurately in animal models.

Purpose of the Study:

• To overcome anesthesia and reproducibility challenges in animal fMRI studies.
• To utilize propofol anesthesia and quantitative arterial spin labeling (QASL) for precise cerebral hemodynamic measurements.
• To assess the reliability of QASL for longitudinal fMRI studies in rats.

Main Methods:

• Utilized propofol anesthesia, known for minimal physiological disturbance.
• Employed quantitative arterial spin labeling (QASL) to measure relative cerebral blood volume (rCBV(lw)), mean transit time (MTT), and capillary transit time (CTT).
• Applied ASL to measure the hemodynamic response in the rat primary somatosensory cortex following forepaw stimulation, with repeated scans on different days.

Main Results:

• Forepaw stimulation led to increased signal intensity and rCBV(lw), with significant decreases in MTT and CTT.
• Repeated scans in two animals demonstrated highly consistent basal and stimulated hemodynamic responses, rCBV(lw), MTT, and CTT values.
• Measurements were reproducible across different experimental days, even when stimulation paradigms varied.

Conclusions:

• Propofol anesthesia causes minimal physiological disturbance, making it suitable for animal fMRI.
• Quantitative arterial spin labeling (QASL) provides reproducible and precise measurements of cerebral hemodynamics in rats.
• The combined use of propofol and QASL holds significant potential for longitudinal fMRI studies in animal models.