Imaging local cerebral blood flow by Xenon-enhanced computed tomography--technical optimization procedures

Area of Science:

• Neuroimaging
• Radiology
• Medical Physics

Background:

• Accurate measurement of local cerebral blood flow (LCBF) is crucial for diagnosing and monitoring neurological conditions.
• Previous methods using Xenon-enhanced computed tomography (XeCT) often relied on assumed normal partition coefficients, risking systematic errors.
• Individual variations in brain-blood partition coefficients (Lλ) can be altered by disease, necessitating in vivo measurements.

Purpose of the Study:

• To describe a non-invasive, computer-assisted serial scanning method for measuring LCBF using Xenon gas inhalation.
• To optimize XeCT protocols for enhanced accuracy and spatial resolution in brain imaging.
• To correlate functional blood flow data with anatomical and pathological observations.

Main Methods:

• Utilized optimized XeCT with 5-second scans at one-minute intervals during 8 minutes of 27%-30% Xenon inhalation.
• Employed rapid Xenon delivery via a face mask and state-of-the-art CT scanners.
• Measured in vivo local brain-blood partition coefficients (Lλ) to calculate LCBF, avoiding assumptions of normality.

Main Results:

• Achieved accurate, non-invasive measurement of LCBF with high spatial resolution (26.5 cubic mm).
• Generated color-coded maps of Lλ and LCBF directly onto CT images for functional-anatomic correlation.
• Reported mean cortical gray matter blood flow of 46.3 ± 7.7, subcortical gray matter of 50.3 ± 13.2, and white matter of 18.8 ± 3.2 in normal volunteers.

Conclusions:

• The described XeCT method provides a safe, useful, and non-invasive approach for assessing LCBF.
• Modern CT scanner stability and rapid Xenon saturation enhance the correlation of functional imaging with brain structure.
• This technique allows for precise functional brain imaging, aiding in the evaluation of both normal and abnormal brain states.