A protocol for assessing subtraction errors of arterial spin-tagging perfusion techniques in human brain

Area of Science:

• Medical Imaging
• Neuroimaging
• Biophysics

Background:

• Arterial spin-labeling (ASL) techniques are crucial for non-invasive brain perfusion imaging.
• Static tissue signal contributions, or subtraction errors, can compromise the accuracy of ASL perfusion quantification.
• Accurate assessment of these errors is essential for reliable clinical interpretation.

Purpose of the Study:

• To propose and validate a novel protocol for assessing static tissue signal contributions in human brain ASL perfusion imaging.
• To exploit the T(1) reduction effect of gadolinium-based contrast agents for error assessment.
• To enable in vivo calibration of ASL parameters that cause subtraction errors.

Main Methods:

• Development of a protocol using multislice FAIR ASL images acquired before, during, and after Gd-DTPA administration.
• Utilizing a range of selective inversion widths to differentiate signal from static tissue.
• Comparison of in vivo results with phantom data to confirm the necessity of in vivo experiments.

Main Results:

• Perfusion images acquired with inversion widths above a specific threshold, avoiding interaction with the imaging slice, showed signal intensities reduced to noise level post-contrast.
• Images acquired with inversion widths below the threshold exhibited significant subtraction errors.
• The protocol demonstrated successful clinical application in human brain imaging.

Conclusions:

• The proposed protocol effectively assesses and quantifies static tissue signal contributions in ASL perfusion imaging.
• The method allows for a one-time in vivo calibration of critical ASL parameters, such as selective inversion widths.
• This calibration is vital for mitigating subtraction errors and enhancing the diagnostic accuracy of ASL perfusion studies.