CT brain perfusion protocol to eliminate the need for selecting a venous output function.

Area of Science:

• Radiology
• Medical Imaging
• Cerebrovascular Imaging

Background:

• Cerebral blood volume (CBV) measurement in computed tomography perfusion (CTP) relies on an arterial input function (AIF).
• Partial volume effects can significantly influence AIFs, leading to overestimated CBV and introducing variability through manual venous output function correction.

Purpose of the Study:

• To develop a CTP protocol that enables AIF selection free from partial volume effects.
• To optimize CTP imaging parameters for accurate AIF determination in cerebrovascular studies.

Main Methods:

• Evaluated the impact of partial volume effects on artery sizes, including the MCA, using a CTP phantom with varying section thicknesses (1, 1.8, 5 mm) and image resolutions (0.5, 1, 1.5 mm).
• Applied selected CTP protocols to clinical data from 6 patients, comparing time-attenuation curves from arteries and reference veins to quantify partial volume influence.

Main Results:

• AIFs derived from MCAs were unaffected by partial volume effects with a 1-mm image resolution and 1.8-mm section thickness.
• Clinical data analysis confirmed that high resolution and thin sections facilitate AIF selection without partial volume influences.
• Observed that large veins are susceptible to partial volume effects, similar to large arteries, challenging their use for correction.

Conclusions:

• A CTP protocol combining 1.8-mm section thickness and 1-mm image resolution is effective for selecting MCAs for AIF measurement without partial volume effects.
• This optimized protocol enhances the reliability of CBV measurements in CTP by ensuring accurate AIFs.