Influence of Thin Slice Reconstruction on CT Brain Perfusion Analysis

Area of Science:

• Neuroimaging
• Radiology
• Medical Physics

Background:

• CT scanners enable dynamic thin-slice acquisition, but thick slices (≥5 mm) are standard in stroke imaging to reduce data and processing.
• Thin-slice CT perfusion (CTP) reconstruction may minimize partial volume effects, potentially improving quantitative accuracy and resolution.
• Assessing the impact of thin-slice reconstruction on CTP constancy is crucial before clinical adoption.

Purpose of the Study:

• To investigate the influence of thin-slice reconstruction on average CTP values compared to standard thick-slice reconstruction.
• To evaluate the effect of different slice thicknesses on absolute and relative perfusion parameters: cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and permeability-surface area product (PS).

Main Methods:

• Analysis of 50 patient CTP studies using 0.8, 2.4, 4.8, and 9.6 mm slice reconstructions.
• Investigation of the impact of Gaussian and bilateral filtering, arterial input function (AIF), and motion correction on perfusion values.

Main Results:

• Absolute CBF, CBV, and PS were significantly lower with 0.8 mm slices compared to 4.8 mm slices (22%, 14%, and 46% respectively).
• Using thin-slice derived AIF and motion correction reduced these differences to 3%, 4%, and 3%.
• The effect of slice thickness on relative perfusion values was minimal.

Conclusions:

• Thin-slice CTP reconstruction, with an unaltered acquisition protocol, yields relative perfusion values without clinically significant bias.
• Absolute perfusion values, especially CBF and CBV, are affected by thin-slice reconstruction due to partial volume effects in large vessels.
• Reconstruction slice thickness must be considered when utilizing absolute perfusion values for clinical decision-making in stroke imaging.