Optimal Scaling Approaches for Perfusion MRI with Distorted Arterial Input Function (AIF) in Patients with Ischemic Stroke

Abstract

Background: Diagnosis and timely treatment of ischemic stroke depends on the fast and accurate quantification of perfusion parameters. Arterial input function (AIF) describes contrast agent concentration over time as it enters the brain through the brain feeding artery. AIF is the central quantity required to estimate perfusion parameters. Inaccurate and distorted AIF, due to partial volume effects (PVE), would lead to inaccurate quantification of perfusion parameters. Methods: Fifteen patients suffering from stroke underwent perfusion MRI imaging at the Tri-Service General Hospital, Taipei. Various degrees of the PVE were induced on the AIF and subsequently corrected using rescaling methods. Results: Rescaled AIFs match the exact reference AIF curve either at peak height or at tail. Inaccurate estimation of CBF values estimated from non-rescaled AIFs increase with increasing PVE. Rescaling of the AIF using all three approaches resulted in reduced deviation of CBF values from the reference CBF values. In most cases, CBF map generated by rescaled AIF approaches show increased CBF and Tmax values on the slices in the left and right hemispheres. Conclusion: Rescaling AIF by VOF approach seems to be a robust and adaptable approach for correction of the PVE-affected multivoxel AIF. Utilizing an AIF scaling approach leads to more reasonable absolute perfusion parameter values, represented by the increased mean CBF/Tmax values and CBF/Tmax images.

Arterial input function segmentation based on a contour geodesic model for tissue at risk identification in ischemic stroke

“…Perfusion analysis was done once global AIF was decided by the AIF selection methods. On the lines on past perfusion studies in ischemic stroke, perfusion analysis was done by deconvolution of the tracer kinetic equation 8,23–25 : $$\begin{equation} C_t=C_a \otimes R(t). \end{equation}$$…”

“…CBF is measured as the maximum of $$R(t)$$ 11 . T max is the time $$t$$ for which $$R(t)$$ attains maximum value 11,25 . After estimating CBF and T max for all brain tissues, CBF and T max are represented visually on axial slices.…”

“…11 T max is the time t for which R(t) attains maximum value. 11,25 After estimating CBF and T max for all brain tissues, CBF and T max are represented visually on axial slices. Tissue at risk was identified by thresholding the T max values by T max >6 s.…”

“…On the lines on past perfusion studies in ischemic stroke, perfusion analysis was done by deconvolution of the tracer kinetic equation 8,[23][24][25] :…”

Arterial input functions in dynamic susceptibility contrast MRI (DSC-MRI) in longitudinal evaluation of brain metastases

“…There are several studies on the improvement of AIF measurements for DSC-MRI regarding partial volume effects and single global AIFs versus multiple AIFs (9,10), and regarding automated AIF search methods (8,(11)(12)(13). Selecting AIFs automatically can reduce both the AIF user-dependent variability and expert labor and automated AIF search algorithms are often used in studies seeking quantitative perfusion parameter estimates (14,15).…”