Automated perfusion‐weighted MRI using localized arterial input functions

Abstract

Purpose: To investigate the utility of an automated perfusion-weighted MRI (PWI) method for estimating cerebral blood flow (CBF) based on localized arterial input functions (AIFs) as compared to the standard method of manual global AIF selection, which is prone to deconvolution errors due to the effects of delay and dispersion of the contrast bolus. Materials and Methods:Analysis was performed on spinand gradient-echo EPI images from 36 stroke patients. A local AIF algorithm created an AIF for every voxel in the brain by searching out voxels with the lowest delay and dispersion, and then interpolating and spatially smoothing them for continuity. A generalized linear model (GLM) for predicting tissue outcome, and MTT lesion volumes were used to quantify the performance of the localized AIF method in comparison with global methods using ipsilateral and contralateral AIFs. Results:The algorithm found local AIFs in each case without error and generated a higher area under the receiver operating characteristic (ROC) curve compared to both global-AIF methods. Similarly, the local MTT lesion volumes had the least mean squared error (MSE). Conclusion:Automated CBF calculation using local AIFs is feasible and appears to produce more useful CBF maps.

Cerebrovascular Occlusive Disease: Quantitative Cerebral Blood Flow Using Dynamic Susceptibility Contrast MR Imaging Correlates with Quantitative H2[15O] PET

“…In this study we validated the bookend approach for quantifying CBF against (31)(32)(33)(34) has shown promising results for reducing these errors through selected localized AIFs near the perfused capillary bed and AIF correction models that utilize more accurate bolus arrival times and reduce delay-dependent dispersion. Our study showed a difference in MR-PET correlation slopes based on clinical indication-carotid versus intracranial vessel occlusions-suggesting the need for the incorporation of such models.…”

Theoretic Basis and Technical Implementations of CT Perfusion in Acute Ischemic Stroke, Part 2: Technical Implementations

“…Initial attempts to measure a local AIF were problematic due to partial volume effects. 29,30 More recently, automated local AIF selection algorithms for MRP have yielded promising results, 31,32 though experience with CTP is lacking. Alternatively, independent component analysis can be used as a tool to define the local AIF.…”

Effect of using local arterial input functions on cerebral blood flow estimation

“…Unfortunately, there is no ethical and accepted way to define a gold standard perfusion metric in humans. Previous work has shown the utility of the local-AIF approach for predicting tissue outcome poststroke (6). In this study we investigate whether the local-AIF method is achieving its theoretical function, that is, if it is increasing blood flow estimates (relative to the global-AIF method) in voxels with D/D.…”

“…One method is to use a delay-insensitive deconvolution approach (4). Another method that has shown potential is the local-AIF method (5,6). In this approach, an AIF is defined for each voxel based on the voxels local to it.…”