Assessment of cerebral perfusion with dynamic susceptibility contrast

Accurate measurements of arterial input function (AIF) are indispensable for the quantification of perfusion parameters such as mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF). Quantification trials of cerebral perfusion using the disconsolation method with dynamic susceptibility contrast MRI (DSC-MRI) have been reported on. Accurately measuring AIF with DSC-MRI is difficult due to non-linearity and the limited dynamic range between ΔR2* and the concentration of contrast media. In this study, we assessed simple methods while using various parameters calculated by the tissue time intensity curve without measuring AIF. The parameters used were appearance time of contrast media (AT), 1'st moment (MT1), the full width at half maximum (FWHM), and up slope at maximum gradient (US). Difference of the appearance time (delta AT) and the CBFratio between the regions in question and the contralateral regions obtained by MT1, FWHM and US were assessed in 38 stroke patients. The CBF calculated by the linear scaling method using the signal of the ASL (ASL, CBF) was used as the standard for a correlation study. The delta AT in patients with middle cerebral artery occlusions supplied by retrograde flow indicated a significantly greater value as compared to patients with other lesions with antegrade flow. US CBF indicated the best correlation among the three CBFs obtained by MT1, FWHM and US. Both the ASL CBFratio and the US CBFratio correlated with delta AT, with the ASL CBFratio being predominant. The CBVratio-CBFratio map showed that the CBVratio tended to decrease when the CBFratio decreased. The map is useful in clinical analysis of cerebral perfusion due to its simplicity and ability to alleviate AIF dependent errors. The validity of the proposed method still needs to be examined by comparing it to the deconvolution method with DSC-MRI, since DSC-MRI can correct the effect of AIF. It might also be compared to Xenon CT, which is less influenced by transit delay. (author)