| Summary: | 碩士 === 長庚大學 === 醫學影像暨放射科學系 === 100 === Dynamic susceptibility contrast (DSC) MRI is a promising technique for assessment of cerebral blood flow (CBF). Absolute quantification of CBF is desirable for stroke management, longitudinal tumor therapy monitoring and diagnoses of dementia. One of the challenges for quantifying CBF with DSC-MRI is to obtain an accurate estimation of arterial input function (AIF). In particular, identifying the AIF from MR images in small animals may be more problematic due to the inevitable partial-volume effects. Previous researchers had proposed a method of using venous output function (VOF) for calibrating the AIF in DSC-MRI of normal human volunteers. In this study, we aimed to investigate this method for calibrating the AIF in rats, and evaluate the deviation caused by the selection of the VOFs within sagittal sinus. The experiment was performed on six Sprague-Dawley rats. An AIF were obtained from regions close to the middle cerebral artery. Relative CBF was calculated by a deconvolution method with the singular value decomposition algorithm. To calibrate the relative CBF into an absolute estimate, a VOF was obtained from the sagittal sinus. A calibration factor (CF) was calculated as the ratio of areas under the curves (AUC) from VOF versus that from the AIF. The absolute CBF maps were then obtained by dividing the relative maps with the CF. Uncertainty of this method was systematically assessed by choosing each of the available voxels in the sagittal sinus. The results showed that the average CBF values 123.9±34.2 ml/100g/min after calibration were consistent with those in literatures. The uncertainty of this method was in the range of 7.6-27.1%. This study demonstrated that the AIF calibration method using a VOF was feasible in rat studies, and the variation caused by the selection of the VOF was estimated.
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