Quantitative assessment of cerebral hemodynamics using CT: Stability, accuracy, and precision studies in dogs

Purpose: The limited clinical availability of currently used methods to mea sure regional cerebral blood volume (CBV) and cerebral blood now (CBF) repr esents an important restriction. We undertook this study to evaluate a new dynamic CT method to measure CBV and CBF in normal and ischemic tissue. Method: A total of 21 dynamic CT studies were performed in seven male beagl es. The contrast enhancement curves of the carotid arteries and of various brain regions were deconvolved to obtain CBV and CBF. The stability of the deconvolution method employed was assessed by comparing three data sets obt ained by analyses of one, two, and four regions of interest (ROIs), all cov ering the entire brain area. The accuracy of CT-derived CBF was analyzed fo r normal (n = 5 studies) and ischemic (n = 7 studies) brain tissue using fl uorescent microspheres. Repetitive CT studies were performed to evaluate th e precision of the CT measurements. Results: The stability of the deconvolution method was high with variabilit ies of 2.3% (CBV), 5.9% (CBF), and 8.9% (mean transit time), respectively. The correlation between the CT and the microsphere measurements was good fo r both normal and ischemia studies (r > 0.78, slope > 0.9). The variability of the CT CBF (30.6%) was higher than that of the CT CBV (12.3%) measureme nts. Conclusion: Our novel dynamic CT method is stable with respect to the sizes of ROIs used, allowing for accurate measurements of CBV and CBF in both no rmal and ischemic tissue. Further studies are necessary to evaluate the var iability of this method under controlled physiologic conditions.