The Influence Of Maximal Values And Peak Enhancement Values Of Arterial And Venous Enhancement Curves On CT Mean Perfusion Parameter Values And Signal-to-Noise Ratio

ObjectiveTo explore maximal values and peak enhancement values of arterial and venous enhancement curves'influence on mean CT perfiision parameter values and signal - to - noise ratio.Materials and Methods17 patients (9 male, 8 female; mean age, 49 years; age range, 14 ⁷9 years ) underwent brain CT perfusion study. All patients were examined with GE Iightspeedl6 CT scanner. Continuous cine canning (80kV, 200mA, 5 mm thickness, 5mm re - constructional interval) by using "Toggling—Table" technique was started 5 seconds after injection of nonionic iodinated contrast material (50ml contrast material at 4ml/sec for 12.5 seconds) by using an auto - power injector.All of the row perfusion data were analyzed with CT perfusion 3 in AW4.1 workstation. Size of region of interest (ROI) in artery or vein of each case was between 2 ⁶ pixels. (l)The analysis process of one case was carried out for 4 times. And we could obtain 4 different arterial and venous time - density curves of each case. Thus it was accessible to acquire 68 perfusion maps. (2)CT perfusion maps were created for 2 times again: venous curves were different (the curve with low venous peak enhancement value and the curve with high venous peak enhancement) but arterial curves were the same to each other; another 2times: arterial curves were different (the curve with low arterial peak enhancement value and the curve with high arterial peak enhancement) but venous curves were the same. Then small round ROIs of the same size were manually placed on the reference CT image in two predetermined locations in the same side: the frontal white matter and the putamen.Maximal values and peak enhancement values of arterjtland venous time -density curves were measured and recorded as well as mean perfusion parameter values,including cerebral blood flow ( CBF) ,cerebral blood volume (CBV), mean transit time ( MIT) and permeability surface area product ( PS) , and their standard deviation (SD). Signal -to -noise ratio (SNR) was computed by divided mean perfusion parameter value measured in white or gray matter by the SD from that mean value.(l)Pearson correlation coefficients were computed, and corresponding P values were calculated to analyze the correlation between arterial or venous curves' peak enhancement values, as well as the maximal values, and signal - to - noise ratio in ROI of perfusion maps. (2)For comparing the groups with different venous curves or with different arterial curves, two - tailed paired Student t tests were used to compare the mean perfusion parameter values. Statistical significance was declared at the 0.05 level.Results(l)Arteiyland venous curves'peak enhancement values, as well as the maximal values, significantly correlated with mean SNR_CBF, SNR_CBV and SNR_MTT in both white matter and gray matter ( P < 0.01) . Maximal value of venous curve also correlated with SNR_PS in white matter (P <0. 05). Arterial-peak enhancement values, the maximal values and venous peak enhancement values did not significantly correlated with SNRpg in both white matter and gray matter. Significant correlation between venous maximal values and SNRpg were not found in gray matter.(2)Mean CBF, CBV and PS values in both white matter and gray matter of the group of low venous peak enhancement values were significantly different...