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目的探讨脑动、静脉增强曲线最高值及增强峰值对 CT 灌注参数及其图像信噪比(SNR)的影响。方法 17例患者行多层螺旋 CT(MSCT)脑灌注扫描后经灌注软件后处理,每一病例处理6次,生成不同的动、静脉增强曲线。记录每次生成的动、静脉曲线最高值和增强峰值及同侧脑白质、灰质感兴趣区(ROI)内灌注参数,即脑血流量(CBF)、脑血容量(cBV)、平均通过时间(MTT)和表面通透性(PS)的平均值,并由参数平均值除以相应标准差,计算相应 SNR。应用 SPSS 10.0软件包对数据进行 Pearson 相关分析及配对 t 检验。结果 (1)白质平均 SNR_(CBF)为1.61±0.36,灰质为3.01±1.14;白质平均 SNR_(CBV)为2.47±0.66,灰质为3.68±1.12;白质平均 SNR_(MTT)为1.54±0.33,灰质为2.53±0.84;白质平均 SNR_(ps)为0.50±0.16,灰质为0.62±0.21。动、静脉曲线最高值及增强峰值与白质和灰质平均 SNR_(CBF)、SNR(CBV) 及 SNR_(MTT) 值(r 值介于0.332～0.922,P 值均<0.01),以及静脉曲线最高值与白质平均 SNR_(ps)值(r=0.256,P<0.05)之间呈正相关;动脉曲线最高值、增强峰值及静脉增强峰值与白质和灰质平均 SNR_(ps)值,以及静脉曲线最高值与灰质平均 SNR_(ps)值之间无明显相关性(r 值介于-0.058～0.210,P 值均>0.05)。(2)高、低静脉组之间平均 CBF、CBV 及 PS 值的差异均有统计学意义(t 值介于3.830～5.337,P 值均<0.01);高、低静脉组之间平均 MTF 值(白质 t=-0.277,灰质 t=0.329,P 值均>0.05)及高、低动脉组之间所有灌注参数平均值( t 值介于-0.987～1.197,P 值均>0.05)差异均无统计学意义。结论动、静脉曲线最高值及增强峰值对脑CT 灌注图像 SNR 的影响具有统计学意义;静脉曲线最高值及增强峰值对灌注参数平均值的影响具有统计学意义;图像后处理时应该将动、静脉曲线调高以提高灌注参数的准确性及图像 SNR。
Objective To investigate the effects of peak value and enhancement peak of cerebral arteriovenous and venous enhancement curves on CT perfusion parameters and signal-to-noise ratio (SNR) of CT images. Methods Seventeen patients underwent multi-slice spiral CT (MSCT) brain perfusion scanning. After perfusion software was processed, each case was treated 6 times to generate different arteriovenous and venous enhancement curves. The maximum and dynamic peak of arterial and venous curves and perfusion parameters of ipsilateral white matter and gray matter area (ROI) were recorded, including cerebral blood flow (CBF), cerebral blood volume (cBV), mean transit time MTT) and surface permeability (PS), and the corresponding SNR was calculated by dividing the average of the parameters by the corresponding standard deviation. Data were analyzed by Pearson correlation and paired t-test using SPSS 10.0 software package. Results The average CBF of white matter was 1.61 ± 0.36, the gray matter was 3.01 ± 1.14. The average white matter CBV was 2.47 ± 0.66, the gray matter was 3.68 ± 1.12. The average MTT of white matter was 1.54 ± 0.33. The gray matter Was 2.53 ± 0.84; white matter average SNR_ (ps) was 0.50 ± 0.16, gray matter was 0.62 ± 0.21. The mean SNR_ (CBF), SNR (CBV) and SNR_ (MTT) values of the maximum and the peak value of arterial and venous varices were significantly different from those of white matter and gray matter (r = 0.332-0.922, P <0.01) (R = 0.256, P <0.05). The peak value of arterial curve, peak value of enhancement and peak value of venous enhancement and the average value of SNR_ (ps) of white matter and gray matter as well as the peak value of There was no significant correlation between the average SNR_ (ps) values of gray matter (r values ranged from -0.058 to 0.210, P values> 0.05). (2) There were significant differences in average CBF, CBV and PS between the high and low venous groups (t = 3.830-5.337, P <0.01), mean MTF between the high and low venous groups (White matter t = -0.277, gray matter t = 0.329, P value> 0.05) and the average of all perfusion parameters between high and low arterial groups (t value ranged from -0.987 to 1.197, P value all> 0.05) Statistical significance. Conclusions The maximum and peak value of arterial and venous curves have statistical significance on the SNR of brain CT perfusion images. The effect of peak value of venous curve and peak value on the average of perfusion parameters is statistically significant. In image post-processing, Vein curve elevation to improve perfusion parameters accuracy and image SNR.