Vos Pieter C, Riordan Alan J, Smit Ewoud J, de Jong Hugo W A M, van der Zwan Albert, Velthuis Birgitta K, Viergever Max A, Dankbaar Jan Willem
Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands.
Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Clin Neurol Neurosurg. 2015 Sep;136:139-46. doi: 10.1016/j.clineuro.2015.06.019. Epub 2015 Jul 2.
Perfusion imaging is increasingly used for postoperative evaluation of extracranial to intracranial (EC-IC) bypass surgery. Altered hemodynamics and delayed arrival of the contrast agent in the area fed by the bypass can influence perfusion measurement. We compared perfusion asymmetry obtained with different algorithms in EC-IC bypass surgery patients.
We retrospectively identified all patients evaluated with computed tomography perfusion (CTP) between May 2007 and May 2011 after EC-IC bypass surgery at our institution. CTP images were analyzed with three perfusion algorithms that differ among their ability to anticipate for delayed arrival time of contrast material: the delay-sensitive first-moment mean transit time (fMTT), the semi-delay-sensitive standard singular value decomposition (sSVD) and the delay-insensitive block-circulant SVD (bSVD). The interhemispheric difference in bolus arrival time (ΔBAT) was determined to confirm altered hemodynamics. Interhemispheric asymmetry in perfusion values (mean transit time (MTT) difference, cerebral blood flow (CBF) ratio and cerebral blood volume (CBV) ratio) was compared between the three algorithms. Presence of a new infarct in the treated hemisphere was evaluated on follow-up imaging and perfusion asymmetry was compared between patients with and without infarction.
Twenty-two patients were included. The median interhemispheric difference in ΔBAT was 0.98 s. The median MTT difference was significantly smaller when calculated with the delay-insensitive algorithm than with the other algorithms (0.44 s versus 0.90 s and 0.93 s, p<0.01). The CBF ratio was similar for all algorithms (111.98 versus 112.59 and 112.60). The CBV ratio was similar for all algorithms (113.20 versus 111.95 and 113.97). There was a significant difference in MTT asymmetry between patients with and without infarction with the delay-insensitive algorithm only (1.57 s versus 0.38 s, p=0.04).
In patients with EC-IC bypass surgery, delay-sensitive algorithms showed larger MTT asymmetry than delay-insensitive algorithms. Furthermore, only the delay-insensitive method seems to differentiate between patients with and without infarction on follow-up.
灌注成像越来越多地用于颅外至颅内（EC-IC）旁路手术的术后评估。血流动力学改变以及造影剂在旁路供血区域的延迟到达会影响灌注测量。我们比较了在EC-IC旁路手术患者中使用不同算法获得的灌注不对称性。
我们回顾性确定了2007年5月至2011年5月期间在我们机构接受EC-IC旁路手术后接受计算机断层扫描灌注（CTP）评估的所有患者。使用三种灌注算法分析CTP图像，这三种算法在预测造影剂延迟到达时间的能力上有所不同：对延迟敏感的一阶平均通过时间（fMTT）、半延迟敏感的标准奇异值分解（sSVD）和对延迟不敏感的块循环SVD（bSVD）。确定半球间团注到达时间差异（ΔBAT）以确认血流动力学改变。比较三种算法之间灌注值的半球间不对称性（平均通过时间（MTT）差异、脑血流量（CBF）比值和脑血容量（CBV）比值）。在随访成像中评估治疗半球是否存在新梗死，并比较有梗死和无梗死患者之间的灌注不对称性。
纳入22例患者。ΔBAT的半球间差异中位数为0.98秒。使用对延迟不敏感的算法计算时，MTT差异中位数明显小于使用其他算法时（0.44秒对0.90秒和0.93秒，p<0.01）。所有算法的CBF比值相似（111.98对112.59和112.60）。所有算法的CBV比值相似（113.20对111.95和113.97）。仅使用对延迟不敏感的算法时，有梗死和无梗死患者之间的MTT不对称性存在显著差异（1.57秒对0.38秒，p=0.04）。
在EC-IC旁路手术患者中，对延迟敏感的算法显示出比延迟不敏感的算法更大的MTT不对称性。此外，似乎只有对延迟不敏感的方法能够在随访中区分有梗死和无梗死的患者。
