MTT Heterogeneity in Perfusion CT Imaging as a Predictor of Outcome after Aneurysmal SAH

Abstract

BACKGROUND AND PURPOSE: Impairment of tissue oxygenation caused by inhomogeneous microscopic blood flow distribution, the so-called capillary transit time heterogeneity, is thought to contribute to delayed cerebral ischemia after aneurysmal SAH but has so far not been systematically evaluated in patients. We hypothesized that heterogeneity of the MTT, derived from CTP parameters, would give insight into the clinical course of patients with aneurysmal SAH and may identify patients at risk of poor outcome. MATERIALS AND METHODS:We retrospectively analyzed the heterogeneity of the MTT using the coefficient of variation in CTP scans from 132 patients. A multivariable logistic regression model was used to model the dichotomized mRS outcome. Linear regression was used to eliminate variables with high linear dependence. T tests were used to compare the means of 2 groups. Furthermore, the time of the maximum coefficient of variation for MTT after bleeding was evaluated for correlation with the mRS after 6 months. RESULTS:On average, each patient underwent 5.3 CTP scans during his or her stay. Patients with high coefficient of variation for MTT presented more often with higher modified Fisher (P ¼ .011) and World Federation of Neurosurgical Societies grades (P ¼ .014). A high coefficient of variation for MTT at days 3-21 after aneurysmal SAH correlated significantly with a worse mRS score after 6 months (P ¼ .016). We found no correlation between the time of the maximum coefficient of variation for MTT after bleeding and the patients' outcomes after 6 months (P ¼ .203).CONCLUSIONS: Heterogeneity of MTT in CTP after aneurysmal SAH correlates with the patients' outcomes. Because the findings are in line with the pathophysiologic concept of the capillary transit time heterogeneity, future studies should seek to verify the coefficient of variation for MTT as a potential imaging biomarker for outcome. ABBREVIATIONS: aSAH ¼ aneurysmal SAH; CTH ¼ capillary transit time heterogeneity; cvMTT ¼ coefficient of variation for MTT; cvMTT-peak ¼ maximum cvMTT after bleeding; DCI ¼ delayed cerebral ischemia; EVD ¼ external ventricular drainage; ICP ¼ intracranial pressure; RTH ¼ relative transit time heterogeneity; Tmax ¼ time-to-maximum; WFNS ¼ World Federation of Neurosurgical Societies

Neuroradiological diagnosis and therapy of cerebral vasospasm after subarachnoid hemorrhage

“…The dynamics of quantitative parameters will become increasingly important as a selection criterion in CT perfusion. Therefore, the possibility of more individualized treatment steps will presumably also be investigated [45,46]. TCD is still a helpful additional diagnostic parameter but does not seem to reliable on its own for detecting CVS: Thus, a meta-analysis including 18 studies showed evidence supporting this method only in the case of spasms in the middle cerebral artery [75].…”

“…That being said, routine CT perfusion in intubated patients particularly in the high-risk phase, i. e., between day 6 and day 10 after SAH, undoubtedly has significant diagnostic value since hypoperfusion with an endovascular treatment option can be detected to a large extent [44]. Newer studies examined subtle changes in parameter maps between individual follow-up CT perfusion examinations [45,46]. It is clear that better selection of EST based on CT perfusion will be the goal in the future.…”

Effects of apolipoprotein E polymorphism on cerebral oxygen saturation, cerebral perfusion, and early prognosis after traumatic brain injury

“…Furthermore, in studies on cerebral perfusion, MTT is considered a sensitive parameter for the early detection of perfusion defects 21,22 . In addition, MTT is less affected by gray and white matter differences and has been shown to be the most reproducible 21,23 . Therefore, in this study, MTT was chosen as the parameter to evaluate cerebral perfusion in patients with TBI.…”

Revisiting the WFNS Score: Native Computed Tomography Imaging Improves Identification of Patients With “False Poor Grade” Aneurysmal Subarachnoid Hemorrhage

“…The patients were managed according to in-house treatment guidelines, which have been described in previous publications. [18][19][20]…”

“…While more elaborate examinations such as CT perfusion imaging are available, these have the major disadvantage of lacking standardized procedures for image acquisition and postprocessing, making data from different neurovascular centers often incomparable. 18,[27][28][29][30][31][32] By contrast, native CT imaging is universally used, well-comparable, and also available in low-budget healthcare systems.…”