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Is dynamic contrast enhanced computer tomography a valuable tool to evaluate the risk of delayed cerebral ischemia in unevaluable patient hospitalized for aneurysmal sub arachnoid hemorrhage?

Introduction: Non-traumatic subarachnoid hemorrhage represents 5% of strokes. For patients in coma or sedated after initial phase of aneurysmal subarachnoid hemorrhage (A-SAH) there are no established parameters to orientate patient management. The aim of our study is to determine whether mean global Ktrans measured by dynamic contrast enhanced CT at day 6 could predict delayed cerebral ischemia (DCI) in clinically unevaluable patient with A-SAH.

Materials and methods: Between January 2011 and January 2017, all patients hospitalized at our institution consulting for non-traumatic subarachnoid hemorrhage were analyzed. Inclusion criteria were: >18 yo, A-SAH, hospitalization in a unit of reanimation within 24 hours, no neurological deficit on admission, Glasgow score <9, DCECT performed in our institution protocol between the 4th and the 8th day after inclusion, MRI performed at 3 months following. All patients had systematically: non-contrast CT scanner, DCECT and CT angiography. 5 parametric maps have been obtained: volume transfer coefficient (Ktrans), mean transit time, time to peak, cerebral blood flow, cerebral blood volume. The quantitative analysis was standardized by the automatic placement of 112 ROI. DCI was defined by a new cerebral infarction identified on MRI at 3 months on FLAIR sequence (FLAIR+ patient). Primary endpoint: is there a link between alteration of Ktrans and occurrence of DCI?

Results: 25 patients have been included, 19 on FLAIR- group, 6 on FLAIR+ group. Using a statistical non parametrical Mann-Whitney test, we found out a significative difference between mean global Ktrans analyzed in FLAIR+ patients and mean global Ktrans analyzed in FLAIR- patients (p=0.039). We did not find in this population a significant difference between the FLAIR+ and FLAIR- patients on the MTT and CBV values, both on the global mean of all the ROI, and on the territories with vasospasm. Subgroup analyzes in FLAIR+ patients did not provide a contributory result either.

Conclusion: Mean global Ktrans measurement on a single DCE CT at day 6 of A-SAH in unevaluable patients predicts the occurrence of DCI and could influence the management of patients at risk.

Keywords : subarachnoid hemorrhage, delayed cerebral ischemia, dynamic contrast enhanced CT, Ktrans, clinically unevaluable patient, MRI, CT angiography.