gms | German Medical Science

Objective: Early detection of vasospasm-related delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH) is of a great importance to prevent the occurrence of delayed infarction associated with permanent disability. CT perfusion (CTP) is used to identify vasospasm-induced perfusion deficits and to support the decision making concerning the initiation of treatment. The aim of this study was to evaluate the diagnostic validity of individual CTP parameters and to establish cut-off values for early prediction of DCI after aSAH.

Method: CTP was routinely performed on day 3 after aSAH. The following CTP parameters were qualitative and quantitative analyzed: cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), time to start (TTS) and time to drain (TTD). ROC analysis was performed for every single parameter in order to establish cut-off values. The occurrence of delayed ischemic neurological deficits (DIND) and delayed cerebral infarction was documented.

Results: A total of 62 patients with aSAH were prospectively enrolled. Early perfusion deficits were found in 35% (21/62) of the patients; ten of them developed DIND (day 5 to day 12) and 14 delayed infarction (day 6 to day 13). Early perfusion deficits were significant correlated to the occurrence of DIND (Pearson 0.26 p=0.03) and delayed infarction (Pearson 0.67 p<0.0001). For the detection of early perfusion deficits the following cut-off values were identified: TTD >4.29 sec, AUC 0.95 p<0.0001; CBF<51.96ml/100ml/min AUC 0.98 p<0.0001; MTT <3.06 sec AUC 0.86 p=0.0005; TTS >1.03 sec AUC 0.84 p=0.0005; TTP >10.04 sec AUC 0.279 p=0.003. CBV showed no significant difference for the diagnosis of early perfusion deficits (AUC 0.68 p=0.006, cut-off <3.02ml/100ml). The sensitivity/specificity of the individual CTP parameters were as followed: TTD 88.9%/87.5%; CBF 94.4%/86.5%; MTT 87.5%/87.5%; TTS 72.2%/93.7%; TTP 77.7%/81.2%; CBV 66.6%/81.2%.

Conclusions: Routine CTP on day 3 after aSAH allows a reliable prediction of DIND and delayed infarction. CBF showed the highest sensitivity but lower specificity at the same time and TTS had the highest specificity but lower sensitivity. TTD is the most sensitive and specific CTP parameter at the same time for the diagnosis of early perfusion deficits and should be part of the quantitative analysis of early CTP.