Comparison of CT Perfusion and Digital Subtraction Angiography in the Evaluation of Delayed Cerebral Ischemia

Abstract

Rationale and Objectives Delayed cerebral ischemia (DCI) is a devastating condition that occurs secondary to aneurysmal subarachnoid hemorrhage (A-SAH). The purpose is to compare CT perfusion (CTP) and digital subtraction angiography (DSA) for determining DCI in A-SAH. Materials and Methods A retrospective study of A-SAH patients admitted at our institution between December 2004 and December 2008 was performed. CTP and DSA were obtained at days 6–8 following aneurysm rupture. Both qualitative and quantitative analyses of CT perfusion deficits were performed. DSA was categorized as presence or absence of vasospasm. The reference standard for determining DCI was based on clinical deterioration or infarction on CT or MRI. The test characteristics of CTP and DSA were calculated and their graphs of conditional probabilities were constructed using Bayesian analysis. Results Fifty-seven patients were included; 79%(45/57) had DCI. Seventy percent(40/57) had CTP perfusion deficits; 80%(36/45) of the DCI and 33%(4/12) of no DCI patients. Sixty-three percent(36/57) had DSA demonstrating vasospasm; 73%(33/45) of the DCI and 25%(3/12) of no DCI patients. Quantitative analysis of the CTP data revealed a significant difference in cerebral blood flow values for the DCI (29.4 mL/100gm/min) and no DCI groups (40.5 mL/100gm/min, p=0.0213). The sensitivity, specificity, positive and negative predictive values for CTP were 0.80(95% CI 0.68–0.92), 0.67(95% CI 0.40–0.93), 0.90(95% CI 0.82–0.96), 0.47(95% CI 0.27–0.62) and for DSA were 0.73(95% CI 0.60–0.86), 0.75(95% CI 0.50–0.99), 0.92(95% CI 0.82–0.98) and 0.43(95% CI 0.26–0.53), respectively. Conclusion CTP and DSA have similar test characteristics and Bayesian analysis for determining DCI in A-SAH patients.

Early whole-brain CT perfusion for detection of patients at risk for delayed cerebral ischemia after subarachnoid hemorrhage

“…This is reflected by available studies, in which CTP was performed once between Days 5 and 14, which represent the days with the highest probability of vasospasm occurrence. 1,4,12,15,17,18,23,28,29,35,36 A correlation between hypoperfusion in CTP and vasospastic infarction was found. However, the retrospective design of these studies, with inappropriate imaging time points and perfusion measurements in preselected regions instead of global brain perfusion, failed to show a therapeutically relevant correlation between hypoperfusion and tissue at risk for stroke development.…”

“…However, the retrospective design of these studies, with inappropriate imaging time points and perfusion measurements in preselected regions instead of global brain perfusion, failed to show a therapeutically relevant correlation between hypoperfusion and tissue at risk for stroke development. 4,12,15,17,18,23,29,35,36 Recently, whole-brain CTP became available, which might at least overcome the problem of focal perfusion measurement. 10,25,37,38 The aim of this prospective study was to evaluate the role of whole-brain CTP for the identification of tissue at risk for DCI and, thereby, of patients at risk for developing DIND and/or vasospasm-associated infarction, either 1) early after aSAH, prior to the vasospasm period; 2) during rapidly progressive TCD-confirmed vasospasm with or without symptoms; and/or 3) on Day 7 in patients who were comatose or sedated and could not be neurologically assessed.…”

“…3,12,17,18,21,28,29 The ideal diagnostic tool should be noninvasive, easy, fast, and repeatable, and should allow not only the identification of patients with vasospasm but also of patients at risk for DIND and DCI. Digital subtraction angiography (DSA) is considered the gold standard for the diagnosis of cerebral vasospasm, but its invasiveness precludes its use for monitoring purposes.…”

“…18,30 Computed tomography perfusion (CTP) allows visualization of brain perfusion and has been applied in brain tumors, ischemic stroke, and aSAH. 1,4,10,12,14,15,[17][18][19]23,25,28,33,[36][37][38] A disadvantage of CTP is the exposure to radiation, which precludes its frequent use. This is reflected by available studies, in which CTP was performed once between Days 5 and 14, which represent the days with the highest probability of vasospasm occurrence.…”

Evaluating the diagnostic accuracy of CT perfusion in patients with cerebral vasospasm after aneurysm rupture: a meta-analysis

“…Three articles were excluded because the reported data could not construct the fourfold tables (6,12,16). Two articles were not included because one was a reduplicated study (8) and one was a conference abstract. With the two articles identified from previous meta-analysis, a total of three articles (10,11,17) were eventually included in this analysis (Figure 1).…”