Elsevier

Academic Radiology

Volume 18, Issue 9, September 2011, Pages 1094-1100
Academic Radiology

Radiological alliance for health services research
Comparison of CT Perfusion and Digital Subtraction Angiography in the Evaluation of Delayed Cerebral Ischemia

https://doi.org/10.1016/j.acra.2011.04.004Get rights and content

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 computed tomography 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 after 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/100 g/minute) and no DCI groups (40.5 mL/100 g/minute, P = .0213). The sensitivity, specificity, and 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.

Section snippets

Study Population

A retrospective study of A-SAH patients was performed from consecutive patients admitted at our institution between December 2004 and December 2008. Inclusion criteria were adult patients (18 years and older) with documented A-SAH at admission and who underwent both CTP and DSA during hospitalization. During the time of this study, CTP was performed as routine imaging for A-SAH patients. DSA was performed in patients who had signs or symptoms of vasospasm and for follow-up evaluation of

Study Population Characteristics

A total of 108 patients were admitted to our institution with A-SAH between December 2004 and December 2008. CTP was performed in 104 patients and DSA was performed in 57 of these 104 patients. Therefore, 57 patients (those who had both CTP and DSA) were included in this study. Seventy-nine percent (45/57) were classified as DCI and 21% (12/57) as no DCI according to the reference standard. The clinical and demographic characteristics of the study population are presented in Table 1. The age

Discussion

DCI is a devastating condition that occurs secondary to A-SAH and contributes to significant morbidity and mortality in this patient population. A diagnosis of DCI is based on clinical criteria for the presence of clinical deterioration not explained by other causes or imaging criteria for new infarction not attributed to the initial hemorrhagic event or postoperative changes (2). The difficulty with using this definition of DCI in clinical practice is that once infarction has occurred,

Conclusion

In summary, this study demonstrates that CTP and DSA have similar test characteristics for determining DCI in A-SAH patients. Performing Bayesian analysis in this study population illustrates the situations when testing with CTP and DSA will likely be useful. This application of probability theory provides a better understanding of the appropriate utilization of CTP and DSA in clinical practice for patients with low and high HH grades.

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  • A.D. was partially supported by Clinical Translational Science Center (CTSC) (NIH UL1-RR024996). This publication was made possible by Grant Number 5K23NS058387-02 from the National Institute of Neurological Disorders and Stroke (NINDS), a component of the National Institutes of Health (NIH). Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NINDS or NIH.

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