Evaluating CT perfusion using outcome measures of delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage

Abstract

Background and purpose: DCI is a serious complication following aneurysmal SAH and remains a leading cause of morbidity and mortality. Our aim was to evaluate CTP in aneurysmal SAH by using outcome measures of DCI.

Materials and methods: This was a retrospective study of consecutive patients with SAH enrolled in a prospective institutional review board-approved clinical accuracy trial. Qualitative CTP deficits were determined by 2 neuroradiologists blinded to clinical and imaging data. Quantitative CTP was performed by using a standardized protocol with region-of-interest placement sampling of the cortex. Primary outcome measures were permanent neurologic deficits and infarction. The secondary outcome measure was DCI, defined as clinical deterioration. CTP test characteristics (95% CI) were determined for each outcome measure. Statistical significance was calculated by using the Fisher exact and Student t tests. ROC curves were generated to determine accuracy and threshold analysis.

Results: Ninety-six patients were included. Permanent neurologic deficits developed in 33% (32/96). CTP deficits were seen in 78% (25/32) of those who developed permanent neurologic deficits and 34% (22/64) of those without (P < .0001). CTP deficits had 78% (61%-89%) sensitivity, 66% (53%-76%) specificity, and 53% (39%-67%) positive and 86% (73%-93%) negative predictive values. Infarction occurred in 18% (17/96). CTP deficits were seen in 88% (15/17) of those who developed infarction and 41% (32/79) of those without (P = .0004). CTP deficits had an 88% (66%-97%) sensitivity, 59% (48%-70%) specificity, and 32% (20%-46%) positive and 96% (86%-99%) negative predictive values. DCI was diagnosed in 50% (48/96). CTP deficits were seen in 81% (39/48) of patients with DCI and in 17% (8/48) of those without (P < .0001). CTP deficits had 81% (68%-90%) sensitivity, 83% (70%-91%) specificity, and 83% (70%-91%) positive and 82% (69%-90%) negative predictive values. Quantitative CTP revealed significantly reduced CBF and prolonged MTT for DCI, permanent neurologic deficits, and infarction. ROC analysis showed that CBF and MTT had the highest accuracy.

Conclusions: CTP may add prognostic information regarding DCI and poor outcomes in aneurysmal SAH.

Fig 1.

ROC curves for each CTP parameter for the outcomes of permanent neurologic deficits (A), cerebral infarction (B), and DCI (C). Gray curves indicate the upper and lower 95% confidence intervals.

Fig 2.

An 88-year-old woman status post surgical clipping of a left posterior communicating artery aneurysm. On day 7, she developed left upper and lower extremity motor deficits. Initial noncontrast CT (not shown) revealed no evidence of acute infarction, new hemorrhage, or hydrocephalus to explain the new onset of symptoms. CTP demonstrates a large right-sided perfusion deficit with elevated MTT (A) and reduced CBF (B) in the right MCA territory (arrows). Noncontrast CT (C) performed on day 21 shows an infarction involving the right insular region (arrows) corresponding to the CTP deficit.