Using CT perfusion during the early baseline period in aneurysmal subarachnoid hemorrhage to assess for development of vasospasm.

INTRODUCTION: The aim of this study is to evaluate computed tomography perfusion (CTP) during admission baseline period (days 0-3) in aneurysmal subarachnoid hemorrhage (A-SAH) for development of vasospasm. METHODS: Retrospective analysis was performed on A-SAH patients from Dec 2004 to Feb 2007 with CTP on days 0-3. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) maps were analyzed for qualitative perfusion deficits. Quantitative analysis was performed using region-of-interest placement to obtain mean CTP values. Development of vasospasm was determined by a multistage hierarchical reference standard incorporating both imaging and clinical criteria. Student's t test and threshold analysis were performed. RESULTS: Seventy-five patients were included, 37% (28/75) were classified as vasospasm. Mean CTP values in vasospasm compared to no vasospasm groups were: CBF 31.90 ml/100 g/min vs. 39.88 ml/100 g/min (P < 0.05), MTT 7.12 s vs. 5.03 s (P < 0.01), and CBV 1.86 ml/100 g vs. 2.02 ml/100 g (P = 0.058). Fifteen patients had qualitative perfusion deficits with 73% (11/15) developed vasospasm. Optimal threshold for CBF is 24-25 mL/100 g/min with 91% specificity and 50% sensitivity, MTT is 5.5 s with 70% specificity and 61% sensitivity and CBV is 1.7 mL/100 g with 89% specificity and 36% sensitivity. CONCLUSION: These initial results support our hypothesis that A-SAH patients who develop vasospasm may demonstrate early alterations in cerebral perfusion, with statistically significant CBF reduction and MTT prolongation. Overall, CTP has high specificity for development of vasospasm. Future clinical implications include using CTP during the baseline period for early identification of A-SAH patients at high risk for vasospasm to prompt robust preventative measures and treatment.

Work-in-progress toward incorporating patients' preferences in practice guidelines for imaging aneurysmal subarachnoid hemorrhage.

RATIONALE AND OBJECTIVES: Patient-centered care has become a primary focus in clinical practice. In developing practice guidelines for clinical care, the patients' perspective is an important component. MATERIALS AND METHODS: Patients' preferences are represented in a decision analytic model as quality-of-life weights for different health states associated with the aneurysmal subarachnoid hemorrhage population. The time-tradeoff method is used to obtain the individual patients' preferences, which are directly measured in quality-adjusted life years. An individualized care model is explained as a means of implementing a patient-centered approach into practice guidelines for clinical care. A method for calculating the expected value for societal benefit from improved decision making using an individualized care model is reviewed. RESULTS: We discuss our work-in-progress towards incorporating patients' preferences in a decision analytic model for aneurysmal subarachnoid hemorrhage patients. The main methodologic concerns for using patients' preferences in cost-effectiveness analyses for developing practice guidelines are discussed. CONCLUSION: Emphasis is placed on using patients' preferences and patient-centered outcome measures in cost-effectiveness analyses.