Pina C. Sanelli

In this changing health care environment that emphasizes providing higher quality of care while lowering health care costs, it has become increasingly important for physicians to justify the imaging exams, diagnostic tests, and treatments they select for their patients. Because imaging utilization has risen dramatically in the past decade, the use of advanced imaging with CT and MRI has been called into question for several clinical indications. It has now become critical for radiologists to demonstrate the value of imaging in specific clinical conditions to avoid both over- and under-utilization. One such approach is performing comparative and cost-effectiveness research to evaluate different imaging exams (ie, CT versus MRI) by assessing the downstream effects of the imaging in the clinical care pathway by weighing the benefits and risks that occur from imaging, treatment, and complications. Health care costs are incorporated into a cost-effectiveness analysis to understand the economic impact on society for a given intervention or imaging exam.

In aneurysmal subarachnoid hemorrhage (SAH), there is substantial burden on health care resources in society, mainly related to its significant disability and long-term care. Despite advances in techniques for aneurysm repair, poor outcomes remain in aneurysmal SAH partly due to delayed diagnosis and treatment of its secondary complications of vasospasm and delayed cerebral ischemia (DCI). Currently, there are several methods available to assist with the diagnosis of vasospasm and DCI, including clinical examination, neurologic monitoring devices, transcranial Doppler sonography (TCD), CTA and CTP (CTAP), MR diffusion and perfusion imaging, and digital subtraction angiography. At the time we performed our study, emerging data indicated that perfusion imaging may be more accurate for identification of DCI than anatomic imaging of arterial

narrowing or changes in blood flow velocity by TCD. Yet, according to the most recent “Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage: A Guideline for Healthcare Professionals from the American Heart Association/American Stroke Association” (2012), both TCD and perfusion imaging with CT or MRI have been assigned the same class IIa recommendation and level B evidence for detection of vasospasm and DCI. Although CTAP has potential to add important diagnostic information for guiding management and treatment decisions, there were no studies at that time that had assessed the added value of CTAP on clinical outcomes to fully understand its impact in this patient population.

In summary, our results have important implications in clinical practice in managing patients with aneurysmal SAH. Our results reveal that CTAP is the preferred initial imaging strategy compared with TCD because it results in both improved clinical outcomes and lower health care costs. Importantly, these results were consistent in both symptomatic and asymptomatic patients, providing supportive evidence for the widespread implementation of CTAP in the aneurysmal SAH population. In the current economic environment aimed at improving health care quality and reducing costs, imaging patients with aneurysmal SAH with CTAP should achieve both aims.

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