76 Chapter 4 Abstract Background and purpose: Contrast enhanced magnetic resonance angiography (CEMRA) can be used to detect intracranial aneurysms and plan treatment in patients presenting with a subarachnoid hemorrhage (SAH). In Chapters 2 and 3 it is shown that the diagnostic accuracy of CEMRA is not sufficient to replace digital subtraction angiography (DSA) completely, but the use of CEMRA in the work up of patients with SAH might avoid the more invasive and expensive DSA in selected cases, reducing risks and costs. In this study the diagnostic accuracy and costs of four scenarios combining CEMRA with DSA in varying degrees, are compared. Methods: Seventy-five patients consecutively presenting with a SAH had all undergone CEMRA and DSA. In this group 65 aneurysms in 58 patients were found, and two observers were asked to assess retrospectively and in consensus, the feasibility of endovascular treatment (the “coilability”) of the aneurysms. Observers were also asked to indicate the need for an additional DSA study in case of uncertainty about their decision based on CEMRA. All DSA images had been evaluated by the same observers in a separate session, blinded for the CEMRA results. These DSA findings served as the standard of reference. Four scenarios which employed various combinations of CEMRA and DSA, were analyzed with regard to diagnostic accuracy and costs. Results: Sensitivity of CEMRA for predicting coilability, by the two observers in consensus, was 84.2% and specificity 88.9%. The diagnostic costs for these 75 patients in the four scenarios varied from € 30,500 to € 54,375. Limiting the number of DSA studies reduces costs and risks, but also the reliability of determining optimal treatment mode. In one of the simulated scenarios a reduction of 46 DSA studies would have led to one unsuccessful coiling attempt and one clipping of an aneurysm that could have been coiled. Conclusion: Acceptable results can be achieved by performing CEMRA as the first study in patients presenting with a SAH, and reserving additional DSA for cases in which CEMRA does not show an aneurysm, and for patients with aneurysms who are to be referred for surgical clipping, but in whom the CEMRA verdict of non-coilability of the aneurysm leaves room for doubt.
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