Summary 161 patients at the time of presentation, and affirms the efficacy of our centre’s policy of letting a multidisciplinary team decide what type of treatment is given to patients with a ruptured intracranial aneurysm. When an intracranial aneurysm has been coiled, follow-up is recommended because recanalization of a coiled aneurysm occurs regularly. In our own population, increasing compaction of the coil mass was observed in 38.1% during follow-up (72 of 189 aneurysms for which a follow-up study was available), and 16 (22%) of these were retreated. DSA has been used for many years now to assess recanalization of coiled aneurysms at follow-up. Recent studies, however, have shown MRA to be a good alternative. Most of these studies use a flow dependent MRA sequence for recanalization assessment. In order to assess the performance of CEMRA in detecting recanalization, we carried out a prospective study using CEMRA in the follow-up of coiled aneurysms, with DSA as standard of reference, and compared the results with those from studies using flow dependent MRA. The results are described in Chapter 6. We found a sensitivity of 81.8% and negative predictive value of 90.5% for CEMRA, which does not differ from values published in the literature for flow dependent MRA sequences. This study shows that CEMRA can be used in the follow-up of coiled aneurysms, but because CEMRA has such a low positive predictive value (36.7%), additional DSA may be required where incomplete occlusion is seen on CEMRA images. The first follow-up study is usually performed at six months after treatment. In our centre it is standard procedure to follow-up a second time 24 months after treatment. Recently the question was raised in the literature whether prolonged follow-up, when an aneurysm is adequately occluded at six months, yields any advantages. Adequately occluded aneurysms are those that are completely occluded or show a small neck remnant (Class 1 and Class 2 of the Roy and Raymond classification (R&R)). We performed a long-term follow-up study of a group of patients with aneurysms that were adequately occluded at six months follow-up, and investigated the relation between Class 2 R&R at six months and late recanalization. We compared our results to those obtained from the Ferns et al. LOTUS study, of which our group of patients was a subset. This we describe in Chapter 7. Three of our 62 patients (4.8%, 95% Confidence Interval (CI) 1.3-14.4%) with a total of 71 aneurysms (2.5%, 95%CI 1.1-12.7%) showed late recanalization; none of these reopened aneurysms were retreated however (0.0%, 95%CI 0.0-6.4%). All three of the recanalized aneurysms had been classified as completely occluded (Class 1) at the end of the coiling procedure, and at six months follow-up. These results are comparable to those of the LOTUS study, leading to the conclusion that prolonged follow-up, within the first 5-10 years after coiling, is not beneficial in in terms of detecting recanalized aneurysms requiring retreatment in patients with coiled aneurysms that are adequately occluded at 6 months. Furthermore, no relationship was found between Class 2 R&R and late recanalization, and thus a simplification of occlusion classification can be introduced: coiling of aneurysms at 6 months can be described as ‘adequate’ or ‘inadequate’. Chapter 8 describes a study assessing cost-effectiveness of different imaging modalities in patients with non-traumatic SAH. CTA, MRA and DSA and combinations of CTA or MRA with DSA are evaluated, using a decision model that calculates costs and benefits in quality-adjusted life-years (QALYs) accruing to
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