Follow up of coiled intracranial aneurysms 103 Introduction In centers where intracranial aneurysms are treated, the preferred method in most cases is by endovascular coiling.1-4 Follow-up of these coiled aneurysms is necessary because in around 20% of aneurysms coiled with initial success recanalization of the aneurysm lumen occurs over time due to compaction of the coils, growth of the aneurysm or migration of coils into intraluminal thrombus.5-9 Additional treatment is reported to be necessary in about half of these recanalyzed aneurysms.6,10 Intra-arterial digital subtraction angiography (DSA) has until recently been the standard follow-up modality but this is an invasive procedure with a risk of complications, and with relatively high costs.11,12 Magnetic resonance angiography (MRA) appears to be a less invasive and less expensive alternative. In two meta-analyses13,14 and several other studies published since,15-20 the value of this technique has been proven. Non-contrast enhanced time-of-flight MRA (TOF-MRA) was used in most of these studies and the additional value of contrast enhanced MRA (CEMRA) is still under study.16,18,19,21,22 The purpose of this study is to evaluate the performance of CEMRA in the follow-up of coiled intracranial aneurysms, with DSA as the standard of reference. MaterialsandMethods Participants Patients were recruited in the Maastricht University Medical Centre (MUMC). The institutional review board of this center approved the study and all patients provided written informed consent. For patients who have been treated by endovascular coiling, follow-up DSA examinations are routinely scheduled at 6 and 24 months after treatment. Patients due to undergo their regular follow-up DSA were asked to participate in the study, and to undergo an additional CEMRA examination. Patients could be recruited for either the 6-month or 24-month follow-up study or for both. Participants underwent the additional MRA study within 24 hours before or after DSA. CEMRA MRA was performed on a 1.5 Tesla Philips system using a dedicated head coil (Intera; Philips, Best, The Netherlands). The scan protocol included an ultra-short first-pass CEMRA sequence with concentric k-space filling. The scan parameters were as follows: parallel imaging (SENSE, factor 2), TR 5.4 / TE 1.68 ms, flip angle 35 degrees, FOV 256 mm (rectangular FOV 65%), matrix 512, slice thickness 0.4 mm, coronal orientation (parallel to basilar artery), one stack. Contrast medium: gadopentetate dimeglumine (Magnevist®, Bayer Schering Pharma, Leverkusen, Germany) 35 ml IV, at 3 ml/s (2 ml for a timing sequence and 33 ml for the CE-MRA sequence), flushed with 25 ml NaCl 0,9% at 3ml/s. CEMRA studies were post-processed and evaluated by two observers on a dedicated workstation (Vitrea; Vital Images, Minnetonka, Minnesota, USA).
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