Quantification of recurrence volumes after endovascular treatment of cerebral aneurysm as surrogate endpoint for treatment stability
- نوع فایل : کتاب
- زبان : انگلیسی
- مؤلف : Thorsten Ries & Karl Wegscheider & Asmus Wulff & Kristin Radelfahr & Dennis Sنring & Nils Daniel Forkert & Jens Fiehler
- چاپ و سال / کشور: 2011
Description
Introduction New coils with unproven clinical benefit enlarge the armamentarium for endovascular aneurysm treatment continuously. Large patient numbers needed to detect benefits of such new techniques prevent timely evaluation of efficacy. We proposemeasuring the volume of aneurysmrecurrences as surrogate endpoint for coil stability. We hypothesize that this method allows detecting effects of newmaterials with reduced sample sizes in comparison to conventional studies with dichotomous endpoints. Methods Institutional review board approval and informed consent were obtained. Fifty-nine patients with decreasing aneurysm size and at least two available follow-up time-offlight magnetic resonance angiographies (ToF-MRAs) were included. Newly developed software for measuring aneurysm volume differences based on ToF-MRA images was used. Based on the observed recurrence volumes and retreatment rates, the sample size for future studies comparing standard versus “new coils” were calculated. Results Mean recurrence volume was 38.92 ىl (SD110.85 ىl). To show a 50% reduction of retreatment rate to control (p= 0.05; power 80%) in a regular study (dichotomous endpoint), the required sample size would be n=356 compared with n= 78 if using the continuous surrogate endpoint “recurrence volume”. When extrapolating our data to data given in the literature, sample sizes could be reduced from n=948 to n=74 without loss of statistical power. Conclusion Further studies on new materials using volumetric analysis based on ToF-MRA as surrogate endpoint could substantially decrease sample size and allow a more timely assessment of possible benefit of new materials with a fraction of the cost.
Neuroradiology (2011) 53:593–598 DOI 10.1007/s00234-010-0764-8 Received: 12 May 2010 / Accepted: 18 August 2010 / Published online: 17 September 2010
