118 Chapter 7 with background information. Patients who did not respond to the invitation letter were contacted by telephone. MR Imaging follow-up protocol MR imaging examinations were performed on 3T systems (Intera R10; Philips Healthcare, Best, The Netherlands) by using the sensitivity encoding (SENSE) phased-array head coil (MR Imaging Devices, Gainesville, FL, USA). The MR imaging protocol included axial T2-weighted fast spin echo and multiple overlapping thin slab acquisition 3D time-of-flight (MOTSA 3D-TOF) MRA sequences. Imaging parameters for the T2-weighted fast spin-echo sequence were the following: TR/TE, 3394/80 ms; 400 x 400 matrix (reconstructed to 512 x 512); FOV, 230-mm; 70% rectangular FOV; 5-mm-thick sections with a 0.5-mm gap. The volume of the MOTSA 3D-TOF MRA was localized on a sagittal 2D phase-contrast scout image. A presaturation band was applied above the imaging volume to saturate incoming venous blood. For the MOTSA 3D-TOF MR imaging, the parameters were the following: a 3D fast-field echo T1- weighted sequence; TR/TE, 21/4 ms; flip angle, 20°; matrix, 512 x 512 (reconstructed to 1024 x 1024); FOV, 200 mm; 85% rectangular FOV; 1.0-mm thick sections, interpolated to 0.5 mm; 160 sections acquired in 8 chunks. The measured voxel size of the MOTSA 3D-TOF MR image was 0.39 x 0.61 x 1 mm, and the reconstructed voxel size was 0.2 x 0.2 x 0.5 mm. The acquisition time of the high-resolution MOTSA 3DTOF sequence was reduced by SENSE parallel imaging. Total MR imaging examination time was 20 minutes. Images were processed into maximum intensity projections and volume rendered 3D images of the circle of Willis. This 3T MRA protocol for follow-up of coiled intracranial aneurysms has been validated in a previous study.13 MR imaging evaluation MRI and MRA images were independently evaluated by 2 experienced neuroradiologists. Discrepancies were resolved in consensus. All MRA studies were scored using the Roy and Raymond (R&R) classification as follows: complete aneurysm obliteration (R&R class 1); residual aneurysm neck (R&R class 2), and residual aneurysm lumen (R&R class 3).2 In order to optimize interobserver agreement these ratings were dichotomized as follows: adequately occluded aneurysm (R&R class 1 and 2) on the one hand, and inadequately occluded aneurysm (R&R class 3) on the other.14 In inadequately occluded R&R class 3 aneurysms, the residual aneurysm lumen was measured in 2 directions. In the case of a de novo aneurysm at the site of the coiled aneurysm, this was not considered a recurrence of the coiled aneurysm. Statistical analysis Percentages with 95% confidence intervals (CI) were calculated for aneurysms that had recanalized. We calculated inter-observer agreement of the dichotomized scores (adequate and inadequate occlusion) per aneurysm in percentages. Correlation between near complete (R&R class 2) initial occlusion status and inadequate occlusion at long term follow-up was calculated for the MUMC cohort and for those patients from the multicenter
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