Arjen Lindenholz

137 Intracranial Atherosclerotic Burden and Cerebral Parenchymal Changes at 7T MRI 6 Imaging protocol Imaging was performed on a 7T whole-body system (Philips Healthcare, Best, The Netherlands) with either a 16-channel ( n = 35) or a 32-channel ( n = 47) receive coil and a volume transmit-receive coil for transmission (Quad TR; Nova Medical, Wilmington, MA, USA). The protocol included a pre- and postcontrast T 1 -weighted intracranial vessel wall sequence (magnetization-prepared inversion recovery turbo spin-echo, MPIR-TSE), time-of-flight MR angiography (TOF-MRA) , diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) imaging. The postcontrast MPIR-TSE sequence was acquired five minutes after the administration of 0.1 mL/kg of a gadolinium-containing contrast agent (gadobutrol, Gadovist 1.0 mmol/mL, Bayer Schering Pharma, Newbury, UK). The TOF-MRA images were used for anatomical verification of the large intracranial vessels seen on the MPIR-TSE images. The following acquisition parameters were used for the MPIR-TSE sequence: field-of-view (FOV) 220 x 180 x 13mm 3 ( n = 40), which was extended during the study period to 250 x 250 x 190 mm 3 ( n = 42), 23 acquired spatial resolution 0.8 x 0.8 x 0.8 mm 3 , reconstructed spatial resolution 0.5 x 0.5 x 0.5 mm 3 , repetition time (TR) 3952 ms, echo time (TE) 37 ms, inversion time (TI) 1375 ms, and acquisition time 10 minutes 40 seconds. In case of the smaller FOV sequence, the FOV was placed in such a way that all large intracranial arteries of the anterior circulation were within the imaging plane, which included the anterior cerebral arteries (ACA; A1 and A2 segments), middle cerebral arteries (MCA; M1 and M2 segments), and the distal parts of the internal (intracranial) carotid arteries (ICA; clinoid, supra-clinoid and terminal segments). Acquisition parameters for the other sequences were as follows: for the TOF-MRA, FOV 190 x 190 x 102 mm 3 , acquired spatial resolution 0.4 x 0.5 x 0.6 mm 3 , reconstructed spatial resolution 0.4 x 0.4 x 0.3 mm 3 , TR 21 ms, TE 2.3 ms, and acquisition time 9 minutes 18 seconds; for the DWI, FOV 220 x 220 x 123 mm 3 , acquired and reconstructed spatial resolution 1.5 x 1.5 x 1.5 mm 3 , TR 17659 ms, TE 57 ms, and acquisition time 6 minutes 10 seconds; and for the FLAIR sequence, FOV 250 x 250 x 190 mm 3 , acquired spatial resolution 0.8 x 0.8 x 0.4 mm 3 , reconstructed spatial resolution 0.5 x 0.5 x 0.5 mm 3 , TR 8000 ms, TE 300 ms, TI 2200 ms, and acquisition time 10 minutes 48 seconds (for more details see reference 11 ). Vessel wall assessment The MR vessel wall images were scored by an expert in reading intracranial vessel wall images (AK, 9 years of experience). The reader was blinded for patient details and clinical information. Interrater reproducibility measures for the assessment of these vessel wall images have been published before (intraclass correlation coefficient, 0.93; 95% CI; 0.90-0.96; Dice similarity coefficient (DSC), 0.81. 25 For the current study, intracranial vessels of the anterior circulation were assessed, including the ACA (A1 and A2 segments), MCA (M1 and M2 segments) and the ICA