Arjen Lindenholz

113 Intracranial Atherosclerosis Assessed with 7T MRI 5 Wilmington, MA). The MRI protocol included a pre- and postcontrast three- dimensional (3D) T 1 -weighted intracranial vessel wall sequence (magnetization- prepared inversion recovery turbo spin echo, MPIR-TSE), diffusion weighted imaging (DWI) sequence, T 2 -weighted fluid-attenuated inversion recovery (FLAIR) sequence and a time-of-flight MR angiography (TOF-MRA) sequence. Postcontrast MRI was acquired 5-10 minutes after precontrast MRI. A gadolinium-containing contrast agent (gadobutrol, Gadovist 1.0 mmol/mL, Bayer Schering Pharma, Newbury, UK), with dose adjusted to participant weight, was administered intravenously an average 5 minutes before the performance of the postcontrast MPIR-TSE sequence. The following imaging parameters were used for the 3DMPIR- TSE sequence: sagittal acquisition, field-of-view (FOV), 220 x 180 x 13 mm ( n = 45), which was the single scan parameter that was optimized during the study period to 250 x 250 x 190 mm (whole brain; n = 45) following technical developments, 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. 16,18,21 For the initial 3D MPIR-TSE sequence, the smaller FOV was planned in such a way (transverse / oblique) that the large cerebral arteries of the circle of Willis were within the imaging plane, which included the distal intracranial carotid arteries, the anterior, middle and posterior cerebral arteries, and whenever possible, the basilar artery and vertebral arteries. The two 3D MPIR-TSE sequences with small and large FOV were tested for equality during the study inclusion. 21 Imaging parameters of the TOF-MRA included: FOV, 190 x 190 x 102 mm; acquired spatial resolution, 0.4 x 0.5 x 0.6mm 3 ; reconstructed spatial resolution, 0.4 x 0.4 x 0.3mm 3 ; TR, 21 ms; TE, 2.3 ms; and acquisition time 9 minutes 18 seconds. 18 The images from the TOF-MRA were used for anatomical verification of the vessels seen on the MPIR-TSE images. Data collection For all participants, demographic information, vascular risk factors, 8 final clinical diagnosis and the Trial of ORG 10172 in Acute Stroke Treatment, or TOAST, classification for classifying stroke/TIA subtype were recorded. 22 The vascular risk factors included: body mass index (BMI), hypertension (yes or no), systolic and diastolic blood pressure, hyperlipidemia (yes or no; including low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (all in mmol/L)), diabetes mellitus (yes or no), any peripheral artery disease (yes or no), any previous cardiovascular disease (yes or no; e.g., angina pectoris, atrial fibrillation, myocardial infarction), renal function (expressed in estimated glomerular filtration rate (eGFR), calculated with the Modification of Diet in Renal Disease (MDRD) equation), C-reactive protein (CRP) level, and smoking status (never, current or former smoking, calculated in pack years).