Arjen Lindenholz

161 MRI Vessel Wall Imaging after Intra-Arterial Treatment for Acute Ischemic Stroke 7 acute ischemic stroke caused by an intracranial anterior circulation occlusion that was visible on computed tomographic angiography (CTA), MR angiography (MRA) or digital subtraction angiography (DSA); and 2. Treatment could be performed within six hours from symptom onset. All patients in the IAT-group were treated under general anesthesia. A thrombosuction device (Penumbra, Inc., Alameda, CA) was used in all patients included in this study. Procedural complications involving the vessel wall, including dissection or perforation, were noted. Imaging Imaging was performed on a 7T whole-body MR system (Philips Healthcare, Best, The Netherlands) with either a 16-channel or a 32-channel receive coil and a volume transmit/receive coil for transmission (Nova Medical, Wilmington, MA, USA). Vessel wall visualization at 7T MRI has been shown to be superior compared with 3T MRI because of a higher contrast-to-noise ratio and image quality. 17,18 The imaging protocol included a dedicated pre- and postcontrast 3D whole- brain T 1 -weighted magnetization-prepared inversion recovery turbo spin-echo (MPIR-TSE) vessel wall sequence and a postcontrast time-of-flight (TOF) MRA. 16 For the postcontrast image acquisitions a gadolinium-containing contrast agent (gadobutrol, Gadovist 1.0 mmol/mL, Bayer Schering Pharma, Newbury, UK), dose- adjusted to patient weight, was administered intravenously. The TOF-MRA images were used for anatomical verification of the vessels seen on the MPIR-TSE images. The following scan parameters were used for the MPIR-TSE sequence: field-of- view (FOV) 220 x 180 x 13 mm 3 , which was optimized to 250 x 250 x 190 mm 3 and satisfactorily tested for equality in vessel wall lesion detection during the study period, 16 acquired spatial resolution 0.8 x 0.8 x 0.8 mm 3 , reconstructed spatial resolution 0.49 x 0.49 x 0.49 mm 3 , repetition time (TR) 3952 ms, echo time (TE) 37 ms, inversion time (TI) 1375 ms, flip-angle (FA) 120 degrees, readout bandwidth 935 Hz, and an acquisition time of 10 minutes 40 seconds. For the small FOV sequence, the FOV was placed so that the distal intracranial carotid artery and middle cerebral artery were included in the FOV. Scan parameters for the TOF- MRA were as follows: 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, FA 30 degrees, readout bandwidth 557 Hz, and an acquisition time of 9 minutes 18 seconds. Image assessment Image assessment was performed offline on a PACS (Picture Archiving and Communication System; IDS7, Sectra Medical Systems, Sectra AB, Sweden). All images were independently assessed by two readers with expertise in reading neurovascular vessel wall images (AK, 9 years of experience and AL, 4 years of experience). Readers were blinded for any patient characteristics. The arterial