Arjen Lindenholz

160 CHAPTER 7 Materials and Methods Study population From December 2009 to November 2017, patients with an acute ischemic stroke in the anterior circulation who were treated at the neurology department of the University Medical Center Utrecht were screened for inclusion. Patients were retrieved from the ongoing Intracranial Vessel wall Imaging (IVI) study (NTR2119, www.trialregister.nl ), a prospective vessel wall MRI study recruiting patients who presented with clinical symptoms of anterior circulation ischemia (transient ischemic attack (TIA) or stroke). 14 Main inclusion criteria for the current study were age older than 18 years and the possibility of undergoing a 7T MRI examination within three months after symptom onset. The patients without IAT were selected basedonananterior circulationnon-lacunar infarct. Patientswith contraindications for MR imaging or for gadolinium-containing contrast agents were excluded, as well as patients with ischemic stroke caused by vasculitis, reversible cerebral vasoconstriction syndrome, small vessel disease or secondary to a recent surgical or interventional procedure. Additional exclusion criteria for the current study were primary treatment with a different strategy than a thrombosuction device for the IAT-group to improve study population homogeneity, and previous IAT or TIA as final diagnosis for the non-IAT group. Findings of 23 patients without IAT have been published before. 15,16 These prior articles dealt with sequence development and vessel wall lesion prevalence whereas in this study we report longer-term intracranial vessel wall enhancement after IAT using thrombosuction compared with patients not treated with IAT. This study was approved by the Institutional Review Board of our hospital and all patients gave written informed consent. For all patients, baseline characteristics including age, sex, vascular risk factors, stroke severity expressed using the National Institutes of Health Stroke Scale (NIHSS) as well as stroke classification and time intervals between IAT and imaging were collected. For the IAT-group, time intervals between symptom onset and treatment, procedural time, number of passes needed for thrombus removal, and concomitant treatment with intravenous (IV) recombinant tissue- type plasminogen activator (alteplase), were additionally collected. Treatment Treatment was performed as part of standard clinical care. All patients who were eligible for intravenous thrombolysis received IV alteplase within the 4.5-hour time window from symptom onset. IAT was introduced in our center during the study period, after the international IAT trial results, and the first patient treated with a thrombosuction device was included in 2014. Themain criteria for IAT were derived from the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in The Netherlands (MR Clean) trial: 1 1. A clinical diagnosis of