Arjen Lindenholz

112 CHAPTER 5 Materials and Methods Study participants FromDecember 2009 to September 2017, patients who presented in our University Medical Center Utrecht with ischemic stroke or TIA of the anterior circulation could be included in the intracranial vessel wall imaging (IVI) study (Trial IDNTR2119, www. trialregisters.nl ). Details of this study have been reported previously. 16,21 Additional inclusion criteria were age older than 18 years, the possibility of undergoing 7T MRI within 3 months after symptom onset, and sufficient understanding of the Dutch language to provide written informed consent. Participants were excluded when TIA or ischemic stroke was secondary to a surgical or radiological intervention, when renal function was impaired (estimated glomerular filtration rate < 30mL/ min/1,73m 2 ), or if there was contraindication to 7T MRI (claustrophobia, contraindicated metal objects in or on the body, pregnancy, or physically unable to endure an MRI examination) or to gadolinium-containing contrast agents. A flowchart of the study inclusion is shown in Figure 1 . This prospective study was approved by the institutional review board of our hospital, and all participants gave written informed consent. Figure 1. Flowchart shows the study inclusion and exclusion criteria with the number of participants that were included for analysis. IC, informed consent. MRI protocol MRI was performed on a 7T whole-body system (Philips Healthcare, Cleveland, Ohio) with either a 16-channel (Nova Medical, Wilmington, MA) ( n = 40) or – because of hardware updates during the study inclusion period – a 32-channel ( n = 50) receive coil, and a volume transmit-receive coil for transmission (Nova Medical,