Iatrogenic Diffusion-Weighted Imaging Lesions: What Is Their Impact and How Can It Be Measured?

Infarct volume in acute ischemic stroke is closely linked with clinical outcome, with larger infarct volumes being associated with a worse prognosis. Small iatrogenic infarcts, which can occur as a result of surgical or endovascular procedures, are often only seen on diffusion-weighted MR imaging. They often do not lead to any overtly appreciable clinical deficits, hence the term covert or silent infarcts. There is relative paucity of data on the clinical impact of periprocedural hyperintense diffusion-weighted MR imaging lesions, partly because they commonly remain undiagnosed. Clearly, a better understanding of iatrogenic periprocedural diffusion-weighted MR imaging lesions and their clinical significance is needed. In this article, we describe the current limitations of our understanding of the significance of iatrogenic diffusion-weighted MR imaging lesions using exemplary data from the ENACT trial (Safety and Efficacy of NA-1 in Patients With Iatrogenic Stroke After Endovascular Aneurysm Repair) and outline a framework for how to investigate their clinical impact.