title: Negative diffusion-weighted imaging after intravenous tissue-type plasminogen activator is rare and unlikely to indicate averted infarction.
abstract: OBJECTIVE
  Some patients treated with intravenous (IV) tissue-type plasminogen activator (tPA) have negative diffusion-weighted imaging (DWI) on follow-up imaging. Without a visible infarct, there may be uncertainty as to whether the patient was having a stroke that was averted by tPA or whether the symptoms had not been cerebrovascular in origin. We evaluated patients presenting with suspected acute stroke with a positive DWI lesion before IV tPA to determine the probability of finding a negative DWI up to 48 hours after treatment.
  
  
  METHODS
  We included patients from the Lesion Evolution in Stroke and Ischemia On Neuroimaging (LESION) project who had acute MRI screening with a positive DWI lesion before IV tPA treatment and had follow-up MRI up to 48 hours later. Experienced readers interpreted all acute and follow-up MRIs looking for ischemic lesions on DWI.
  
  
  RESULTS
  There were 231 patients who met study inclusion criteria, of which 225 patients (97.4%) had a persistent positive DWI corresponding to the acute stroke lesion on all follow-up imaging. Four patients (1.7%) had transient DWI lesion reversal with positive DWI on subsequent follow-up imaging. There were only 2 cases (0.9%) of complete DWI lesion reversal on all follow-up imaging.
  
  
  CONCLUSIONS
  Averted infarction after IV tPA is rare, occurring in 0.9% of patients with pretreatment positive DWI evidence of acute ischemia. For IV tPA-treated patients who have a negative DWI on follow-up imaging, a cause other than acute stroke should be explored.
authors.affiliation: Section on Stroke Diagnostics and Therapeutics, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
authors.forename: Jason W
authors.initials: JW
authors.lastname: Freeman
authors.forename: Marie
authors.initials: M
authors.lastname: Luby
authors.forename: José G
authors.initials: JG
authors.lastname: Merino
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Latour
authors.forename: Sungyoung
authors.initials: S
authors.lastname: Auh
authors.forename: Shlee S
authors.initials: SS
authors.lastname: Song
authors.forename: Alejandro
authors.initials: A
authors.lastname: Magadán
authors.forename: John K
authors.initials: JK
authors.lastname: Lynch
authors.forename: Steven
authors.initials: S
authors.lastname: Warach
authors.forename: Amie W
authors.initials: AW
authors.lastname: Hsia
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020521:Stroke / Q000175:diagnosis / Q000473:pathology* / Q000517:prevention & control*; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D005343:Fibrinolytic Agents; D010959:Tissue Plasminogen Activator
keywords: MRI; acute stroke; diffusion-weighted imaging; tPA; thrombolytic therapy