title: M2 occlusions as targets for endovascular therapy: comprehensive analysis of diffusion/perfusion MRI, angiography, and clinical outcomes.
abstract: BACKGROUND
  The ideal population of patients for endovascular therapy (ET) in acute ischemic stroke remains undefined. Recent ET trials have moved towards selecting patients with proximal middle cerebral artery (MCA) or internal carotid artery occlusions, which will likely leave a gap in our understanding of the treatment outcomes of M2 occlusions.
  
  
  OBJECTIVE
  To examine the presentation, treatment, and outcomes of M2 compared with M1 MCA occlusions in patients undergoing ET by assessing comprehensive MRI, angiography, and clinical data.
  
  
  RESULTS
  We found that M2 occlusions can lead to massive strokes defined by hypoperfused and infarcted volumes as well as death or moderate to severe disability in nearly 50% of patients at discharge. Compared with M1 occlusions, M2 occlusions achieved similar Thrombolysis in Cerebral Infarction (TICI) 2b/3 recanalization rates, with significantly less hemorrhage. M2 occlusions presented with smaller infarct and hypoperfused volumes and had smaller final infarct volumes regardless of recanalization. TICI 2b/3 recanalization of M2 occlusions was associated with smaller infarct volumes compared with TICI 0-2a recanalization, as well as less infarct expansion, in patients who received IV tissue plasminogen activator as well as those that did not. Successful reperfusion of M2 occlusions was associated with improved discharge modified Rankin scale.
  
  
  CONCLUSIONS
  If suitable as targets of ET, M2 occlusions should be given the same consideration as M1 occlusions.
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Sunil A
authors.initials: SA
authors.lastname: Sheth
authors.affiliation: Department of Radiology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Yoo
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Saver
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA Department of Emergency Medicine, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Sidney
authors.initials: S
authors.lastname: Starkman
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Latisha K
authors.initials: LK
authors.lastname: Ali
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Doojin
authors.initials: D
authors.lastname: Kim
authors.affiliation: Division of Interventional Neuroradiology, University of California Los Angeles, Los Angeles, California, USA Department of Neurosurgery, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Nestor R
authors.initials: NR
authors.lastname: Gonzalez
authors.affiliation: Division of Interventional Neuroradiology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Jahan
authors.affiliation: Division of Interventional Neuroradiology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tateshima
authors.affiliation: Division of Interventional Neuroradiology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Duckwiler
authors.affiliation: Division of Interventional Neuroradiology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Fernando
authors.initials: F
authors.lastname: Vinuela
authors.affiliation: Department of Neurology, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Liebeskind
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002533:Cerebral Angiography / Q000401:mortality / Q000639:trends*; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000401:mortality / Q000639:trends*; D057510:Endovascular Procedures / Q000401:mortality / Q000639:trends*; D005260:Female; D006801:Humans; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000401:mortality / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends; D011446:Prospective Studies; D016896:Treatment Outcome
keywords: Index terms; MRI; endovascular stroke treatment; middle cerebral artery; stroke; thrombectomy