title: Crossed cerebellar diaschisis in acute stroke detected by dynamic susceptibility contrast MR perfusion imaging.
abstract: OBJECTIVE
  Crossed cerebellar diaschisis (CCD), the decrease in blood flow and metabolism in the cerebellar hemisphere contralateral to a supratentorial stroke, is frequently reported on positron-emission tomography (PET) and single-photon emission CT (SPECT) but is rarely described with MR perfusion techniques. This study was undertaken to determine the frequency of CCD observed in acute stroke by retrospective review of a research data base of patients with acute stroke evaluated by diffusion-weighted (DWI) and dynamic contrast susceptibility perfusion MR imaging (PWI).
  
  
  METHODS
  PWI scans of 301 consecutive patients with acute stroke and positive DWI abnormality from a research data base were reviewed. Contralateral cerebellar hypoperfusion was identified by inspection of time-to-peak (TTP) maps for asymmetry with an absence of cerebellar abnormalities on T2-weighted scans, DWI, or disease of the vertebrobasilar system on MR angiography. In a subset of the cases, quantitative analysis of perfusion scans was performed using an arterial input function and singular value decomposition (SVD) to generate cerebral blood flow (CBF) maps.
  
  
  RESULTS
  A total of 47 of 301 cases (15.61%) met the criteria of CCD by asymmetry of cerebellar perfusion on TTP maps. On quantitative analysis, there was corresponding reduction of CBF by 22.75 +/- 10.94% (range, 7.45% to 52.13%) of the unaffected cerebellar hemisphere).
  
  
  CONCLUSIONS
  MR perfusion techniques can be used to detect CCD, though the frequency presented in this series is lower than that commonly reported in the PET/SPECT literature. Nevertheless, with its role in acute stroke and noninvasive nature, MR perfusion may be a viable alternative to PET or SPECT to study the phenomenon and clinical consequences of supratentorial stroke with CCD.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. ddmlin@jhmi.edu
authors.forename: D D M
authors.initials: DD
authors.lastname: Lin
authors.forename: J T
authors.initials: JT
authors.lastname: Kleinman
authors.forename: R J
authors.initials: RJ
authors.lastname: Wityk
authors.forename: R F
authors.initials: RF
authors.lastname: Gottesman
authors.forename: A E
authors.initials: AE
authors.lastname: Hillis
authors.forename: A W
authors.initials: AW
authors.lastname: Lee
authors.forename: P B
authors.initials: PB
authors.lastname: Barker
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002526:Cerebellar Diseases / Q000209:etiology / Q000473:pathology*; D002531:Cerebellum / Q000098:blood supply / Q000473:pathology*; D002560:Cerebrovascular Circulation; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D020521:Stroke / Q000150:complications / Q000473:pathology*; D055815:Young Adult