title: Dynamic CT perfusion imaging for the detection of crossed cerebellar diaschisis in acute ischemic stroke.
abstract: OBJECTIVE
  Although the detection of crossed cerebellar diaschisis (CCD) by means of different imaging modalities is well described, little is known about its diagnosis by computed tomography perfusion (CTP) imaging. We investigated the detection rate of CCD by CTP imaging and the factors related to CCD on CTP images in patients with acute ischemic stroke.
  
  
  METHODS
  CT perfusion maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time-to-peak (TTP) obtained from 81 consecutive patients affected by an acute ischemic stroke were retrospectively reviewed. Whole-brain perfusion maps were obtained with a multichannel CT scanner using the toggling-table technique. The criteria for CCD was a unilateral supratentorial ischemic lesion and an accompanying decrease in perfusion of the contralateral cerebellar hemisphere on the basis of CTP maps by visual inspection without a set threshold. Maps were quantitatively analyzed in CCD positive cases.
  
  
  RESULTS
  The criteria for CCD were fulfilled in 25 of the 81 cases (31%). Detection rates per CTP map were as follows: MTT (31%) > TTP (21%) > CBF (9%) > CBV (6%). Supratentorial ischemic volume, degree of perfusion reduction, and infratentorial asymmetry index correlated strongly (R, 0.555-0.870) and significantly (p < 0.05) with each other in CCD-positive cases.
  
  
  CONCLUSIONS
  It is possible to detect CCD on all four of the CTP-based maps. Of these maps, MTT is most sensitive in detecting CCD. Our data indicate that CTP imaging is a valid tool for the diagnosis of CCD in patients affected by an acute hemispheric stroke.
authors.affiliation: Department of Radiology, Wonju Christian Hospital, Yonsei University Wonju College of Medicine, Gangwon-do 220-701, Korea.
authors.forename: Young Wook
authors.initials: YW
authors.lastname: Jeon
authors.forename: Seo Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Ji Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Kum
authors.initials: K
authors.lastname: Whang
authors.forename: Myung Soon
authors.initials: MS
authors.lastname: Kim
authors.forename: Young Ju
authors.initials: YJ
authors.lastname: Kim
authors.forename: Myeong Sub
authors.initials: MS
authors.lastname: Lee
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D002526:Cerebellar Diseases / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008279:Magnetic Resonance Imaging; D008297:Male; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D020521:Stroke / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol