title: Avoiding "pseudo-reversibility" of CT-CBV infarct core lesions in acute stroke patients after thrombolytic therapy: the need for algorithmically "delay-corrected" CT perfusion map postprocessing software.
abstract: OBJECTIVE
  Rarely, acute ischemic stroke (AIS) patients have pretreatment CT-CBV abnormalities larger than final infarct volumes. We sought to determine: (1) the prevalence of CT-CBV "reversibility" in AIS patients treated with thrombolytic therapy, and (2) whether the presumed tissue salvage of these CT-CBV lesions depends on the CTP software.
  
  
  METHODS
  We reviewed the admission CT-CBV maps (calculated with an algorithm sensitive to tracer arrival time) and follow-up images of 148 AIS patients who received thrombolytic therapy. When the follow-up infarct appeared smaller than the admission CT-CBV lesion, the CTP source images were reprocessed using "delay-correction" software (GE, CTP 4). Original and "delay-corrected" CT-CBV ischemic lesion volumes were compared to each other and follow-up infarct volumes using the Student t test.
  
  
  RESULTS
  11/148 (7.4%) patients had admission CT-CBV larger than follow-up lesions (mean difference -69.5 cc, range -146.0 to -14.0 cc; P<0.05). For all patients, the admission CT-CBV lesions were smaller on the delay- versus nondelay-corrected maps (mean difference -83.1, range -233 to -2 cc; P<0.05). Only 2 patients had delay-corrected CT-CBV lesions larger than follow-up infarctions, with a 12- to 17-cc difference in volume. 7/9 of the remaining patients had extracranial hemodynamic factors potentially delaying tracer arrival, including atrial fibrillation (AF; n=4), congestive heart failure (CHF; n=4), or extracranial internal carotid artery (ICA) stenosis (n=1).
  
  
  CONCLUSIONS
  True "reversibility" of CT-CBV "core" lesions in AIS patients after thrombolytic therapy is rare, with small volumes of "salvaged" tissue. Pseudoreversibility of core lesions in standard CT-CBV maps can be avoided by using specific algorithmically optimized delay-correction software. Further investigation is warranted to determine whether this finding applies to algorithms provided by other vendors.
authors.affiliation: Department of Radiology, Division of Neuroradiology, Gray 273A, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA. pschaefer@partners.org
authors.forename: Pamela W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: Kit
authors.initials: K
authors.lastname: Mui
authors.forename: Shahmir
authors.initials: S
authors.lastname: Kamalian
authors.forename: Raul G
authors.initials: RG
authors.lastname: Nogueira
authors.forename: R Gilberto
authors.initials: RG
authors.lastname: Gonzalez
authors.forename: Michael H
authors.initials: MH
authors.lastname: Lev
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002544:Cerebral Infarction / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012984:Software / Q000592:standards*; D020521:Stroke / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy; D015912:Thrombolytic Therapy / Q000379:methods / Q000592:standards*; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards*