title: Multiparametric iterative self-organizing MR imaging data analysis technique for assessment of tissue viability in acute cerebral ischemia.
abstract: OBJECTIVE
  Defining viability and the potential for recovery of ischemic brain tissue can be very valuable for patient selection for acute stroke therapies. Multiparametric MR imaging analysis of ischemic lesions indicates that the ischemic lesion is inhomogeneous in degree of ischemic injury and recovery potential. We sought to define MR imaging characteristics of ischemic lesions that are compatible with viable tissue.
  
  
  METHODS
  We included patients with supratentorial ischemic stroke who underwent multiparametric MR imaging studies (axial multi-spin-echo T2-weighted imaging, T1-weighted imaging, and diffusion-weighted imaging) at the acute (< 24 hours) and outcome (3 months) phases of stroke. Using the algorithm Iterative Self-Organizing Data Analysis Technique (ISODATA), the lesion was segmented into clusters and each was assigned a number, called the tissue signature (white matter = 1, CSF = 12, all others between these two). Recovery was defined as at least a 20% size reduction from the acute phase ISODATA lesion volume to the outcome phase T2-weighted imaging lesion volume. The tissue signature data were collapsed into the following categories: < or = 3, 4, 5, and > or = 6. Logistic regression analysis included the following parameters: lesion volume, tissue signature value, apparent diffusion coefficient (ADC) value, relative ADC (rADC) expressed as a ratio, T2 value, and T2 ratio. The model with the largest goodness of fit value was selected.
  
  
  RESULTS
  We included 48 patients (female-male ratio, 26:22; age, 64 [+/-14] years; 15 treated with recombinant tissue plasminogen activator [rt-PA] within 3 hours of onset; median National Institutes of Health Stroke Scale score, 7 [range, 2-26]). Median symptom onset-to-MR imaging time interval was 9.5 hours. With ISODATA processing, we generated 200 region-of-interest tissue records (one to nine tissue records per patient). Regarding tissue recovery, we detected a three-way interaction among ADC, ISODATA tissue signature, and previous treatment with rt-PA (P = .003). In the group not treated with rt-PA, ischemic tissues with acute rADC greater than the median (0.79) and tissue signature < or = 4 were more likely to recover (80% vs. 31% and 13%, odds ratio [95% CI]: 0.12 [0.05, 0.30] and 0.04 [0.01, 0.18] for tissue signatures 5 and 6, respectively).
  
  
  CONCLUSIONS
  ISODATA multiparametric MR imaging of acute stroke clearly shows inhomogeneity and different viability of the ischemic lesion. Ischemic tissues with lower acute phase ISODATA tissue signature values (< or = 4) and higher rADC values (> or = 0.79) are much more likely to recover than those with higher signature values or lower rADC values. The effect of these factors on tissue recovery, however, is dependent on whether preceding treatment with rt-PA had been performed. Our approach can be a valuable tool in the design of therapeutic stroke trials with an extended time window.
authors.affiliation: Department of Neurology, Henry Ford Health Sciences Center, Detroit, MI, USA.
authors.forename: Panayiotis D
authors.initials: PD
authors.lastname: Mitsias
authors.forename: James R
authors.initials: JR
authors.lastname: Ewing
authors.forename: Mei
authors.initials: M
authors.lastname: Lu
authors.forename: Mohammed M
authors.initials: MM
authors.lastname: Khalighi
authors.forename: Mamatha
authors.initials: M
authors.lastname: Pasnoor
authors.forename: Hassan B
authors.initials: HB
authors.lastname: Ebadian
authors.forename: Qingming
authors.initials: Q
authors.lastname: Zhao
authors.forename: Sunitha
authors.initials: S
authors.lastname: Santhakumar
authors.forename: Michael A
authors.initials: MA
authors.lastname: Jacobs
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Papamitsakis
authors.forename: Hamid
authors.initials: H
authors.lastname: Soltanian-Zadeh
authors.forename: David
authors.initials: D
authors.lastname: Hearshen
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Patel
authors.forename: Michael
authors.initials: M
authors.lastname: Chopp
mesh_terms: D000208:Acute Disease; D000368:Aged; D000465:Algorithms; D001921:Brain / Q000473:pathology; D001925:Brain Damage, Chronic / Q000175:diagnosis / Q000503:physiopathology; D002544:Cerebral Infarction / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data*; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D011446:Prospective Studies; D015203:Reproducibility of Results; D015912:Thrombolytic Therapy; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D014022:Tissue Survival / Q000502:physiology*
chemical_list: D010959:Tissue Plasminogen Activator