White matter changes in comatose survivors of anoxic ischemic encephalopathy and traumatic brain injury: comparative diffusion-tensor imaging study.
OBJECTIVE
To analyze white matter pathologic abnormalities by using diffusion-tensor (DT) imaging in a multicenter prospective cohort of comatose patients following cardiac arrest or traumatic brain injury (TBI).


METHODS
Institutional review board approval and informed consent from proxies and control subjects were obtained. DT imaging was performed 5-57 days after insult in 49 cardiac arrest and 40 TBI patients. To control for DT imaging-processing variability, patients' values were normalized to those of 111 control subjects. Automated segmentation software calculated normalized axial diffusivity (λ1) and radial diffusivity (λ⊥) in 19 predefined white matter regions of interest (ROIs). DT imaging variables were compared by using general linear modeling, and side-to-side Pearson correlation coefficients were calculated. P values were corrected for multiple testing (Bonferroni).


RESULTS
In central white matter, λ1 differed from that in control subjects in six of seven TBI ROIs and five of seven cardiac arrest ROIs (all P < .01). The λ⊥ differed from that in control subjects in all ROIs in both patient groups (P < .01). In hemispheres, λ1 was decreased compared with that in control subjects in three of 12 TBI ROIs (P < .05) and nine of 12 cardiac arrest ROIs (P < .01). The λ⊥ was increased in all TBI ROIs (P < .01) and in seven of 12 cardiac arrest ROIs (P < .05). Cerebral hemisphere λ1 was lower in cardiac arrest than in TBI in six of 12 ROIs (P < .01), while λ⊥ was higher in TBI than in cardiac arrest in eight of 12 ROIs (P < .01). Diffusivity values were symmetrically distributed in cardiac arrest (P < .001 for side-to-side correlation) but not in TBI patients.


CONCLUSIONS
DT imaging findings are consistent with the known predominance of cerebral hemisphere axonal injury in cardiac arrest and chiefly central myelin injury in TBI. This consistency supports the validity of DT imaging for differentiating axon and myelin damage in vivo in humans.
From the Department of Neuroradiology (A.W.v.d.E., D.D., D.G.), the Neurosurgical ICU (P.S., L.P.), and the Medical ICU (C.E.L.), Hôpital Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, 47-83 boulevard de l'Hôpital, 75651 Paris Cedex 13, France; Departments of Radiology (A.W.v.d.E.) and Neurology (P.E.V.), Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands; INSERM, UMRS 678, Université Pierre et Marie Curie-Paris 6, Paris, France (V.P., H.B.); Department of Radiology, Massachusetts General Hospital, Boston, Mass (O.K., J.D., R.G.); Division of Neuroscience Critical Care, Department of Anesthesiology Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Md (R.D.S.); Department of Neuroradiology, Guy de Chauliac Hospital, Montpellier, France (N.M.d.C.); Department of Neuroradiology, Roger Salengro Hospital, Lille, France (C.D.); Department of Neuroradiology, Centre Hospitalier Universitaire, Rouen, France (E.T.); and Cyclotron Research Center, University of Liège, Liège, Belgium (S.L., A.V.).
Anke W
AW
van der Eerden
Omid
O
Khalilzadeh
Vincent
V
Perlbarg
Julien
J
Dinkel
Paola
P
Sanchez
Pieter E
PE
Vos
Charles-Edouard
CE
Luyt
Robert D
RD
Stevens
Nicolas
N
Menjot de Champfleur
Christine
C
Delmaire
Eleonore
E
Tollard
Rajiv
R
Gupta
Didier
D
Dormont
Steven
S
Laureys
Habib
H
Benali
Audrey
A
Vanhaudenhuyse
Damien
D
Galanaud
Louis
L
Puybasset
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000473:pathology*; D016022:Case-Control Studies; D003128:Coma / Q000473:pathology; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000473:pathology*; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011446:Prospective Studies