Time course of ADCw changes in ischemic stroke: beyond the human eye!
OBJECTIVE
Using newly developed computerized image analysis, we studied the heterogeneity of apparent diffusion coefficient of water (ADCw) values in human ischemic stroke within 10 hours of onset.


METHODS
Echo-planar trace diffusion-weighted images from 9 patients with focal cortical ischemic stroke were obtained within 10 hours of symptom onset. An Iterative Self-Organizing Data Analysis (ISODATA) clustering algorithm was implemented to segment different tissue types with a series of DW images. ADCw maps were calculated from 4 DW images on a pixel-by-pixel basis. The segmented zones within the lesion were characterized as low, pseudonormal, or high, expressed as a ratio of the mean+/-SD of ADCw of contralateral noninvolved tissue.


RESULTS
The average ADCW in the ischemic stroke region within 10 hours of onset was significantly depressed compared with homologous contralateral tissue (626.6+/-76.8 versus 842.9+/-60.4x10(-6) mm2/s; P<0.0001). Nevertheless, ISODATA segmentation yielded multiple zones within the stroke region that were characterized as low, pseudonormal, and high. The mean proportion of low:pseudonormal:high was 72%:20%:8%.


CONCLUSIONS
Despite low average ADCW, computer-assisted segmentation of DW MRI detected heterogeneous zones within ischemic lesions corresponding to low, pseudonormal, and high ADCw not visible to the human eye. This supports acute elevation of ADCw in human ischemic stroke and, accordingly, different temporal rates of tissue evolution toward infarction.
Nagesh
V
V
Department of Neurology, Henry Ford Health Sciences Center, Detroit Campus of Case Western Reserve University, Mich, USA.
Welch
K M
KM
Windham
J P
JP
Patel
S
S
Levine
S R
SR
Hearshen
D
D
Peck
D
D
Robbins
K
K
D'Olhaberriague
L
L
Soltanian-Zadeh
H
H
Boska
M D
MD
D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001921:Brain / Q000098:blood supply / Q000378:metabolism; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism; D002561:Cerebrovascular Disorders / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D004058:Diffusion; D018450:Disease Progression; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014867:Water / Q000378:metabolism
D014867:Water