Predictors of apparent diffusion coefficient normalization in stroke patients.
OBJECTIVE
We sought to describe the frequency of normalization of apparent diffusion coefficient (ADC) values that are decreased in hyperacute stroke and to identify characteristics of tissue demonstrating normalization.


METHODS
Sixty-eight acute ischemic stroke patients underwent MRI examination (including diffusion/perfusion imaging and MR angiography) within 6 hours (mean, 2.8 hours) after symptom onset, after 24 hours, and again 4 to 7 days later. Lesion volumes with decreased ADC and delayed time to peak in perfusion imaging were determined. In patients showing ADC normalization, volumes with ADC decrease graded as <50%, 50% to 60%, 60% to 70%, and 70% to 80% of the contralateral value were determined by thresholding. Patients were categorized as normalizers (demonstrating ADC normalization in >5 mL tissue with initially decreased ADC) or nonnormalizers (demonstrating ADC normalization in <5 mL tissue).


RESULTS
Fourteen patients (19.7%) were classified as normalizers. Eleven of 31 patients (35.5%) initially imaged <3 hours after stroke onset and 3 of 37 (7.5%) of those imaged 3 to 6 hours after onset were normalizers. ADC normalization occurred predominantly in the basal ganglia and white matter after thrombolytic therapy in patients with more distal vessel occlusions. All normalizers demonstrated at least partial tissue reperfusion. Tissue with more severe initial decrease in ADC was less likely to demonstrate normalization.


CONCLUSIONS
ADC normalization is not a rare event in acute stroke after tissue reperfusion. Brain tissue with initially decreased ADC, especially within 3 hours after stroke onset, may include "tissue at risk."
Fiehler
Jens
J
Department of Neuroradiology, University Hospital Eppendorf, University of Hamburg, Hamburg, Germany. fiehler@uke.uni-hamburg.de
Knudsen
Karina
K
Kucinski
Thomas
T
Kidwell
Chelsea S
CS
Alger
Jeffry R
JR
Thomalla
Götz
G
Eckert
Bernd
B
Wittkugel
Oliver
O
Weiller
Cornelius
C
Zeumer
Hermann
H
Röther
Joachim
J
D000208:Acute Disease; D000328:Adult; D000368:Aged; D002545:Brain Ischemia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D020521:Stroke / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D013997:Time Factors