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Updated: Aug 29, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Predictors of apparent diffusion coefficient normalization in stroke patients
Jens Fiehler1, Karina Knudsen, Thomas Kucinski
1Department of Neuroradiology, University Hospital Eppendorf, University of Hamburg, Hamburg, Germany. fiehler@uke.uni-hamburg.de
Background And Purpose:
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."
Insights
Apparent diffusion coefficient (ADC) normalization in acute stroke is common, particularly within 3 hours of symptom onset. This suggests that brain tissue with initially decreased ADC may represent viable tissue at risk.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Hyperacute stroke is characterized by decreased apparent diffusion coefficient (ADC) values.
- Understanding the dynamics of ADC normalization is crucial for identifying salvageable brain tissue.
Purpose of the Study:
- To determine the frequency of ADC value normalization in hyperacute stroke.
- To identify characteristics of brain tissue that demonstrates ADC normalization.
Main Methods:
- Sixty-eight acute ischemic stroke patients underwent serial MRI scans (diffusion/perfusion imaging, MR angiography) within 6 hours of symptom onset, at 24 hours, and 4-7 days later.
- Lesion volumes with decreased ADC and delayed time to peak (TTP) in perfusion imaging were quantified.
- Patients were classified as normalizers (>5 mL ADC normalization) or non-normalizers (<5 mL ADC normalization).
Main Results:
- ADC normalization occurred in 19.7% of patients (14/68).
- Normalization was more frequent in patients imaged within 3 hours (35.5%) versus 3-6 hours (7.5%) of stroke onset.
- Normalization was observed in basal ganglia and white matter, often associated with reperfusion and more distal occlusions; less severe initial ADC decrease predicted normalization.
Conclusions:
- Apparent diffusion coefficient normalization is a frequent occurrence in acute stroke patients who experience reperfusion.
- Brain tissue exhibiting decreased ADC within 3 hours of stroke onset may represent tissue at risk and potentially salvageable.
