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Updated: Aug 17, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
[Quantitative relationships between ADC and perfusion changes in acute ischemic stroke using combined
M Hamon1, R M Marié, P Clochon
1Service de Neuroradiologie, Avenue Cote de Nacre, CHU de Caen, 14033 Caen, France. hamon-mi@chu-caen.fr
Unlabelled:
MR-based diffusion- and perfusion-weighted imaging (DWI/PWI) has become the standard imaging technique to assess the individual brain pathophysiological status in acute ischemic stroke. The finding of a "mismatch" with larger PWI than DWI abnormality is thought to reflect the presence of tissue at-risk of infarction, i.e., penumbra. However, there has been no detailed study of the quantitative relationships between perfusion and diffusion changes in stroke patients. According to the experimental concept of penumbra, the ADC would be expected to remain unchanged despite decreasing perfusion until a critical threshold is reached. We have tested this hypothesis directly in man.
Methods:
DWI/PWI was performed in 7 patients with MCA territory stroke within 4-10 hrs from onset. Mismatch was defined on diffusion and rMTT maps, and circular ROIs were positioned within the ADC lesion (D), the mismatch area (M), and the normal appearing cortex (N); mirror ROIs were also obtained, and affected/unaffected ratios for ADC and rCBF were computed for each ROI.
Results:
The mean (+/-1 SD) ADC ratios were 0.60 +/- 0.09, 0.95 +/- 0.10 and 1.02 +/- 0.04 in L, M and N, respectively; the corresponding rCBF ratios were 0.32 +/- 0.12, 0.75 +/- 0.14 and 0.97 +/- 0.09, respectively. The relationship was non-linear, with the rCBF but not the ADC ratio for M being significantly lower (p < 0.01) than that for N. A threshold for decline in ADC was apparent around 0.50 rCBF ratio.
Comment:
These results directly document in man that the ADC declines only after hypoperfusion has reached a certain degree (about 50%), consistent with the concept of the ischaemic penumbra.
Insights
Diffusion- and perfusion-weighted imaging (DWI/PWI) reveals that apparent diffusion coefficient (ADC) declines only after hypoperfusion reaches approximately 50%, supporting the ischemic penumbra concept in acute stroke patients.
Area of Science:
- Neuroimaging
- Stroke Imaging
- Ischemic Stroke Pathophysiology
Context:
- Diffusion- and perfusion-weighted imaging (DWI/PWI) is standard for acute ischemic stroke assessment.
- The "mismatch" between PWI and DWI abnormalities suggests tissue at risk (penumbra).
- Quantitative relationships between perfusion and diffusion in stroke patients lack detailed study.
Purpose:
- To investigate the quantitative relationship between perfusion and diffusion changes in acute ischemic stroke.
- To test the hypothesis that apparent diffusion coefficient (ADC) remains unchanged until a critical perfusion threshold is reached.
Summary:
- DWI/PWI was performed in 7 MCA territory stroke patients within 4-10 hours of onset.
- Apparent diffusion coefficient (ADC) and relative cerebral blood flow (rCBF) ratios were computed for lesion, mismatch, and normal areas.
- Results showed ADC declines significantly only when rCBF drops below approximately 50%.
Impact:
- Provides direct in-human evidence supporting the ischemic penumbra concept.
- Establishes a quantitative threshold for ADC decline relative to hypoperfusion.
- Enhances understanding of tissue viability in acute ischemic stroke.
