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Updated: Oct 8, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Evolution of apparent diffusion coefficient, diffusion-weighted, and T2-weighted signal intensity of acute stroke
M G Lansberg1, V N Thijs, M W O'Brien
1Stanford Stroke Center, Stanford University Medical Center, Palo Alto, CA 94304, USA.
Background And Purpose:
Serial study of such MR parameters as diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC), ADC with fluid-attenuated inversion recovery (ADC(FLAIR)), and T2-weighted imaging may provide information on the pathophysiological mechanisms of acute ischemic stroke. Our goals were to establish the natural evolution of MR signal intensity characteristics of acute ischemic lesions and to assess the potential of using specific MR parameters to estimate lesion age.
Methods:
Five serial echo-planar DWI studies with and without an inversion recovery pulse were performed in 27 patients with acute stroke. The following lesion characteristics were studied: 1) conventional ADC (ADC(CONV)); 2) ADC(FLAIR); 3) DWI signal intensity (SI(DWI)); 4) T2-weighted signal intensity (SI(T2)), and 5) FLAIR signal intensity (SI(FLAIR)).
Results:
The lesion ADC(CONV) gradually increased from low values during the first week to pseudonormal during the second week to supranormal thereafter. The lesion ADC(FLAIR) showed the same pattern of evolution but with lower absolute values. A low ADC value indicated, with good sensitivity (88%) and specificity (90%), that a lesion was less than 10 days old. All signal intensities remained high throughout follow-up. SI(DWI) showed no significant change during the first week but decreased thereafter. SI(T2) initially increased, decreased slightly during week 2, and again increased after 14 days. SI(FLAIR) showed the same initial increase as the SI(T2) but remained relatively stable thereafter.
Conclusion:
Our findings further clarify the time course of stroke evolution on MR parameters and indicate that the ADC map may be useful for estimating lesion age. Application of an inversion recovery pulse results in lower, potentially more accurate, absolute ADC values.
Insights
Apparent diffusion coefficient (ADC) mapping in acute ischemic stroke can estimate lesion age. Low ADC values accurately predict lesions less than 10 days old, aiding in stroke diagnosis and management.
Area of Science:
- Neuroimaging
- Radiology
- Stroke Research
Background:
- Acute ischemic stroke pathophysiology is complex.
- Magnetic Resonance Imaging (MRI) parameters offer insights into stroke mechanisms.
- Understanding lesion evolution is crucial for diagnosis.
Purpose of the Study:
- To characterize the natural evolution of MR signal intensities in acute ischemic lesions.
- To evaluate the utility of specific MR parameters, including apparent diffusion coefficient (ADC), for estimating lesion age.
- To investigate the impact of inversion recovery pulses on ADC values.
Main Methods:
- Serial echo-planar diffusion-weighted imaging (DWI) studies were conducted in 27 acute stroke patients.
- Evaluated parameters included conventional ADC (ADC(CONV)), ADC with fluid-attenuated inversion recovery (ADC(FLAIR)), and signal intensities (SI) on DWI, T2-weighted, and FLAIR sequences.
- Five serial DWI studies were performed per patient.
Main Results:
- Lesion ADC(CONV) and ADC(FLAIR) increased over time, from low values in the first week to supranormal levels later.
- Low ADC values demonstrated high sensitivity (88%) and specificity (90%) for identifying lesions <10 days old.
- Signal intensities showed varied temporal changes, with DWI SI decreasing after the first week and T2/FLAIR SI exhibiting distinct patterns.
Conclusions:
- ADC mapping is a valuable tool for estimating the age of acute ischemic lesions.
- The observed evolution of ADC values provides a clearer understanding of stroke progression on MRI.
- Inversion recovery pulses yield lower, potentially more accurate, ADC values.
