Related Experiment Video
Updated: Jun 24, 2026
Multimodal Cross-Device and Marker-Free Co-Registration of Preclinical Imaging Modalities
Published on: October 27, 2023
Penumbral mismatch is underestimated using standard volumetric methods and this is exacerbated with time
H Ma1, J A Zavala, H Teoh
1National Stroke Research Institute, Austin Health, University of Melbourne, 300 Waterdale Rd, Heidelberg West, Vic 3081, Australia.
Background And Aims:
The mismatch between perfusion weighted images (PWI) and diffusion weighted images (DWI) using MR is increasingly being applied in patient selection for therapeutic trials. Two approaches to the calculation of the mismatch volume exist--the commonly used volumetric and the more precise co-registration method, the latter of which considers lesion topography. That there are differences in the mismatch volume analysed by each method and that these are time dependent was hypothesised.
Methods:
Patients within 48 h of ischaemic stroke onset had baseline MR PWI/DWI mismatch and T2 outcome volumes at 3 months. Volumetric mismatch volume was defined as PWI minus DWI lesion. Co-registration mismatch volume was defined as the PWI defect lesion not overlapped by the co-registered DWI lesion.
Results:
72 patients of median age 74.0 years were studied. Median baseline MR was at 5.9 h (IQR 3.0, 20.4 h) after stroke onset. Consistent underestimation of the mismatch volume occurred using the volumetric method (volumetric median 9.3 ml, IQR 0, 63 ml; co-registration median 20.1 ml, IQR 3.2, 69.8 ml; p<0.0001). This difference increased with time from stroke onset (p = 0.006).
Conclusions:
Volumetric analysis consistently underestimates the PWI/DWI mismatch volume compared with the more precise co-registration method. This effect increases with time.
Insights
The volumetric method consistently underestimates perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) mismatch volume in stroke patients compared to co-registration. This underestimation worsens over time, impacting patient selection for therapeutic trials.
Area of Science:
- Neuroimaging
- Radiology
- Stroke Medicine
Background:
- Magnetic Resonance Imaging (MRI) using perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) is crucial for selecting stroke patients for therapeutic trials.
- Two methods exist for calculating the PWI/DWI mismatch volume: volumetric and co-registration.
- The co-registration method accounts for lesion topography, offering greater precision than the volumetric method.
Purpose of the Study:
- To investigate the differences in PWI/DWI mismatch volume calculations between volumetric and co-registration methods.
- To determine if these differences are time-dependent after ischemic stroke onset.
Main Methods:
- Analyzed baseline MR PWI/DWI mismatch and T2 outcome volumes in 72 ischemic stroke patients within 48 hours of onset.
- Defined volumetric mismatch as PWI lesion minus DWI lesion.
- Defined co-registration mismatch as the PWI defect not overlapped by the co-registered DWI lesion.
Main Results:
- The volumetric method consistently underestimated the mismatch volume compared to co-registration (median 9.3 ml vs. 20.1 ml, p<0.0001).
- This underestimation by the volumetric method significantly increased with time from stroke onset (p=0.006).
- Median age of patients was 74.0 years, with a median MRI scan at 5.9 hours post-stroke.
Conclusions:
- Volumetric analysis of PWI/DWI mismatch volume is less accurate than co-registration.
- The discrepancy between methods increases over time, highlighting the importance of precise volumetric assessment in acute stroke management and clinical trials.
