Abstract
One in four ischaemic stroke patients are ineligible for thrombolytic treatment due to unknown onset time. Quantification of absolute MR relaxation times and signal intensities are potential methods for estimating stroke duration. We compared the accuracy of these approaches and determined whether changes in relaxation times and signal intensities identify the same ischaemic tissue as diffusion MRI. Seven Wistar rats underwent permanent middle cerebral artery occlusion to induce focal ischaemia and were scanned at six time points. The trace of the diffusion tensor (DAV), T1ρ and T2 were acquired at 4.7 T. Results show relaxation times, and signal intensities of the MR relaxation parameters increase linearly with ischaemia duration (P<0.001). Using T1ρ and T2 relaxation times, an estimate of 4.5 h after occlusion has an uncertainty of ± 12 and ± 35 min, respectively, compared with over 50 min for signal intensities. In addition, we present a pixel-by-pixel method that simultaneously estimates stroke onset time and identifies potentially irreversible ischaemic tissue using absolute relaxation times. This method demonstrates signal intensity changes during ischaemia display an ambiguous pattern and highlights the possibility that diffusion MRI overestimates the true extent of irreversible ischaemia. In conclusion, quantification of absolute relaxation times at a single time point enables a more accurate estimation of stroke duration than signal intensities and provides more information about tissue status in ischaemia.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.