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Author Spotlight: Noninvasive Cerebral Blood Flow Determination in Human Functional Brain Region for Diagnosis of Neurological Disorders
Published on: May 31, 2024
Arterial spin labeling MRI with multiple post-labeling delays reveals interictal hypo- and hyper-perfusion patterns
Myriam Abdennadher1, Lena Václavů2, Joseph Sisto3
1Departments of Neurology, Boston University Chobanian and Avedisian School of Medicine, Boston, Massachusetts, USA; Boston Medical Center, Boston, Massachusetts, USA.
Background And Purpose:
Interictal cerebral blood flow (CBF) may be useful for seizure focus localization. However, its accuracy is debatable. Studies suggested interictal hypoperfusion at the seizure focus, yet others suggested hyperperfusion. This study aims to investigate the patterns of interictal perfusion in epilepsy subjects compared to healthy controls using multiple labeling-delays arterial spin labeling MRI, and to explore the accuracy of perfusion estimation using single post-labeling delay arterial-spin labeling MRI by comparing it to multiple post-labeling delays arterial-spin labeling MRI.
Materials And Methods:
We analyzed CBF in 40 participants, 15 healthy (35.9 ± 9.5 years, 47% women) and 25 epilepsy (41.1 ± 10.5 years; 52% women). We acquired a multiple post-labeling delays arterial spin labeling MRI using Hadamard encoding, and structural MRI. Perfusion quantification was performed using in-house software and analyzed using surface-based method. Z-scores of CBF and its absolute value (|Z-score|) were calculated to evaluate abnormal perfusion.
Results:
Brain perfusion showed interictal hypo- and/or hyper-perfusion in epilepsy compared to healthy participants involving focal to whole brain alterations. Epilepsy subjects had higher |Z-score| in most cortical regions compared to the healthy group. CBF generated from single post-labeling delay arterial-spin labeling MRI correlated with ones from multiple post-labeling delays in most cortical regions, yet the level of correlation was affected by regional arterial transit time and the labeling scheme. In regions with shorter arterial transit time, correlation peaked at shorter post-labeling delay (1300ms); whereas in regions with longer arterial transit time, correlation peaked at longer post-labeling delay (2250ms).
Conclusions:
Our findings suggest that the interictal CBF may fluctuate between hypo- and hyper- perfusion, and the involvement of brain regions may extend well beyond the seizure focus. Additionally, while single-post-labeling delay is efficient and clinically feasible, the accuracy of its assessment of perfusion depends on brain regions and the labeling scheme.
Insights
Interictal cerebral blood flow (CBF) in epilepsy can fluctuate between hypo- and hyper-perfusion, extending beyond the seizure focus. Single-delay ASL MRI offers efficiency but its accuracy for perfusion estimation varies by brain region and labeling scheme.
Area of Science:
- Neuroimaging
- Epilepsy Research
- Cerebrovascular Physiology
Background:
- Interictal cerebral blood flow (CBF) is explored for seizure focus localization.
- Conflicting studies report interictal hypoperfusion versus hyperperfusion at the seizure focus.
- Arterial spin labeling (ASL) MRI is a non-invasive technique for CBF measurement.
Purpose of the Study:
- Investigate interictal perfusion patterns in epilepsy patients versus healthy controls using multi-delay ASL MRI.
- Assess the accuracy of single-delay ASL MRI for perfusion estimation compared to multi-delay ASL MRI.
- Explore the influence of arterial transit time and labeling scheme on single-delay ASL MRI accuracy.
Main Methods:
- Analyzed CBF in 40 participants (15 healthy, 25 epilepsy) using multi-delay ASL MRI and structural MRI.
- Quantified perfusion using in-house software and surface-based analysis.
- Calculated Z-scores of CBF and absolute Z-scores (|Z-score|) to identify abnormal perfusion.
Main Results:
- Epilepsy patients exhibited interictal hypo- and/or hyper-perfusion compared to controls, with focal to whole-brain alterations.
- Epilepsy subjects showed significantly higher |Z-score| in most cortical regions.
- Single-delay ASL MRI CBF correlated with multi-delay ASL MRI CBF, with accuracy dependent on regional arterial transit time and labeling scheme.
Conclusions:
- Interictal CBF in epilepsy is variable, showing both hypo- and hyper-perfusion, with affected brain regions potentially widespread.
- Single-delay ASL MRI is clinically feasible but its perfusion assessment accuracy is region- and scheme-dependent.
- Multi-delay ASL MRI provides a more comprehensive understanding of interictal perfusion patterns in epilepsy.
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