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Increased Parenchymal Free Water May Be Decreased by Revascularization Surgery in Patients with Moyamoya Disease
Shoko Hara1,2, Masaaki Hori2,3, Koji Kamagata2
1Department of Neurosurgery, Tokyo Medical and Dental University.
Purpose:
Moyamoya disease (MMD) is a cerebrovascular disease associated with steno-occlusive changes in the arteries of the circle of Willis and with hemodynamic impairment. Previous studies have reported that parenchymal extracellular free water levels may be increased and the number of neurites may be decreased in patients with MMD. The aim of the present study was to investigate the postoperative changes in parenchymal free water and neurites and their relationship with cognitive improvement.
Methods:
Multi-shell diffusion MRI (neurite orientation dispersion and density imaging and free water imaging using a bi-tensor model) was performed in 15 hemispheres of 13 adult patients with MMD (11 female, mean age 37.9 years) who had undergone revascularization surgery as well as age- and sex-matched normal controls. Parameter maps of free water and free-water-eliminated neurites were created, and the regional parameter values were compared among controls, patients before surgery, and patients after surgery.
Results:
The anterior and middle cerebral artery territories of patients showed higher preoperative free water levels (P ≤ 0.007) and lower postoperative free water levels (P ≤ 0.001) than those of normal controls. The change in the dispersion of the white matter in the anterior cerebral artery territory correlated with cognitive improvement (r = -0.75; P = 0.004).
Conclusion:
Our study suggests that increased parenchymal free water levels decreased after surgery and that postoperative changes in neurite parameters are related to postoperative cognitive improvement in adult patients with MMD. Diffusion analytical methods separately calculating free water and neurites may be useful for unraveling the pathophysiology of chronic ischemia and the postoperative changes that occur after revascularization surgery in this disease population.
Insights
Moyamoya disease (MMD) patients showed reduced parenchymal free water after revascularization surgery. Postoperative white matter changes in MMD correlate with cognitive improvements, suggesting diffusion MRI can track recovery.
Area of Science:
- Neuroimaging
- Cerebrovascular Diseases
- Diffusion MRI
Background:
- Moyamoya disease (MMD) involves steno-occlusive changes in cerebral arteries, leading to hemodynamic impairment.
- Previous research indicates increased parenchymal free water and decreased neurites in MMD patients.
- Understanding postoperative changes is crucial for managing MMD.
Purpose of the Study:
- To investigate postoperative changes in parenchymal free water and neurites in MMD patients.
- To explore the relationship between these microstructural changes and cognitive improvement after revascularization surgery.
Main Methods:
- Multi-shell diffusion MRI, including neurite orientation dispersion and density imaging (NODDI) and free water imaging (FWI) with a bi-tensor model.
- Comparison of free water and free-water-eliminated neurite parameters between MMD patients (pre- and post-surgery) and healthy controls.
- Analysis of 15 hemispheres from 13 adult MMD patients who underwent revascularization surgery.
Main Results:
- MMD patients exhibited higher preoperative free water levels in anterior and middle cerebral artery territories compared to controls.
- Postoperative free water levels significantly decreased in MMD patients (P ≤ 0.001).
- A significant correlation was found between white matter dispersion changes in the anterior cerebral artery territory and cognitive improvement (r = -0.75; P = 0.004).
Conclusions:
- Revascularization surgery in MMD patients leads to a reduction in parenchymal free water levels.
- Postoperative microstructural changes, particularly in white matter, are linked to cognitive recovery in MMD.
- Diffusion analytical methods offer valuable insights into MMD pathophysiology and surgical outcomes.
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