Diffusion tensor imaging findings of the brainstem in subjects with tonsillar ectopia

Area of Science:

• Neuroimaging
• Neurology
• Radiology

Background:

• Chiari I Malformation (CM-I) involves cerebellar tonsil descent.
• Borderline tonsillar ectopia (BTE) represents a milder form.
• Understanding microstructural changes in these conditions is crucial.

Purpose of the Study:

• To compare diffusion tensor imaging (DTI) metrics (ADC, FA, AD, RD) across cranial sites in CM-I, BTE, and controls.
• To correlate DTI metrics with the severity of tonsillar ectopia.

Main Methods:

• Magnetic Resonance Imaging (MRI) and DTI were performed on 73 subjects with CM-I/BTE and 35 controls.
• Apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) were measured at various brain levels.

Main Results:

• CM-I patients showed higher ADC (medulla) and RD (cerebellar peduncles, thalamus, globus pallidus) than controls.
• FA (medulla) and AD (medulla, pons) were higher in CM-I patients.
• BTE subjects had higher ADC and AD (pons) compared to controls.
• CM-I subjects exhibited higher ADC (medulla) and AD (pons) than BTE subjects.
• Positive correlations were found between ADC, AD, FA at the medulla/pons and tonsillar ectopia size.

Conclusions:

• DTI reveals significant microstructural differences in the brainstem of CM-I and BTE patients.
• DTI metrics correlate with the severity of tonsillar ectopia.
• DTI is a valuable tool for assessing tissue-level microstructural changes in these conditions.