Comparison of 3D Magnetization-transfer- and Spectral-presaturation-with-inversion-recovery-based Neuromelanin...

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)
• Neuroanatomy

Background:

• Neuromelanin visualization is crucial for studying neurodegenerative diseases.
• Three-dimensional (3D) gradient echo (GRE) sequences with magnetization transfer (MT) pulses are commonly used for neuromelanin imaging.
• Spectral presaturation with inversion recovery (SPIR) is proposed as an alternative to MT pulses.

Purpose of the Study:

• To optimize SPIR parameters for neuromelanin imaging.
• To compare the effectiveness of SPIR with MT pulses for visualizing neuromelanin in the substantia nigra pars compacta (SNc) and locus coeruleus (LC).

Main Methods:

• Acquisition of neuromelanin images using MT pulse and SPIR (flip angles [FAs] = 19º, 22º, 25º) in 30 healthy volunteers.
• Standardized acquisition time of 5 minutes, with adjusted slab thickness and acquisition areas (brainstem for MT, whole brain for SPIR).
• Visual and quantitative assessment of SNc and LC contrast and signal-to-noise ratio.

Main Results:

• SPIR with flip angles of 19º and 22º showed superior visual scores for SNc compared to other sequences.
• SPIR with a flip angle of 22º yielded the best visual score for LC.
• Quantitative analysis revealed significantly lower contrast for MT in SNc compared to SPIR sequences.

Conclusions:

• SPIR imaging offers an improved method for neuromelanin detection in the SNc and LC compared to MT pulse in 3D imaging.
• SPIR provides a viable alternative to MT pulses for enhanced neuromelanin visualization.