Optimization of T1-w/T2-w ratio for myelin using different TE and exponents

Motivation: Myelin allows efficient neuronal signaling but conventional imaging often lacks myelin specificity. The T1-w/T2-w ratio has been shown to enhance the myelin signal. Goal(s): Improve the myelin signal enhancement by optimizing TE and using exponents in the T1-wx1/GRASEx2 ratio. Approach: For fourteen volunteers, T1-wx1/GRASEx2 and myelin water fraction (MWF), a myelin-specific measure, were correlated using different TE and exponents. Repeatability was assessed in six volunteers. Results: The parameters TE = 50 ms (± 10 ms), x1 = 0.65 (± 0.50) and x2 = 3.15 (± 0.60) provided the optimized correlation between ratio and MWF. The optimized metric showed higher correlation to MWF. Impact: The findings show potential for improving myelin signal by using a generalized version of the T1-w/T2-w ratio which can be easily computed from structural brain images. Myelin integrity is a promising biomarker for the diagnosis and monitoring of neurological disorders.