Assessment of White Matter Changes Using Quantitative T1ρ Mapping in an Open-Field Low-Intensity Blast Mouse Model of Mild Traumatic Brain Injury (mTBI).

Blast-induced mild traumatic brain injury (mTBI) occurs when shock waves travel through blood vessels and cerebrospinal fluid, leading to cerebral demyelination, which results in cognitive impairments and neuropsychiatric issues that impact quality of life. This study aims to evaluate myelin changes in white matter in mice with mTBI induced by an open-field low-intensity blast (LIB) using a newly implemented 3D adiabatic T1ρ prepared fast spin echo (Adiab-T1ρ-FSE) sequence for quantitative T1ρ MRI mapping. Thirty male C57BL/6 mice, including 15 mTBI and 15 sham controls, were scanned on a 3T Bruker MRI scanner. Luxol fast blue (LFB) staining was performed to assess myelin content differences between the mTBI and sham control groups. A significantly higher T1ρ value in the medial corpus callosum (MCC) was found in mTBI mice compared to controls (126.8 ± 2.5 ms vs. 129.8 ± 2.5 ms; p < 0.001), consistent with the reduced myelin observed in LFB staining (0.80 ± 0.14 vs. 1.02 ± 0.06; p = 0.004). Moreover, a significant negative correlation between T1ρ and histological myelin content measurements was observed (r = -0.57, p = 0.02). Our findings demonstrate that T1ρ is a promising biomarker for detecting mTBI-associated demyelination in the brain.