Mouse brain fixation to preserve In vivo manganese enhancement for ex vivo manganese-enhanced MRI.

Purpose: To develop a tissue fixation method that preserves in vivo manganese enhancement for ex vivo magnetic resonance imaging (MRI). The needs are clear, as conventional in vivo manganese-enhanced MRI (MEMRI) applied to live animals is time-limited, hence limited in spatial resolution and signal-to-noise ratio (SNR). Ex vivo applications can achieve superior spatial resolution and SNR through increased signal averaging and optimized radiofrequency coil designs. A tissue fixation method that preserves in vivo Mn(2+) enhancement postmortem is necessary for ex vivo MEMRI.

Materials And Methods: T1 measurements and T1 -weighted MRI were performed on MnCl2 -administered mice. The mice were then euthanized and the brains were fixed using one of two brain tissue fixation methods: aldehyde solution or focused beam microwave irradiation (FBMI). MRI was then performed on the fixed brains.

Results: T1 values and T1 -weighted signal contrasts were comparable between in vivo and ex vivo scans on aldehyde-fixed brains. FBMI resulted in the loss of Mn(2+) enhancement.

Conclusion: Aldehyde fixation, not FBMI, maintained in vivo manganese enhancement for ex vivo MEMRI.