Staining methods for magnetic resonance microscopy of the rat fetus

✍ Scribed by Alexandra Petiet; Laurence Hedlund; G. Allan Johnson

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 744 KB
• Volume: 25
• Category: Article
• ISSN: 1053-1807
• DOI: 10.1002/jmri.20932

✦ Synopsis

Abstract

Purpose

To develop a magnetic resonance histology (MRH) staining and fixation method by immersion to enhance the signal‐to‐noise ratio (SNR) with a paramagnetic contrast agent permitting microscopic acquisition within a 3‐hour scan time.

Materials and Methods

Methods were optimized for embryonic day 18.5 (E18.5) rat fetuses and imaging at 9.4T with an RF refocused spin‐echo pulse sequence (TR/TE = 75 msec/5.2 msec). Fixation/staining was performed by immersion in Bouin's fixative containing varied concentrations of ProHance (from 10:1 to 500:1 Bouin's:ProHance) and for varied immersion durations (up to 24 hours).

Results

The results showed a significant change in T1 and T2 relaxation times as a function of concentration of contrast agent and immersion duration. As the contrast agent penetrated the tissues, T1 was reduced as desired (typically by 10×), but at the same time T2 was profoundly reduced (typically by 3×) due to both protein cross‐linking from the fixative and the high concentration of contrast agent. A systematic assessment of this staining protocol showed an increased SNR (by 5×) over that in unstained specimens.

Conclusion

This staining protocol reduced scan time for very‐high‐resolution images (19.5 μm) to only 3 hours, making MRH a routine tool for evaluating fetal development. J. Magn. Reson. Imaging 2007;25:1192–1198. © 2007 Wiley‐Liss, Inc.