Low field magnetic resonance imaging in rat in vivo

Objective. - This work aims at demonstrating the interest of low field magnetic resonance imaging (MRI) for in vivo imaging in rat. Material and methods. - MRI is performed using an open resistive 0.1 T magnet with a homogeneous zone measuring 6 cm x 10 cm x 10 cm. Rats under isoflurane gaseous anesthesia are placed in a technical cell for small animal imaging. Radio frequency solenoidal coils are developed for each application. Gradient echo T-1 and T-2-weighted sequences are programmed to acquire 3D data in vivo in rats. Results. - Acquisition times are comprised between 1 min for scout sequences and 2 h 10 min to acquire volumes with in-plane pixel size ranging from 0.37 to 1 min and a slice thickness between 0.37 min and 1.88 mm. Information obtained from our acquisitions are comparable to those reported in the literature about five applications: 1: intracerebral glioma; 2: cerebral contrast enhancement using manganese; 3: description of knee joint anatomy; 4: cardiac dynamic acquisition synchronized on cardiac rhythm; 5: whole body (thorax and abdomen) acquisition. Conclusion. - Rat MRI using all 0.1 T device allows to answer to the biological questions studied in this work at the expense of long acquisition times compared to high field MRI. Low field MRI offers economical and technical characteristics that could make it attractive to a non-specialized scientific community aiming at realizing daily MRI in vivo in rat. (c) 2008 Elsevier Masson SAS. All rights reserved.