Use of Nuclear Magnetic Resonance Imaging Angiography to Follow-Up Arterial Remodeling in an Animal Model

Appropriately sized arteries in small animals may be possible
models for studying the remodeling process as occurs after arterial
balloon injury in humans. Magnetic resonance imaging (MRI) is able
to noninvasively image tissue in vivo. To date, small animal angiog
raphy models have mostly used research-dedicated instruments and
resolution, which are not universally available.Experiments were
carried out on a rat aorta model of remodeling in vivo (n=40).
Arteries were injured by oversized balloon dilation; control
arteries were uninjured. Angiography imaging was performed
immediately before sacrifice with an unmodified clinical MRI unit,
a 1.5 Tesla MR tomograph with a 20-cm-diameter coil. Longitudinal
MRI pictures of the aorta and morphometry of tissue sections to
measure luminal and arterial wall areas were analyzed with use of
computer-assisted techniques.Comparison of dimensions demonstrated
correlation between MRI and histology measurements of the lumen.
MRI and morphometry showed a gradual increase in mean luminal area
over 6 weeks following injury. The lumen increase correlated with
total arterial area and thickness.In this rat aorta model,
remodeling documented at histology was followed-up in vivo. The use
of such clinical MRI scanners has potential to reduce animal
numbers needed to follow-up the remodeling process after
therapeutic intervention.