Using invasive imaging techniques such as intra-vascular ultrasound, the burden of atherosclerotic plaque disease in any given individual has previously been shown to correlate with the likelihood of future cardivascular events .  Magnetic Resonance Imaging (MRI) has the advantage of being non-invasive and, compared to other currently available molecular imaging modalities, it has good spatial resolution, making it ideal for imaging the thin arterial wall.  However, compared to positron emission tomography and optical imaging, it has a lower sensitivity.

To try and overcome this limitation, the authors of this study designed a novel elastin-specific magnetic resonance contrast agent (ESMA), to help to define atherosclerotic plaque burden in an Apoe-/- mouse model.  Elastin shows increased expression during plaque development and also has biological signalling functions.  Furthermore, using magnetic resonance signal values the amount of elastin can be quantified.

After administration of the ESMA, the authors noted a gradual increase in MRI signal from plaque, which was diminished in those mice treated with pravastatin.  This signal increased with time, and the authors correlated their MRI signal findings with immunoblotting and histology to confirm the amount of elastin present.
Conclusions:

Elastin represents a feasible target for molecular imaging of atherosclerosis using MRI.  The ability to quantify the amount of elastin present means that this technique has the potential both to assess atherosclerotic plaque burden and how it responds to treatment.

• Makowksi MR, Wiethoff AJ, Blume U et al.  Assessment of atherosclerotic plaque burden with an elastin-specific magnetic resonance contrast agent.  Nature Med 2011;17(3):383-389.