Reinhard Meier MD, PhD, Presenter: Nothing to Disclose

Nicolas Beziere, Abstract Co-Author: Nothing to Disclose

Claudio von Schacky, Abstract Co-Author: Nothing to Disclose

Moritz Wildgruber MD, PhD, Abstract Co-Author: Nothing to Disclose

Ernst J. Rummeny MD, Abstract Co-Author: Nothing to Disclose

Vasilis Ntziachristos PhD, Abstract Co-Author: Stockholder, iThera Medical GmbH

We investigated the use of multispectral optoacoustic tomography (MSOT) in a murine model to monitor therapy effects of arthritic inflammation in vivo through an L- and P-selectin targeting contrast agent.

This preclinical imaging study was performed using multispectral optoacoustic tomography (MSOT) able to record the optoacoustic signal detected by a cylindrically focus 64-elements transducer after illumination by a tunable pulsed laser in the near infra-red range (680-900 nm), yielding transverse images of entire mice in real time. A polyglycerol-sulfate grafted with near-infrared fluorophore was used (dPGS-ICG), allowing highlighting of the expression of L- and P-selectins, directly correlating to the state of inflammation of the joint and surrounding tissue. In twenty mice we induced arthritis by injection of collagen in one leg while keeping the other leg untouched as a healthy reference. These mice underwent MSOT and MR imaging at day 5, 35 and 42 after arthritis induction and simultaneous therapy onset. 10 mice were allocated to the therapy group receiving prednisolone and methotrexate, while 10 other mice served as controls treated with PBS. Data was processed using a model-based image reconstruction process followed by a least-square method spectral fitting. Clinical assessment of arthritis as well as ex vivo planar fluorescent imaging was used to validate the results obtained by imaging.

MSOT allowed clear identification of the probe over the anatomical signal. MSOT signal intensity directly and quantitatively correlated to the advancement of the disease in the joint. The findings matched well with MR imaging showing Gadolinium infiltration in the synovial fluid. Arthritic inflammation was significantly lower in the therapeutic compared to the control group (p<0.05) on day 35 and 42 after therapy onset as measured with MSOT and confirmed by MR imaging, clinical examination and histopathology. 

MSOT allows for therapy monitoring of arthritic inflammation. In the future, we see this imaging method may help to determine treatment response in an early state. For non-responders earlier change in therapy strategy could lead to reduction of unnecessary side effects. 

Given the current development of the MSOT technology, it is expected that similar approaches will rapidly be translated in the clinic as a fast and relatively cheap staging procedure.

Meier, R, Beziere, N, von Schacky, C, Wildgruber, M, Rummeny, E, Ntziachristos, V, Multispectral Optoacoustic Tomography (MSOT) for Therapy Monitoring of Arthritis.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007760.html