ACR Day 5 Abstract Roundup - Imaging's New Frontiers

Today was the final day of the American College of Rheumatology's 2009 Scientific Meeting. Here are some of the study highlights from the finale.

In Vivo Fluorescence Imaging of TNF-Induced Endothelial Inflammation by Targeting E-Selectin Authors: Gompels LL, Inglis J, Vincent T, et al. Purpose: To "the use of in vivo fluorescence imaging, targeting E-selectin expression in mouse TNFα induced paw edema."

Results: "In vivo optical imaging of E-selectin is a sensitive, specific and non invasive method of measuring endothelial activation in inflammation. The novel use of fluorescently labeled biomarkers has significant potential for visualization of disease states such as inflammatory arthritis. This will facilitate in vivo interrogation of molecular pathways and assessment of both local and systemic effects of therapies."

Objective Disease Activity Assessment for Rheumatoid Arthritis Using Optical Monitoring Authors: Meier AJL, Rensen WJH, de Nijs RNJ Purpose: "There is a need for an objective, reproducible, fast, quantitative and accurate disease activity monitor for disease progression monitoring in patients with rheumatoid arthritis (RA). Optical spectral transmission is a promising solution, since optical contrast can be related to physiological parameters in the body, such as blood concentration and oxygenation. At relevant wavelengths and intensities, optical radiation is completely harmless. Additionally, the cost of optical methods is low compared to other modalities. Due to the highly scattering nature of tissue, non-invasive optical methods for medical imaging are limited to the extremities of the human body. For application in joint diseases, this is acceptable, because imaging of hands and wrists can provide sufficient clinical information. This study aims to assess feasibility of disease activity monitoring by optical methods."

Results: Researchers reported that "optical spectral transmission measurements correlate with clinical assessment of joint inflammation, and therefore might be useful in monitoring disease activity of RA patients," and that "further study using a multi-joint device is necessary to demonstrate the usability of optical measurements in clinical practice."

Macrophage PET Imaging as Biomarker for Very Early Rheumatoid Arthritis Authors: Elzinga E, Voskuyl AE, Hoetjes NJ, et al. Purpose: To investigate "whether subclinical synovitis can be visualized using [¹¹C]-(R)-PK11195-PET in arthralgia patients with presence of anti-CCP antibodies, without clinical symptoms of arthritis. The second purpose was to determine whether the presence of PET abnormalities may predict the development of clinical arthritis."

Results: Researchers reported that "a positive [¹¹C]-(R)-PK11195-PET signal was found in 25% of all included anti-CCP positive arthralgia patients. High PET-uptake was found in a subgroup of patients, all of these developed clinical arthritis," and that these findings "suggest that high joint-uptake of [¹¹C]-(R)-PK11195 may aid to predict the development of arthritis in patients at risk of RA."

Lentiviral-Based Bioluminescent Imaging of Synovial Inflammatory Subtypes in Experimental Arthritis and Human Synovial Fibroblasts Authors: Geurts J, Vermeij EA, Arntz OJ, et al. Purpose: To evaluate "the applicability of lentiviral-based (LV) promoter-luciferase reporters for assessing differential inflammation subtypes in experimental arthritis and primary OA and RA synovial fibroblasts (SF)."

Results: Results of this study indicate that "Saa3 promoter activity is a more sensitive read-out for synovial inflammation than ^99mTc uptake in experimental arthritis," and that "the Saa3 promoter response in stimulated primary OA/RA SF can distinguish between molecularly distinct high or low inflammatory subtypes." Researchers noted that "these results demonstrate the sensitivity and versatility of genetic bioluminescent reporters for quantitative imaging of heterogeneous synovial inflammation."

Near Infrared Lymphatic Imaging and Quantification of Lymphatic Draining Function in a Murine Model of Inflammatory Arthritis Authors: Zhou Q, Wood R, Schwarz Em, et al. Purpose: "The lymphatic system may play a functional role to limit inflammation in affected joints in rheumatoid arthritis (RA). However, approaches to non-invasively measure lymphatic draining function in murine models of RA are lacking. We have developed a near infrared (NIR) fluorescence lymphatic imaging technique and used it to examine lymphatic flow from affected joints to draining lymph nodes (LNs) of arthritic mice."

Results: "NIR-ICG imaging is a powerful new tool to monitor dynamic changes in lymphatic draining function of inflamed joint tissue in mice. In the acute phase of joint inflammation, increased lymphatic flow exceeds lymphatic draining capacity, associated with severe joint swelling. Later enhanced lymphatic drainage from joints and PLNs reduces the degree of joint swelling. This technique could be used to assess the efficacy of intervention therapy to improve lymphatic draining function in models of RA."

Monocyte Scintigraphy in Rheumatoid Arthritis, Dynamics of Monocyte Migration in Immune-Mediated Inflammatory Disease Authors: Thurlings RM, Wijbrandts CA, Bennink R, et al. Purpose: To develop a technique that enables researchers to "analyze the migration of labelled autologous monocytes in RA patients using single photon emission computer tomography (SPECT)."

Results: Results of this study indicate that "monocytes migrate continuously into the inflamed synovial tissue of RA patients, but at a slow macrophage-replacement rate," suggesting that "the rapid decrease in synovial macrophages that occurs after antirheumatic treatment might rather be explained by an alteration in macrophage retention than in monocyte influx and that RA might be particularly sensitive to treatments targeting inflammatory cell retention."