Copyright ©2014 Baishideng Publishing Group Inc. All rights reserved.
World J Rheumatol. Nov 12, 2014; 4(3): 72-79
Published online Nov 12, 2014. doi: 10.5499/wjr.v4.i3.72
Quantifying synovial inflammation: Emerging imaging techniques
Deepak Tripathi, Vikas Agarwal
Deepak Tripathi, Vikas Agarwal, Department of Clinical Immunology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow UP 226014, India
Author contributions: Tripathi D and Agarwal V contributed solely to this paper.
Supported by ICMR, No. 5/4-5/4/ortho/08/NCD-1
Correspondence to: Vikas Agarwal, MD, DM, Additional Professor, Department of Clinical Immunology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow UP 226014, India.
Telephone: +91-52-22494318 Fax: +91-52-22668812
Received: April 12, 2014
Revised: July 23, 2014
Accepted: September 6, 2014
Published online: November 12, 2014

Imaging techniques to assess synovial inflammation includes radiography, ultrasound, computed tomography, magnetic resonance imaging (MRI) and recently positron emission tomography. The ideal objective of imaging approaches are to quantify synovial inflammation by capturing features such as synovial hyperplasia, neo-angiogenesis and infiltration of immune cells in the synovium. This may enable clinicians to estimate response to therapy by measuring the improvement in the inflammatory signals at the level of synovium. Ultrasound can provide information regarding thickening of the synovial membrane and can reveal increased synovial blood flow using power Doppler technique. Bone marrow edema and synovial membrane thickness on MRI scan may serve as indicators for arthritis progression. Enhancement of the synovium on dynamic contrast MRI may closely mirror the inflammatory activity in the synovium. Diffusion tensor imaging is an advance MRI approach that evaluates the inflammation related to cell infiltration or aggregation in an inflamed synovium. In this review, we summarize the newer imaging techniques and their developments to evaluate synovial inflammation.

Keywords: Synovitis, Imaging, Diffusion tensor imaging, Positron emission tomography, Computed tomography, Ultrasound

Core tip: Nowadays, more and more emphasis is being put on capturing the microscopic features of inflammation on non-invasive techniques of imaging. Emerging magnetic resonance imaging techniques seem to have potential to capture these molecular events and replace synovial histology in future. In this paper we have reviewed exciting recent advances in the field of imaging that pick up inflammatory signals from inflamed synovium and are likely to be available for routine clinical practice in near future.