RESEARCH - Diffusion tensor anisotropy MRI: a new tool to assess synovial inflammation

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Rheumatology Advance Access published online on January 27, 2009

Rheumatology, doi:10.1093/rheumatology/ken499

Diffusion tensor anisotropy magnetic resonance imaging: a new tool to

assess synovial inflammation

Vikas Agarwal1, Manoj Kumar2, Jitesh K. Singh3, Ram K. S. Rathore3,

Ramnath Misra1 and Rakesh K. Gupta2

1Department of Clinical Immunology, 2Department of Radiodiagnosis,

Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow and

3Department of Mathematics and Statistics, Indian Institute of

Technology, Kanpur, UP, India.

Abstract

Objective. Diffusion tensor imaging (DTI) has been used to study the

structure of ordered biological tissue. DTI-derived metrics correlate

with inflammatory cytokines and adhesion molecules, expressed in the

brain abscess. We aimed to study the role of DTI-derived metrics in

delineating the synovitis and their correlation with inflammatory

proteins expressed in the SF of chronic inflammatory arthritis

patients.

Methods. DTI was performed on 18 patients and 6 healthy controls. A

follow-up DTI at 6 months was performed in 10 patients. Quantification

of inflammatory cytokines (TNF-, IL-1â) and soluble intercellular

adhesion molecule-1 (sICAM-1) in SF and their correlation with

DTI-derived metrics was performed.

Results. DTI-derived metrics, fractional anisotropy (FA), cylindrical

isotropy (CL), planar anisotropy (CP) and spherical isotropy (CS),

were significantly altered in the inflamed synovium of the patients as

compared to the healthy controls. Significant correlation between FA

and TNF- (r = 0.68, P = 0.002) and IL-1â (r = 0.48, P < 0.05) and

inverse correlations between mean diffusivity (MD) and TNF- (r =

-0.54, P < 0.05) and CS and TNF- (r = -0.53, P < 0.05) and CP and

IL-1â and sICAM (r = 0.48, P < 0.05 and r = 0.49, P < 0.05,

respectively) were observed. A significant correlation between

post-contrast signal intensity (PCI) and IL-1â and sICAM-1 (r = 0.61,

P = 0.01 and r = 0.46, P = 0.05) and volume and sICAM-1 (r = 0.45, P =

0.05) was observed, respectively.

Conclusion. Results of this pilot study suggest that the DTI-derived

metrics have the potential to delineate synovial inflammation;

however, it is not superior to conventional MRI for its detection and

assessment of therapeutic response.

http://rheumatology.oxfordjournals.org/cgi/content/abstract/ken499v1?papetoc

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