Diffusion tensor anisotropy magnetic resonance imaging: a new tool to assess synovial inflammation.
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-alpha, IL-1beta) 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-alpha (r = 0.68, P = 0.002) and IL-1beta (r = 0.48, P < 0.05) and inverse correlations between mean diffusivity (MD) and TNF-alpha (r = -0.54, P < 0.05) and CS and TNF-alpha (r = -0.53, P < 0.05) and CP and IL-1beta 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-1beta 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.


CONCLUSIONS
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.
Agarwal
Vikas
V
Department of Clinical Immunology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, UP, India.
Kumar
Manoj
M
Singh
Jitesh K
JK
Rathore
Ram K S
RK
Misra
Ramnath
R
Gupta
Rakesh K
RK
D000328:Adult; D001168:Arthritis / Q000175:diagnosis* / Q000276:immunology; D001172:Arthritis, Rheumatoid / Q000175:diagnosis / Q000276:immunology; D016022:Case-Control Studies; D016207:Cytokines / Q000032:analysis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000032:analysis; D053583:Interleukin-1beta / Q000032:analysis; D007719:Knee Joint / Q000276:immunology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000175:diagnosis / Q000276:immunology; D012680:Sensitivity and Specificity; D013583:Synovial Membrane / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis; D055815:Young Adult
D016207:Cytokines; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1