Objective To prospectively evaluate the ability of 7.0 T magnetic resonance (MR) imaging enhanced with ultrasmall superparamagnetic iron oxide (USPIO) particles in detecting synovial macrophages in a rat model of collagen-induced arthritis (CIA).Methods CIA was induced by subcutaneous injection of chicken type Ⅱ collagen.Arthritis rats were randomly divided into early,middle and late model group.Other rats served as controls.Knees of rats were imaged by a 7.0 T MR imager before and 24 hours after USPIO intravenous administration (200 μ.mol Fe/kg) on Day 14,28,42,respectively.The MR imaging protocol included T1-weighted (T1W) spin-echo (SE) sequences,T2-weighted (T2W) SE sequences,T2 * W gradientecho (GRE) sequences.After the completion of MR imaging,rats were sacrificed to obtain histopathologic samples of synovial membrane and staining.LSD-t test and one-way ANOVA were used for statistical analysis.Results Knees of arthritis rats in early,middle and late model groups developed synovial thickening and joint effusion on images from all sequences,whereas not developed in the control group.On USPIO-enhanced images,synovial tissue of arthritis knees showed slight to distinct signal intensity loss on post contrast T2WI and T2WI.However,no signal intensity enhancement of inflamed synovium was observed on postcontrast T1WI.Meanwhile,no control knees developed any visually detectable changes between pre-and postcontrast images.The quantitative analyses were coincident with the visual differences in signal changes between preand postcontrast images.Histologic examination confirmed uptake of iron in the macrophages of arthritic knees.Conclusion USPIO enhanced 7.0 T MR imaging can detect synovial macrophages in different period of CIA,which may be an additional tool for early and accurate diagnosis of RA.

Objective To discuss the value of high frequency ultrasound for the evaluation of subclinical rheumatoid arthritis.Methods Forty-four rheumatoid arthritis patientswho reached disease activity score (DAS28) clinical remis-sion were included.Ultrasound assess were carried out in all 68 joints,including bilateral temporomandibular joints,sternoclavicular joint,acromioclavicular joint,shoulder joint,elbow joint,wrist joint,1-5 metacarpophalangeal joints and the interphalangeal joint of the thumb,the 2-5 proximal interphalangeal joints,the 2-5 distal interphalangeal joints,hip,knee joint,ankle joint,tarsus joint,the 1-5 metatarsophalangeal joint,1-5 toeinterphalangeal joints.Analysis for the correlation between PD,GS score and gender,age,course of disease and clinical disease activity index were conducted.The pain visual analogue scale (VAS),time of morning stiffness,swollen joint count (SJC) and tender joint count (TJC),health assessment questionnaire (HAQ) score,erythrocyte sedimentation rate (ESR),and C-reactive protein (CRP) and rheumatoid factor (RF),anti cyclic citrullinated peptide (anti CCP) antibody,simplified disease activity index (SDAI),DAS28-CRP,DAS28-ESR were compared.Using Pearson and Spearman to analyze ultrasonic joint synovitis index score and clinical indexes,Student's t-test was employed to assess the significance of difference between two independent sample.Results Twenty-six patients reached/European League against Rheumatism (ACR/EULAR) 2011 remission,19 patients achieved ACR remission,and 3 patients achieved ultrasound remission.There was correlation between GS score and the course of disease and the number of swollen joints (r=0.602,0.470,P＜0.01).There was a positive correlation between ultrasound PD score and the patient's pain score,the total score of patients,ACR/EULAR2011,DAS28-ESR,DAS28-CRP (r=0.323,0.337,0.329,0.360,0.343,P＜0.05).The ultrasound PD score also had a positive correlation with CRP,ESR,time of morning stiffness (r=0.474,0.490,0.415,P＜0.01).Conclusion The subclinical arthrosynovitis can be detected by high frequency ultrasound in most rheumatoid arthritis patients at clinical remission.The PD ultrasound has advantage in evaluating RA activity over GS ultrasound.