Improved wrist pannus volume measurement from contrast-enhanced MRI in rheumatoid arthritis using shuffle transform.

BACKGROUND: Contrast-enhanced MRI is of value in assessing rheumatoid pannus in the hand, but the images are not always easy to quantitate. OBJECTIVE: To develop and evaluate an improved measurement of volume of enhancing pannus (VEP) in the hand in human rheumatoid arthritis (RA). METHODS: MR images of the hand and wrist were obtained for 14 patients with RA at 0, 1 and 13 weeks. Volume of enhancing pannus was measured on images created by subtracting precontrast T1-weighted images from contrast-enhanced T1-weighted images using a shuffle transformation technique. Maximum intensity projection (MIP) and 3D volume rendering of the images were used as a guide to identify the pannus and any contrast-enhanced veins. RESULT: Visualisation of pannus was much improved following the shuffle transform. Between 0 weeks and 1 week, the mean value of the within-subject coefficient of variation (CoV) was 0.13 and the estimated total CoV was 0.15. There was no evidence of significant increased variability within the 13-week interval for the complete sample of patients. CONCLUSION: Volume of enhancing pannus can be measured reproducibly in the rheumatoid hand using 3D contrast-enhanced MRI and shuffle transform.

Anatomically corresponded regional analysis of cartilage in asymptomatic and osteoarthritic knees by statistical shape modelling of the bone.

Magnetic resonance imaging (MRI) is emerging as the method of choice for measuring cartilage loss in osteoarthritis (OA), but current methods of analysis are imperfect for therapeutic clinical trials. In this paper, we present and evaluate, in two multicenter multivendor studies, a new method for anatomically corresponded regional analysis of cartilage (ACRAC) that allows analysis of knee cartilage morphology in anatomically corresponding focal regions defined on the bone surface. In our first study, 3-D knee MR Images were obtained from 19 asymptomatic female volunteers, followed by segmentations of the bone and cartilage. Minimum description length (MDL) statistical shape models (SSMs) were constructed from the segmented bone surfaces, providing mean bone shapes and a dense set of anatomically corresponding positions on each individual bone, the accuracy of which were measured using repeat images from a subset of the volunteers. Cartilage thicknesses were measured at these locations along 3-D normals to the bone surfaces, yielding corresponded cartilage thickness maps. Functional subregions of the joint were defined on the mean bone shapes, and propagated, using the correspondences, to each individual. ACRAC improved reproducibility, particularly in the central, load bearing subregions of the joint, compared with measures of volume obtained directly from the segmented cartilage surfaces. In our second study, MR Images were obtained from 31 female patient-volunteers with knee OA at baseline and six months. We obtained manual segmentations of the cartilage, and automatic segmentations of the bone using active appearance models (AAMs) built from the bone SSMs of the first study. ACRAC enabled the detection of significant thickness loss in the central, load-bearing regions of the whole femur (-5.57% p = 0.01, annualized) and the medial condyle (-13.08% , p = 0.024 Bonferroni corrected, annualized). We conclude that statistical shape modelling of bone surfaces defines correspondences invariant to individual joint size or shape, providing focal measures of cartilage with improved reproducibility compared to whole compartment measures. It permits the identification of anatomically equivalent regions, and provides the ability to identify the main load-bearing regions of the joint, based on the imputed premorbid state. The method permitted detection of tiny morphological change in cartilage thickness over six months in a small study, and may be useful for OA disease analysis and treatment monitoring.

Effects of oral prednisolone on biomarkers in synovial tissue and clinical improvement in rheumatoid arthritis.

OBJECTIVE: To create greater understanding of the changes in synovial tissue parameters that occur in conjunction with clinical response by using an effective therapy, in order to facilitate the planning of future studies with therapeutic agents for rheumatoid arthritis (RA). METHODS: Twenty-one patients with active RA were randomized to receive either oral prednisolone (n = 10) or placebo (n = 11) for 2 weeks. In all patients, synovial tissue biopsy specimens were obtained by arthroscopy directly before treatment and after 14 days of treatment. Immunohistochemical analysis was performed to characterize the cell infiltrate and vascularity. Stained tissue sections were analyzed by digital imaging. Statistical analysis was performed using an analysis of covariance model. RESULTS: After treatment, the mean Disease Activity Score in 28 joints (DAS28) was 2.0 units lower (95% confidence interval [95% CI] 1.0-3.0) in patients who received prednisolone than in those who received placebo. In the prednisolone group, the mean (+/-SD) DAS28 decreased from 6.27 +/- 0.95 to 4.11 +/- 1.43 after therapy; minimal change was observed in the placebo group. For macrophages, the estimated effect of prednisolone was large. Patients receiving active treatment had fewer (mean 628 cells/mm(2) [95% CI 328-927]) macrophages after therapy compared with those receiving placebo. A reduction in the total number of CD68+ macrophages, from 1,038 +/- 283 cells/mm(2) before treatment to 533 +/- 248 cells/mm(2) after treatment, was observed in the prednisolone group. There were clear trends toward decreased infiltration by T cells, plasma cells, and fibroblast-like synoviocytes after active treatment. We observed a trend toward a reduction in alphavbeta3+ newly formed blood vessels and expression of vascular growth factors after prednisolone therapy. CONCLUSION: Prednisolone therapy in RA is associated with a marked reduction in macrophage infiltration in synovial tissue, suggesting that synovial macrophage numbers could be used as a biomarker for clinical efficacy.