AB0720 Monitoring of changes of size, shape and bone mineral density of bone erosions in high resolution ct datasets of patients with rheumatoid arthritis under treatment

Abstract

Background Diagnosis and monitoring of patients with rheumatoid arthritis (RA) is largely based on radiographs, therefore the sensitivity to detect small changes of bone erosions is limited. This is also true for MRI, where the spatial resolution is limited. Objectives To use high resolution peripheral quantitative CT (HR-pQCT) combined with advanced 3D image processing to quantify longitudinal shape and size changes of bones erosion of the metacarpophalangeal (MCP) joints of patients with RA. Methods HR-pQCT images of the second to fourth MCP joint from 10 RA patients were acquired on an XtremeCT scanner (Scanco Switzerland) with an isotropic voxel size of 82µm. Patients were scanned at baseline and after 1.1±0.4 years. 5 patients were treated with Methotrexate (MTX, mean age±SD 53.1±18.8 years, 1 male), 5 with tumor necrosis factor inhibitors (TNFi, 46±13.9 years, all women). The periosteal surface was segmented independently in baseline (BL) and follow-up (FU) datasets. The BL segmentation was rigidly registered to the FU segmentation and also used for the FU images. Erosions were segmented independently in both BL and FU data. We evaluated change in volume, surface area, and sphericity (a measure between 0 and 1 for how closely the erosion resembles a sphere). We also dilated the erosions to obtain 4 concentric volumes of interests (VOIs) in which BMD was measured. Results 10 erosions in the MTX group and 11 erosions in the TNFi group were evaluated. Mean±SD (min/max) % changes of volume, surface area and sphericity were 0.58±18.78 (-20.91/26.28), 4.7±19.9 (-23.93/35.45) and -3.01±10.36 (-24.73/12.44) in the MTX group and -13.97±37.92 (-63.68/75.1), -10.7±33.03 (-60.97/38.23) and 4.73±21.6 (-19.28/61.04) in the TNFi group. % BMD changes in the dilated VOIs 1 to 4 were 0.6±13.64, 2.16±15.2, -0.22±11.07 and -2.55±6.06 for the MTX group and 10.83±21.62, 15.84±27.01, 12.4±19.05 and 9.14±13.56 for the TNFi group. The % change in erosion volume negatively correlated with the % change in BMD in VOI 1 to 4. For all 21 erosions combined, Spearman’s rho were -0.49, -0.54, -0.54 and -0.5. All correlations were significant (p<0.05). Intra-operator BMD precision (root mean squares coefficients of variation) ranged from 2.66% (VOI1) to 3.73% (VOI3). Image/graph Conclusions In this small pilot study we demonstrated that shape and volume changes of bone erosions of the MCPs can be quantified and that small BMD changes in the vicinity of the erosions can be detected. Our preliminarily analysis indicated differences in erosion volume and surrounding BMD changes between the two groups, however, the initial results were not adjusted for age and other potential covariates. A limitation of the HR-pQCT technique is a loss of precision due to motion artifacts, due to long scan times (∼8min). Disclosure of Interest None Declared

Automated three-dimensional registration of high-resolution peripheral quantitative computed tomography data to quantify size and shape changes of arthritic bone erosions

“…Preliminary results were presented at EULAR 2013 [26] and at ACR 2013 [27]. The present work was performed in partial fulfilment of the requirements for obtaining the degree Dr rer.…”

Endogenous Melanin and Hydrogen‐Based Specific Activated Theranostics Nanoagents: A Novel Multi‐Treatment Paradigm for Rheumatoid Arthritis

“…For one thing, the clinical imaging modalities frequently used for RA, such as radiography (RX) and magnetic resonance (MR) imaging, consistently demonstrate low sensitivity and accuracy in tracing early RA. [ 4 , 5 ] Thus, there is an urgent need for a molecular imaging technique with superior spatiotemporal resolution, higher signal‐to‐noise ratio, and low phototoxicity to facilitate precise diagnosis of RA. [ 6 ] For another, the existing treatments for RA, such as disease‐modifying antirheumatic drugs (DMARDs), biological agents (tocilizumab), and glucocorticoids (GCs), commonly exhibit several shortcomings such as single therapeutic function and unclear deliverability, which limits therapeutic efficiency.…”