Sonographic assessment of cartilage damage at metacarpal head in rheumatoid arthritis: qualitative versus quantitative methods

OBJECTIVE

To test the validity of the Outcome Measure in Rheumatology (OMERACT) semiquantitative score by comparing with a quantitative method in the sonographic (US) assessment of hyaline cartilage at the metacarpal head (MH) in patients with rheumatoid arthritis (RA) and healthy subjects (HS).

METHODS

The hyaline cartilage from second to fifth MHs of both hands was scanned. Hyaline cartilage was scored semiquantitatively and quantitatively (by measuring cartilage thickness and comparing with reference values). In RA patients, radiographic joint space narrowing (JSN) was scored on the same joints using the Simple Erosion Narrowing Score (SENS).

RESULTS

Four-hundred and eight MHs in 51 RA patients and 320 MHs in 40 HS were evaluated. The OMERACT semiquantitative score was quicker to perform than the quantitative method (6.0 ± 0.5 vs 8.0 ± 1.5 min, p< 0.01). A significant correlation between the US scores (R = 0.68), and between the US scores and the JSN-SENS (R = 0.61 and R = 0.63, for semiquantitative and quantitative method, respectively) was found. The frequency of cartilage abnormalities was similar between the two US methods in RA patients (58.8% and 51.0% RA patients for semiquantitative and quantitative method, p= 0.46), while the former revealed more abnormalities in HS (27.5% and 7.5% of HS, p= 0.02).

CONCLUSION

The higher feasibility of the OMERACT semiquantitative score suggests its use as first-choice method in the evaluation of cartilage damage. However, despite its limits, the quantitative assessment of HC, providing patient-tailored information due to age- and sex-corrected cut-off values, may represent a valid supplement for optimizing the evaluation of cartilage damage in selected cases.

DTI BASED STRUCTURAL DAMAGE CHARACTERIZATION FOR DISORDERS OF CONSCIOUSNESS

MRI Diffusion Tensor Imaging (DTI) has been recently proposed as a highly discriminative measurement to detect structural damages in Disorders of Consciousness patients (Vegetative State/Unresponsive Wakefulness Syndrome-(VS/UWS) and Minimally Consciousness State-MCS). In the DTI analysis, certain tensor features are often used as simplified scalar indices to represent these alterations. Those characteristics are mathematically and statistically more tractable than the full tensors. Nevertheless, most of these quantities are based on a tensor diffusivity estimation, the arithmetic average among the different strengths of the tensor orthogonal directions, which is supported on a symmetric linear relationship among the three directions, an unrealistic assumption for severely damaged brains. In this paper, we propose a new family of scalar quantities based on Generalized Ordered Weighted Aggregations (GOWA) to characterize morphological damages. The main idea is to compute a tensor diffusitivity estimation that captures the deviations in the water diffusivity associated to damaged tissue. This estimation is performed by weighting and combining differently each tensor orthogonal strength. Using these new scalar quantities we construct an affine invariant DTI tensor feature using regional tissue histograms. An evaluation of these new scalar quantities on 48 patients (23 VS/UWS and 25 MCS) was conducted. Our experiments demonstrate that this new representation outperforms state-of-the-art tensor based scalar representations for characterization and classification problems.