We developed a new precise 3D segmentation technique for quantification of bone erosions in HR-pQCT datasets that correlates to the volume, shape and surface area of the erosion. The technique allows fast and effective measurement of the erosion size and could therefore be helpful for rapid and quantitative assessment of erosion size.

Longitudinal changes in erosion size and shape and of BMD in the vicinity of an erosion can be measured. BMD changes are associated with progression and regression of erosions. However, the semi-automated and manual approaches did not classify longitudinal changes of erosion volume in the same way. Further research is necessary to define the nature of these differences.

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Purpose The treatment of skin lesions of various kinds is a common task in clinical routine. Apart from wound care, the assessment of treatment efficacy plays an important role. In this paper, we present a new approach to measure the skin lesion surface in two and three dimensions. Methods For the 2D approach, a single photo containing a flexible paper ruler is taken. After semi-automatic segmentation of the lesion, evaluation is based on local scale estimation using the ruler. For the 3D approach, reconstruction is based on Structure from Motion. Roughly outlining the region of interest around the lesion is required for both methods. Results The measurement evaluation was performed on 117 phantom images and five phantom videos for 2D and 3D approach, respectively. We found an absolute error of 0.99±1.18  cm2 and a relative error 9.89± 9.31% for 2D. These errors are <1  cm2 and <5% for five test phantoms in our 3D case. As expected, the error of 2D surface area measurement increased by approximately 10% for wounds on the bent surface compared to wounds on the flat surface. Using our method, the only user interaction is to roughly outline the region of interest around the lesion. Conclusions We developed a new wound segmentation and surface area measurement technique for skin lesions even on a bent surface. The 2D technique provides the user with a fast, user-friendly segmentation and measurement tool with reasonable accuracy for home care assessment of treatment. For 3D only preliminary results could be provided. Measurements were only based on phantoms and have to be repeated with real clinical data.

Background High-resolution peripheral quantitative computed tomography (HR-pQCT) is a novel imaging instrument for bony damage in rheumatoid arthritis (RA). Objectives Agreement on a case definition for pathologic erosions is required given the sensitivity of HR-pQCT for detecting cortical bone disruptions. The reliability of erosion detection and measurement between readers is crucial to evaluate with this new technology, as HR-pQCT is undergoing validation as an outcome measurement tool. Methods HR-pQCT images of the 2nd and 3rd metacarpophalangeal joints of RA patients and control subjects were used in an iterative process to achieve consensus on a case definition for erosions. This case definition was applied by 11 independent readers to score 58 joints. Each surface (radial, ulnar, palmar, and dorsal) of the proximal phalanx and metacarpal head were characterized for image quality, presence of cortical break as well as appearance of the respective cortical break (physiological or pathological). Moreover, the total amount of pathologic erosions per quadrant as well as their width and depth in two perpendicular muliplanar reformations were recorded. Results The case definition requires the presence of a cortical break extending over at least two slices and seen in 2 orthogonal views. The break must be non-linear in shape to differentiate from vascular channels penetrating the cortical surface, and have underlying trabecular bone loss. Inter-reader agreement for erosion detection was at 90.2%. Discrepant scoring was attributable to lower quality images with multiple bony pathologies overlapping each other. Erosion size ranged from 0.016 to 0.890 cm in maximal width (mean 0.184 cm) and 0.030 to 0.800 cm in maximal depth (mean 0.186 cm), with between 12.3 and 24.0% variability in measurement between readers. Conclusions We have devised a new case definition for erosions visualized with HR-pQCT imaging. Inter-reader reliability for erosion detection is good, yielding promise to use HR-pQCT as an outcome measurement tool for bony damage. Further refinement of selection of landmarks for erosion size measurement, or automated volumetric methods, will be pursued. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.3360

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