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The potency of magnetic resonance imaging (MRI) to measure the exact extent of osteonecrosis of the femoral head (ONFH) remains uncertain. The objective of this study was to determine if the volume of necrosis assessed with MRI accurately reflects the volume of architectural mineral alterations in osteonecrosis of the femoral head by comparison with high-resolution microfocus X-ray computed tomography (HR-μCT). Fourteen male patients aged 53 years [46.2;59.0] suffering from ONFH were prospectively enrolled to undergo preoperative MRI and ex vivo analysis using HR-μCT. The necrotic zone on T1-weighted MRI scans was defined as total necrosis (delimited by the low-signal peripheral band) or dark necrosis (low-signal lesions only). The HR-μCT scans delimited outer necrosis and inner necrosis by including or excluding the sclerotic zone. The intra-class correlation coefficient (ICC) was calculated to compare the agreement of surface areas and volumes of necrosis measurements with the two techniques. There was an overall excellent agreement between MRI dark necrosis volume and HR-μCT outer necrosis volume (ICC=0.91[0.54;0.98]) while the MRI total necrosis volume showed poor agreement with both HR-μCT delimitations of necrosis volume. For surface area, agreement between MRI dark necrosis and HR-μCT delimitations was good for inner necrosis (ICC=0.70[0.21;0.9]) and moderate for outer necrosis (ICC=0.58[0.07;0.85]). This study demonstrates that measurement of the MRI lesions provides a reliable assessment of the extent of ONFH-related architectural damage. ispartof: Bone vol:130 ispartof: location:United States status: Published online

International audience; Venous thrombosis screening exams use 2D ultrasound images, from which medical experts obtain a rough idea of the thrombosis aspect and infer an approximate volume. Such estimation is essential to follow up the thrombosis evolution. This paper proposes a method to calculate venous thrombosis volume from non-parallel 2D ultrasound images, taking advantage of a priori knowledge about the thrombosis shape. An interactive ellipse fitting contour segmentation extracts the 2D thrombosis contours. Then, a Delaunay triangulation is applied to the set of 2D segmented contours positioned in 3D, and the area that each contour defines, to obtain a global thrombosis 3D surface reconstruction, with a dense triangulation inside the contours. Volume is calculated from the obtained surface and contours triangulation, using a maximum unit normal component approach. Preliminary results obtained on 3 plastic phantoms and 3 in vitro venous thromboses, as well as one in vivo case are presented and discussed. An error rate of volume estimation inferior to 4,5% for the plastic phantoms, and 3,5% for the in vitro venous thromboses was obtained.

International audience; Presents a method for the quantitative analysis of the left ventricle mobility, based on the development of a 3D deformable dynamic model. The model is a superquadric-one with different parametric deformations. The data input for the adjustment of this model is a sequence of volumes of the left ventricle obtained in an echocardiography test. An electromechanical device controlled by the computer is adapted. This allows the acquisition of 60 slices in a rotational 3D symmetry. A specialist cardiologist segments the volumes. An objective function is defined to the adjustment of model parameters. The energy of the error is minimized when the parameters are adjusted using a similar focus to the training of the Back Propagation neural network. The dynamics of the position, orientation, size, torsion and its shape have been recovered from the model. This focus permits the obtaining of results which are clinically useful. If we compare quantitatively the volume of the left ventricle and the volume of the developed superquadrics, as a function of time, a small error around 1% is observed in the volume calculation. Therefore, we can conclude that the deformable superquadric captures the global parameters of the left ventricle.

Will Ernest. Dodekatheon et Pantheon. In: Bulletin de correspondance hellenique. Volume 75, 1951. pp. 233-246.