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Clinical scores of mammographic breast density are highly subjective. Automated technologies for mammography exist to quantify breast density objectively, but the technique that most accurately measures the quantity of breast fibroglandular tissue is not k

Byline: D. C. Newitt (1), B. van Rietbergen (2), S. Majumdar (1) Keywords: Key words:Finite element analysis -- High-resolution -- MRI -- Osteoporosis -- Trabecular bone Abstract: The authors have developed a system for the characterization of trabecular bone structure from high-resolution MR images. It features largely automated coil inhomogeneity correction, trabecular bone region segmentation, serial image registration, bone/marrow binarization, and structural calculation steps. The system addresses problems of efficiency and inter- and intra-operator variability inherent in previous analyses. The system is evaluated on repetitive scans of 8 volunteers for both two-dimensional (2D) apparent structure calculations and three-dimensional (3D) mechanical calculations using micro-finite element analysis. Coil correction methods based on a priori knowledge of the coil sensitivity and on low-pass filtering of the high-resolution mages are compared and found to perform similarly. Image alignment is found to cause small but significant changes in some structural parameters. Overall the automated system provides on the order of a 3-fold decrease in trained operator time over previous manual methods. Reproducibility is found to be dependent on image quality for most parameters. For 7 subjects with good image quality, reproducibility of 2--4% is found for 2D structural parameters, while 3D mechanical parameters vary by 4--9%, with percent standardized coefficients of variation in the ranges of 15--34% and 20--38% respectively. Author Affiliation: (1) MRSC, Department of Radiology, University of California, San Francisco, CA, USA , US (2) University of Eindhoven, Eindhoven, The Netherlands, NL Article note: Received: 11 June 2001 / Accepted: 6 November 2001

Byline: J. C. Lin (1), S. Grampp (1), T. Link (1), M. Kothari (1), D. C. Newitt (1), D. Felsenberg (2), S. Majumdar (1) Keywords: Key words:Bone mineral density -- Femur -- Fractal dimension -- Osteoporosis -- Radiography -- Singh index Abstract: Conventional radiography and fractal analysis were used to quantify trabecular texture patterns in human femur specimens and these measures were used in conjunction with bone mineral density (BMD) to predict bone strength. Radiographs were obtained from 51 human femur specimens (25 male, 26 female). The radiographs were analyzed using three different fractal geometry based techniques, namely semi-variance, surface area and Fourier analysis. Maximum compressive strength (MCS) and shear stress (MSS) were determined with a material testing machine BMD was measured using quantitative computed tomography (QCT). MCS and MSS both correlated significantly with BMD (MCS: R= 0.49--0.54 MSS: R= 0.69--0.72). Fractal dimension also correlated significantly with both biomechanical properties (MCS: R= 0.49--0.56 MSS: R= 0.47--0.54). Using multivariate regression analysis, the fractal dimension in addition to BMD improved correlations versus biomechanical properties. Both BMD and fractal dimension showed statistically significant correlation with bone strength. The fractal dimension provided additional information beyond BMD in correlating with biomechanical properties. Author Affiliation: (1) Magnetic Resonance Science Center, Department of Radiology, University of California San Francisco, California USA , US (2) Department of Radiology, Benjamin Franklin, University Hospital, Free University Berlin, Berlin, Germany, DE Article note: Received: 15 April 1998 / Accepted: 23 September 1998