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Dual-energy X-ray absorptiometry (DXA, or DEXA [1]) is a means of measuring bone mineral density (BMD) with spectral imaging. Two X-ray beams, with different energy levels, are aimed at the patient's bones. When soft tissue absorption is subtracted, the bone mineral density (BMD) can be determined from the absorption of each beam by bone. Dual ...
DXA is only able to provide the areal bone mineral density. High-resolution peripheral quantitative computed tomography (HR-pQCT) is better than DXA at detecting bone microarchitecture, modeling whole-bone geometry using 3-dimensional information from scans. This method allows estimation of bone strength and other mechanical properties. [20]
This technique is computationally fast, but the 2D results do not provide a good sense of depth of the original data. To improve the sense of 3D, animations are usually rendered of several MIP frames in which the viewpoint is slightly changed from one to the other, thus creating the illusion of rotation.
The correlation with DXA can be as high as 99% when measuring fat-free mass, if strict guidelines are adhered to. [ 13 ] [ 14 ] It is important to recognize that correlation is not a measure of accuracy or method agreement, BIA methods typically exhibit 2 standard deviation (2SD) limits of agreement with reference methods (e.g., DXA, MRI or 4C ...
A scanner used to measure bone density using dual energy X-ray absorptiometry. Bone density, or bone mineral density, is the amount of bone mineral in bone tissue.The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. [1]
The trabecular bone score is a textural parameter that can be applied to DEXA, which quantifies the local variations in gray level. TBS is derived from the evaluation of the experimental variogram, obtained from the grayscale DEXA. [citation needed] It was found that TBS is a reflection of the structural condition of the bone microarchitecture.
The improvement to DXA with DXL is that, for each pixel scanned by DXA, the exact thickness of the measured object is also measured using lasers. The DXL results allow for a more accurate estimation of bone density by using three separate inputs (low and high x-ray energies plus thickness) rather than two for each pixel in the measuring region.
A wide variety of body composition measurement methods exist. The gold standard measurement technique for the 4-compartment model consists of a weight measurement, body density measurement using hydrostatic weighing or air displacement plethysmography, total body water calculation using isotope dilution analysis, and mineral content measurement by dual-energy X-ray absorptiometry (DEXA). [1]