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Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to more porous bone, and consequent increase in fracture risk.
Dual-energy X-ray absorptiometry is a means of measuring bone mineral density (BMD) using spectral imaging. Two X-ray beams, with different energy levels, are aimed at the patient's bones. When soft tissue absorption is subtracted out, the bone mineral density (BMD) can be determined from the absorption of each beam by bone. Dual-energy X-ray absorptiometry is the most widely used and most thoroughly studied bone density measurement technology.
Osteopenia, known as "low bone mass" or "low bone density", is a condition in which bone mineral density is low. Because their bones are weaker, people with osteopenia may have a higher risk of fractures, and some people may go on to develop osteoporosis. In 2010, 43 million older adults in the US had osteopenia. Unlike osteoporosis, osteopenia does not usually cause symptoms, and losing bone density in itself does not cause pain.
In physical fitness, body composition refers to quantifying the different components of a human body. The selection of compartments varies by model but may include fat, bone, water, and muscle. Two people of the same gender, height, and body weight may have completely different body types as a consequence of having different body compositions. This may be explained by a person having low or high body fat, dense muscles, or big bones.
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, although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. The measurement is painless and non-invasive and involves low radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip. The forearm may be scanned if the hip and lumbar spine are not accessible.
Quantitative computed tomography (QCT) is a medical technique that measures bone mineral density (BMD) using a standard X-ray computed tomography (CT) scanner with a calibration standard to convert Hounsfield units (HU) of the CT image to bone mineral density values. Quantitative CT scans are primarily used to evaluate bone mineral density at the lumbar spine and hip.
Senile osteoporosis has been recently recognized as a geriatric syndrome with a particular pathophysiology. There are different classification of osteoporosis: primary, in which bone loss is a result of aging and secondary, in which bone loss occurs from various clinical and lifestyle factors. Primary, or involuntary osteoporosis, can further be classified into Type I or Type II. Type I refers to postmenopausal osteoporosis and is caused by the deficiency of estrogen. While senile osteoporosis is categorized as an involuntary, Type II, and primary osteoporosis, which affects both men and women over the age of 70 years. It is accompanied by vitamin D deficiency, body's failure to absorb calcium, and increased parathyroid hormone.
Steroid-induced osteoporosis is osteoporosis arising from the use of glucocorticoids analogous to Cushing's syndrome but involving mainly the axial skeleton. The synthetic glucocorticoid prescription drug prednisone is a main candidate after prolonged intake. Bisphosphonates are beneficial in reducing the risk of vertebral fractures. Some professional guidelines recommend prophylactic calcium and vitamin D supplementation in patients who take the equivalent of more than 30 mg hydrocortisone, especially when this is in excess of three months. The use of thiazide diuretics, and gonadal hormone replacement has also been recommended, with the use of calcitonin, bisphosphonates, sodium fluoride or anabolic steroids also suggested in refractory cases. Alternate day use may not prevent this complication.
Tomosynthesis, also digital tomosynthesis (DTS), is a method for performing high-resolution limited-angle tomography at radiation dose levels comparable with projectional radiography. It has been studied for a variety of clinical applications, including vascular imaging, dental imaging, orthopedic imaging, mammographic imaging, musculoskeletal imaging, and chest imaging.
Abaloparatide, sold under the brand name Tymlos among others, is a parathyroid hormone-related protein (PTHrP) analog medication used to treat osteoporosis. It is an anabolic agent.
The trabecular bone score is a measure of bone texture correlated with bone microarchitecture and a marker for the risk of osteoporosis. Introduced in 2008, its main projected use is alongside measures of bone density in better predicting fracture risk in people with metabolic bone problems.
Eldecalcitol is an analog of calcitriol, the active form of vitamin D.
Dual X-ray absorptiometry and laser technique (DXL) in the area of bone density studies for osteoporosis assessment is an improvement to the DXA Technique, adding an exact laser measurement of the thickness of the region scanned. The addition of object thickness adds a third input to the two x-ray energies used by DXA, better solving the equation for bone and excluding more efficiently these soft tissues components.
Ronald Marc Summers is an American radiologist and senior investigator at the Diagnostic Radiology Department at the NIH Clinical Center in Bethesda, Maryland. He is chief of the Clinical Image Processing Service and directs the Imaging Biomarkers and Computer-Aided Diagnosis (CAD) Laboratory. A researcher in the field of radiology and computer-aided diagnosis, he has co-authored over 500 journal articles and conference proceedings papers and is a coinventor on 12 patents. His lab has conducted research applying artificial intelligence and deep learning to radiology.
Single photon absorptiometry is a measuring method for bone density invented by John R. Cameron and James A. Sorenson in 1963.
Spectral imaging is an umbrella term for energy-resolved X-ray imaging in medicine. The technique makes use of the energy dependence of X-ray attenuation to either increase the contrast-to-noise ratio, or to provide quantitative image data and reduce image artefacts by so-called material decomposition. Dual-energy imaging, i.e. imaging at two energy levels, is a special case of spectral imaging and is still the most widely used terminology, but the terms "spectral imaging" and "spectral CT" have been coined to acknowledge the fact that photon-counting detectors have the potential for measurements at a larger number of energy levels.
Ignac Fogelman was a professor of Nuclear Medicine at King’s College London, Honorary Consultant Physician at Guy’s and St Thomas’ NHS Trust, and Director of the Osteoporosis Screening & Research Unit at Guy’s Hospital. He was born in 1948 in Germany and died on 5 July 2016 in the United Kingdom. He is known as the father of bone imaging by some researchers and academics.
Radiofrequency Echographic Multi Spectrometry (REMS) is a non-ionizing technology for osteoporosis diagnosis and for fracture risk assessment. REMS processes the raw, unfiltered ultrasound signals acquired during an echographic scan of the axial sites, femur and spine. The analysis is performed in the frequency domain. Bone mineral density (BMD) is estimated by comparing the results against reference models.
Photon-counting mammography was introduced commercially in 2003 and was the first widely available application of photon-counting detector technology in medical x-ray imaging. Photon-counting mammography improves dose efficiency compared to conventional technologies, and enables spectral imaging.
John A. Shepherd is an American physicist, professor of epidemiology and population sciences and director of the Shepherd Research Laboratory at the University of Hawaii Cancer Center in Honolulu, Hawaii. He is an expert in the use of dual-energy X-ray absorptiometry (DXA) for quantitative bone and soft tissue imaging, and pioneered the use of 3D optical imaging of the whole body for quantifying body composition and associated diseases including cancer risk, obesity, diabetes, and frailty. In 2016, he was the President of the Board of the International Society for Clinical Densitometry.
References
- ↑ Leijten, Alex D.; Hampsink, Brieke; Janssen, Marcel; Klein, Willemijn M.; Draaisma, Jos M. T. (September 2019). "Can digital X-ray radiogrammetry be an alternative for dual-energy X-ray absorptiometry in the diagnosis of secondary low bone quality in children?". European Journal of Pediatrics. 178 (9): 1433–1441. doi:10.1007/s00431-019-03425-5. ISSN 0340-6199. PMC 6694095 . PMID 31352546.
- ↑ Jorgensen, J. T.; Andersen, P. B.; Rosholm, A.; Bjarnason, N. Hannover (September 2000). "Digital X-ray radiogrammetry: a new appendicular bone densitometric method with high precision". Clinical Physiology. 20 (5): 330–335. doi:10.1046/j.1365-2281.2000.00268.x. PMID 10971543.
- ↑ Böttcher, J.; Pfeil, A.; Rosholm, A.; Petrovitch, A.; Seidl, B. E.; Malich, A.; Schäfer, M. L.; Kramer, A.; Mentzel, H. J.; Lehmann, G.; Hein, G.; Kaiser, W. A. (December 2005). "Digital x-ray radiogrammetry combined with semiautomated analysis of joint space widths as a new diagnostic approach in rheumatoid arthritis: A cross-sectional and longitudinal study". Arthritis & Rheumatism. 52 (12): 3850–3859. doi:10.1002/art.21606. PMID 16320332.
- ↑ Rosholm, A.; Hyldstrup, L.; Bæksgaard, L.; Grunkin, M.; Thodberg, H. H. (1 November 2001). "Estimation of Bone Mineral Density by Digital X-ray Radiogrammetry: Theoretical Background and Clinical Testing". Osteoporosis International. 12 (11): 961–969. doi:10.1007/s001980170026. PMID 11804024. S2CID 23451120.
- ↑ Friis, M (May 2001). "Digital X-ray Radiogrammetry on Hand X-rays Obtained on Mammographic X-ray Equipment". Bone. 28 (5): S101–S248. doi:10.1016/S8756-3282(01)00454-9.
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