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In this essay, I will give brief definition of the one of the musculoskeletal disorders, osteoporosis, and its progression as well as outlining and discuss the possible imaging techniques such as conventional radiography, quantitative computed tomography (QCT), single photon absorptiometry (SPA), dual photon absorptiometry (DPA), quantitative ultrasonography (QUS), dual-energy x-ray absorptiometry (DEXA or DXA) and bone measurement density (BMD) (Greenstein, 1997). Also I will contribute to management and treatment of osteoporosis as pointing out the patient issues. In addition recent research or developments will be discussed within the diagnostic imaging techniques (The Royal College of Radiologists, 2007).
There are three million osteoporosis patients in the United Kingdom and there are 230.000 osteoporotic fractures every year. 1150 of them are dying every month in the UK as a result of hip fractures. Osteoporosis is a metabolic bone disease that affects the bones as a result of the decreasing of the bone mass while causing them to become thin, weak and fragile. There are three kinds of osteoporosis, the primary osteoporosis without underlying cause and the secondary osteoporosis with underlying and juvenile osteoporosis in which mostly affects the children (NOS, 2009).
Osteoporosis is not usually diagnosed until the weakening of the bones lead to a fractured bone. People do not realize that they have got the brittle bones until they have a fracture because it develops gradually over several years and there are no obvious symptoms in the early stages of the condition but BMD help us to assess the amount of bone mineral. BMD is also the most important factor affect the bone strength and risk of fracture (Donnas and Yiannakopoulos, 2007).
Although osteoporosis usually does not cause any pain unless having a fracture, some patients have joint pains and having difficulty in sitting and standing. When the bones are severely weaken then the wrist, hip or spinal fractures might occur. A fractured bone in elderly can be serious because the bone cannot repair itself efficiently (Jergas et al., 1999). Women are at greater risk of developing osteoporosis than men because of the declining of the hormone oestrogen level after the menopause and they have less bone mass and take in less calcium than men. Also women who have early menopause (before the age of 45) are also likely to develop osteoporosis as well as having hysterectomy and removing of the ovaries because female hormone oestrogen and male hormone testosterone are essential in keeping the bones strong as processing some minerals such as calcium (Hippisley & Coupland, 2009). However, osteoporosis can be triggered by hormone related diseases such as hyperthyroidism, disorders of adrenal glands, pituitary gland, diabetes, long term bed rest, heavy drinking, smoking, a close family history of osteoporosis, malabsorption problems, inadequate amounts of calcium, low vitamin D levels and very low body mass (Minne et al, 2002). Regular exercise is important in improving bone density and helping prevent osteoporosis. The sunlight, lifestyle and diet are also play an important role to have healthy bones. Weight bearing exercises such as running, dancing, aerobics are useful to strength the muscles, ligaments and joints. Resistance exercises such as weight lifting are likely to strength the muscles (De Sousa & Khujineri, 1999).
Single-Photon Absorptiometry (SPA) SPA measures forearm bone density. The beam is passed through bone and soft tissue to a detector. The amount of mineral in the path is then quantified. The distal radius is usually used as the site of measurement because the amount of soft tissue in this area is small. SPA may provide an accurate assessment of bone density of spine or hip and is now invalid by the use of single x-ray absorptiometry (SXA) which do not require an isotope supply (Chausmer, 2001).
Single X-ray Absorptiometry (SXA) is the x-ray based equivalent of SPA whichis used as a filtered X-ray spectrum. It is used only for the radius and calcaneus. The distal radius is the most sensitive region for bone density measurement because it reflects the high turnover of trabecular bone (Theodorou et al, 2002).
Dual Photon Absorptiometry (DPA) is an extension of the SPA as measures the density of the spine or hip which is acceptable for diagnosing osteoporosis but insufficient for detecting changes. DPA represents a progress over SPA and allows the direct measurement vertebral or femoral bone density. DPA is good to assess the vertebral bone and relatively low radiation dose technique however it is expensive and it has a longer scanning time, and it is not as widely available as SPA (NCBI, 2003).
Dual-energy X-ray absorptiometry (DXA) is the most commonly used technique now. It works in a similar way to DPA, but uses an X-ray source instead of a radioactive isotope. This measurement technique is superior to DPA because the radiation source does not decay and the energy stays constant over time. It is a gold standard for BMD measurement today. DXA is a bone density scan. It scans the two main areas, lower spine and hip, because these areas at risk from osteoporotic fractures as using axial or central scan. On the other hand, peripheral scanner assesses the forearm and the heel. It measures the density of bones and compares it to the average healthy adults (T score) and to age-matched adults (Z score). T scores are generally used to identify osteoporosis. On the other hand, Z score is less used but helpful in decide persons who should undergo a work up for secondary causes of osteoporosis. The difference between this average and patientââ‚¬â„¢s bone density is calculated and if the T score is between 0 to -1 then this shows as normal, if it is between the -1 to -2.5 then it is osteopenia, which is the category between the normal and osteoporosis. If it is below than -2.5, then the bone is osteoporotic (NOS, 2009).
This scan predicts how likely to have breaking bones as well as being diagnostic but other scans and tests can be used to identify what is happening into the bones. This technique is quite useful because low bone density may indicate a possible risk of fracture. Bone density scan helps us to decide whether drug treatment is needed with the patient who has osteopenic result. If bone density is not sufficiently low to require treatment, repeat scan might be performed after two to five years to determine whether a treatment is needed at a later date. If a person is on a drug treatment that they tolerate well and they have not had fractures whilst on that treatment, then it is likely that the drug is working and another scan is not necessary. However, if a person has problems taking a treatment, or has fractures despite being on a treatment, then the doctor may decide that another scan to check bone density would be useful to make an informed decision about what to do next. This technique uses a radiation dose. Patient does not need to clothes off but metal around the hips and spines should be avoided (RSNA, 1994).
Since 1999, the Royal College of Physiciansââ‚¬â„¢ clinical guidelines for prevention and treatment of osteoporosis have been used to decide who needs a scan to help with decisions about drug treatments. This guidance recommends that bone density measurements should be available to post menopausal women over 45 years at high risk of osteoporosis on the other hand bone density measurements are not an effective method to monitor the response to treatment because changes in bone density may not be detected for up to two years (Chausmer, 2001).
Currently, DEXA is the most correct and suggested technique for BMD measurement. It is a sensitive technique and can detect changes in bone density only 6-12 months after a previous measurement. The National Osteoporosis Foundation recommends bone density testing for women aged 65 or older, postmenopausal women younger than 65 years who have at least 1 additional risk factor, all postmenopausal women with a fracture and women who used estrogen replacement therapy for several years (Chausmer, 2001).
The National Osteoporosis Society Advisory Committee in the UK recommends bone density measurements for the menopausal woman in whom the decision to use HRT; those with osteopenia as reported by a radiologist for spine x-ray; patients taking prednisolone; patients with disease known to cause this disease bone disease; and select patients in whom the response to healing should be monitored (Jergas et a., 1999).
DEXA is inexpensive, high accuracy, precision, low radiation dose, speed of examinations and resolution. DEXA is well suited to monitor the effect of the treatment. At present, DEXA is the most specific method for measuring BMD. DEXA scan is useful after the x-ray to see if bone density is low and confirm that fractures are caused by osteoporosis (NCBI, 2003).
X-ray An x-ray cannot reliably measure bone density but it is useful to identify spinal fractures. Although it is not usually reliable in the early stage of osteoporosis, it can still be helpful for the additional diagnosis because the plain film shows that the trabecular bone is sparse and reduction in bone density. In the vertebral bodies, trabeculae are vertically oriented as its primary stress bearing and they will appear accentuated because of resorption of the secondary stress bearing horizontal trabeculae. The vertebral bodies may be appeared as a biconcave shape. The loss of trabecular bone may lead to metaphyses seem radiolucent. Plain x-ray is good to show thinning of the cortices. This means that end-plate margins will demonstrate thinned subchondral cortex and the pedicles will appear to have less cortical thickness (Theodorou et al., 2002).
Plain radiography is widely available but not preferred because it is quite insensitive and no suitable for the early detection of osteoporosis. Changes on plain radiographs can be shown simply following an approximately 30% of the bone is lost. However, plain radiographs are valuable to rule out osteoporotic fractures.
CT CT helps to measure bone density and any following compression fractures in the spine when getting an accurate result can be more difficult. The advantage of the CT methods is that the result of the BMD and that is measured only in the trabecular bone. However CT scan uses higher levels of radiation than a DEXA scan therefore in this case DEXA is more preferable than the CT scan (Genant et al., 2008).
BMD measurements with a CT scanner have the major advantage that the trabecular component may be defined and thus can be detained to these parts. For both single and dual energy CT methods, careful calibration of the CT should be undertaken. In addition, decalcifications of the trabeculae do not only affect the specific BMD but as well the atomic composition of the area. BMD can thus be measured by delineate the trabecular part of the bone being investigated, by calculating the mean Hounsfield number in the area, and by applying the calibration equation to this measured value.
Quantitative computed tomography (QCT) is the only three-dimensional densitometer capable of differentiating between cortical and trabecular bone. It measures bone density in the lumbar spine. QCT is the only method to provide 3D volumetric BMD analysis and high resolution CT allows the analysis of trabecular structure. QCT is more precise than DXA, especially for elderlies. One major disadvantage of QCT is that artefacts hamper the CT data, reducing its accuracy. Another limitation is QCT has a considerably high radiation dose. For most clinical purposes DEXA becomes very useful method over QCT (RSNA, 1994).
MRI MRI uses strong magnetic field and radio waves to produce detailed pictures of soft tissue such as ligaments and muscles. It does not provide information about bone tissue so cannot diagnose osteoporosis or measure bone density. However, sometimes fractures might be identified using MRI, especially hip or vertebral fractures not seen on a normal x-ray. Often, MRI is used to indicate if another disease is present (Theodorou, 2002).
MRI is not a common to use in the diagnosis of osteoporosis and is not likely to become now because of its cost and the long time is needed to attain a scan. On the other hand, some recent research developed that non-invasive MR techniques can provide microstructural information about the bone within simple bone densitometry (Minne et al., 2002).
MRI is valuable in the measurement for vertebral body fractures, non-spinal insufficiency fractures the bone mass strength. The signal intensity of bone marrow provides the differentiation of neoplastic fractures (Greenstein, 1997).
Bone (radioisotope) scanning Other than SPA and DPA, nuclear medicine is not useful or effective to measure BMD. However, bone scans can be useful to diagnose fractures that are not noticeable on x-rays. Radionuclide bone scans are mostly useful for screening the whole skeleton for the location of osteoporotic fractures. Radionuclide scans are particularly good in the diagnosis of sacral deficiency fractures, for which the appearances may be distinguishing. According to Schmitz (2002) FDG-PET is potentially effective when differentiate osteoporotic vertebral fractures. Given an injection of radio opaque dye will show it clearly on the x-ray. Other tests then are required to make sure the fractures are not caused by other conditions (De Sousa & Khujneri, 1999).
Ultrasound scanning DEXA of the hip and spine is a relatively expensive technique using large, static equipments which are usually placed in the hospital. Therefore some research states that ultrasound should be used as it will be less expensive and portable techniques which predict the risk of the fractures. Ultrasound is also used to examine structures inside the body (NOS, 2009).
The portable and relatively inexpensive ultrasound machines have been developed, which are designed to look at bone structure and strength, usually of the heel bone (calcaneus) wrist or finger. They give a picture of the bone and provide measurements of the speed of the ultrasound wave through the bone. On the other hand, quantitative ultrasound scanning (QUS) measurements cannot be used to diagnose of osteoporosis also it cannot be used to monitor rates of bone loss or bone gain with treatment (NOS, 2009).
Some studies suggested that heel ultrasound in older women identify the risk of hip fracture as well as DEXA. Heel ultrasound is also useful in predicting osteoporotic fracture risk in women around the time of the menopause and wrist fracture in women in their early post menopausal years. There is no certain evidence that heel ultrasound can accurately predict fracture at other sites in women prior to the menopause, or in men. There may also be problems using drug treatments based on ultrasound readings because research studies to determine the benefits of osteoporosis drug treatments were all based on DXA readings (Petty et al., 2004).
Due to difficulties with using heel ultrasound to diagnose and monitor osteoporosis and the lack of well- established, normal reference ranges, heel scans are not generally used in the same way as DXA scans. The QUS bone analysis is a non-ionizing technique which is less expensive and precise for define the risk of osteoporotic fracture patients (Theodorou et al., 2002).
QUS has been technically validated in vitro and clinical vivo studies. Clinical studies are used when QUS parameters are responsive for ages and useful differentiating osteoporotic subjects and they present a potential prediction for risk fractures when to contrast to that of axial DXA. Normative data is identified for several devices such as conventional bone densitometry as well as may be assessed to note their different pathophysiologic behaviour. Whether QUS is used to monitor treatment which is not been decisively revealed in treatment, QUS may show distinction between individuals. These differences might be prognostic differences and which may not be a simple fault measurement (Jergas et al., 1999).
Bone markers tests During the bone remodelling process, chemicals are produced which are detected in the blood and urine. These products are known as biochemical markers of bone turnover. The bone marker test is easy to process and requires a sample of urine or blood for testing. Although the test measures the rate at which bone is likely to be fractured or formed, it cannot be used to diagnose osteoporosis and determine bone strength (Minne et al., 2002).
Bone markers assess the effectiveness of the treatment. Most treatments for osteoporosis work by reducing the rate of bone turnover, so monitoring bone loss using this technique may allow adjustment of the dosage of a treatment or change to another therapy if bone turnover is not reduced or back to normal within six months (Dontas & Yiannakopoulos, 2007).
Osteoporosis is treated by a team of health care providers including physicians, nurses, and physical therapists. There are different kinds of treatments available for osteoporosis. The first one is the hormone replacement therapy (HRT) is used for females who are in menopause. This therapy helps to maintain bone density and reduce fracture rates during the treatment. However, HRT is not always useful for the first stage of the treatment as it can raise the risk of stroke and heart related diseases (Petty et al., 2004). Testosterone is the second treatment which is used for males if there is inadequate production of male sex hormones. Biphosphonates are non-hormonal drugs that keep up bone density and reduce fracture rates. Calcitonin is a hormone made by the thyroid gland. It inhibits the cells that break down bone. Calcium and vitamin D supplements can be advantage for older people to reduce the risk of hip fracture. Having enough calcium in young age is likely to diminish the risk of the osteoporosis. Medications such as alendronate and risedronate help to increase bone density and decreases any chance of future fractures but the heart burn is a possible side effects of these medications ( Dell et al., 2009).
To conclude, osteoporosis is a very common condition that can be prevented by good quality nutrition and a healthy life style as well as having medications if necessary. Exercise, adequate calcium and vitamin D are important steps that everybody can take to improve their bone strength.Â Different imaging techniques or methods can help to estimate the risk of fracture as well as assess the effects of injuries or illness. Some of the techniques are much preferable than the others such as CT/QCT which is the one of the most preferable technique to measure the bone mass, detect osteoporosis in the early stages. Attention should be given to measuring BMD before identifying other risk factors to quantitate the level of fracture risk with patients, because the result of fractures are usually severe and there may not be any symptoms other than fractures are concerned with the development of the osteoporosis (Dell et al., 2009).