Bone scan
Bone scans can help identify hidden fractures that cannot be seen in regular x-rays, they can also help detect bone cancer, arthritis, reason for mysterious bone pain and bone infections. In a normal x-ray, the radiation passes through the body and creates an image on the x-ray placed on the other side of the body, whereas in a bone scan the radiation travels to the surface of the body that is in turn detected by a camera. All metal items in contact with the body have to be removed before a bone scan. There are no restrictions on eating and drinking. Bone scans are not performed on pregnant women. You have to arrive 4 hours before the scan and let the tracer settle well into your body.Bone scan procedure involves:
- An injection with tracers is injected into the vein in your arm.
- After this you have to wait for 2-4 hours to allow the tracers to circulate and become absorbed by your bones. In organs and tissues such as the bones, this radionuclide gets accumulated.
- You will be asked to drink lots of water to pass out the unabsorbed radioactive material through the urine. The absorbed radioactive material will flush out through the urine by 24 hours.
- During the bone scan, you will be made to lie motionless on the table, as a device with an arm-like gadget holding the gamma camera passes above the body. When the tracers enter the body, they emit gamma waves of radiation that can be detected by a special camera.
- The camera in turn generates images that can be inferred by radiologists or nuclear medicine specialists.
- The scan takes about 30-60 minutes for the entire skeletal and even less if only for specified areas.
When no abnormal area is seen with high or low accumulation of the tracers, the radioactive material is evenly distributed. This indicates that the bone area that is scanned is normal. In abnormal cases, radioactive material accumulates in a particular area of the bone. This is known as a hot spot. Hot spots can indicate a healing fracture, bone cancer, bone infection, arthritis or a disease of an abnormal bone metabolism. Certain spots may indicate less absorption of the radioactive material, they are called cold spots. This could indicate cancer or lack of blood supply to the bone.
Bone marrow biopsy
Bone marrow biopsy is a technique to remove a small section of the tissue from the body to study it under the microscope for any further analysis and tests. This test is recommended by doctors if they see an abnormal result in the complete blood count of a person or for examining any other regular disease that might be present in the bone marrow. Bone marrow biopsies are used to check for blood disorders like leukemia, certain types of anemia or problems affecting the bone marrow such as multiple myeloma or polycythemia vera. Besides they can throw light on any infections or cancers that are originating in the bone marrow. A bone marrow biopsy aids in studying abnormal appearance and numbers of red blood cells, white blood cells or platelets in conditions such as thrombocytopenia. It is essential to keep the health care provider of any medications that are taken. A local anesthetic is usually given to numb the skin. A sedative may be prescribed to calm the patient throughout the bone marrow biopsy procedure.
- Samples are usually taken from the hip bone after cleaning the area.
- A biopsy needle is inserted into the bone.
- Core of the needle is removed and the needle is turned in both the directions thus forcing a small sample of the bone marrow into the needle.
- The needle is removed from the site and pressure is applied on that area to restrict bleeding and the area is bandaged.
- There might some discomfort after the biopsy needle is removed as the anesthesia effect cannot reach the bone interiors.
- Bone marrow biopsy will take about 20 minutes and after the biopsy you may be asked to lie down for another 60 minutes to check for bleeding from the site.
Results of bone marrow biopsties are available after 1 to 3 days. Normal results are indicated by normal numbers of mature and growing bone marrow cells. Abnormal results of a bone marrow biopsy are indicated by abnormal appearance of normal numbers of mature and growing bone marrow cells and presence of fibrous tissue in the bone marrow. There may be special stains that confirm infection in the bone marrow.
Bone density test
Special x-rays are used to determine how many grams of bone mineral content (calcium and other bone minerals) is filled into a section of the bone. Bones with high mineral content indicate very dense bones thus indicating the bones are strong and have fewer chances of breakage. Bone density tests are recommended by doctors to check for osteoporosis. Bone density tests are done either by central or peripheral devices. Central devices are huge machines on which the patient can lie down. Such devices are mainly used to check the lumbar vertebrae (lower region of the spine), the narrow neck of the femur bone adjoining the hip and the bones of the wrist and the forearm.
Dual energy X-ray absorptiometry (DXA): This test produces exact results and is the most preferred choice to diagnose osteoporosis. The patient will be asked to lie down on a padded platform as an imager (an apparatus like a mechanical arm) passes above the body. The required information is captured by the device and the test is completed within 20 minutes. The amount of radiation exposure in this test is equal to one-tenth of a chest x-ray radiation. DXA scan can detect even a 1% change in the bone, that which can not be achieved through an ordinary x-ray.
Quantitative CT scan: The bone density (especially spine) is measured with the help of a computerized tomography (CT) scanner along with computer software. The scan produces a three-dimensional picture which also relates to the aging consequences of the bone and diseases other than osteoporosis. The patient is made to lie down on a movable table that is directed into a big tube-like area where images are pictured. The test is completed within 20 minutes and the radiation exposure is slightly more when compared to the DXA scan.
Peripheral devices are moveable machines that measure the bone density on the periphery of the skeleton. e.g. finger, wrist or heel.
They are smaller machines when compared to the central devices and can be found in pharmacies and have their own restrictions. These machines are used to check for the bone density in the heel, or wrist or fingers.
Bibliography / Reference
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