Nuclear Bone Scan
A nuclear bone scan, also known as radionuclide imaging or bone scintigraphy, gives us a black and white graphical depiction of the entire human skeleton, including areas of greater darkening around areas of bone that have become injured, in some way. The cellular metabolism in our bone tissues vary, depending on the physical health of our bones. In areas where our bones are healthy and strong, the tissues are in a dormant state maintaining bone structure. When areas of our bones become broken or injured, the osteoblasts in our bones respond by increasing the rate in which the produce new bone to replace the bone that has become damaged or work out. For this test, a radiographic material (Bq of technetium-99m-MDP) is injected into a vein, and this material filters through the entire body and is absorbed into our bone. The areas where new bone is growing at a faster rate will absorb more of this nuclear material, showing the doctors where certain bone abnormalities are. These tests show this and only this - bone abnormalities. They only show where the bones are remodeling themselves and building themselves up. These tests down show exactly what caused the bone abnormalities, or what the actual conditions of the bones are. There are several types of injuries and medical conditions which may cause dark spots (also known as "hot") spots on the images, including arthritis, fractures, infections, tumors, and cancer. In order to reach a specific diagnosis, doctors may order blood tests or additional radiographic examinations, including X-rays, CT Scans, and MRIs.
What are the differences and similarities between a nuclear bone scan and an X-Ray? What type of results may the bone scan show that X-Rays can't? Here are some of the similarities and the differences. Both bone scans and X-rays involve radiation exposure to the patient in order to image the body for development on film of computer graphic. Both of these tests provide 2-dimentional black and white images which show the outline of the skeletal bones, as well as some amount of bone detail. The reason why some doctors order bone scans are when they suspect that the patient may have sustained small bone fractures in their spine that can't be confirmed by spinal X-Rays.
Patients won't experience any physical pain related to the radioactive material injected into them or the scanning they receive from the gamma camera. However, this procedure requires that patients remain flat an motionless for a period up to 60 minutes, which may be painful on all people, and especially to patients that currently have back pain.
Technique: The bone scan involves the injection of the radionuclide substance, and the follow-up scan being performed 2-3 hours later. A gamma camera is used during the scan portion of the procedure due to its ability detect the densities of the radiographic material after they are absorbed by our bones. The medical image produced by this camera will show relatively uniform densities of grayscale colors in the healthy parts of the bones, and much darker colors around areas of bone in which new bone growth is occurring. These areas of the bone will produce blacker densities on the images and are sometimes referred to as hot spots.
Hot spots are likely to be absorbed in sections of bone where the rate of new bone growth activity is 5-15% higher than normal. These tests only show where areas of bone have become damages and are thus being reformed. These tests don't tell doctors what specific injuries or disease processes have caused the damage. Tests such as an indium 111-labeled white blood cell test combined with a Technetium-99m-MDP injection may provide doctors with more diagnostic information and the cause of the bone damage.
Like we said before, hot spots indicate the likelihood that a previous bone injury occurred, as a result of infections, fractures, or tumors. Certain types of tumors don't show up on bone scans. Confirmation of some type of bone tumors/lesions may require another diagnostic test - known as positron emission tomography (PET).
Patients should empty their bladders before the beginning of the test. During this procedure, doctors may also perform an additional test known as Single photon emission computed tomography (SPECT). SPECT is an imaging test in which radiographers zero in on the lesions of the bones that are observed during the bone scan. The SPECT test provides a more three dimensional view of the lesion that is thought to be the cause of bone pain or back pain.