Why would my doctor order a bone scan?
Bone scans, also known as bone scintigraphy, can examine the whole body or a specific area of concern. It is the most commonly ordered nuclear medicine exam, and uses a small amount of radioactive material (called a radiopharmaceutical) injected into a vein that travels through your bloodstream into your bones. A gamma camera detects the radiation emitted from your body, which is put together by a computer that creates images of the bones.
Areas that take up little or no amount of the radiopharmaceutical appear as "cold" spots, and could show a lack of blood supply to the bone. Areas which take up more radiopharmaceutical show up as "hot" spots, indicating increased blood flow or bone turnover, and could point to problems like arthritis, a tumour, a fracture, or an infection.
Depending on the area of concern, a bone scan can image the entire body or pay particular attention to certain parts. It is useful in surveying areas with many small bones and joints like the spine, foot, and ankle because it can provide detailed, localized information about bone metabolism. For example, it could be used to pinpoint abnormal areas of activity around facet joints within the spine which may be the source of chronic back pain. The images produced could provide information to guide potential pain therapy injections.
Nuclear medicine exams, including bone scans, are pretty common – Mayfair Diagnostics performs thousands of bone scans each year. Often, a bone scan is ordered if an X-ray is normal, yet symptoms persist or change, because it is more sensitive. A standard X-ray may be able confirm a fracture or arthritis, but a more detailed look might require a bone scan.
WHAT HAPPENS DURING A BONE SCAN?
A bone scan involves two separate appointments booked on the same day. The first appointment will take approximately 15 minutes. During this time, the radiopharmaceutical is injected into an arm vein and travels throughout the body. You will be asked to lie on your back on the imaging bed while a gamma camera is placed over your body. The first set of images documents increased or decreased flow to the areas of concern. Afterwards, you will be able to go about your normal daily activities until the second appointment (2-5 hours after the first).
During the second appointment, imaging will be performed without any additional injections, to document uptake in the bones. It will take approximately 30-45 minutes. You will be asked to hold as still as possible, while breathing normally – movement can blur the images and make them more difficult to interpret. If required, additional imaging called “SPECT/CT” may also be performed towards the end of this second appointment.
SPECT/CT (Single Photon Emission Computed Tomography/Computed Tomography) imaging combines two imaging types to help localize the area of abnormal activity that may be present on the planar bone scan image. For the "SPECT" part, the nuclear medicine gamma camera rotates 360 degrees around the body and acquires measurements of the radiation being emitted, which the system reconstructs into a 3D image. For the "CT" portion, a low-dose CT image is taken, similar to those from a classic diagnostic CT scan, but using limited radiation. In this case, they are fused electronically with the SPECT images to get the SPECT/CT image.
IS A BONE SCAN SAFE?
The radiopharmaceutical is excreted from the body through your urine and will decay within the body over the 48 hours following your exam. Keeping hydrated and voiding frequently will help eliminate it from your body.
A bone scan involves a small dose of ionizing radiation from the radiopharmaceutical injected into your vein, and also from the CT scan during the CT portion of SPECT/CT imaging. CT imaging is a form of X-ray and the exposure to radiation from this scan is slightly higher than that of standard X-rays, but the associated risk is still small. Overall, the radiation exposure from a bone scan with SPECT/CT is about the equivalent of exposure to the earth's natural background radiation over two years. In most cases, the benefits, such as the early detection of a serious illness, outweigh the small increased risk from radiation exposure.
Mayfair Diagnostics complies with policies and has procedures in place for nuclear medicine radiation safety, including a Radiation Safety Officer who ensures we follow all policies and procedures. If you are pregnant, or if there is a chance you are pregnant, we will not perform the exam. If you are breastfeeding, please inform the technologist. The exam will still be performed, but you will be advised to pump and discard breast milk, or store it for a specific period of time before using.
HOW DO I GET A BONE SCAN?
This exam is covered under your Alberta Health Care Insurance Plan and must be requested by a health care practitioner. To determine whether it is appropriate for you, your doctor will often review your medical and family history, risk factors, how long symptoms have been present, and how they affect daily activities. If this exam is indicated as a best next course of action, your doctor will provide you with a requisition and the appointment can be booked.