In a single-photon-emission computed tomography (SPECT) bone scan, a patient's bones will be imaged with a gamma camera after a radioactive tracer has been injected. The scan itself takes around 30 minutes to an hour and requires the patient to lie very still on a table. The entire process includes a three to four hour wait for the tracer to circulate and patients should plan on setting aside a half day for a SPECT bone scan.
This test is highly sensitive and provides a detailed image of the bones. A doctor may request a SPECT bone scan if there are concerns about hairline fractures, especially in the spine. These fractures will not show up on conventional imaging studies. In some cases, doctors ask for a three phase test, where three sets of images are taken over the course of several hours, while in other instances, a single set of images is enough.
The first step in a SPECT bone scan is the placement of the tracer material. This material will be absorbed by the bones as it circulates through the body and the dose of radiation involved is very low. After the scan, it will be eliminated in sweat and urine. The risk of allergic reactions to the tracer is low, but patients should make sure doctors are aware of allergies, and pregnant patients should consult their obstetricians to determine if the scan is safe.
It takes approximately three hours for the tracer to fully circulate. Some clinics allow patients to leave and come back, while others accommodate patients who would prefer to wait in the clinic. Once the tracer is absorbed, the patient is asked to lie on a table and will be scanned. The SPECT bone scan takes around an hour if a full body image is being taken, and requires less time if only one area of the body is being imaged. Patients who feel uncomfortable lying down may be able to receive sedatives and can listen to music or books on tape during the test to relax. It is advisable to urinate before the scan for comfort.
After the SPECT bone scan, patients will be advised to drink lots of water to help clear the tracer from the body more quickly. The doctor can discuss the results after they have been reviewed and determine if additional testing is needed or if a treatment plan can be developed for the patient.