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"Does a SPECT create a 3-D picture of my insides?"


Is it safe? I don't want to do it if not.


SPECT is an acronym for single photon emission computed tomography. This is an imaging modality that falls under the umbrella of nuclear imaging. There are two features that make SPECT and other nuclear imaging distinct from most other forms of radiologic tests.

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First, in most radiologic studies, a beam or external force is applied to the patient's body and is picked up by a detector, producing a still image based on the effect the body has had on that external force. The simplest example is a plain X-ray image. An X-ray is passed through the body and absorbed by film behind the patient. Different parts of the body absorb either more or less of the X-ray energy and based on this principle a still image is created on the X-ray film. In nuclear imaging, the patient is given a chemical substance (called a tracer) that actually produces the energy beams on an atomic scale from within the body, which are then used for imaging. In this way the patient becomes the energy source and a detector scans the patient and processes the information to produce an image. The other special characteristic of nuclear imaging is that it occurs in real time. Whereas most radiologic studies give a picture of the body at the exact point in time the study was done, nuclear imaging tests such as SPECT give results over time as a detector slowly scans the patient's body. This allows radiologists to study not only what the body looks like, but also how it works. SPECT is a type of nuclear imaging study that is particularly useful in determining how well blood is flowing to various organs. For this reason is is often used to see how well blood is flowing to different parts of the heart, but there are some other applications such as studying the brain in patients with seizures. Because the scanner for SPECT captures information over time, it can rotate around the patient and thus it can produce a 3D image, not to mention many other views of the organ being studied, which allow radiologists to gain as much information as possible from the test. For most people, the SPECT scan is a very safe study. The tracer chemical used is radioactive, which is unnerving to some patients, but the radiation level to which you are exposed is actually very low. The lowest amount of radiation possible is used and is typically an amount equal to what you would receive from the environment over the course of one year (low levels of radiation come in from space and we are always exposed to them by virtue of living in this universe). The most common complications patients experience from a SEPCT scan are pain, bleeding, or swelling where the needle is inserted into your arm to inject the tracer. These are usually minor. A very small number of people can have an allergic reaction to the tracer chemical. Although there are some possible risks to the SPECT test, most people experience no complications at all. The information the test can give your doctors is substantial and if they have recommended the test, this means that the benefits of the information they expect to gain from the test far outweigh the minor risks of the study. For specific information on why you need this test and the risks specific to you, I would suggest you call or make an appointment to speak with the doctor who ordered the test or the radiologist who will be performing it.

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