Thallium rest/stress testing is the common name for myocardial perfusion imaging studya diagnostic procedure that uses thallium or another one of the new technetium-based radiopharmaceutical, such as sestamibi or tetrofosmin, to measure the distribution of blood flow to the myocardium in two stages: during exercise (or after infusion of a drug that induces an exercise-like state) and at rest.
The study begins much like a regular stress test in that an EKG monitors heart rhythm while the patient exercises. But with a thallium stress test, an intravenous tube has been placed in the patients arm. About a minute before the end of the exercise session, the thallium is administered which emits a low level of radioactivity that makes the heart visible to specialized detectors called gamma cameras. After the thallium accumulates in the myocardium, images are taken during this rest stage. Some procedures require more than one radiopharmaceutical injection. For example, a delayed image may be obtained up to 24 hours after the initial procedure to evaluate myocardial perfusion over time. Nevertheless, only one imaging code should be used.
Next, ask these two questions, suggests Kenneth McKusick, MD, FACR, FACNP, coding and reimbursement chair for the Society of Nuclear Medicine.
1. Is it a single imaging study or two-imaging study?
In other words, is it a rest or stress study? Or is it a rest and stress study? he says.
For a solitary rest or stress test use 78460 or 78464 codes that represent single studies. For a stress and rest test, use 78461 or 78465codes that represent multiple studies, he explains.
2. Is it a two-dimensional study or a three-
For example, 78460 and 78461 are planar studies, which means the procedure provides a two-dimensional view of the process or function of the organ being imaged, explains McKusick. But 78464 and 78465 are 3-D computer-reconstructed images or SPECT (Single Photon Emission Computed Tomography).
The answers to these questions are what drives the selection of the myocardial perfusion codes, he stresses. Whether or not one or two injections of radiopharma-ceuticals are given does not influence coding.
The confusion, he points out, lies in the fact that a thallium stress test may be done with either one or two injections while one with the new technetium -99m radio-
pharmaceutical requires two injections.