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DESCRIPTIONPositron emission tomography (PET) scans are based on the use of positron-emitting radionuclide tracers, which simultaneously emit 2 high energy photons in opposite directions. These photons can be simultaneously detected (referred to as coincidence detection) by a PET scanner, consisting of multiple stationary detectors that encircle the thorax. Compared to single photon emission computed tomography (SPECT) scans, coincidence detection offers greater spatial resolution.
A variety of tracers are used for PET scanning, including fluorine-18, rubidium-82, oxygen-15, nitrogen-13, and carbon-11. Because of their short half-life, tracers must be made locally. With the exception of fluorine and rubidium, all the tracers must be manufactured with an on-site cyclotron. Rubidium-82 is produced by a strontium-82/rubidium-82 generator. The half-life of fluorine-18 is long enough that it can be manufactured commercially at offsite locations and shipped to imaging centers. The tracers may be coupled with a variety of physiologically active molecules, such as oxygen, water, or ammonia. Fluorine-18 is often coupled with fluorodeoxyglucose (FDG) as a means of detecting glucose metabolism, which in turn reflects metabolic activity, and thus viability, of the target tissue. Tracers that target the mitochondrial complex also are being developed.
Cardiac PET scanning focuses on 2 distinct clinical situations:
This policy focuses on the cardiac applications of PET scanning.
POLICYI. For Myocardial Perfusion Studies:
Cardiac PET scanning may be considered medically necessary to assess myocardial perfusion and thus diagnose CAD in patients with indeterminate SPECT scan, or in patients for whom SPECT could be reasonably expected to be suboptimal in quality on the basis of body habitus.
For myocardial perfusion studies, patient selection criteria for PET scans involve an individual assessment of the pretest probability of CAD, based both on patient symptoms and risk factors:
The risk can be estimated using the patient's age, sex, and chest pain quality. The range for intermediate risk can vary.
The following table summarizes a characterization for patient populations at intermediate risk for CAD:
II. For Myocardial Viability:
Cardiac PET scanning may be considered medically necessary to assess the myocardial viability in patients with severe left ventricular dysfunction as a technique to determine candidacy for a revascularization procedure (e.g., PET scans are commonly performed in potential heart transplant candidates to rule out the presence of viable myocardium).
III. Diagnosis of Cardiac Sarcoidosis
Cardiac PET scanning may be considered medically necessary for the diagnosis of cardiac sarcoidosis in patients who are unable to undergo magnetic resonance imaging (MRI) scanning. Examples of patients who are unable to undergo MRI include, but are not limited to, patients with pacemakers, automatic implanted cardioverter-defibrillators (AICDs), or other metal implants.
POLICY GUIDELINESPatients selected to undergo PET scans for myocardial viability are typically those with severe left ventricular dysfunction being considered for revascularization. A PET scan may determine whether the left ventricular dysfunction is related to viable or non-viable myocardium. Patients with viable myocardium may benefit from revascularization, while those with non-viable myocardium will not. As an example, PET scans are commonly performed in potential heart transplant candidates to rule out the presence of viable myocardium.
For both of these indications, a variety of studies have suggested that PET scans are only marginally more sensitive or specific than SPECT scans. Therefore, the choice between a PET scan (which may not be available locally) and a SPECT scan represents another clinical issue. PET scans may provide the greatest advantage over SPECT scans in obese patients (BMI of 35 kg/m2 or greater) for whom tissue attenuation of tracer is of greater concern.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member’s specific benefit plan language.
POLICY HISTORY11/18/2009: Policy added as a result of the decision to separate the Positron Emission Tomography (PET) medical policy into application specific policies, this one addressing cardiac applications only. Upon creation of this separate policy, cardiac applications have been revised as outlined: The Policy Description Section revised for a clearer understanding of PET specific to cardiac applications, Policy Statement Section revised to add diagnosing CAD to medically necessary implications for myocardial perfusion studies, and added a guideline for CAD risk factors, Policy Coding Section updated to include Covered Codes specific to cardiac applications for PET, and added non-Covered Codes Table.
04/20/2010: Policy reviewed. No changes to policy description; statement unchanged. Added additional patient selection criteria to the Policy Guidelines section. Minor typographical errors corrected.
08/23/2011: The first policy statement was revised to change "in patients who may be prone to artifact that could lead to an indeterminate test, such as severely obese (BMI>35 kg/m2) patients" to "in patients for whom SPECT could be reasonably expected to be suboptimal in quality on the basis of body habitus." Added medically necessary policy statement regarding diagnosis of cardiac sarcoidosis.
09/25/2012: Policy reviewed; no changes.
05/07/2013: Removed ICD-9 procedure code 87.42 from the Code Reference section.
11/06/2013: Policy reviewed; no changes.
10/30/2014: Policy reviewed; description updated. Policy statement unchanged.
SOURCESBlue Cross Blue Shield Association policy # 6.01.20
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.
The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.
A PET scan essentially involves 3 separate activities:
When the radiopharmaceutical is provided by an outside distribution center, there may be an additional separate charge, or this charge may be passed through and included in the hospital bill. In addition, there will likely be an additional transportation charge for radiopharmaceuticals that are not manufactured on site.
Not Medically Necessary Codes