**Notice:** It is not appropriate to bill Medicare for services that are not
covered (as described by this entire LCD) as if they are covered. When billing
for non-covered services, use the appropriate modifier.  
  
Compliance with the provisions in this policy may be monitored and addressed
through post payment data analysis and subsequent medical review audits.  
  
**Appropriate Indications for Subsequent PET Scans**

  1. Assessment of therapeutic effect after completion of potentially curative therapy, if additional or alternative therapy will be employed for residual or progressive disease.
  2. Assessment of therapeutic effect after localized, non-surgical therapy (e.g., stereotactic radiotherapy, radiofrequency or thermal ablation, etc.) of apparently limited or clinically significant lesions.
  3. Suspected recurrence/progression:   

    * New symptoms suggestive of tumor recurrence or progression;
    * New physical findings (e.g., palpable lesion) suspicious for recurrence/progression (consider biopsy, if easily accessible, and especially if first recurrence);
    * Rising tumor markers or other signs or laboratory values suggestive of paraneoplastic phenomena;
    * Findings on other imaging that are equivocal or suspicious.
  4. Restaging after documentation of recurrence/progression, if extent of disease will alter therapy or if new baseline needed prior to change in therapy.
  5. Evaluating response to treatment, when a change in therapy is contemplated and routine imaging (e.g., CT) either does not or is not expected to provide optimal information for such decision.
  6. Follow-up of indeterminate findings on a clinically indicated PET scan performed for restaging or suspected recurrence/progression, to assess for trends in FDG uptake within suspected lesions over time. Such follow-up studies typically are performed no sooner than three months after the "indeterminate" PET scan.

  
**Caveats Regarding Use of Oncologic PET**

  1. "Watchful waiting" does not constitute a "therapy." After an Initial Therapy Strategy PET, further PET restaging is not justified unless treatment has been given or unless a significant change in patient status suggests progression/transformation of disease.
  2. Routine modalities (e.g., diagnostic CT, bone scintigraphy, MRI) should be employed before PET if the clinical decision to be made is likely to be answered by those modalities, such as:  

    * If there is specific clinical suspicion of involvement of an organ or region, documentation of a single site of involvement is necessary/sufficient for clinical decision making, and documentation of additional disease would not change patient management (imaging should be targeted to the area/organ of concern);
    * If the major site of clinical concern is one that is typically poorly imaged by FDG-PET, such as:  

      * If the clinical concern is brain involvement (use MRI, or contrast-enhanced CT, if patient cannot undergo MRI);
      * If the clinical concern is within the urinary tract consider CT, ultrasonography, or MRI.
    * If the patient's tumor is known to be poorly FDG avid;  

      * If disease is reasonably assumed to be limited to an organ or system generally well imaged by other modalities (e.g., bone scintigraphy for disease limited to skeleton).
  3. PET should be employed instead of or before conventional imaging if:  

    * Available data suggest that PET is likely to obviate additional advanced imaging tests or invasive procedures or is likely to be more accurate than other modalities in detection or characterization of lesions that would change patient management;
    * Patient has contrast allergy or other contraindication to contrast administration that renders other modalities less effective;
    * Patient is being monitored for known disease that either has been previously shown to be better characterized on PET than on other modalities or has been shown to be adequately FDG-avid for follow-up with PET and was not previously imaged with other modalities (e.g., bone metastases well visualized on previous PET and either not as well visualized on bone scintigraphy or bone scintigraphy not done).
  4. Special care should be taken to avoid conditions that may promote false-positive or false-negative FDG PET studies. Although clinical circumstances sometimes warrant modification of these guidelines, if clinically feasible, routine follow-up PET imaging should be delayed:  

    * For at least three weeks after chemotherapy;
    * For at least 8-12 weeks following radiation therapy, unless the clinical question involves a site outside the field of radiation;
    * Until resolution or near-resolution of acute infectious or inflammatory processes that may mimic or mask active tumor;
    * At least one week after short-acting marrow stimulants and three weeks after long-acting marrow stimulants.
  5. Incidental findings are common on PET/CT studies, and further follow-up of such findings should be tempered by clinical circumstances and patient prognosis:  

    * Reasonable efforts should be made to obtain previous imaging studies to evaluate for chronicity of indeterminate findings before ordering follow-up imaging studies or interventions;
    * Clinical impact should be assessed in the individual patient (e.g., a potentially malignant thyroid nodule may be of little overall significance in a patient with advanced metastatic disease).

  
**Relative Advantages of Various Advanced Imaging Modalities in Oncology**  
  
The advantages of metabolic imaging have made PET the imaging modality of
choice for staging, restaging, and therapy monitoring for many oncologic
indications, especially in advanced stages. However, the more precise anatomic
detail offered by diagnostic-quality CT and MRI, especially with the added
information supplied by contrast enhancement, is often sufficient or even
preferable for a number of oncologic indications. More precise delineation of
tumor extent is often needed for tumor staging and planning of interventions.
More accurate size measurements are often needed for routine follow-up of
therapeutic efficacy. In most cases, contrast-enhanced CT is sufficient for
such determinations, when needed. However, the unique tissue contrast offered
by MRI provides additional benefits in many cases. A few general
considerations, **but not those which are applied to the pre-payment of
claims** , include:

  1. CT is typically used as the initial modality to help detect or characterize abnormal growths; to help diagnose tumors; to provide information about the extent, or stage, or disease; to help in guiding biopsy procedures or in planning treatment; to determine whether a cancer is responding to treatment; and to monitor for recurrence.
  2. CT is also commonly used to guide local treatments, such as cryotherapy, radiofrequency ablation, and the implantation of radioactive seeds, and to help plan external-beam radiation therapy or surgery.
  3. MRI is typically more accurate in evaluation of brain lesions, including known or suspected primary or metastatic tumors.
  4. MRI is typically more accurate than CT in the evaluation of musculoskeletal neoplasms.
  5. MRI typically shows greater sensitivity, though lesser specificity, for detection of liver metastases than CT or PET, while CT shows greater sensitivity for pulmonary metastases.
  6. MRI is often more helpful in delineating extent of tumor in anatomically complex regions (e.g., the skull base), in evaluating perineural or paravertebral spread of tumor, in evaluation of specific types of lesions in specific organs (e.g., pancreas, salivary gland), and in locoregional staging of breast cancer in suspected cases of multifocal or multicentric disease, contralateral lesions, or regional metastases (especially in patients with dense breasts).
  7. In the above situations, MRI may be used for planning of interventions, as well.
  8. PET is typically (for most solid tumors) the most accurate overall staging modality for patients with known or suspected advanced disease, as well as the most accurate restaging modality for suspected recurrence after therapy.
  9. PET is typically much more accurate in early treatment monitoring, if such is necessary to determine possible changes in therapy.
  10. The utility of PET may be limited in small lesions, in areas of high background activity (e.g., brain, urinary tract), or lesions that often show poor FDG avidity (e.g., castrate-sensitive prostate cancer).
  11. Additional types of imaging may be more appropriate for diseases likely confined to specific organ systems (e.g., bone scintigraphy for skeletal disease) or with specific molecular properties (e.g., OctreoScan for neuroendocrine tumors or ProstaScint for prostate cancer).

  
**General Frequency Guidance on the Use of Advanced Imaging Modalities
(CT/MRI/PET)**

  1. It is recommended that, when possible, the ordering physician should select a single imaging modality if that modality is most likely to provide the most accurate information for providing the most optimal patient care.
  2. If the initially selected advanced imaging test does not provide sufficient information for clinical decision-making, then it is appropriate to select a second imaging modality if, in the opinion of the physician, this will likely provide clinically useful information in patient management. In general, multiple such studies should be employed successively, when needed, and should only be performed together when both are reasonably expected to provide information independently important to patient management.
  3. There are multiple reasons for the longitudinal (e.g., excluding baseline assessment, staging/re-staging) use of advanced imaging modalities (e.g., CT, MRI, and PET), such as:  

    * Surveillance, whereby the patient is assumed to have either no known disease, or stable or clinically insignificant disease: It is not unreasonable to expect such surveillance to occur every 6-12 months for an overall duration (e.g., five years) which is consistent with the tumor biology of that neoplasm.
    * Suspected recurrence/progression (as detailed above), whereby frequency guidance is not applicable to more of a timeline approach to management.
    * Evaluating response to treatment, when a change in therapy is contemplated: In general, imaging should be no more often than after 2 cycles of chemotherapy and/or 6-8 weeks since the prior imaging evaluation.
  4. Finally, there are other applications of advanced imaging, including, but not restricted to, image-directed biopsy and radiation therapy treatment planning, where frequency guidance is not applicable.

**Notice:** Services performed for any given diagnosis must meet all of the
indications and limitations stated in this policy, the general requirements
for medical necessity as stated in CMS payment policy manuals, any and all
existing CMS national coverage determinations, and all Medicare payment rules.
Refer to Billing and Coding: Multiple Imaging in Oncology, A56848, for
applicable CPT/HCPCS codes and diagnosis codes.