Description
Positron emission tomography (PET) scanning can be used to assesses brain metabolism and perfusion. Uses include identifying epileptic foci prior to surgery, differentiation of residual tumor versus scar, helping differentiate inconclusive findings on brain MRI and identifying causes of cognitive decline.¹⁵

Current agents that show promise in assessing plaques of the protein beta-amyloid include: florbetapir F 18, florbetaben F 18, and flutemetamol F 18 with PET. PET/MR is also being studied. Some other new agents look at the tau protein and microglial activation.

GENERAL INFORMATION

It is an expectation that all patients receive care/services from a licensed clinician. All appropriate supporting documentation, including recent pertinent office visit notes, laboratory data, and results of any special testing must be provided. If applicable: All prior relevant imaging results and the reason that alternative imaging cannot be performed must be included in the documentation submitted.

Where a specific clinical indication is not directly addressed in this guideline, medical necessity determination will be made based on widely accepted standard of care criteria. These criteria are supported by evidence-based or peer-reviewed sources such as medical literature, societal guidelines and state/national recommendations.

Policy
INDICATIONS FOR BRAIN PET SCAN

Brain PET scans are considered MEDICALLY NECESSARY for the following indications:

Known brain tumor or cancer^1,2 when brain MRI is indeterminant or insufficient to:

• Differentiate radiation necrosis or post-treatment change from residual/recurrent tumor.
• Differentiate low from high grade glioma.
• Evaluation of primary brain lymphoma.
• Evaluation of meningiomas (FDG or SSTR analogs (such as GA-68 Dotatate)).
• To guide intervention/biopsy.

To determine operability of refractory seizures^3,4,5

Post-treatment/procedural evaluation

• A follow-up study may be needed to help evaluate a patient’s progress after treatment, procedure, intervention, or surgery. Documentation requires a medical reason that clearly indicates why additional imaging is needed.

Mild Cognitive Impairment or Dementia⁶

• For the detection of early Alzheimer’s disease†
• For the differentiation between Alzheimer’s disease, dementia with Lewy body disease (DLB) and frontotemporal lobar degeneration (FTD)†
• To assess for the presence of beta amyloid plaque in Alzheimer’s disease when being considered for treatments that target beta-amyloid plaque (such as Leqembi)†

†Note: AFTER an initial insufficient evaluation with a Brain MRI‡ and the following 2 criteria have been met:^7,8

• Objective cognitive impairment^9,10 has been demonstrated by:
  • Either by Mini Mental Status Evaluation (MMSE) or Montreal Cognitive Assessment (MoCA) less than 26.¹¹
  • OR by Neuropsychological testing showing at least mild cognitive impairment.^12,13
• Potential treatable causes have been assessed and addressed,⁹ such as:
  • Metabolic causes, such as thyroid or vitamin deficiency, anemia, or toxic metabolic encephalopathy.
  • Medication side effects.¹⁴
  • Medical causes, such as vascular or traumatic or inflammatory.

‡Note: Brain CT is acceptable if brain MRI is contraindicated. However, brain CT cannot be substituted for MRI when brain PET is requested for evaluation of amyloid plaque because MRI is a prerequisite to beta-amyloid targeted treatment.

Other Indications
Further evaluation of indeterminate findings on prior imaging (unless follow up is otherwise specified within the guideline):

• For initial evaluation of an inconclusive finding on a prior imaging report that requires further clarification
• One follow-up exam of a prior indeterminate MR/CT finding to ensure no suspicious interval change has occurred (No further surveillance unless specified as highly suspicious or change was found on last follow-up exam.)

References

14. Campbell NL, Boustani MA, Lane KA, et al. Use of anticholinergics and the risk of cognitive impairment in an African American population. Neurology. Jul 13 2010;75(2):152-9. doi:10.1212/WNL.0b013e3181e7f2ab
15. Wippold FJ, 2nd, Brown DC, Broderick DF, et al. ACR Appropriateness Criteria Dementia and Movement Disorders. J Am Coll Radiol. Jan 2015;12(1):19-28. doi:10.1016/j.jacr.2014.09.025

Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive. 

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community,  and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies, and accredited national guidelines.

"Current Procedural Terminology © American Medical Association. All Rights Reserved" 

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