Description
Positron Emission Tomography (PET) scanning using FDG (fluorodeoxyglucose) assesses brain metabolism and perfusion. Uses include identifying epileptic foci prior to surgery, differentiation of residual tumor versus scar, and causes of cognitive decline.

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.

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

INDICATIONS FOR BRAIN PET SCAN
Known brain tumor or cancer

• To differentiate radiation necrosis or post-treatment change from residual/recurrent tumor when brain MRI‡¹ is inconclusive
• To differentiate low- from high-grade glioma when brain MRI‡ is inconclusive^2,3
• For evaluation of primary brain lymphoma when brain MRI‡ is inconclusive⁴
• For evaluation of meningiomas when brain MRI‡ is inconclusive^4,5
• To guide intervention/biopsy

To determine operability of refractory seizures^6,7,8

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 Dementia⁹

• 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)†; or
• To assess for the presence of beta amyloid plaque in Alzheimer’s disease when being considered for Aduhelm treatment†

†Note: AFTER an initial insufficient evaluation with a brain MRI‡ and the following 2 criteria have been met:^10,11

• Objective cognitive impairment^12,13 has been demonstrated by:
  • Either by Mini Mental Status Evaluation (MMSE) or Montreal Cognitive Assessment (MoCA) less than 26¹⁴
  • OR by neuropsychological testing showing at least mild cognitive impairment^15,16
• Potential treatable causes have been assessed and addressed,¹² such as:
  • Metabolic causes, such as thyroid or vitamin deficiency, anemia, or toxic metabolic encephalopathy
  • Medication side effects¹⁷
  • 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 Aduhelm treatment.
 

References

1. Albano D, Bosio G, Bertoli M, et al. 18F-FDG PET/CT in primary brain lymphoma. J Neurooncol. 2018; 136(3):577‐583. doi:10.1007/s11060-017-2686-3.
2. Albert MS, DeKosky ST, Dickson D, et al. The diagnosis of mild cognitive impairment due to Alzheimer’s disease: Recommendations from the National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease. Alzheimers Dement. May 2011; 7(3):270-279.
3. American College of Radiology (ACR). ACR Appropriateness Criteria®. https://acsearch.acr.org/list. Published 2017.
4. American College of Radiology (ACR). ACR-ASNR Practice Parameter for Brain PET/CT Imaging in Dementia. 2015.
5. American College of Radiology (ACR). ACR Appropriateness Criteria®. Seizures and epilepsy. 2014.
6. Bashir U, Mallia A, Stirling J, et al. PET/MRI in oncological imaging: State of the art. Diagnostics. 2015; 5:333-357.
7. 7.      Bohnen NI, Djang DS, Herholz K, et al. Effectiveness and Safety of 18F-FDG PET in the Evaluation of dementia: A review of the recent literature. J Nuc Med. 2012 Jan 1; 53(1):59-71. Epub 2011 Dec 15.
8. Davis DH, Creavin ST, Yip JL, et al. Montreal Cognitive Assessment for the diagnosis of Alzheimer's disease and other dementias. Cochrane Database Syst Rev. 2015.
9. 9.      De-Bonilla-Damiá Á, Fernández-López R, Capote-Huelva FJ, et al. Role of 18F-FDG PET/CT in primary brain lymphoma. Utilidad de la 18F-FDG PET/TC en el linfoma cerebral primario. Rev Esp Med Nucl Imagen Mol. 2017; 36(5):298‐303.
10. Duerden EG, Albanese MC. Localization of pain-related brain activation: a meta-analysis of neuroimaging data. Human Brain Mapping. 2013; 34(1):109-49. doi: 10.1002/hbm.21416.
11. Dunet V, Pomoni A, Hottinger A, et al. Performance of 18F-FET versus 18F-FDG-PET for the diagnosis and grading of brain tumors: Systematic review and meta-analysis. Neuro-Oncology. 2016 Mar; 18(3):426–34.
12. Grinenko O, Li J, Mosher JC, et al. A fingerprint of the epileptogenic zone in human epilepsies. Brain. 2018 Jan 1; 141(1):117-131.
13. Heiss W, Raab P, Lanfermann H. Multimodality assessment of brain tumors and tumor recurrence. J Nucl Med. October 2011; 52:1585-1600.
14. Iaccarino L, Sala A, Caminiti SP, et al. The emerging role of PET imaging in dementia. F1000Res. 2017; 6:1830.
15. Ishii K. PET Approaches for diagnosis of dementia. AJNR Am J Neuroradiol. 2014 Nov; 35(11):2030-38.
16. Jones AL, Cascino GD. Evidence on use of neuroimaging for surgical treatment of temporal lobe epilepsy: A systematic review. JAMA Neurol. April 2016; 73(4):464-470.
17. Kawai N, Miyake K, Okada M, Yamamoto Y, Nishiyama Y, Tamiya T. No Shinkei Geka. 2013; 41(2):117‐ 126.
18. 18.   Lewitschnig S, Gedela K, Toby M, et al. ¹⁸F-FDG PET/CT in HIV-related central nervous system pathology. Eur J Nucl Med Mol Imaging. 2013; 40(9):1420‐1427. doi:10.1007/s00259-013-2448-1.
19. Maza S, Buchert R, Brenner W, et al. Brain and whole-body FDG-PET in diagnosis, treatment monitoring and long-term follow-up of primary CNS lymphoma. Radiol Oncol. 2013; 47(2):103‐110. Published 2013 May 21. doi:10.2478/raon-2013-0016.
20. Motara H, Olusoga T, Russell G, et al. Clinical impact and diagnostic accuracy of 2-[18F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (PET/CT) brain imaging in patients with cognitive impairment: A tertiary centre experience in the UK. Clin Radiol. 2017; 72(1):63‐73. doi:10.1016/j.crad.2016.08.003.
21. National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines in Oncology. 2020.
22. https://www.nccn.org/professionals/imaging/content.
23. Singhal T. Positron emission tomography applications in clinical neurology. Semin Neurol. 2012; 32(4):421-31. doi: 10.1055/s-0032-1331813.
24. Sperling RA, Johnson KA, Reiman EM, et al. Alzheimer's Plaques in PET Brain Scans Identify Future Cognitive Decline. Science Daily. 2012.
25. Steriade C, Martins W, Bulacio J, et al. Localization yield and seizure outcome in patients undergoing bilateral SEEG exploration. Epilepsia. 2019 Jan; 60(1):107-120.
26. Tang Y, Liow JS, Zhang Z, et al. The Evaluation of Dynamic FDG-PET for Detecting Epileptic Foci and Analyzing Reduced Glucose Phosphorylation in Refractory Epilepsy. Front Neurosci. 2019; 12:993. Published 2019 Jan 9. doi:10.3389/fnins.2018.00993.
27. Verger A, Langen KJ. PET Imaging in Glioblastoma: Use in Clinical Practice. In: De Vleeschouwer S, editor. Glioblastoma [Internet]. Brisbane (AU): Codon Publications; 2017 Sep 27. Chapter 9. Available from: https://www.ncbi.nlm.nih.gov/books/NBK469986/ doi: 10.15586/codon.glioblastoma.2017.ch9.
28. Widjaja E, Raybaud C. Advances in neuroimaging in patients with epilepsy. NeurosurgFocus. 2008; 25(3):E3.
29. Wippold FJ 2nd, Brown DC, Broderick DF, et al. ACR Appropriateness Criteria®. Dementia and movement disorders. J Am Coll Radiol. 2015 Jan; 12(1):19-28.
30. Tang Y, Liow JS, Zhang Z, et al. The Evaluation of Dynamic FDG-PET for Detecting Epileptic Foci and Analyzing Reduced Glucose Phosphorylation in Refractory Epilepsy. Front Neurosci. 2019; 12:993. Published 2019 Jan 9. doi:10.3389/fnins.2018.00993.
31. Verger A, Langen KJ. PET Imaging in Glioblastoma: Use in Clinical Practice. In: De Vleeschouwer S, editor. Glioblastoma [Internet]. Brisbane (AU): Codon Publications; 2017 Sep 27. Chapter 9. Available from: https://www.ncbi.nlm.nih.gov/books/NBK469986/ doi: 10.15586/codon.glioblastoma.2017.ch9.
32. Widjaja E, Raybaud C. Advances in neuroimaging in patients with epilepsy. NeurosurgFocus. 2008; 25(3):E3.
33. Wippold FJ 2nd, Brown DC, Broderick DF, et al. ACR Appropriateness Criteria®. Dementia and movement disorders. J Am Coll Radiol. 2015 Jan; 12(1):19-28.
34. Zhang XY, Yang Zl, Lu GM, et al. PET/MR imaging: New frontier in Alzheimer’s disease and other dementias. Front Mol Neurosci. 2017 Nov 1; 10:343.

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, Blue Cross Blue Shield Association technology assessment program (TEC) 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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