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 FUNCTIONAL BRAIN MRI^1,2
Pre-Operative/Procedural Evaluation¹
In the following where fMRI may have a significant role in the mapping of a lesion in relation to eloquent cortex (i.e., language, motor, sensory and visual centers) to determine the appropriateness of surgical intervention

• Focal brain lesion (i.e., tumor or vascular malformation) for presurgical planning^3,4,5,6
• Pre-operative evaluation for epilepsy surgery^7,8
• Brain tumor for radiation treatment planning^9,10

Post-Operative/Procedural Evaluation

• Therapeutic follow-up. A documented medical reason must clearly explain the medical necessity for follow up (i.e., evaluation of post-treatment eloquent cortex).

Rationale
Functional MRI (fMRI) of the brain is a non-invasive imaging technique, using radio waves and a strong magnetic field, to image the brain activity of a patient prior to undergoing brain surgery for tumors or epilepsy. It is based on the increase in blood flow to the local vasculature when parts of the brain are activated and helps to determine the location of vital areas of brain function. fMRI images capture blood oxygen levels in parts of the brain that are responsible for perception, cognition, and movement allowing neurosurgeons to operate with less possibility of harming areas that are critical to the patient’s quality of life. fMRI is primarily used for presurgical planning, operative risk assessment and therapeutic follow-up.

Task vs Resting-State fMRI
During resting-state fMRI (rs-fMRI), unlike task-based functional MRI, the individual is not required^12,13,14 to perform any specific task. This is beneficial for patients who have difficulty performing tasks, such as pediatric and certain neurologic or psychiatric patients. This technique has been well-utilized in research, and its clinical use is increasing considerably, especially in presurgical planning (e.g., mapping epileptic foci) and neuropsychiatric diseases. For the above indications, non-tasked based fMRI such as resting state fMRI can also be performed. 

fMRI as an alternative to the invasive Wada test and direct electrical stimulation — fMRI is considered an alternative to the Wada test and direct electrical stimulation as it is a non-invasive method for location of vital brain areas. The Wada test is used for the pre-operative evaluations of patients with brain tumors and seizures to determine which side of the brain is responsible for vital cognitive functions, e.g., speech and memory. It can assess the surgical risk of damaging the vital areas of the brain. The Wada test is invasive, involving an angiography procedure to guide a catheter to the internal carotid where a barbiturate is injected, putting one hemisphere of the brain to sleep. Direct electrical stimulation mapping is invasive requiring the placement of electrodes in the brain. The electrodes are used to stimulate multiple cortical sites in the planned area of resection to allow the surgeons to identify and mark which areas can be safely resected.^15,16

fMRI and brain tumors — fMRI may significantly affect therapeutic planning in patients who have potentially resectable brain tumors. Due to its non-invasiveness, its relatively high spatial resolution, and its pre-operative results, fMRI is used before surgery in the evaluation of patients with brain tumors. fMRI may have a significant role in mapping lesions that are located in close proximity to vital areas of brain function (language, sensory motor, and visual). It can determine the precise spatial relationship between the lesion and adjacent functionally essential parenchyma, allowing removal of as much pathological tissue as possible during resection of brain tumors without compromising essential brain functions. fMRI provides an alternative to other invasive tests, such as the Wada test and direct electrical stimulation.¹⁷

fMRI and seizures — Brain fMRI can influence the diagnostic and therapeutic decisions of the seizure team, thereby affecting the surgical approach and outcomes. Brain surgery is often the treatment for patients with refractory epilepsy, especially patients with a single seizure focus. fMRI can be used to image and localize abnormal brain function in patients with seizures. fMRI can help determine brain functions (language, sensory motor, and visual) of areas bordering the lesion, resulting in better outcomes with less neurologic deficit.¹⁸

fMRI is increasingly being used to evaluate candidates for surgical treatment of intractable epilepsy (Phase 1 evaluation) and can aid in surgical decision-making. It can 1) help to improve functional outcome by enabling surgery that spares functional cortex, 2) guide surgical intervention by revealing when reorganization of function has occurred, and 3) show when abnormal cortex is also functionally active, and hence that surgery may not be the best option^19,20

Contraindication and Preferred Studies

• Contraindications and reasons why a CT/CTA cannot be performed may include: impaired renal function, significant allergy to IV contrast, pregnancy (depending on trimester).
• Contraindications and reasons why an MRI/MRA cannot be performed may include: impaired renal function, claustrophobia, non-MRI compatible devices (such as non- compatible defibrillator or pacemaker), metallic fragments in a high-risk location, patient exceeds wight limit/dimensions of MRI machine.

References

1. American College of Radiology, American Society of Neuroradiology, Society for Pediatric Radiology. ACR–ASNR–SPR practice parameter for the performance of functional magnetic resonance imaging (fMRI) of the brain. American College of Radiology. 2022; https://www.acr.org/-/media/ACR/Files/Practice-Parameters/fMR-Brain.pdf.
2. Kumar V, Heiba I M, Prabhu S S, Chen M M, Colen R R et al. The role of resting-state functional MRI for clinical preoperative language mapping. Cancer Imaging. 2020; 20: 47. 10.1186/s40644-020- 00327-w.
3. Jiao Y, Lin F, Wu J, Li H, Chen X et al. Brain Arteriovenous Malformations Located in Language Area: Surgical Outcomes and Risk Factors for Postoperative Language Deficits. World Neurosurg. 2017; 105: 478-491. 10.1016/j.wneu.2017.05.159.
4. Lakhani D, Sabsevitz D, Chaichana K, Quiñones-Hinojosa A, Middlebrooks E. Current State of Functional MRI in the Presurgical Planning of Brain Tumors. Radiology. Imaging cancer. 2023; 5: e230078. 10.1148/rycan.230078.
5. Silva M, See A, Essayed W, Golby A, Tie Y. Challenges and techniques for presurgical brain mapping with functional MRI. Neuroimage Clin. 2018; 17: 794-803. 10.1016/j.nicl.2017.12.008.
6. Vysotski S, Madura C, Swan B, Holdsworth R, Lin Y et al. Preoperative FMRI Associated with Decreased Mortality and Morbidity in Brain Tumor Patients. Interdiscip Neurosurg. 2018; 13: 40-45. 10.1016/j.inat.2018.02.001.
7. Benjamin C F A, Dhingra I, Li A X, Blumenfeld H, Alkawadri R et al. Presurgical language fMRI: Technical practices in epilepsy surgical planning. Hum Brain Mapp. 2018; 39: 4032-4042. 10.1002/hbm.24229.
8. Yoganathan K, Malek N, Torzillo E, Paranathala M, Greene J. Neurological update: structural and functional imaging in epilepsy surgery. Journal of neurology. 2023; 270: 2798-2808. 10.1007/s00415- 023-11619-z.
9. Kovács A, Tóth L, Glavák C, Liposits G, Hadjiev J et al. Integrating functional MRI information into conventional 3D radiotherapy planning of CNS tumors. Is it worth it? J Neurooncol. 2011; 105: 629-37. 10.1007/s11060-011-0633-2.
10. Wang M, Ma H, Wang X, Guo Y, Xia X et al. Integration of BOLD-fMRI and DTI into radiation treatment planning for high-grade gliomas located near the primary motor cortexes and corticospinal tracts. Radiat Oncol. Mar 8 2015; 10: 64. 10.1186/s13014-015-0364-1.
11. Washington State Health Care Authority. WSHCA Health Technology Assessment 20150116A Functional Neuroimaging for Primary Degenerative Dementia or Mild Cognitive Impairment. 2015; https://www.hca.wa.gov/about-hca/programs-and-initiatives/health-technology-assessment/functional-   neuroimaging-primary-degenerative-dementia-or-mild-cognitive-impairment.
12. Karambelkar J, Gandhi A, Trunz L, Talekar K, Faro S. National medicare trends in the utilization of fMRI. Neuroscience Informatics. 2022; 2: 100031.
13. Lee M, Smyser C, Shimony J. Resting-state fMRI: a review of methods and clinical applications. AJNR Am J Neuroradiol. 2013; 34: 1866-72. 10.3174/ajnr.A3263.
14. Lv H, Wang Z, Tong E, Williams L, Zaharchuk G et al. Resting-State Functional MRI: Everything That Nonexperts Have Always Wanted to Know. AJNR Am J Neuroradiol. 2018; 39: 1390-1399. 10.3174/ajnr.A5527.
15. Binder J. Functional MRI is a valid noninvasive alternative to Wada testing. Epilepsy Behav. 2011; 20: 214-22. 10.1016/j.yebeh.2010.08.004.

16. Massot-Tarrús A, Mirsattari S. Roles of fMRI and Wada tests in the presurgical evaluation of language functions in temporal lobe epilepsy. Frontiers in neurology. 2022; 13: 884730. 10.3389/fneur.2022.884730.
17. Petrella J, Shah L, Harris K, Friedman A, George T et al. Preoperative functional MR imaging localization of language and motor areas: effect on therapeutic decision making in patients with potentially resectable brain tumors. Radiology. Sep 2006; 240: 793-802. 10.1148/radiol.2403051153.
18. Janecek J K, Swanson S J, Sabsevitz D S, Hammeke T A, Raghavan M et al. Language lateralization by fMRI and Wada testing in 229 patients with epilepsy: rates and predictors of discordance. Epilepsia. 2013; 54: 314-22. 10.1111/epi.12068.
19. Liégeois F, Cross J H, Gadian D G, Connelly A. Role of fMRI in the decision-making process: epilepsy surgery for children. J Magn Reson Imaging. 2006; 23: 933-40. 10.1002/jmri.20586.
20. Vakharia V, Duncan J, Witt J, Elger C, Staba R. Getting the best outcomes from epilepsy surgery. Annals of Neurology. 2018; 83: 676-690. https://doi.org/10.1002/ana.25205.

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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