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Functional magnetic resonance imaging (fMRI) is a noninvasive method for evaluation of eloquent brain areas. Images are collected while specific activities are performed to assist in the presurrgical localization of critical cortical areas and evaluation of language lateralization. fMRI is also being investigated in combination with diffusion tensor imaging, which measures white matter tract organization, and electroencephalogram (EEG) to identify seizure focus.
Before neurological surgery for seizure disorders or resection of brain tumors, localization of certain areas of the brain, such as speech centers, is important. For example, from 25% to 60% of patients who undergo left anterior temporal lobectomy develop dysnomia (language/naming difficulties). Most often these “eloquent” areas are assessed using the Wada test and direct electrical simulation. Both of these tests are invasive and require involvement of various specialists. Direct intracortical electrical stimulation involves functional mapping of the exposed cortex with electrodes, which may elicit a motor or verbal response including arrest of speech, random answering, or perseveration to stimulation. The Wada test is an inactivating method that blocks the function of one hemisphere by injection of amobarbital into the carotid artery, allowing functional testing of the reserve capacity of the nonanesthetized hemisphere.
Functional MRI is an activation method that uses sequences based on T2-weighted blood oxygen level-dependent (BOLD) response. These studies are often done on MR scanners with field strengths of 1.5 Tesla or greater. The interhemispheric difference between activated volumes in the left and right hemispheric regions of interest is calculated as the laterality index (LI), which ranges from -1 to 1. A positive laterality index is considered left-dominant, while a negative laterality index is right dominant. Functional MRI-determined laterality indices may be derived for several different functional areas (regions of interest) that include either Broca’s area (language production) or Wernicke’s area (language comprehension). Various thresholds (e.g., -0.1 to +0.1, or -0.5 to +0.5) have been proposed to differentiate laterality from bilaterality. Bilateral activation patterns can result from the detection of language-associated, but not language-essential cortex. Therefore, bilateral activation is not necessarily indicative of a bilateral distribution of language-essential cortex and may be task dependent. In addition, sensitivity and specificity may change with the application of different statistical thresholds.
Simultaneous EEG-fMRI is being investigated for the localization of seizures. EEG-fMRI combines the temporal resolution of EEG and the spatial resolution of fMRI. Simultaneous EEG-fMRI may allow the detection of cerebral hemodynamic changes associated with seizures and interictal epileptiform discharges that are identified on scalp EEG. Another potential use of EEG-fMRI is to facilitate the implantation strategy of invasive subdural electrodes.
There are several fMRI hardware (eg, fMRI Hardware System; NordicNeuroLab AS) and fMRI software packages (eg, BrainAcquireRx™/BrainProcessRx™ Data Suite; Kyron Clinical Imaging) with 510(k) marketing clearance from the U.S. Food and Drug Administration for use in conjunction with a MRI scanner to perform fMRI.
POLICYFunctional MRI may be considered medically necessary as a complementary test in the preoperative evaluation of patients with refractory epilepsy or brain tumors who are candidates for neurosurgery when the lesion is in close proximity to an eloquent area of the brain (e.g., controlling verbal or motor fuction) and testing is expected to have an important role in assessing the spatial relationship between the lesion and eloquent brain area.
Functional MRI is considered investigational for all other applications.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
Medically Necessary is defined as those services, treatments, procedures, equipment, drugs, devices, items or supplies furnished by a covered Provider that are required to identify or treat a Member's illness, injury or Nervous/Mental Conditions, and which Company determines are covered under this Benefit Plan based on the criteria as follows in A through D:
A. consistent with the symptoms or diagnosis and treatment of the Member's condition, illness, or injury; and
B. appropriate with regard to standards of good medical practice; and
C. not solely for the convenience of the Member, his or her Provider; and
D. the most appropriate supply or level of care which can safely be provided to Member. When applied to the care of an Inpatient, it further means that services for the Member's medical symptoms or conditions require that the services cannot be safely provided to the Member as an Outpatient.
For the definition of Medically Necessary, “standards of good medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. BCBSMS makes no payment for services, treatments, procedures, equipment, drugs, devices, items or supplies which are not documented to be Medically Necessary. The fact that a Physician or other Provider has prescribed, ordered, recommended, or approved a service or supply does not in itself, make it Medically Necessary.
Investigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY12/21/2006: Policy added
3/22/2007: Reviewed and approved by the Medical Policy Advisory Committee (MPAC)
6/19/2009: Policy reviewed, policy statement re-written for clarity
07/09/2010: Policy description updated regarding use of functional MRI. Added "as a complementary test" to the policy statement; intent unchanged. FEP verbiage added to the Policy Exceptions section.
08/02/2011: Policy reviewed; no changes.
07/17/2012: Policy reviewed; no changes.
10/17/2013: Policy reviewed; no changes.
07/31/2014: Policy reviewed; description updated regarding direct intracortical electrical stimulation and the Wada test. Medically necessary policy statement revised to change "is considered" to "may be considered."
08/28/2015: Medical policy revised to add ICD-10 codes. Code descriptions updated for CPT code 96020 and ICD-9 diagnosis code 198.3 in the Code Reference section.
10/20/2015: Policy description updated regarding the use of EEG-fMRI. Policy statements unchanged. Policy guidelines updated to add medically necessary and investigative definitions.
SOURCE(S)Blue Cross Blue Shield Association Policy # 6.01.47
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.