Pending Policies - Radiology


Magnetoencephalography (MEG) and Magnetic Source Imaging (MSI)

Number:RAD601.038

Effective Date:05-15-2018

Coverage:

*CAREFULLY CHECK STATE REGULATIONS AND/OR THE MEMBER CONTRACT*

Magnetoencephalography (MEG) and magnetic source imaging (MSI) may be considered medically necessary in the following situations:

For the purpose of determining the laterality of language function, as a substitute for the Wada test, in patients being prepared for surgery for epilepsy, brain tumors, and other indications requiring brain resection; or

As part of the preoperative evaluation of patients with intractable epilepsy (seizures refractory to at least two first-line anticonvulsants), when standard techniques, such as magnetic resonance imaging (MRI) and electroencephalogram (EEG), do not provide satisfactory localization of epileptic lesion(s).

Magnetoencephalography (MEG) and magnetic source imaging (MSI) are considered experimental, investigational and/or unproven for all other indications.

Description:

Magnetoencephalography

Magnetoencephalography (MEG) is a noninvasive functional imaging technique that records weak magnetic forces associated with brain electrical activity. Using mathematical modeling, recorded data are then analyzed to provide an estimated location of electrical activity. This information can be superimposed on an anatomic image of the brain, typically a magnetic resonance imaging (MRI) scan, to produce a functional/anatomic image of the brain, referred to as magnetic source imaging (MSI). The primary advantage of MSI is that, while conductivity and thus measurement of electrical activity as recorded by electroencephalogram is altered by surrounding brain structures, magnetic fields are not. Therefore, MSI permits a high-resolution image.

Detection of weak magnetic fields requires gradiometer detection coils coupled to a superconducting quantum interference device (SQUID), which requires a specialized room shielded from other magnetic sources. Mathematical modeling programs based on idealized assumptions are then used to translate detected signals into functional images. In its early evolution, clinical applications were limited by the use of only 1 detection coil requiring lengthy imaging times, which, because of body movement, also were difficult to match with the MRI. However, more recently, the technique has evolved to multiple detection coils in an array that can provide data more efficiently over a wide extracranial region.

Applications

One clinical application is localization of epileptic foci, particularly for screening of surgical candidates and surgical planning. Alternative techniques include MRI, positron emission tomography (PET), or single photon emission computed tomography (SPECT) scanning. Anatomic imaging (i.e., MRI) is effective when epilepsy is associated with a mass lesion, such as a tumor, vascular malformation, or hippocampal atrophy. If an anatomic abnormality is not detected, patients may undergo a PET scan. In a small subset of patients, extended electrocorticography (ECoG) or stereotactic electroencephalography (SEEG) with implanted electrodes is considered the criterion standard for localizing epileptogenic foci. MEG/MSI has principally been investigated as a supplement to or an alternative to invasive monitoring.

Another clinical application is localization of the pre- and postcentral gyri as a guide to surgical planning in patients scheduled to undergo neurosurgery for epilepsy, brain neoplasms, arteriovenous malformations, or other brain lesions. These gyri contain the "eloquent" sensorimotor areas of the brain, the preservation of which is considered critical during any type of brain surgery. In normal situations, these areas can be identified anatomically by MRI, but frequently, anatomy is distorted by underlying disease processes. In addition, location of eloquent functions varies, even among healthy people. Therefore, localization of the eloquent cortex often requires such intraoperative invasive functional techniques as cortical stimulation with the patient under local anesthesia or somatosensory-evoked responses on ECoG. Although these techniques can be done at the same time as the planned resection, they are cumbersome and can add up to 45 minutes of anesthesia time. Furthermore, these techniques can sometimes be limited by the small surgical field. A preoperative test, which is often used to localize the eloquent hemisphere, is the Wada test. MEG/MSI has been proposed as a substitute for the Wada test.

Regulatory Status

The U.S. Food and Drug Administration (FDA) regulates magnetoencephalography devices as class II devices cleared for marketing through the 510(k) process. The FDA product codes OLX and OXY are used to identify the different components of these devices. OLX coded devices are source localization software for electroencephalography (EEG) or MEG; the software correlates electrical activity of the brain using various neuroimaging modalities. This code does not include electrodes, amplitude-integrated electroencephalograph, automatic event-detector software used as the only or final electroencephalograph analysis step, EEG software with comparative databases (normal or otherwise, or EEG software that outputs an index, diagnosis, or classification.

The OLY coded devices are magnetoencephalographs that acquire, display, store, and archive biomagnetic signals produced by electrically active nerve tissue in the brain to provide information about the location of active nerve tissue responsible for certain brain functions relative to brain anatomy. This includes the magnetoencephalograph recording device (hardware, basic software).

The intended use of these devices is to “non-invasively detect and display biomagnetic signals produced by electrically active nerve tissue in the brain. When interpreted by a trained clinician, the data enhance the diagnostic capability by providing useful information about the location relative to brain anatomy of active nerve tissue responsible for critical brain functions.” (1) More recent approval summaries add: “MEG is routinely used to identify the locations of visual, auditory, somatosensory, and motor cortex in the brain when used in conjunction with evoked response averaging devices. MEG is also used to noninvasively locate regions of epileptic activity within the brain. The localization information provided by MEG may be used, in conjunction with other diagnostic data, in neurosurgical planning.” (2)

The MagView Biomagnetometer System (Tristan Technologies) has the unique intended use for patient populations who are neonates, infants, and those children with head circumferences of 50 cm or less. (3)

MEG devices (hardware, software) are summarized in Table 1.

Table 1. MEG Devices Cleared by FDA (Product Codes OLX and OLY)

Device

Manufacturer

Date Cleared

510(k) No.

Neuromagneometer

Biogmagnetic Technologies

Feb 1986

K854466

700 Series Biomagnetometer

Biogmagnetic Technologies

Jun 1990

K901215

Neuromag-122

Phillips Medical Systems

Oct 1996

K962764

Magnes 2500 Wh Biomagnetometer

Biogmagnetic Technologies

May 1997

K962317

CTF Systems, Whole-Cortex Meg System

CTF Systems

Nov 1997

K971329

Magnes II Biomagnetometer

Biogmagnetic Technologies

May 1998

K941553

Image VUE EEG

Sam Technology

Aug 1988

K980477

Electroencephalograph Software eemagine

eemagine Medical Imaging Solutions

Oct 2000

K002631

Curry Multimodal Neuroimaging Software

Neurosoft

Feb 2001

K001781

Neurosoft’s Source

Neurosoft

Sep 2001

K011241

Megvision Model Eq 1000c Series

Eagle Technology

Mar 2004

K040051

Elekta Oy

Elekta Neuromag Oy

Aug 2004

K041264

MaxInsight

eemagine Medical Imaging Solutions

Jul 2007

K070358

Elekta Neuromag With Maxfilter

Elekta Neuromag Oy

Oct 2010

K091393

Geosource

Electrical Geodesics

Dec 2010

K092844

Babymeg Biomagnetometer System (also called Artemis 123 Biomagnetometer)

Tristan Technologies

Jul 2014

K133419

MagView Biomagnetometer System

Tristan Technologies

Apr 2016

K152184

EEG: electroencephalogram; FDA: Food and Drug Administration.

In January 2000, Biomagnetic Technologies acquired Neuromag, a Finnish MEG company, and began doing business as 4-D NeuroImaging. The latter company ceased operations in 2009.

Rationale:

The policy was created in 2002 and has been updated periodically with literature review. The most recent literature review covers the period through August 3, 2017.

Assessment of a diagnostic technology typically focuses on 3 categories of evidence: 1) its technical reliability (test-retest reliability or interrater reliability); 2) clinical validity (sensitivity, specificity, and positive and negative predictive value) in relevant populations of patients; and 3) clinical utility demonstrating that the diagnostic information can be used to improve patient outcomes.

Magnetoencephalography/Magnetic Source Imaging for Localization of Seizure Foci

Clinical Context and Test Purpose

The purpose of magnetoencephalography (MEG) and magnetic source imaging (MSI) in the mapping of epileptic foci is to facilitate surgical treatment planning for persons with drug-resistant epilepsy.

The question addressed in this literature review is: Does the use of MEG/MSI enhance localization of epileptic foci in conjunction with other noninvasive testing or replace invasive testing and, thus, result in changes in clinical management and improvement in health outcomes?

The following PICOTS were used to select literature to inform this review.

Patients

The relevant population of interest is patients with drug-resistant epilepsy who are being evaluated for resective surgery.

Interventions

The intervention of interest is MEG/MSI used to map epileptic foci.

Comparators

MEG/MSI is primarily used as preoperative adjunct to other noninvasive tests used in clinical practice for epileptic foci localization. These tests include electroencephalography (EEG), magnetic resonance imaging, positron emission tomography (PET), and single-photon emission computerized tomography.

Outcomes

Outcomes of interest are diagnostic accuracy (e.g., test accuracy, test validity [sensitivity, specificity]) and clinical utility (e.g., consideration of avoidance of invasive testing).

Timing

MEG/MSI is used when evaluating a patient with drug-resistant epilepsy for interventional surgery.

Setting

MEG/MSI is provided in an interdisciplinary specialty care setting.

Technical Reliability

The technical reliability can be assessed by correlating results for of MEG/MSI for epileptic foci localization with the results of invasive intracranial diagnostic testing. Invasive intracranial and ictal video EEG are considered the reference standard. Methods of intracranial electrical monitoring include stereotactically implanted depth electrodes, implanted strip electrodes, and implanted grids that require craniotomy. Implanted electrodes can be used to monitor for epilepsy and during intraoperative evaluation, which is referred to as electrocortigraphy.

Implanted electrodes can detect interictal and ictal spike activity to localize epileptic foci. Generally, MEG/MSI as well as other noninvasive imaging or EEG evaluations are performed in the interictal state. Interictal brain spike activity is thought to reflect “irritative” activity rather than the seizure origin itself. Epilepsy has been described as a “network disease” and thus there may be an imperfect correlation between interictal and ictal activity localization.

A 2003 Blue Cross Blue Shield Association (BCBSA) Technology Evaluation Center (TEC) Assessment on MEG/MSI reviewed the available evidence and did not conclude that MEG/MSI was equivalent to invasive intracranial EEG or electrocortigraphy for localizing epileptic foci. (4)

Section Summary: Technical Reliability

There are no randomized trials or prospective comparative studies that address the correlation between MEG/MSI performed preoperatively and intracranial EEG or intraoperative electrocortigraphy to localize epileptic foci. The evidence is limited to observational case series, which do not provide a basis for conclusions about the reliability of MEG/MSI.

Clinical Validity

This section is based on a 2008 BCBSA TEC Special Report that reviewed the evidence on MEG for localization of epileptic lesions. (5) MEG has been proposed as a method for localizing seizure foci for patients with normal or equivocal magnetic resonance imaging (MRI) and negative video- electroencephalography (EEG) examinations, so-called “nonlesional” epilepsy. Such patients often undergo MEG, positron emission tomography, or ictal-single photon emission computed tomography (SPECT) to localize the seizure focus. They then often undergo invasive intracranial EEG (IC-EEG), a surgical procedure in which electrodes are inserted next to the brain. Definitive proof that MEG is effective would be comparative evidence that when compared with not using MEG, it improved patient outcomes. Such improvement in outcomes would include more patients being rendered seizure-free, use of a less invasive and morbid diagnostic workup, and overall improved patient outcomes. This is a complicated array of outcomes that has not been thoroughly evaluated in a comprehensive manner. Because MEG is used to make decision regarding further diagnostic testing, which may affect the decision to have surgery and the extent of surgery, solely examining surgical outcomes excludes the assessment of outcomes of patients who did not have surgery.

Ideally, a randomized trial comparing the outcomes of patients who receive MEG as part of their diagnostic workup compared with patients who do not receive MEG could determine whether MEG improves patient outcomes. However, almost all of the studies evaluating MEG have been retrospective, where MEG, other tests, and surgery have been selectively applied to patients. Because patients often drop out of the diagnostic process before having IC-EEG, and many patients ultimately do not undergo surgery, most studies of associations between diagnostic tests and between diagnostic tests and outcomes are biased by selection and ascertainment biases. For example, studies that evaluate the correlation between MEG and IC-EEG invariably do not account for the fact that MEG information was sometimes used to deselect a patient from undergoing IC-EEG. In addition, IC-EEG findings only imperfectly correlate with surgical outcomes, meaning that it is an imperfect reference standard.

Numerous studies have shown associations between MEG findings and other noninvasive and invasive diagnostic tests, including IC-EEG, and between MEG findings and surgical outcomes. However, such studies do not allow any conclusions whether MEG added incremental information to aid the management of such patients and whether patients’ outcomes were improved as a result of the additional diagnostic information.

A representative study of MEG by Knowlton et al. (2008) demonstrated many of the problematic issues of evaluating MEG. (6) In this study of 160 patients with nonlesional epilepsy, all had MEG, but only 72 proceeded to IC-EEG. The calculations of diagnostic characteristics of MEG are biased by incomplete ascertainment of the reference standard. However, even examining the diagnostic characteristics of MEG using the 72 patients who underwent IC-EEG, sensitivities and specificities were well below 90%, indicating the likelihood of both false-positive and false-negative studies. Predictive values based on these sensitivities and specificities mean that MEG can neither rule in nor rule out a positive IC-EEG, and that MEG cannot be used as a triage test before IC-EEG to avoid potential morbidity in a subset of patients.

One study more specifically addressed whether MEG can improve the yield of IC-EEG, thus, allowing more patients to receive surgery. In a 2009 study by Knowlton et al., MEG results modified the placement of electrodes in 18 (23%) of 77 patients who were recommended to have IC-EEG. (7) Seven (39%) of 18 patients had positive intracranial seizure recordings involving additional electrode placement because of MEG results. It was concluded that 4 (5%) patients were presumed to have had surgery modified as a result of the effect of MEG electrode placement.

Section Summary: Clinical Validity

There are no clinical trials or other high-quality studies demonstrating the diagnostic accuracy of MEG in determining location of seizure foci. Available evidence on diagnostic accuracy is limited by ascertainment and selection biases because MEG findings were used to select and deselect patients in the diagnostic pathway, thus making it difficult to determine the role of MEG for the purpose of seizure localization.

Clinical Utility

Several studies correlated MEG findings with surgical outcomes. Lau et al. (2008) performed a meta-analysis of 17 such studies. (8) In this meta-analysis, sensitivity and specificity had unorthodox definitions. Sensitivity was the proportion of patients cured with surgery in whom the MEG-defined epileptic region was resected, and specificity was the proportion of patients not cured with surgery in whom the MEG- defined epileptic region was not resected. Pooled sensitivity was 84%, meaning that among the total number of cured patients, 16% occurred despite the MEG-defined region not being resected. Pooled specificity was 52%, meaning that among 48% of patients not cured, the MEG-localized region was resected. These results are consistent with an association between resection of the MEG-defined region and surgical cure, but that it is an imperfect predictor of surgical success. However, it does not address the question as to whether MEG contributed original information to improve the probability of cure. In a retrospective review of 22 children with medically intractable focal epilepsy (median age at epilepsy surgery, 11 years), Kim et al. (2013) used a cutoff of 70% or more for the number of MEG-identified spike dipole sources located within the resection margin to define a positive study. (9) Sensitivity, specificity, and positive and negative predictive values for seizure-free status postoperatively were 67%, 14%, 63%, and 17%, respectively.

Other studies implied a value of MEG, but it is difficult to make firm conclusions regarding its value. In a 2013 study by Schneider et al., 14 patients with various findings on MEG, IC-EEG, and interictal SPECT underwent surgery for nonlesional neocortical focal epilepsy. (10) Concordance of IC-EEG and MEG occurred in 5 patients, 4 of whom became seizure-free. This concordance of the 2 tests was the best predictor of becoming seizure-free. Although this was prognostic for success, whether this would actually change surgical decision making, such as declining to operate where there is not such concordance, is uncertain. A similar study by Widjaja et al. (2013) showed that concordance of MEG findings with the location of surgical resection correlated with better seizure outcomes. (11) However, the authors acknowledged that MEG was entrenched in clinical practice, and the decision to proceed further in diagnostic and therapeutic endeavors was based on results of MEG and other tests.

Other case series of surgical patients have suggested a value to MEG. A study by Albert et al. (2014) reviewed a series of pediatric patients undergoing surgery for epilepsy who had only undergone noninvasive monitoring prior to surgery. (12) MEG was proposed to have avoided the need for the morbidity associated with invasive monitoring. Of 16 patients, 62.5% were seizure-free following surgery, and 20% experienced improvement. Two cases required additional surgery with invasive monitoring. Although most patients improved, it cannot be determined whether the outcomes were equivalent to the standard practice of pre-resection invasive monitoring. A study by Wang et al. (2015) compared 18-fluoro-deoxyglucose positron emission tomography (FDG-PET) and MEG in identifying the epileptogenic zone, using invasive monitoring as the reference standard. (13) FDG-PET identified the zone in 8 (50%) of patients and MEG identified the zone in 12 (75%) of patients. Although MEG was more sensitive than FDG-PET in this study, it still missed epileptogenic areas identified by invasive monitoring. Another study, by Koptelova et al. (2013) compared MEG with video EEG monitoring in 22 patients. (14) Of 75 “irritative” zones identified in the 22 patients by either method, a higher proportion was identified by MEG. Note that there is no true reference standard in this type of analysis. However, in analyses of intraoperative EEG, several zones identified only with this method were only identified by MEG, confirming to some extent increased sensitivity over video EEG. These recent studies suggest clinical utility for MEG in evaluation of epilepsy patients, but, due to the aforementioned problems, firm conclusions about the clinical utility of MEG cannot be determined.

In 2009, the American Clinical MEG Society released a position statement that supported routine clinical use of MEG/MSI for presurgical evaluation of patients with medically intractable seizures. (15) This statement cited a 2008 study by Sutherling et al. as being a “milestone class I study.” Class I evidence usually refers to randomized comparisons of treatment. However, the authors of Sutherling et al. study described it as a “prospective, blinded crossover-controlled, single-treatment, observational case series.” (16) The study attempted to determine the proportion of patients in whom diagnostic or treatment strategy was changed as a consequence of MEG. They concluded that the test provided nonredundant information in 33% of patients, changed treatment in 9% of surgical patients, and benefited 21% of patients who had surgery. There was no control group in this study. Benefit of MEG was inferred by assumptions of what might have occurred in the absence of MEG results. Less than half of 69 enrolled patients went on to receive IC-EEG; thus, there appeared to be incomplete accounting for outcomes of all patients in the study. A similar study by De Tiege et al. (2012) also attempted to determine the number of patients in whom management decisions were altered based on MEG results. (17) They concluded that clinical management was altered in 13% of patients.

Section Summary: Clinical Utility

Evidence supporting the effect of MEG on patient outcomes is indirect and incomplete. Surgical management may be altered in a minority of patients based on MEG, but the evidence does not support conclusion that outcomes are improved as a result of these management changes. Trials with a control group are needed to determine whether improved outcomes can be attributed to the change in management induced by knowledge of MEG findings.

MEG/MSI for Localization of Eloquent and Sensorimotor Areas

Clinical Context and Test Purpose

The purpose of MEG/MSI in the localization of eloquent and sensorimotor areas of the brain in persons with cortical brain lesions is to create a precise surgical plan for resective procedures to avoid postoperative speech, sensory, and motor dysfunction where possible.

The question addressed in this literature review is: Does the use of MEG/MSI to map eloquent and sensorimotor brain areas accurately localize these areas and reduce postoperative functional impairment and, thus, result in changes in management and improvement in health outcomes?

The following PICOTS were used to select literature to inform this review.

Patients

The relevant population of interest is patients with brain lesions who are being evaluated for resective surgery.

Interventions

The intervention of interest is use of MEG/MSI to map eloquent and sensorimotor brain areas.

Comparators

MEG/MSI is primarily a noninvasive alternative to the preoperative Wada test (intracarotid sodium amobarbital procedure) used to map eloquent brain areas.

Outcomes

Outcomes of interest are diagnostic accuracy (e.g., test accuracy, test validity [sensitivity, specificity]) and clinical utility (e.g., consideration of avoidance of invasive testing).

Timing

MEG/MSI is used when a patient with a brain lesion in close proximity to eloquent or sensorimotor areas is being evaluated for interventional surgery.

Setting

MEG/MSI is provided in an interdisciplinary specialty care setting.

Technical Reliability

The 2003 BCBSA TEC Assessment assessing MEG/MSI concluded that the evidence supported the technique as relatively accurate when identifying functional brain areas. However, the evidence supporting this conclusion was based on a limited number of subjects in nonrandomized studies. (4)

Clinical Validity

The 2003 BCBSA TEC Assessment of MEG/MSI concluded that evidence for this particular indication was insufficient to demonstrate efficacy. (4) At that time, studies reviewed had relatively weak designs and small sample sizes. There are 2 ways to analyze the potential utility of MEG for this indication: MEG could potentially be a noninvasive substitute for the Wada test, which is a standard method of determining hemispheric dominance for language. The Wada test requires catheterization of the internal carotid arteries, which carries the risk of complications. The determination of language laterality is important to know to determine the suitability of a patient for surgery and what types of additional functional testing might be needed before or during surgery. If MEG provided concordant information with the Wada test, then such information would be obtained in a safe, noninvasive manner.

Several studies have shown high concordance between the Wada test and MEG. In the largest study, by Papanicolaou et al. (2004), among 85 patients, there was concordance between the MEG and Wada tests in 74 (87%). (18) In no cases were the tests discordant in a way that the findings were completely opposite. Discordant cases occurred mostly when the Wada test indicated left dominance and MEG indicated bilateral language function. In an alternative type of analysis, when the test is being used to evaluate the absence or presence of language function in the side in which surgical treatment is being planned, using the Wada procedure as the criterion standard, MEG was 98% sensitive and 83% specific. Thus, if the presence of language function in the surgical site requires intraoperative mapping and/or a tailored surgical approach, use of MEG rather than Wada would have “missed” 1 case where such an approach would be needed (false-negative MEG), and resulted in 5 cases where such an approach was unnecessary (false-positive MEG). However, it should be noted that the Wada test is not a perfect reference standard, and some discordance may reflect inaccuracy of the reference standard. In another study by Hirata et al. (2004), MEG and the Wada test agreed in 19 (95%) of 20 cases. (19)

Section Summary: Clinical Validity

Available evidence comprises studies that correlate the results of MEG with results of intracarotid amobarbital injection (Wada test), which is an alternative method for localization. Evidence has generally shown that concordance between MEG and the Wada test is high. However, the studies have not been replicated and their generalizability is limited.

Clinical Utility

One potential use (utility) of MEG would be to map the sensorimotor area of the brain to avoid such areas in the surgical resection area. Intraoperative mapping just before resection is generally done as the reference standard. Preoperative mapping as potentially done by MEG might aid in determining the suitability of the patient for surgery or for assisting in the planning of other invasive testing. Similar to the situation for localization of epilepsy focus, the literature is problematic in terms of evaluating the comprehensive outcomes of patients due to ascertainment and selection biases. Studies tend to be limited to correlations between MEG and intraoperative mapping. Intraoperative mapping would be performed anyway in most resection patients. Several studies evaluated in the 2003 BCBSA TEC Assessment showed good to high concordance between MEG/MSI findings and intraoperative mapping. (4) A 2006 technology assessment of functional brain imaging prepared by the Ontario Ministry of Health reviewed 10 studies of MEG and invasive functional mapping and showed good to high correspondence between the 2 tests. (20) However, these studies do not demonstrate that MEG would replace intraoperative mapping or reduce the morbidity of such mapping by allowing a more focused procedure.

Recent studies of the use of MEG in localizing the sensorimotor area provide only indirect evidence of utility. A 2013 study by Niranjan et al. reviewed results of 45 patients in whom MEG was used for localizing somatosensory function. (21) In 32 patients who underwent surgery, surgical access routes were planned to avoid regions identified as somatosensory by MEG. All patients retained somatosensory function. It is unknown to what extent MEG provided unique information not provided by other tests. In a 2012 study by Tarapore et al., 24 patients underwent MEG, transcranial magnetic stimulation, and intraoperative direct cortical stimulation to identify the motor cortex. (22) MEG and navigated transcranial magnetic stimulation were both able to identify several areas of motor function, and the median distance between corresponding motor areas was 4.71 mm. When comparing MEG with direct cortical stimulation, median distance between corresponding motor sites (12.1 mm) was greater than the distance between navigated transcranial magnetic stimulation and direct cortical stimulation (2.13 mm). This study did not determine whether MEG provided unique information that contributed to better patient outcomes.

Section Summary: Clinical Utility

There are no clinical trials that demonstrate the clinical utility of using MEG for localization and lateralization of eloquent and sensorimotor regions of the brain. Because MEG is a less invasive alternative to the Wada test, this evidence indicates that it is a reasonable alternative. There is also some evidence that the correlation of MEG and intraoperative mapping of eloquent and sensorimotor regions is high, but the test has not demonstrated sufficient accuracy to replace intraoperative mapping.

Ongoing and Unpublished Clinical Trials

Some currently unpublished trials that might influence this review are listed in Table 2.

Table 2. Summary of Key Trials

NCT No.

Trial Name

Planned Enrollment

Completion Date

Ongoing

Autism spectrum disorders

NCT02278328

Magnetoencephalography/Magnetic Resonance Spectroscopy Dose Response Study of Arbaclofen in Autism Spectrum Disorder

20

Jun 2018

Cognition

NCT01974427

Functional Brain Imaging in Healthy Volunteers to Study Cognitive Functions

120

Apr 2023

Cerebral primitive tumor

NCT02077504

Magnetoencephalographic Study of Glial Tumors Electromagnetic Signature

28

Aug 2017 (ongoing)

Movement disorders

NCT02132052

Defining Cognitive and Motor Phenotypes of Parkinson’s Disease (PD) With Magnetoencephalography

18

Dec 2018

Mild traumatic brain injury

NCT02069613

Multimodal Approach to Testing the Acute Effects of Mild Traumatic Brain Injury (mTBI)

200

Sep 2017

Unpublished

Partial epilepsy

NCT01735032

Contribution of Multimodal Imaging (MRI, PET, MEG) in Pre-Surgical Evaluation of Drug-resistant Focal Epilepsy

140

May 2016 (unknown)

Fibromyalgia

NCT02159300

Brain Rhythms in Fibromyalgia: A Magnetoencephalography (MEG) Study (FMP)

40

Jun 2015 (completed)

Schizophrenia

NCT01317121

Multi-site Communication Deficits Underlying Cognitive Dysfunction in the Prodromal Phase and First Episode of Schizophrenia

144

Jun 2016 (unknown)

NCT: national clinical trial.

Summary of Evidence

For individuals who have drug-resistant epilepsy and are being evaluated for possible resective surgery who receive magnetoencephalography (MEG)/magnetic source imaging (MSI), the evidence for MEG/MSI as an adjunct to standard clinical workup includes various types of case series. Relevant outcomes are test accuracy and functional outcomes. Published evidence on MEG is suboptimal, with no clinical trials demonstrating clinical utility. Literature on diagnostic accuracy has methodologic limitations, primarily selection and ascertainment bias. Studies of functional outcomes do not fully account for the effects of MEG, because subjects who received MEG are not fully accounted for in the studies. The evidence is insufficient to determine the effects of the technology on health outcomes.

For individuals who have brain lesions and a planned brain resection who receive MEG/MSI, the evidence for MEG/MSI for localization of eloquent function areas includes comparative studies. Relevant outcomes include test accuracy and functional outcomes. Available studies have reported that this test has high concordance with the Wada test, which is currently the main alternative to localize eloquent functions. Management is changed in some patients based on MEG testing, but it has not been demonstrated that these changes lead to improved outcomes. The evidence is insufficient to determine the effects of the technology on health outcomes.

Clinical Input Received through Physician Specialty Societies and Academic Medical Centers

Blue Cross Blue Shield Association requested and received input from 2 physician specialty societies (5 reviewers) and 2 academic medical centers in 2011. While the various physician specialty societies and academic medical centers may collaborate with and make recommendations through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted. There was support for use of MEG/MSI for localization of language function, and as part of preoperative evaluation of intractable seizures. Those providing clinical input indicated that use of MEG/MSI in the preoperative evaluation leads to identification of additional individuals whose epilepsy may be cured using a surgical approach.

Practice Guidelines and Position Statements

American Clinical Magnetoencephalography Society (ACMEGS)

The ACMEGS is a professional society of physicians and other professionals with doctoral degrees involved in all aspects of MEG including simultaneously collected electroencephalogram (EEG) and coregistration of localization results to magnetic resonance imaging.

In 2009, ACMEGS released a position statement supporting routine clinical use of MEG plus MSI for presurgical evaluation of patients with medically intractable seizures. (15)

In 2011, ACMEGS issued a series of clinical practice guidelines on magnetic evoked fields (MEFs) addressing different aspects of this technology (recording and analysis of spontaneous cerebral activity, [23] presurgical functional brain mapping using MEFs, [24] MEG-EEG reporting, [25] and qualifications of MEG-EEG personnel [26]). Methods of guideline development were not described.

Guideline 2 on presurgical functional brain mapping indicated that:

“Magnetoencephalography shares with EEG high temporal resolution, but its chief advantage in pre-surgical functional brain mapping is in its high spatial resolution. Magnetic evoked fields are therefore done for localization; unlike electrical evoked potentials (EPs), MEF latencies and latency asymmetries are not typically used to detect abnormalities.” (24)

Proposed indications for MEG include localization of somatosensory, auditory, language, and motor evoked fields. (24)

In 2017, ACMEGS issued another position statement supporting routine use of MEG/MSI for obtaining noninvasive localizing or lateralizing information regarding eloquent cortices (somatosensory, motor, visual, auditory, and language) in the presurgical evaluation of patients with operable lesions preparing for surgery. (27)

Contract:

Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions. Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there are any exclusions or other benefit limitations applicable to this service or supply. If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.

Coding:

CODING:

Disclaimer for coding information on Medical Policies

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.

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers. Only the written coverage position in a medical policy should be used for such determinations.

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps.

CPT/HCPCS/ICD-9/ICD-10 Codes

The following codes may be applicable to this Medical policy and may not be all inclusive.

CPT Codes

95965, 95966, 95967

HCPCS Codes

S8035

ICD-9 Diagnosis Codes

Refer to the ICD-9-CM manual

ICD-9 Procedure Codes

Refer to the ICD-9-CM manual

ICD-10 Diagnosis Codes

Refer to the ICD-10-CM manual

ICD-10 Procedure Codes

Refer to the ICD-10-CM manual


Medicare Coverage:

The information contained in this section is for informational purposes only. HCSC makes no representation as to the accuracy of this information. It is not to be used for claims adjudication for HCSC Plans.

The Centers for Medicare and Medicaid Services (CMS) does not have a national Medicare coverage position. Coverage may be subject to local carrier discretion.

A national coverage position for Medicare may have been developed since this medical policy document was written. See Medicare's National Coverage at <http://www.cms.hhs.gov>.

References:

1. U.S. Food and Drug Administration (FDA). Devices@FDA: CTF Systems, Inc. Whole-Cortex MEG system (with optional EEG subsystem) (K971329). 1997; Available at <http://www.accessdata.fda.gov> (accessed - 2017 September 18).

2. U.S. Food and Drug Administration (FDA). Devices@FDA: Elekta Neuromag with MaxFilter (K091393). 2010; Available at <http://www.accessdata.fda.gov> (accessed - 2017 September 18).

3. U.S. Food and Drug Administration. Section 510(k) Premarket Notification (K152184) MagView Biomagnetometer. 2016; Available at <https://www.accessdata.fda.gov> (accessed - 2017 August 3).

4. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Magnetoencephalography (MEG) and magnetic source imaging (MSI): presurgical localization of epileptic lesions and presurgical function mapping. TEC Assessments 2003; Volume 18, Tab 6.

5. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC). Special Report: Magnetoencephalography and magnetic source imaging for the purpose of presurgical localization of epileptic lesions-a challenge for technology evaluation. TEC Assessments 2008; Volume 23, Tab 8.

6. Knowlton RC, Elgavish RA, Limdi N, et al. Functional imaging: I. Relative predictive value of intracranial electroencephalography. Ann Neurol. Jul 2008; 64(1):25-34. PMID 18412264

7. Knowlton RC, Razdan SN, Limdi N, et al. Effect of epilepsy magnetic source imaging on intracranial electrode placement. Ann Neurol. Jun 2009; 65(6):716-723. PMID 19557860

8. Lau M, Yam D, Burneo JG. A systematic review on MEG and its use in the presurgical evaluation of localization- related epilepsy. Epilepsy Res. May 2008; 79(2-3):97-104. PMID 18353615

9. Kim H, Kankirawatana P, Killen J, et al. Magnetic source imaging (MSI) in children with neocortical epilepsy: surgical outcome association with 3D post-resection analysis. Epilepsy Res. Sep 2013; 106(1-2):164-172. PMID 23689013

10. Schneider F, Irene Wang Z, Alexopoulos AV, et al. Magnetic source imaging and ictal SPECT in MRI-negative neocortical epilepsies: additional value and comparison with intracranial EEG. Epilepsia. Feb 2013; 54(2):359- 369. PMID 23106128

11. Widjaja E, Shammas A, Vali R, et al. FDG-PET and magnetoencephalography in presurgical workup of children with localization-related nonlesional epilepsy. Epilepsia. Apr 2013; 54(4):691-699. PMID 23398491

12. Albert GW, Ibrahim GM, Otsubo H, et al. Magnetoencephalography-guided resection of epileptogenic foci in children. J Neurosurg Pediatr. Nov 2014; 14(5):532-537. PMID 25238627

13. Wang Y, Liu B, Fu L, et al. Use of interictal (18) F-fluorodeoxyglucose (FDG)-PET and magnetoencephalography (MEG) to localize epileptogenic foci in non-lesional epilepsy in a cohort of 16 patients. J Neurol Sci. Aug 15 2015; 355(1-2):120-124. PMID 26066558

14. Koptelova AM, Arkhipova NA, Golovteev AL, et al. [Magnetoencephalography in the presurgical evaluation of patients with drug-resistant epilepsy]. Zh Vopr Neirokhir Im N N Burdenko. 2013; 77(6):14-21. PMID 24558750

15. Bagic A, Funke ME, Ebersole J. American Clinical MEG Society (ACMEGS) position statement: the value of magnetoencephalography (MEG)/magnetic source imaging (MSI) in noninvasive presurgical evaluation of patients with medically intractable localization-related epilepsy. J Clin Neurophysiol. Aug 2009; 26(4):290-293. PMID 19602984

16. Sutherling WW, Mamelak AN, Thyerlei D, et al. Influence of magnetic source imaging for planning intracranial EEG in epilepsy. Neurology. Sep 23 2008; 71(13):990-996. PMID 18809834

17. De Tiege X, Carrette E, Legros B, et al. Clinical added value of magnetic source imaging in the presurgical evaluation of refractory focal epilepsy. J Neurol Neurosurg Psychiatry. Apr 2012; 83(4):417-423. PMID 22262910

18. Papanicolaou AC, Simos PG, Castillo EM, et al. Magnetocephalography: a noninvasive alternative to the Wada procedure. J Neurosurg. May 2004; 100(5):867-876. PMID 15137606

19. Hirata M, Kato A, Taniguchi M, et al. Determination of language dominance with synthetic aperture magnetometry: comparison with the Wada test. NeuroImage. Sep 2004; 23(1):46-53. PMID 15325351

20. Health Quality Ontario. Functional brain imaging: An evidence-based review. Ont Health Tachnol Assess Ser. 2006; 6(22):1-79 PMID 23074493.

21. Niranjan A, Laing EJ, Laghari FJ, et al. Preoperative magnetoencephalographic sensory cortex mapping. Stereotact Funct Neurosurg. 2013; 91(5):314-322. PMID 23797479

22. Tarapore PE, Tate MC, Findlay AM, et al. Preoperative multimodal motor mapping: a comparison of magnetoencephalography imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation. J Neurosurg. Aug 2012; 117(2):354-362. PMID 22702484

23. Bagic AI, Knowlton RC, Rose DF, et al. American Clinical Magnetoencephalography Society Clinical Practice Guideline 1: recording and analysis of spontaneous cerebral activity. J Clin Neurophysiol. Aug 2011; 28(4):348- 354. PMID 21811121

24. Burgess RC, Funke ME, Bowyer SM, et al. American Clinical Magnetoencephalography Society Clinical Practice Guideline 2: presurgical functional brain mapping using magnetic evoked fields. J Clin Neurophysiol. Aug 2011; 28(4):355-361. PMID 21811122

25. Bagic AI, Knowlton RC, Rose DF, et al. American Clinical Magnetoencephalography Society Clinical Practice Guideline 3: MEG-EEG reporting. J Clin Neurophysiol. Aug 2011; 28(4):362-363. PMID 21811123

26. Bagic AI, Barkley GL, Rose DF, et al. American Clinical Magnetoencephalography Society Clinical Practice Guideline 4: qualifications of MEG-EEG personnel. J Clin Neurophysiol. Aug 2011; 28(4):364-365. PMID 21811124

27. Bagic AI, Bowyer SM, Kirsch HE, et al. American Clinical MEG Society (ACMEGS) Position Statement #2: The value of magnetoencephalography (MEG)/magnetic source imaging (MSI) in noninvasive presurgical mapping of eloquent cortices of patients preparing for surgical interventions. J Clin Neurophysiol. May 2017; 34(3):189-195. PMID 28059855

28. Magnetoencephalography/Magnetic Source Imaging. Chicago, Illinois: Blue Cross Blue Shield Association Medical Policy Reference Manual. (September 2017) Radiology 6.01.21.

Policy History:

Date Reason
5/15/2018 Document updated with literature review. Coverage unchanged. References 3 and 27 added; some references removed.
12/1/2017 Reviewed. No changes.
5/15/2016 Document updated with literature review. Coverage unchanged.
4/1/2015 Reviewed. No changes.
5/1/2014 Document updated with literature review. Coverage unchanged. CPT/HCPCS code(s) updated.
12/15/2013 Document updated with literature review. Coverage unchanged.
11/15/2011 Document updated with literature review. The following was added to the Coverage: Magnetoencephalography (MEG) and magnetic source imaging (MSI) may be considered medically necessary as part of the preoperative evaluation of patients with intractable epilepsy (seizures refractory to at least two first-line anticonvulsants), when standard techniques, such as magnetic resonance imaging (MRI) and electroencephalogram (EEG), do not provide satisfactory localization of epileptic lesion(s).
4/1/2009 Revised/updated entire document
5/15/2007 Revised/updated entire document
2/1/2002 New medical document

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