Development of a Clinical Functional Magnetic Resonance Imaging Service

Abstract

One of the limitations of anatomical based imaging approaches is its relative inability to identify whether specific brain functions may be compromised by the location of brain lesions or contemplated brain surgeries. For this reason, methods for identifying the regions of eloquent brain that should not be disturbed are absolutely critical to the surgeon. By accurately identifying these regions preoperatively, virtually every pre-surgical decision from the surgical approach, operative goals (biopsy, sub-total vs. gross-total resection), and the potential need for awake craniotomy with intraoperative cortical-mapping is affected. Of the many techniques available to the surgeon, functional magnetic resonance imaging (fMRI) has become the primary modality of choice due to the ability of MRI to serve as a “one-stop shop” for assessing both anatomy and functionality of the brain. Given their prevalence, brain tumors serve as the model pathology for the included discussion; however, a similar case can be made for the use of fMRI in other neurological conditions, most notably epilepsy. The value of fMRI was validated in 2007 when the Centers for Medicare and Medicaid Services (CMS) established three new current procedural terminology (CPT) codes for clinical fMRI based upon its use for pre-therapeutic planning. In this article we will discuss the specific requirements for establishing an fMRI program, including specific software and hardware requirements. In addition, the nature of the fMRI CPT codes will be discussed.

Susceptibility-Based Neuroimaging: Standard Methods, Clinical Applications, and Future Directions

“…[17] The increase of blood flow washes out deoxyhemoglobin (dhb) with oxyhemoglobin (ohb); dhb is a paramagnetic substance, and so produces a substantially higher signal decay than ohb, resulting in a relative increase in signal as the concentration of dhb is reduced. This phenomenon is known as the Blood Oxygenation Level Dependent signal (BOLD) contrast.…”

Intraoperative Use of Functional MRI for Surgical Decision Making after Limited or Infeasible Electrocortical Stimulation Mapping

“…After being implemented as a research effort at multiple neurosurgical centers, fMRI was approved for clinical use in the United States when the Centers for Medicare and Medicaid Services (CMS) established current procedural terminology codes for its use in surgical planning . Typically, surgeons request fMRI for functions relevant to eloquent cortex surrounding a lesion, including language, motor, or vision.…”

“…5,6 However, functional magnetic resonance imaging (fMRI) is now also widely accepted as a preoperative technique to localize eloquent cortex in patients with brain lesions and epilepsy, and can be applied in clinical practice. 7,8 fMRI can be used prior to surgery to determine the proximity of eloquent cortex to a lesion, and hence whether the patient has a favorable surgical risk for resection, 9,10 and if so, whether ECS should be performed. 11 fMRI utilizes blood oxygen level-dependent (BOLD) signal that arises due to the hemodynamic response to neuronal activation.…”

The Significance of Streamlined Postprocessing Approaches for Clinical fMRI

“…Presurgical planning for resectable brain lesions was the original clinical application of BOLD fMRI and remains the sole widely accepted clinical application (if we consider the broader category of pretherapeutic planning, including planning for radiation therapy and hemispheric language lateralization for epilepsy) for which Current Procedural Terminology codes were established in 2007. 5 Currently, expansion of clinical indications to include posttherapeutic monitoring of eloquent cortex has also been accepted. In a nutshell, clinical functional MR imaging enables neuroradiologists to go beyond mere characterization of anatomic findings and instead provide critical functional-anatomic correlation that is essential for accurate assessment of the risks of neurosurgical or radiation treatment.…”

“…In particular, the advent of fully integrated FDA-approved clinical fMRI systems during the past 5 years represents an extremely important development that has resulted in greater ease of clinical fMRI practice and has opened the door to clinical fMRI for a larger number of academic medical centers and even for a growing number of radiology private practice groups in the United States. 5 Such integrated systems have replaced older less reliable research systems that had to be assembled part by part through the purchase of individual components from separate vendors. Such components include stimulus-presentation software and hardware; scanner-triggering software; multimedia projectors or video goggles; mirrors; response keypads; in some cases, fiber optic gloves or other sensor devices; eye-tracking equipment; and respiratory belts, depending on individual center research applications.…”