Prior to 1996, in the United States, data regarding the scope and degree of death and disability from traumatic brain injuries (TBIs) was limited. To both reduce the occurrence of TBIs and increase access to treatment services, Congress passed the Traumatic Brain Injury Act of 1996, which authorized federal agencies like the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the Administration for Community Living, (ACL), to partner with state organizations to conduct research and develop health initiatives for treatment and prevention of TBIs.[1]
 
According to the Center for Disease Control, TBIs are defined as “a disruption in the normal function of the brain that can be caused by a bump, blow, or jolt to the head, or penetrating head injury,”[2] and recent estimates indicate that in 2019 there were 223,135 TBI-related hospitalization and 64,362 TBI-related deaths.[3] Recent cumulative data suggests that TBI hospitalization are primarily the result of falls[4] and motor vehicle collisions and gun-related suicide were the most common cause of TBI deaths.[5]-[6]
 
TBI cases are classified as mild, moderate, or severe, with structural injuries to the brain varying on a case-by-case basis, the severity of which may result in short-term or long-term conditions such as headaches, reduced cognitive function, sleep disorders, and other emotional and mental difficulties. Many TBI cases, however, are classified as mild traumatic brain injuries (mTBIs), commonly referred to as concussions, with symptoms that generally resolve in hours, days, or weeks, but in some instances can persist for months or years.  
 
The severity of a TBI is assessed using structural and functional neuroimaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI). Structural MRIs produce anatomical images of soft tissue structures of the brain, whereas functional MRIs (fMRIs) are more advanced forms of neuroimaging used to assess brain activity when conventional imaging return normal findings and symptomology remains persistent.[7] Advanced neuroimaging techniques include:
 

• Arterial Spin Labeling (ASL) which measures cerebral blood perfusion (blood flow), usually in the grey matter of the brain, by magnetically labeling water protons in the blood and tracking their movement through tissues.

 

• Diffuse Tensor Imaging (DTI) which analyzes the directionality and motion of water molecules to evaluate and map out the nerve fiber tracts through the brain to assess myelination, structure, and connectivity of white matter.

 

• Quantitative Electroencephalography (qEEG) measurement of electrical patterns which reflect cortical activity for detecting cerebral hemispheric abnormalities related to cerebrovascular disease and although qEEG can detect abnormalities, it cannot differentiate between kinds of pathology (i.e., ischemic infarction, intracranial hemorrhages, brain tumors, and head trauma).

 

• Magnetic Resonance Spectroscopy (MRS) which measures the presence and concentration of certain metabolites.

 

• Single-Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) which use radioactive substances to create 3-D images of the movement of blood through an organ.

 

• Magnetoencephalography (MEG) which measures the flow of electrically charged ions through cells and shows absolute neuronal activity obtained directly from neuronal electrical activity, whereas other fMRI techniques measure the oxygenation of blood flowing near active neurons which show only relative neuronal activity.

 
Although both structural and functional MRIs are used in clinical settings, as of 2014, there was “insufficient evidence supporting routine clinical use of advanced neuroimaging for diagnosis and/or prognostication at the individual patient level,” which, among other things, is due to methodological constraints and limitations.[8] In turn, these constraints and limitations require a high degree scrutiny when parties to civil litigation attempt to introduce fMRI data as evidence in TBI cases.
 
Admissibility of ASL, DTI, and qEEG Techniques in Washington State Courts
 
In Washington State, comprehensive statistical data associated with the admissibility percentage of fMRI data such as ASL, DTI, and qEEG is yet unavailable, but the available data indicates that jurisdictional admissibility of expert testimony based on neuroimaging technologies may vary; however, neuroimaging evidence will often be admissible and left for challenge on cross-examination. 
 
Admissibility of an expert's scientific testimony originates from Fed. R. Civ. P. 702/ER 702 and falls under two (2) different standards depending on jurisdiction; articulated in Daubert v. Merrell Dow Pharmaceuticals (1993) and Frye v. United States.  Frye continues to be followed in the state courts of Washington. Under Frye, the scientific community is essentially the gatekeeper determining evidence admissibility.  If the scientific community finds a method or theory acceptable, the court must admit the evidence.  Upon a finding of general acceptance, admissibility is unlikely to be revisited in subsequent cases.  It is important to note, however, that superior courts (and even judge to judge) throughout Washington State may have divergent ruling regarding the admissibility of ASL and DTI because a bright line rule regarding admissibility has not been established.  Yet, plaintiffs are likely to cite, and Washington courts are likely to rely upon Anderson v. Akzo Nobel Coatings, Inc., 172 Wn.2d 593 (2011) and Frye to support their decision to admit fMRI evidence such as ASL and DTI.^[9]
 
In a recent King County Superior Court case, Amy Peach and Matt Peach v. RLI Insurance Company et al. (Case No. 17-2-16248-1 SEA), the Court denied defendants’ motion to exclude testimony of an expert regarding DTI and ASL.  On May 30, 2019, that court found the ASL and DTI evidence admissible because the science and methodology underlying ASL and DTI is accepted in the medical community. The court’s ruling was based on “volumes of testimony from numerous experts, opinions from other jurisdictions, and medical journal articles.”  Interestingly, that court held that “[t]he new 3-D image will not be admitted but can be used illustratively.” Another King County Superior Court case from 2020, Marquez v. Nwestco, also held ASL and DTI admissible citing Anderson.
 
Admissibility of qEEG data in Washington State court, as with ASL and DTI, is determined on a case-by-case basis at the discretion the judge and any successful challenge will require a showing that the technique is not generally accepted in the scientific community for the particular purpose for which it is being presented and that the evidence runs contrary to ER 702. 
 
In a recent King County Superior Court case, Habenicht v. Medina, et al., No. 20-2-17024-1-KNT (King County Sup. Ct., 2020), the Court granted the defendants’ motion to exclude the plaintiff’s qEEG evidence as not generally accepted in the relevant scientific community for purposes of diagnosis and treatment of plaintiff’s alleged traumatic brain injury under Frye and further under ER 702, which requires causation to be established with reasonable medical certainty. Notably, a recent study concluded that “the evidence does not support the clinical use of qEEG either at the time of the injury or remote from the injury to diagnose mTBI...,” and “the evidence does not support the use of qEEG to differentiate mTBI from other diagnoses.”^[10]
 
Although the Habenicht holding was favorable to the defense, admissibility of qEEG (and other advanced neuroimaging techniques) will ultimately remain within the discretion of the court, and superior courts throughout Washington State may have divergent opinions regarding the admissibility of such neuroimaging techniques.
 
Potential Arguments Against Admissibility and/or Limiting Use
 
In support of challenges based on Frye and ER 702, the following arguments against admission of fMRI can be presented to any retained neuroradiologist for further discussion and assessment prior to incorporation into briefing:
 

• Neuroimaging technologies have a limited role in the clinical setting of behavioral disorders or psychiatric disease.

 

• fMRI scans present differences in brain activation between control and experimental states. fMRI yields a relative, not an absolute, measure of brain activity.

 

• fMRI images reported and used for comparison may represent an average of data which produce apparent patterns of data that are spatially misleading.

 

• Variability in brain anatomy between individuals creates uncertainty in localization.

 

• The complexity and variability of the experimental designs and methods used in fMRI research, and especially the variability from one lab to another, may undermine the generalizability of results.

 

• Many brain-imaging studies assume that the differential activation of a particular region of the brain during a specific mental operation means that that region is the neural substrate for that operation, and that the absence of activity in a region during a specific operation means that that region is not a neural substrate for that operation. Neither assumption is necessarily true. The complexities of widely distributed structure-function relationships should make it harder to establish sufficiently reliable support for generalizable associations between brain region activation and cognitive functions of interest.

 

• Even to the extent scientists generally support an inference from relative activity levels in the brain region(s) of interest to psychological function, there may still be a gap between that function and the concept that is material to legal judgments.

 

• Advanced brain imaging techniques, such as fMRI, DTI, perfusion imaging, PET, and SPECT are used in clinical care only and in a few clinical settings in which sufficient literature and/or clinical evidence has demonstrated sensitivity and specificity.

 

• The validity of using single-subject fMRI data to uncover evidence of behavioral aberration, pain, or deception is problematic. Further, the applicability of normative imaging databases (typically comprising young, healthy subjects) in courtroom testimony is questionable.

 

• The neuroradiology community arguably has not arrived at a consensus view of the value of DTI regarding mTBI. Until fMRI techniques, such as DTI, standardize acquisition, analysis, and interpretation techniques, scrutiny should disfavor admission.

 
Conclusion
 
Generally, if a party submits sufficient evidence to show the reliability of an fMRI technique, courts are less likely to grant admissibility challenges for blanket exclusion of evidence.  Rather, the Courts will leave challenges for cross-examination. Moreover, courts are more likely to admit neuroimaging evidence where it is not used to “prove” a diagnosis, rather to show that the imaging is “consistent” with the diagnosis (i.e., TBI). Nonetheless, challenging the introduction of neuroimaging is prudent to ensure scrutinization of the technique prior to any presentment to a jury. As an aside, the defense bar should compile all known rulings on advanced neuroimaging techniques for further statistical and legal analysis.