Admissibility of Diffusion Tensor Imaging (DTI)

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Previously published by Consumer Attorneys of California Forum, May/June 2023
Written by Christopher Kreeger

A young woman is stopped in traffic on her way home from work, hit in the rear and pushed into the vehicle in front. A fireman knocks on her window, opens her door and helps her out. She instinctually checks on the other drivers to make sure everyone is fine and calls her husband. There is significant damage to all vehicles and the EMT/ER records indicate headaches with neck and back pain, but no loss of consciousness (“LOC”). CT scans of her head, neck and back are all negative and she is advised to follow up with her primary care doctor. She follows up with her primary doctor the next day and gets a prescription for 800mg ibuprofen and physical therapy. No mention of concussion in the records.

A few weeks later she is accompanied by her husband at your office on the referral from a good friend and he describes how his wife is complaining of headaches, light and sound sensitivity, confusion, amnesia, problems with attention and concentration, multitasking, and organizational skills, nausea, dizziness, processing information; and she is now emotional all the time and was never like this before.

During the meeting she shares the last thing she remembers is being stopped waiting for the light to turn green and the next thing she remembers is the fireman knocking on her window. She is desperately trying to make sense of what happened and is in tears because she cannot take care of her family; she admits she cannot even keep track of the kids’ after-school activities or where she needs to be to pick them up.

A month later she finally sees a specialist (neurologist or physical medicine and rehabilitation) who documents the mechanism of injury, her immediate onset of symptoms, a change in her mental status, the lack of any prior symptoms and no better explanation for her complaints. Doctor recommends a 3T MRI with Diffusion Tensor Imaging (“DTI”) of the brain, which clearly shows axonal shearing in the frontal lobe consistent with her symptoms. Diagnosis: concussion from motor vehicle accident.

brain scan with the use of DTI (diffusion tensor imaging)

DTI is a specialized MRI technique that can reveal anatomy and abnormalities in microscopic brain tissue that are not visible on standard MRI, which it is not sensitive enough to identify it. The basic concept behind DTI is that water molecules diffuse differently through the axons depending on their integrity.

Fast forward through the claims process: adjuster says there was no LOC at the scene, no evidence of a concussion in the EMT/ER records and her brain scans at the ER were all negative; claim for concussion denied. She is now faced with doing something she never envisioned: suing another human being.

Fast forward to litigation and the attorney assigned to defend the case gets out the playbook on defending a head injury case:

  1. Statements to EMS and ER personnel are more accurate than attorney guided statements; no LOC at scene means no concussion.
  2. A better explanation: Pre-existing conditions like history of depression, headaches, drug use or prior brain trauma all cause similar symptoms.
  3. Get all prior/subsequent scans and hire neuroradiologist to identify any pre-existing problems that may explain current symptoms, pre-existing brain degeneration was the real cause of plaintiff’s cognitive deficits.
  4. Establish plaintiff’s pre-accident baseline of functioning by obtaining all employment, academic, social media and military records to create skepticism about the reliability of post-accident testing and complaints. Try to use former friends and co-workers who can provide a more candid evaluation of plaintiff and their career before and after the accident.
  5. Get all of the raw data from plaintiff’s neuropsychological testing.
  6. Defense Medical Exam with neuropsychologist (testing), neuroradiologist (films), bio-mech (forces insufficient to cause brain injury) and psychiatrist (impact of mental illness on symptoms), damages experts like vocational rehabilitation, Life Care Planner, and Economist.
  7. Finally, MIL to exclude DTI.
    1. DTI cannot be used to diagnose TBI/ concussion,
    2. DTI used in research not clinical settings, not reliable,
    3. DTI is an experimental method often used by plaintiff attorneys when conventional studies (CT/MRI) are negative,
    4. White Paper,
    5. Emory Conference,
    6. The Radiological Society of North America Position Statement, and
    7. No standardized database.
    8. DME declaration/deposition supports MIL to exclude,
    9. DTI Not generally accepted in the scientific community to diagnose a brain injury Kelly/Frye/Daubert.
    10. DTI is hearsay because once a DTI machine scans the brain, the image is sent to outside servers for processing and interpretation and the conclusions therein are case specific hearsay and violate People v. Sanchez.

Per Evidence Code sections 801(b) and 802, the trial court acts as a gatekeeper to exclude expert opinion testimony that is (1) based on matter of a type on which an expert may not reasonably rely, (2) based on reasons unsupported by the material on which the expert relies, or 3) speculative.

The seminal cases are:

  • Frye v. United States (D.C. Cir. 1923) 293 F. 1013: The proponent of scientific evidence must establish that opinions are based upon scientifically established methodology that is “generally accepted” in its specified field. General Acceptance NOT Universal Acceptance!
  • Daubert v. Merrell Dow Pharmaceuticals Inc. (1993) 509 U.S. 579: whether the theory can be and has been tested; whether it has been subjected to peer review; its known or potential error rate; the existence and maintenance of standards controlling its operation; and whether it has attracted widespread acceptance within a relevant scientific community.
  • People v. Kelly (1976) 17 Cal.3d 24: the proponent of the evidence must establish: (1) the reliability of the method, usually by expert testimony; (2) the witness furnishing such testimony must be properly qualified as an expert to give an opinion on the subject, and (3) the proponent of the evidence must demonstrate that correct scientific procedures were used in the particular case. See also Sargon v. University of Southern California (2012) 55 Cal.4th 747 (2012). (Kelly/Sargon is the California rule.)

There have been prior California Kelley/ Frye/Sargon substantive DTI rulings. For example, see Wiener v. Stone, Case Number 18CIV00255, San Mateo Superior Court, ruling by Judge Nancy L. Fineman (5/27/21).

  1. Judicially recognized under Kelley/ Frye and Daubert standards, several California trial court rulings but no appellate court ruling yet, several federal district court rulings, several out of state rulings,
  2. Peer-Reviewed scientific literature supports reliability,
  3. Consensus of disinterested experts,
  4. Published guidelines for clinical use,
  5. Reliable in clinical setting,
  6. FDA approved,
  7. Proponent’s experts are qualified,
  8. DME uses DTI in their clinical/hospital practice.
  9. Unanimity in the scientific community is not required, only a consensus. People v. Leahy (1994) 8 Cal.4th 587, 612.

There have not yet been any California appellate Sanchez DTI rulings. Once the MRI/DTI image is taken in the office it is sent to an outside lab where a postprocessing program called QMENTA and NeuroQuant interprets the images by mathematical calculations and volumetric measurements. Courts have made clear that while “documents like letters, reports, and memoranda are often hearsay because they are prepared by a person outside the courtroom and are usually offered to prove the truth of the information they contain,” only “people can make hearsay statements; machines cannot.” (People v. Lund (2021) 64 Cal.App.5th 1119, 1131, internal citations omitted.) The California Supreme Court acknowledges this in People v. Sanchez (2016) 63 Cal.4th 665, 690, fn. 16, stating: “As we have noted, ‘Only people can make hearsay statements; machines cannot.’” Here, there is no person creating the QMENTA or NeuroQuant reports. These are purely generated by a computer software program, using MRI data from radiologist’s lab. These reports therefore cannot be hearsay.

Final thoughts: Go on the offense and file an MIL to preclude defendant from disputing validity of DTI.