Neuroimaging in Litigation: What It Shows, What It Does Not Prove

Neuroimaging does three things in neurological litigation. It documents structural pathology that exists. It excludes certain kinds of pathology that do not. And it creates a visible, tangible exhibit that attorneys and juries can see. The third function is the one that gets a clinical finding into a demonstrative. The first two are where the analysis actually lives — and they are the two that are most often confused with each other, in both directions, by people who reason about imaging without reasoning about the modality.

CT and MRI — Complementary, Not Interchangeable

CT and MRI are the two workhorses of neurological imaging, and they answer different questions.

CT is fast, widely available, and sensitive to acute intracranial hemorrhage, skull fracture, and large structural abnormalities. It is the first-line study in trauma, in suspected acute stroke, and in the undifferentiated patient with altered mental status. Its limits are real: sensitivity for subtle parenchymal injury is low, early ischemic changes can be invisible in the first hours, and the posterior fossa — brainstem and cerebellum — is notoriously difficult to assess on CT because of beam-hardening artifact from the surrounding bone.

MRI has superior soft-tissue resolution. It detects small infarcts, contusions, diffuse axonal injury, white matter disease, and posterior fossa pathology that CT will miss. Specialized sequences add substantially to its diagnostic reach: diffusion-weighted imaging (DWI) detects cytotoxic edema within hours of ischemia; fluid-attenuated inversion recovery (FLAIR) highlights chronic white matter change; susceptibility-weighted imaging (SWI) and gradient echo (GRE) detect microhemorrhages invisible to other sequences. MRI takes longer, requires patient cooperation, and is not always available emergently.

The point for an attorney is not to develop an opinion about which modality is "better." It is to understand that the choice of modality and the timing of the study define what can and cannot be seen in a particular case. A normal CT does not exclude pathology an MRI would detect. A normal MRI, depending on sequence selection, does not exclude findings a different sequence would have captured. What was imaged, and when, determines what the imaging can say.

What Imaging Can Demonstrate

Appropriately obtained and interpreted, neuroimaging provides objective evidence of several things that matter in litigation.

• Structural pathology. Hemorrhage, infarction, contusion, mass lesions, hydrocephalus, herniation, skull or spine fracture. These are visible findings that a reasonable reader will agree on.
• Location and extent of injury. Imaging maps where in the brain damage has occurred, which a competent expert can correlate with the clinical deficits the patient exhibits. A lesion in the left motor cortex should produce right-sided weakness; a lesion in the occipital lobe should produce visual field deficits. Mismatches between imaging findings and neurological examination are meaningful.
• Chronicity, within ranges. Imaging features evolve in characteristic ways. Acute intracranial hemorrhage appears hyperdense on CT and transitions through isodensity to hypodensity over days to weeks. Acute infarction shows restricted diffusion on DWI with corresponding low ADC, then pseudo-normalizes at roughly seven to ten days before evolving to T2/FLAIR hyperintensity. Subacute hemorrhage on MRI shifts in T1 and T2 signal as hemoglobin degrades. These evolutions are informative, but they describe windows of hours to days, not clock-precision timestamps.
• Vascular anatomy. CT angiography and MR angiography identify aneurysms, arterial stenoses, occlusions, and vascular malformations with high sensitivity for lesions at or above the resolution threshold of the technique.

What Imaging Cannot Demonstrate

The boundary conditions are what distinguish a defensible opinion from an overreaching one.

• Imaging cannot rule out injury it is not designed to detect. Concussion, by definition, is a functional disturbance that produces no finding on standard CT or conventional MRI. A normal scan does not mean the patient was not injured. It also does not prove that they were.¹
• Imaging findings do not prove causation. An abnormality establishes that pathology exists; it does not establish that a specific event produced it. A patient presenting after a motor vehicle collision may have white matter hyperintensities that are entirely age-related, old infarcts from a years-ago event, or incidental findings wholly unconnected to the collision in question.²
• Imaging cannot precisely date an injury. The evolution of findings spans ranges, not points. A statement that "this injury occurred exactly forty-eight hours ago" is not supportable from imaging alone. A statement that the findings are consistent with an injury occurring within a specified window is often supportable, and is the appropriate register.³
• Imaging does not measure function. A scan shows structure, not capability. Two patients with identical-appearing lesions may have profoundly different clinical trajectories depending on premorbid status, neuroplasticity, rehabilitation, age, and individual factors that no modality visualizes.
• Not every abnormality is clinically significant. Incidental findings are common — small vessel ischemic changes in older patients, asymptomatic meningiomas, arachnoid cysts, developmental variants, prominent Virchow-Robin spaces. Their presence on a scan obtained after a traumatic event does not establish that they are new, caused by the event, or responsible for the patient's symptoms.⁴

Where the Interpretation Goes Wrong

Several misinterpretation patterns recur in neurological litigation, and each has a typical-case shape worth recognizing.

• Conflating presence of abnormality with proof of causation. An MRI shows white matter hyperintensities after a motor vehicle collision. The plaintiff's theory attributes them to the collision. But white matter hyperintensities are extraordinarily common in the general adult population, increase with age, correlate with hypertension, diabetes, migraine history, and a dozen other vascular risk factors, and accumulate over decades. Without a pre-incident baseline scan — which rarely exists — attributing new findings to a specific event is not defensible on imaging alone.²⁴
• Overreliance on advanced imaging techniques. Diffusion tensor imaging, functional MRI, volumetric analysis, and related techniques are sometimes offered as forensic proof of brain injury in mild TBI cases where conventional imaging is unremarkable. These methods are powerful research tools. They are not, at present, validated for individual-case adjudication. The limiting factors are specific and worth naming on cross: substantial inter-scanner and inter-protocol variability, lack of robust normative databases at the individual level, sensitivity to motion and technical artifact, and the absence of consensus thresholds that separate "abnormal" from normal variant. A DTI-based opinion that does not engage these limitations is not doing the work the evidence requires.⁵⁶
• Ignoring timing and evolution of findings. An acute ischemic stroke at six hours looks different on CT than the same stroke at forty-eight hours. A subdural hematoma transitions from hyperdense to isodense to hypodense over days to weeks. An opinion that compares two scans without accounting for the interval between them, or that characterizes findings as "acute" without engaging the imaging evolution, tends to dissolve under cross-examination.
• Cherry-picking findings. Radiology reports often include multiple observations. An opinion that emphasizes one finding while ignoring others — or that isolates a subtle finding from the radiologist's overall impression — presents an incomplete picture. A thoughtful review reads the full report and engages with what it does and does not say.

Radiologist and Clinician — Different Work

Radiologists interpret images and generate reports, and they often do so without full access to the clinical history. That is by design, and it has its own virtues: a description of what is on the film, unmoored from prior assumptions about what ought to be there.

The treating or consulting neurologist does something different. A neurologist integrates imaging findings with the clinical examination, the symptom history, and the medical context. In litigation, this distinction matters. A radiology report may describe findings without opining on causation or clinical significance. The analytical question — are these findings consistent with the alleged mechanism, better explained by preexisting disease, or correlated with this patient's documented deficits — is typically a clinical question, answered by someone with both imaging fluency and clinical context.

Reading the Imaging in Context

A careful review of a case where imaging is central to the evidence works through a small set of specific questions:

• Was the modality appropriate to the claimed injury? CT for acute hemorrhage and fracture; MRI for subtle parenchymal injury, early ischemia, or posterior fossa pathology.
• When was the imaging obtained relative to the incident, and does the timing match what the imaging appears to show? A finding read as "acute" on a scan obtained three weeks after the alleged event is worth a second look.
• Is there pre-incident imaging available for comparison? Without a baseline, distinguishing new pathology from preexisting disease is often impossible — and the absence of a baseline is itself a fact the analysis has to honor, not paper over.
• Are the findings specific to the alleged mechanism, or are they compatible with alternative explanations — age, vascular risk factors, prior injury, chronic disease?
• Do the findings correlate with the clinical examination and the documented deficits? A left-hemispheric lesion should not be advanced as the cause of left-sided weakness, and an opinion that does so has not been read carefully.
• Is the advanced-imaging evidence, if any, being offered at the level the literature currently supports? DTI, fMRI, and volumetric data can inform clinical impressions; they are not yet evidence that an individual plaintiff has a specific injury at the level of forensic certainty most courts require.

The usable analytical work in an imaging-heavy case is not proving what the images show. That is the radiologist's work, and the images themselves. The work is deciding what the images mean in the specific clinical context of the specific patient — and declining to extend the evidence past what it can carry.

References

Footnotes

1. Bigler ED. Neuroimaging biomarkers in mild traumatic brain injury (mTBI). Neuropsychol Rev. 2013;23(3):169–209. doi:10.1007/s11065-013-9237-2 ↩

2. Debette S, Markus HS. The clinical importance of white matter hyperintensities on brain magnetic resonance imaging: systematic review and meta-analysis. BMJ. 2010;341:c3666. doi:10.1136/bmj.c3666 ↩ ↩²

3. Kidwell CS, Wintermark M. Imaging of intracranial haemorrhage. Lancet Neurol. 2008;7(3):256–267. doi:10.1016/S1474-4422(08)70041-3 ↩

4. Wardlaw JM, Smith EE, Biessels GJ, et al. Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration. Lancet Neurol. 2013;12(8):822–838. doi:10.1016/S1474-4422(13)70124-8 ↩ ↩²

5. Shenton ME, Hamoda HM, Schneiderman JS, et al. A review of magnetic resonance imaging and diffusion tensor imaging findings in mild traumatic brain injury. Brain Imaging Behav. 2012;6(2):137–192. doi:10.1007/s11682-012-9156-5 ↩

6. Douglas DB, Iv M, Douglas PK, et al. Diffusion Tensor Imaging of TBI: Potentials and Challenges. Top Magn Reson Imaging. 2015;24(5):241–251. doi:10.1097/RMR.0000000000000062 ↩