How Imaging Errors Contribute to Stroke Misdiagnosis

Overview of Stroke Imaging Modalities and Potential Issues

Every minute of delayed treatment destroys roughly 1.9 million neurons, according to Stroke. Accurate stroke diagnosis depends on selecting the right imaging tool at the right moment. Each modality offers a distinct trade-off between speed, availability, and diagnostic sensitivity, and understanding these differences is essential to recognizing where errors are most likely to occur.

• Non-contrast CT (NCCT) is typically the first study done when a stroke is suspected. It helps to rule out hemorrhage, but is often not sensitive enough to detect early ischemic changes, according to Frontiers in Neuroscience.
• CT Angiography (CTA) can identify large vessel occlusions that may be treated by mechanical thrombectomy. Timing and contrast administration errors can significantly degrade image quality.
• CT Perfusion (CTP) identifies and estimates the irreversibly damaged brain tissue (known as the ischemic core) and any salvageable, oxygen-deprived tissue (known as the penumbra), helping extend treatment windows. This type of imaging is highly dependent on several issues, introducing a distinct layer of interpretive risk.
• MRI with Diffusion-Weighted Imaging (DWI) is the gold standard for detecting ischemic stroke, capable of identifying infarcts within minutes of onset. However, it is slower, less accessible, and can still miss very early or very small lesions.
• MR Angiography (MRA) provides vascular detail without radiation or contrast or catheters, though it is more susceptible to flow artifacts and generally slower than CTA in the acute setting. Flow artifacts are things like image distortions, signal loss, and saturation effects mimicking an occlusion and result from blood flow.

Types of Imaging Errors

Imaging errors in stroke fall into four overlapping categories, each capable of derailing the diagnostic process at a different point from image acquisition through final interpretation.

False Negatives (Missed Stroke)

False negatives represent the most consequential imaging failure: a stroke is present, but the scan appears normal or inconclusive, and treatment is delayed or never initiated.

Non-Contrast CT False Negatives

Non-contrast CT, despite its speed and availability, is fundamentally limited in the early part of an ischemic stroke. A normal CT alone cannot and should not rule out stroke for several reasons.

The base of the skull on CT scans has a blind spot. The brainstem and cerebellum sit deep inside the head, surrounded by thick bone. When a CT scanner sends X-ray beams through that much bone, it creates visual “noise” in the image. This interference can hide a stroke, even a fairly large one.

Some strokes are simply too small for a CT scan to see. Lacunar strokes happen in tiny, deep blood vessels supplying structures like the internal capsule, which controls movement, and the thalamus, which processes sensation and consciousness. These infarcts (areas of brain tissue that are dead or dying) typically fall below the detail level that a CT scanner can reliably see.

MRI False Negatives

Even an MRI is not infallible. DWI-negative strokes occur in a meaningful minority of cases, particularly within the first few hours of symptom onset or when lesions are extremely small. Brainstem strokes show up disproportionately in this “missed” category because the thick bone at the base of the skull distorts MRI images there, too, not just CT scans.

False Positives (Stroke Mimics Misidentified as Stroke)

Several unrelated conditions can produce brain scan appearances that look like a stroke.

Brain tumors are common offenders.

After a seizure, some patients experience temporary weakness or paralysis on one side of the body, a phenomenon known as Todd’s paralysis. This can trigger scan changes that look like a stroke, and because no one may have witnessed the seizure itself, the underlying cause is easy to miss. Severe migraines with one-sided weakness can produce scan abnormalities resembling stroke, particularly in younger patients.

Finally, certain whole-body chemical imbalances, such as dangerously low blood sugar, can alter brain appearance on MRI in ways that mimic stroke.

Interpretive Errors

Interpretive errors arise not from the scan itself but from the human reading it, and they are more common than most clinicians understand.

• Early ischemic changes on non-contrast CT are notoriously subtle. Certain findings require deliberate search and experience to identify reliably. Under time pressure or with insufficient training, these signs are routinely missed.
• Hemorrhagic transformation (bleeding into an established area of dead or dying tissue) can be confused with primary intracerebral hemorrhage (a stroke that occurs when a blood vessel bursts inside the brain), with significant treatment implications. Distinguishing the two requires correlation with the timing of symptom onset, prior imaging, and the distribution of blood products, steps that may be skipped in a fast-moving workflow.
• Bilateral or multifocal infarcts (tissue death occurring in different areas of the brain), particularly those involving small or symmetric structures, are frequently underreported. A reader who identifies one lesion may anchor on that finding and fail to search systematically for additional infarcts that would change the picture entirely.
• Vessel localization errors on CTA (misidentifying the site or side of a blockage) can misdirect thrombectomy planning or lead to incorrect predictions, which can cause later errors.

Technical and Acquisition Errors

Even a correctly ordered study can fail if acquisition is flawed.

• Motion artifact is among the most common technical problems in acute stroke imaging.
• CT perfusion is particularly vulnerable to software and threshold errors.
• Incomplete protocol selection (e.g., ordering a standard head CT when CTA or perfusion imaging was clinically indicated) represents a systems-level error that no amount of interpretive skill can compensate for.
• Contrast timing errors on CTA can make vessel occlusions (blockages) harder to detect and increase the likelihood of a missed large vessel blockage.

What Can I Do If an Imaging Error Contributed to My Loved One’s Stroke Misdiagnosis?

When a stroke is missed or diagnosed too late, families are often left with difficult questions and difficult complications. If an imaging error may have played a role, it is natural to wonder whether the outcome could have been different and whether something was overlooked during the diagnostic process.

Imaging studies are important tools in identifying strokes, but interpreting those images can be complex. In some situations, signs of a stroke may be:

• Missed
• Misread
• Delayed in communication
• Not acted upon appropriately

However, an unexpected outcome does not automatically mean negligence occurred. Determining what happened requires a careful review of the medical care provided.

Our stroke misdiagnosis lawyers can help by conducting a thorough evaluation of the circumstances surrounding your loved one’s diagnosis and treatment. This typically begins with gathering and reviewing:

• Medical records
• Imaging studies
• Physician notes
• The timeline of care

We work with qualified medical experts who can assess whether the imaging was interpreted appropriately and whether the care met accepted medical standards.

The goal of this review is to provide clarity. In some cases, families find reassurance that appropriate care was provided despite a tragic outcome. In others, the evidence may indicate that preventable errors contributed to a delayed diagnosis and resulting harm.

If negligence is identified, we can explain the available legal options and help you understand the next steps. Pursuing a stroke misdiagnosis claim is always your decision. Whether you are seeking answers, accountability, or compensation for the challenges your family now faces, we are here to provide guidance, information, and support if and when you are ready.

We Can Help If an Imaging Error Contributed to Your or Your Loved One’s Stroke Misdiagnosis

If your loved one suffered harm after a stroke was missed or delayed, you do not have to sort through the questions alone. Our team can review the medical care that was provided, help you understand what happened, and explain any options that may be available. Whether you are seeking answers, closure, or considering legal action, we are here to provide guidance and support if and when you are ready.

Call Newsome Law whenever you are ready.

Read more about Rich Newsome

Rich Newsome

Catastrophic Injury Locked-In Syndrome Attorney

Rich Newsome is a dedicated attorney specializing in catastrophic injury and medical malpractice cases. With over 25 years of experience, she is committed to advocating for victims and their families, ensuring they receive the justice and compensation they deserve.