Ultrasound or MRI for foot nerve pain: which is better?

“Do I need a scan?” is a fair question, and the honest answer is “sometimes.” For many foot nerve problems, the history and examination tell most of the story. Imaging earns its place when it can show a cause, confirm a suspicion, or rule something out.

What each test shows

Clinical assessment and nerve conduction studies are the mainstays of diagnosing nerve entrapment in the lower limb. Ultrasound and MRI add information about the potential cause and location of the entrapment, and that information can guide management.^[1]

• Ultrasound uses sound waves to show soft tissues in real time. Findings can include a nerve that looks darker than normal (hypoechoic), changes in the nerve’s width, and a sonographic Tinel sign, where pressing with the probe over the nerve reproduces the tingling.^[1]
• MRI shows soft tissue in fine detail. Findings include increased signal in the nerve, atrophy of the muscles it supplies and swelling in muscle that has lost its nerve supply.^[1]
• Both can reveal a cause of pressure on the nerve, such as scarring, a mass, or an anatomical variant.^[1] MRI reviews of lower limb compression neuropathies cover nerves from the sciatic down to the plantar nerves and Morton’s neuroma.^[5]
• X-rays don’t show nerves, but they show bones, joints and spurs that may be involved.

Which is better?

It depends on the question. For Morton’s neuroma, a meta-analysis of 14 studies, all using surgery as the reference, found similar sensitivity: 0.91 for ultrasound and 0.90 for MRI, with no significant difference. The pooled specificity was higher for MRI, but the confidence interval around it was wide, and the authors suggested ultrasound may be the most cost-effective method.^[2] Ultrasound also lets the examiner press on the exact spot that hurts while looking at it.

Why a scan doesn’t always settle it

Scans show structure, and structure does not always equal symptoms.

• In the spine, a systematic review of 3,110 people with no symptoms found disc degeneration on imaging in 37% of 20-year-olds and 96% of 80-year-olds. The authors concluded that many degenerative changes are likely part of normal aging and that findings must be interpreted in the context of the patient’s condition.^[3]
• In the foot, fatty change in a small muscle of the foot has been linked to a nerve beneath the heel. A 2025 systematic review found it in roughly 4% to 11% of the general population, at similar rates in people with and without foot pain.^[4]

That is why scan reports are read alongside your symptoms and an examination. It is also why “the MRI is normal” and “the MRI shows something” are each only part of the answer. Our guide to normal EMG but still nerve pain makes a similar point about nerve testing.

Don’t wait years for the answer

Delay is a real problem. In a review of nine people with sural nerve injury after surgery, the average time between the operation and completion of imaging was about 80 weeks.^[6] If nerve-type symptoms follow an operation or injury and aren’t settling, a prompt evaluation is better than waiting and wondering.

How imaging fits into your care

At the Lower Extremity Nerve Institute, imaging is arranged through an imaging provider when it would change the plan. Bring any scans and reports you already have. We review the results with you, and earlier scans can save a repeat test. See nerve testing for foot pain for the full set of tests.

When to see a specialist

Book an evaluation if burning, tingling or numbness in your foot has lasted more than a few weeks, or if your scans came back normal while the symptoms carry on.