What Can an MRI Scan Detect? Complete List

MRI is one of the most versatile diagnostic tools available. Its ability to produce detailed images of soft tissues, organs, bones, and blood vessels makes it valuable for diagnosing hundreds of conditions. This guide lists what an MRI scan can detect, organised by body area, so you know what this technology can and can't do.

Brain and Head

• Brain tumours — Primary tumours (gliomas, meningiomas, acoustic neuromas) and metastases from cancers elsewhere in the body. MRI can detect tumours as small as a few millimetres.
• Stroke — Acute ischaemic stroke can be detected within minutes using diffusion-weighted imaging (DWI), often before it's visible on CT. Haemorrhagic stroke is also well visualised.
• Multiple sclerosis (MS) — Demyelinating plaques in white matter. MRI is the single most important test for diagnosing and monitoring MS — the McDonald criteria for MS diagnosis require MRI evidence.
• Aneurysms — Abnormal bulging of blood vessels. MR angiography can screen for cerebral aneurysms without radiation or contrast in many cases.
• Dementia — Patterns of brain atrophy: hippocampal atrophy in Alzheimer's, frontal and temporal lobe atrophy in frontotemporal dementia, generalised atrophy in vascular dementia.
• Epilepsy — Structural causes of seizures including cortical malformations, hippocampal sclerosis, tumours, and vascular abnormalities.
• Pituitary disorders — Adenomas (found incidentally in up to 10% of brain MRIs) and other sellar/parasellar lesions.
• Infections — Encephalitis, meningitis, brain abscesses. Contrast-enhanced MRI shows the ring-enhancing pattern typical of abscesses.
• Traumatic brain injury — Contusions, diffuse axonal injury (seen on SWI/GRE sequences), subdural and epidural collections.
• Hydrocephalus — Enlargement of the ventricles from excess cerebrospinal fluid.

Spine and Spinal Cord

• Disc herniations and protrusions — Bulging or ruptured intervertebral discs pressing on nerves or the spinal cord. MRI shows exactly which level and direction the disc is pressing.
• Spinal stenosis — Narrowing of the spinal canal or neural foramina. Graded as mild, moderate, or severe based on the degree of narrowing.
• Spinal cord compression — From any cause (disc, tumour, abscess, haematoma). MRI is the investigation of choice for suspected cord compression — it's a clinical emergency.
• Cauda equina syndrome — Compression of the nerve bundle at the base of the spinal cord. MRI is the only way to confirm this surgical emergency.
• Spinal tumours — Intramedullary (within the cord), intradural extramedullary, and extradural tumours.
• Spinal infections — Discitis, vertebral osteomyelitis, epidural abscess.
• Syringomyelia — Fluid-filled cavities (syrinx) within the spinal cord.
• Degenerative changes — Spondylosis, facet joint arthropathy, ligamentum flavum thickening. Very common in adults over 30 — a Brinjikji et al. study found disc degeneration on MRI in 37% of asymptomatic 20-year-olds.

Joints and Musculoskeletal System

• Ligament tears — ACL, PCL, MCL, and LCL tears in the knee; rotator cuff tears and labral tears in the shoulder; ulnar collateral ligament in the elbow.
• Meniscal tears — Graded 1-3 on MRI. Only grade 3 (signal reaching the articular surface) represents a true tear visible at arthroscopy.
• Labral tears — In the shoulder (glenoid labrum) and hip (acetabular labrum). MR arthrography (with intra-articular contrast) is particularly sensitive.
• Tendon injuries — Tendinopathy, partial tears, and complete ruptures. Common in the Achilles, rotator cuff, and patellar tendons.
• Cartilage damage — Chondral defects graded I-IV. MRI can detect cartilage thinning and full-thickness loss.
• Bone marrow oedema — Stress fractures, bone bruises (contusions), early avascular necrosis, and reactive marrow changes.
• Avascular necrosis (AVN) — Loss of blood supply to bone, most commonly the femoral head. MRI detects AVN far earlier than X-ray.
• Soft tissue masses — Lipomas, ganglion cysts, sarcomas, and other tumours.
• Muscle tears and haematomas — Grade I-III muscle injuries, intramuscular haematomas.
• Nerve entrapment — Carpal tunnel syndrome (median nerve), cubital tunnel syndrome (ulnar nerve).

Abdomen and Pelvis

• Liver lesions — Haemangiomas (found in ~5% of adults), focal nodular hyperplasia, hepatocellular carcinoma, metastases, and cirrhosis. Contrast-enhanced liver MRI with hepatocyte-specific agents (e.g., Primovist) is the gold standard for characterising liver lesions.
• Pancreatic conditions — Tumours (including small pancreatic neuroendocrine tumours), pancreatitis, cysts (IPMN, mucinous cysts).
• Bile duct conditions (MRCP) — Gallstones in the common bile duct, strictures, cholangiocarcinoma. MRCP provides a non-invasive alternative to diagnostic ERCP.
• Kidney conditions — Renal cell carcinoma, complex cysts (Bosniak classification), hydronephrosis. Note: simple kidney stones are better seen on CT.
• Prostate cancer — Multiparametric MRI (mpMRI) is now the standard first-line investigation for suspected prostate cancer (NICE guidelines, 2019). It detects clinically significant cancer with high sensitivity and helps target biopsies.
• Uterine and ovarian conditions — Fibroids (size, number, location for treatment planning), endometriosis (including deep infiltrating endometriosis), ovarian masses.
• Bowel conditions — Crohn's disease activity and complications (MR enterography), small bowel tumours, perianal fistulae.
• Rectal cancer staging — MRI is the primary tool for local staging of rectal cancer, determining whether the tumour involves the mesorectal fascia.

Heart and Blood Vessels

• Cardiomyopathies — Hypertrophic, dilated, arrhythmogenic right ventricular, and restrictive cardiomyopathy. Cardiac MRI is considered the reference standard.
• Myocarditis — Inflammation of the heart muscle. Cardiac MRI with late gadolinium enhancement is the best non-invasive test for diagnosing myocarditis.
• Heart attack damage — Late gadolinium enhancement shows the exact location and extent of scarring after myocardial infarction.
• Valve disease — Severity of regurgitation and stenosis can be quantified.
• Congenital heart defects — Structural abnormalities present from birth.
• Aortic conditions — Aneurysms, dissection, coarctation.
• Peripheral vascular disease — MR angiography of the legs, renal arteries, carotid arteries.

What MRI Cannot Detect Well

Despite its versatility, MRI has genuine limitations:

• Lung detail — Lungs contain mostly air, which produces very little MRI signal. CT is far superior for lung nodules, pneumonia, and pulmonary embolism.
• Cortical bone detail — The hard outer shell of bone produces minimal signal. CT and X-ray are better for assessing fracture lines and calcifications.
• Kidney stones — Non-contrast CT is the most sensitive test for stones. MRI can miss small calculi.
• Very small lesions — Anything below the scanner's resolution (roughly 0.5-1mm) may not be visible.
• Real-time imaging — MRI isn't suited for watching dynamic processes in real time. Ultrasound and fluoroscopy are better for this.

For more on choosing between imaging types, see our guides on MRI vs CT, MRI vs ultrasound, and MRI vs X-ray.

Frequently Asked Questions

Can an MRI detect cancer?

Yes. MRI is an important tool in cancer diagnosis and staging. It detects tumours in the brain, spine, breast, prostate, liver, kidneys, uterus, ovaries, and many other locations. However, a tissue biopsy is usually needed to confirm the diagnosis and determine the cancer type and grade. MRI finds the abnormality; pathology identifies it.

Can an MRI detect heart problems?

Yes. Cardiac MRI is one of the best methods for assessing heart muscle health, identifying scarring or fibrosis, evaluating valve function, and diagnosing cardiomyopathies. It provides information that echocardiography alone often can't.

Can an MRI detect blood clots?

Yes. MRI can detect blood clots in veins and arteries, including deep vein thrombosis and cerebral venous sinus thrombosis. However, CT is usually the first-line test for suspected pulmonary embolism because of its speed.

Can an MRI miss things?

Yes. No imaging test is 100% sensitive. Very small lesions, early-stage conditions, and abnormalities in areas where MRI has limitations (lungs, cortical bone) may not be detected. That's why clinical assessment, blood tests, and sometimes multiple imaging types are used together for a complete picture.

Is a full body MRI a good screening tool?

Full body MRI is increasingly used for preventive screening, particularly for cancer detection. It can identify abnormalities across multiple body regions in one session. It's not perfect — lung tissue and small early lesions are limitations — but it's the most thorough single radiation-free screening tool available.