MRI for Cancer Detection

Magnetic Resonance Imaging (MRI) has become a cornerstone in cancer detection due to its ability to produce highly detailed images of soft tissue without exposing patients to ionising radiation. This makes MRI a safe and repeatable choice, especially for early detection and for populations needing frequent monitoring, such as those at high risk for certain cancers. The use of gadolinium-based contrast agents and multiparametric protocols, which combine T2-weighted, diffusion-weighted (DWI/ADC), and dynamic contrast-enhanced (DCE) sequences, has established MRI as the gold standard for identifying and characterising tumours in the prostate and breast^1,2.

Recent advancements have introduced whole-body diffusion MRI, enabling the rapid and radiation-free detection of metastatic disease throughout the body, rivalling PET/CT in sensitivity for many cancer types³. MRI’s superior soft-tissue contrast and functional imaging capabilities make it particularly effective for diagnosing cancer at early, potentially curable stages. As a result, MRI plays a crucial role in both initial diagnosis and ongoing assessment, supporting precise treatment planning and improved patient outcomes.

Learn more about MRI for Cancer Detection

How MRI Works in Cancer Detection

The human body primarily comprises water, around 55-75 per cent⁴. Water's chemical composition consists of hydrogen and oxygen atoms. Inside each hydrogen atom resides a small particle called a proton. Protons have a positive electrical charge and are sensitive to magnetic fields^5,6.

MRI machines use large, powerful magnets to generate a strong magnetic field around the patient⁷. When a person is placed inside the machine, this field causes the hydrogen atoms in their body to align in a particular direction.

The MRI machine then sends radio frequency (RF) pulses, temporarily disrupting the alignment of these hydrogen atoms. Once the RF pulses stop, the hydrogen atoms realign, releasing energy as radio waves picked up by the MRI scanner.

Since tissues contain varying amounts of water (and therefore hydrogen atoms) and release energy at different rates, the MRI scanner can differentiate between tissue types and produce high-resolution cross-sectional images⁸.

An MRI scanner typically has a large, cylindrical tube-like structure. This is where the patient lies during the imaging process. Inside the MRI are⁷:

• The primary magnets: Usually, a superconducting magnet cooled to low temperatures using liquid helium.
• Coils: Antennas that send radio waves and receive signals from the protons.

The MRI room typically has a control room where the technologist operates the machine. This area includes screens and buttons to control the MRI process and monitor the patient.

Computer and software systems control the MRI and radio wave pulses. These systems process the signals received from the coils and convert them into images.

Contrast vs. Non-Contrast MRI: The Role of Gadolinium

MRI scans can be performed with or without a special dye called gadolinium:

Contrast MRI (with gadolinium):

• When used, gadolinium contrast is administered through an injection to highlight specific tissues or blood vessels. This is particularly helpful for detecting tumours, inflammation, or changes in blood supply, which are key indicators for cancers that may appear similar to normal tissue on standard scans⁹.
• Gadolinium alters the MRI signals in areas where it accumulates (typically in places with leaky or abnormal blood vessels, such as tumours), making abnormal tissue stand out more clearly on the scan¹⁰.
• Gadolinium is generally safe but may be avoided in patients with severe kidney problems due to a rare risk of complications.

Non-Contrast MRI (without gadolinium):

• Non-contrast MRI is useful when functional information is sufficient, or when avoiding contrast is necessary, such as for patients with kidney impairment, allergies, or during pregnancy¹¹.
• Some cancers and many soft tissue masses can be characterised without contrast, especially using advanced sequences like diffusion-weighted imaging (DWI), which detects how water moves in tissue¹².

Types of MRI Scans Used in Cancer Detection

MRI in oncology leverages a range of sequences and techniques to improve the detection, characterisation, and staging of cancer. Each method provides unique tissue contrasts or functional information critical for accurate staging.

• T1-weighted imaging provides anatomical detail with high resolution. It is useful for assessing fat and subacute haemorrhage, as well as evaluating post-contrast enhancement¹³.
• T2-weighted imaging emphasises differences in water content, making it sensitive to oedema, cysts, and many tumours¹⁴. It also aids in highlighting abnormal tissue due to increased water content.
• Short-Tau Inversion Recovery (STIR) suppresses fat signals, enhancing the detection of lesions within fat-rich tissues¹⁵. It is widely used in musculoskeletal and whole-body imaging for metastasis detection.
• DWI and Apparent Diffusion Coefficient (ADC) quantify the diffusion of water molecules in tissues¹⁶. Tumours often restrict diffusion, appearing bright on DWI and dark on ADC maps. This is particularly valuable for early tumour detection, assessment of aggressiveness, and distinguishing benign from malignant masses.
• Dynamic Contrast-Enhanced (DCE) MRI involves rapid imaging after the injection of gadolinium to track the dynamics of the contrast agent¹⁷. It reveals tumour vascularity and permeability - hallmarks of malignancy. DCE is essential for breast, prostate, and other organ-specific imaging as part of multiparametric protocols.
• MR Spectroscopy provides metabolic and biochemical profiles of tissues. It assists in distinguishing tumour recurrence from post-treatment changes and characterising tumour metabolism.
• Whole-body DWI enables the detection of primary and metastatic tumours throughout the body without the use of ionising radiation¹⁸. It is especially powerful for cancer staging and treatment monitoring, showing high sensitivity for lymph node and bone metastases.

What Types of Cancer Can MRI Detect?

MRI is highly valued in oncology for its ability to detect and characterise a range of cancers across different organs with strong sensitivity, often outperforming other imaging techniques, especially in soft-tissue evaluation. Sensitivity varies by cancer type, MRI technique, and use of contrast agents, but advanced protocols achieve excellent diagnostic accuracy in many organs.

Benign and Other Non-Cancerous Tumours Detectable by MRI

Magnetic Resonance Imaging (MRI) is a crucial modality for identifying benign tumours and distinguishing them from malignant lesions across organ systems. Its superior soft-tissue contrast, multiplanar capability, and versatility make it valuable in diagnosing and characterising non-cancerous masses. 

Anatomical Overview of Benign Tumours Detectable by MRI

Central Nervous System (CNS):

• Meningioma
• Schwannoma
• Pituitary adenoma
• Epidermoid/dermoid cyst
• Low-grade glioma (some may be non-cancerous

MRI signs: Well-defined, smoothly marginated lesions; lack of significant surrounding swelling^31,32.

Head & Neck:

• Pleomorphic adenoma (salivary gland)
• Juvenile angiofibroma (in adolescents)
• Warthin’s tumour
• Cervical lymphangioma and hemangioma (vascular malformations)
• Benign thyroid nodule
• Paraganglioma (may be benign)

MRI signs: Well-circumscribed, even (homogenous) signal, often hyperintense on T2³³.

Thorax:

• Pulmonary hamartoma
• Thymic cysts
• Bronchogenic cyst
• Lipoma (chest wall, mediastinum)

MRI signs: Homogenous fat signal (for lipomas), lack of invasion into surrounding structures³⁴.

Abdomen & Pelvis: 

• Hepatic hemangioma
• Renal angiomyolipoma
• Adrenal adenoma
• Ovarian cystadenoma
• Uterine fibroid (leiomyoma)
• Pancreatic cystadenoma
• Mesenteric/omental cyst

MRI signs: Characteristic signal properties (e.g., fat suppression for angiomyolipoma, vascular pooling for hemangioma), well-defined borders^35,36.

Musculoskeletal:

• Lipoma
• Fibromatosis (some forms)
• Enchondroma
• Osteoid osteoma
• Giant cell tumour (can be locally aggressive)
• Schwannoma/neurofibroma
• Baker’s cyst (popliteal)

MRI signs: Well-defined margins, homogenous appearance, no cortical bone destruction, absence of soft tissue invasion^37,38.

Paediatric:

• Lymphangioma & hemangioma (head and neck, body wall)
• Teratome (sacrococcygeal, mediastinal, cervical)
• Juvenile angiofibroma (nasopharynx)
• Simple cystic lesions (renal, liver, ovarian, splenic)
• Lipoblastoma

MRI is especially useful in children to avoid ionising radiation and to better characterise tissue properties and anatomical relations^33,36,39.

“Red-Flag” MRI Signs That Warrant Biopsy

Certain MRI features suggest a higher risk of malignancy (“red flags”) that should prompt histopathological confirmation via biopsy, even for lesions that might otherwise appear benign:

• Deep location: Lesions located deep to the fascia have a higher malignant potential, although this is not always a standalone criterion³⁷.
• Large size: Tumours >5 cm are suspicious, particularly if growing quickly⁴⁰.
• Heterogeneous signal: Marked heterogeneity on T2-weighted images suggests necrosis, haemorrhage, or aggressive growth.
• Irregular/poorly defined margins: Malignant tumors are more likely to have jagged or infiltrative borders compared to benign lesions, which have smooth, well-demarcated edges⁴¹.
• Invasion: Infiltration of adjacent structures, soft tissue, bone, neurovascular involvement, or evidence of metastatic spread⁴².
• Atypical enhancement: Nodular, ring, or patchy contrast enhancement patterns raise suspicion.
• Associated symptoms: Neurological deficits (for CNS lesions), unexplained pain, or systemic symptoms can warrant urgent evaluation⁴³.

Accuracy of MRI in Detecting Cancer and Its Limitations

As shown above, MRI demonstrates high sensitivity and moderate to high specificity in cancer detection, which varies by tumor type and anatomical region. MRI is widely used for prostate cancer, where it efficiently helps distinguish clinically significant tumors⁴⁴. In breast cancer, contrast-enhanced MRI serves as a reliable tool, often able to detect malignancies that may be subtle or inconspicuous using other modalities⁴⁵. 

In the evaluation of brain and head and neck tumors, MRI proves effective in revealing malignant lesions, with its accuracy influenced by both the specific imaging techniques employed and the site involved⁴⁶. The diagnostic accuracy for differentiating tumour progression from treatment effects or benign conditions can be further enhanced by using a combination of multiple MRI techniques.

False-Negative Hot-Spots

Certain lesions are prone to false negatives or underdiagnosis on MRI, such as:

• Micronodules: Very small lesions, especially in the lungs, are often missed due to limited spatial resolution and respiratory movement^47,48.
• Mucinous tumours: Tumours with a high water content or mucinous composition (e.g., mucinous adenocarcinomas) may not exhibit typical MRI signal changes, leading to misinterpretation or a missed diagnosis⁴⁹.
• Low cellularity/metabolically inactive tumors: These may not exhibit the expected enhancement or signal restriction, especially in the early stages or small size.

Major Limitations

• Motion artefacts: Patient movement, respiration, and cardiac motion can blur images, reducing lesion detectability, especially in abdominal, thoracic, and pediatric applications⁵⁰. Motion artefacts are particularly problematic in uncooperative patients or children.
• Metal implants: Orthopedic hardware, dental instruments, and other metallic implants can produce marked artefacts, signal voids, distortion, or “black holes”, which may obscure lesions, especially near the implant site⁵¹. Some artifacts cannot be fully compensated, limiting MRI’s diagnostic value in those regions.
• Claustrophobia: MRI requires patients to remain still in a closed bore, which can provoke anxiety or claustrophobia, sometimes making completion of the scan impossible without sedation or alternative imaging.

This can hinder throughput and limit MRI availability for certain populations.

MRI vs. Other Cancer Tests

Safety, Contra-Indications & Contrast Agents

Implants & Devices: MR Safe vs. Conditional

• MR Safe: Objects made of non-conducting, non-metallic, non-magnetic material that pose no additional risk in the MR environment.
• MR Conditional: Implants/devices that are compatible only under specific conditions (e.g., specific scanner field strength, position, or waiting period post-implantation). These conditions must be precisely followed, often depending on the implant's material and its interaction with the MRI magnetic field.
• MR Unsafe: Items known to pose hazards in any MR environment (e.g., ferromagnetic objects).

Gadolinium-Based Contrast Agents (GBCS) Risks

• Nephrogenic Systemic Fibrosis (NSF): Rare, serious risk for patients with severely impaired renal function (eGFR < 30mL/min).
• Pregnancy: Use only if absolutely essential; animal studies show potential risks, and some human data suggest a possible increased risk of stillbirth or neonatal death, but not major congenital anomalies⁵². In general, alternative imaging is preferred during pregnancy.
• Allergy/Anaphylaxis: Mild reactions, such as nausea or hives, are possible; severe allergic reactions are very rare. GBCAs are not contraindicated in patients with mild allergies, but increased vigilance is required.

Claustrophobia & Acoustic Noise Mitigation

• Mitigation strategies include short-bore, open MRI designs and patient-centric approaches, which significantly reduce claustrophobic reactions compared to conventional scanners.

If you want to read more about the potential side effects from MRI and how these can be combated, read our article here.

Preparing for Your MRI

Here are a few tips to help you prepare for your MRI⁵³:

• Take your usual medications and eat normally, unless instructed to fast for specific MRI protocols. Fasting is not always required however⁵⁴. 
• Avoid heavy caffeine intake and stay hydrated.
• Inform staff about any metal implants or devices, and bring safety cards for “MR-Conditional” implants, such as pacemakers or aneurysm clips.
• Remove all metal items, including jewellery, hairpins, dental plates, and transdermal patches with foil, to prevent image distortion.
• Bring your referral, prior images, and insurance pre-authorisation to avoid delays.
• Wear comfortable, metal-free clothing; ask about earplugs, music, or mirror goggles if you’re claustrophobic.
• If contrast is planned, fast for 4–6 hours prior to the procedure. Inform staff about any kidney issues or past reactions to contrast agents, as safer alternatives may be available.
• Arrange an escort home if you need sedation for claustrophobia.

During & After Your MRI

Upon arrival for your MRI, you will need to check in and complete a screening form. This will allow you to confirm the presence of implants, allergies, and whether you might need any anxiety medication.

During the scan, you will lie down on a sliding table. A dedicated surface or phased-array coil is typically placed over the limb or region of interest⁵⁵. The scan typically lasts 30-45 minutes of actual “table time”, during which the technician may acquire multiple sequences (settings). You may be asked to hold your breath for short periods during the scan to minimise motion and improve image clarity.

You’ll hear a series of loud knocking or tapping sounds as the MRI machine works. This is completely normal. The scan usually takes about 20 to 45 minutes, and you’ll be offered earplugs or headphones to make the experience more comfortable. 

You’ll stay in touch with the team via a two-way intercom and a squeeze bulb, allowing you to communicate or pause the scan if needed. If contrast is required, it’s injected halfway through, possibly causing a brief cool sensation. After the final sequence, the coil is removed, and you’re free to go. 

After the MRI scan, you will be free to go home and continue with your day without any precautions⁵⁶. If you received a sedative, you will need another person to pick you up. You will also not be able to drive, consume alcohol, or operate heavy machinery 24 hours after the sedative. 

A team of experts will review your results and determine whether a follow-up is necessary, recommending the appropriate treatment if needed. If abnormalities are found, you may undergo ongoing monitoring every 2-3 months to track recurrence. You can receive support in the form of counselling and advice on how to handle aspects like claustrophobia. 

If you have a scan with us here at Ezra, you will receive your report within five to seven days and have the option to discuss it with a medical practitioner. You can also access your scan images through the online portal.

Who Should Consider an MRI Scan?

High-Risk Screening Cohorts (BRCA, Lynch, HCC Surveillance)

Individuals with high-risk genetic profiles such as BRCA1/2 mutations or Lynch syndrome are recommended for regular MRI screening because of their significantly increased lifetime cancer risk. For example, annual breast MRI screening starting at age 25 is recommended for BRCA mutation carriers, as it enhances early cancer detection and improves survival rates^57,58. 

MRI colonography or colonoscopy is indicated for Lynch syndrome, and MRI is increasingly utilised for hepatocellular carcinoma (HCC) surveillance in populations at risk for liver disease, thanks to its superior sensitivity for detecting early-stage lesions compared to ultrasound^59,60.

Symptom-Driven Diagnostic Triggers

Symptom-driven MRI is warranted when clinical presentation or findings suggest conditions that require high-contrast, multiplanar imaging, such as unexplained neurological deficits, refractory headaches, spinal pain, or ambiguous mass lesions⁶¹. Correlating imaging findings with patient-reported symptoms substantially increases diagnostic accuracy, especially in cases with non-specific or overlapping clinical features.

Special Situations: Paediatrics (Sedation, Pregnancy, Renal Failure)

MRI is preferred in children for complex or unclear diagnoses, but sedation is often necessary to ensure immobility, demanding specialised monitoring due to higher risks of respiratory and cardiovascular complications in the MRI setting⁶². During pregnancy, MRI is considered safe after the first trimester and is reserved for cases where a diagnosis will significantly impact management, with contrast usage minimised unless absolutely necessary⁶³. In patients with renal failure, non-contrast MRI does not pose additional risk, but gadolinium-based contrast should be avoided or used with caution due to potential risk of nephrogenic systemic fibrosis.

Benefits of Early Cancer Detection with MRI

Early detection of cancer with MRI leads to significantly better patient outcomes, as cancers identified at an early stage are more likely to be smaller, node-negative, and have higher survival rates compared to those found later. Studies demonstrate that high-risk cohorts undergoing routine MRI screening achieve detection of stage 0 or 1 tumours in over 90 per cent of cases, reducing the need for extensive, aggressive treatment and increasing the likelihood of breast-conserving therapy or less intensive interventions^64–66. 

Early diagnosis not only enhances survival, but also preserves quality of life by minimizing physical and psychological impacts associated with more advanced disease and harsher treatments. 

MRI Scan Cost

Ezra’s Full Body Plus MRI scan in the UK costs £2,695 and is currently available at their partner clinic in Marylebone, London, with more locations planned in the future. No referral is required, so you can book your scan directly without consulting a GP or specialist first. Most people pay out-of-pocket, as insurance typically does not cover self-referred scans, but you may be able to seek reimbursement depending on your policy. 

Emerging Technologies

• AI Triage: Artificial intelligence tools are increasingly used to triage MRI scans, efficiently flagging abnormal findings to streamline diagnostic workflows and reduce radiologist workload^67,68. Early studies confirm that these systems maintain high sensitivity and specificity for critical pathologies.
• Ultra-High-Field 7T MRI: This offers significantly improved spatial and contrast resolution, enabling enhanced visualisation of subtle anatomical, functional, and metabolic abnormalities in the brain and joints, with particular benefits for diagnosing complex neurologic disorders and early detection of disease processes^69,70.
• Whole-Body MRI Screening Trials: Whole-body MRI screening, particularly in high-risk cohorts, has demonstrated high specificity and respectable sensitivity for early cancer detection, leading to timely interventions for curable cancers^30,71. However, some studies have highlighted limitations, including false positives and the need for adjunctive modalities in certain malignancies.

Understanding Your MRI Results

How Radiology Reports Are Structured

Radiology reports generally have a standardised format to guide referring doctors and patients:

• Findings: Provides a detailed, objective description of what the radiologist sees on the images, such as anatomical structures, abnormalities, or disease features. This section employs technical language and provides detailed descriptions of each relevant observation.
• Impression: Summarises the key findings and offers an expert interpretation, including the most likely diagnosis or differential diagnoses. This section is designed to be clear and actionable for treatment planning and is often the most crucial part for both patients and doctors.
• RADS Lexicons: Certain standardised systems, such as BI-RADS (for breast imaging) or O-RADS (for ovarian/adnexal imaging), are used to categorise findings and indicate the likelihood of disease. These lexicons ensure uniform reporting and guide management decisions.

Questions to Ask Your Radiologist or Oncologist

• What are the most important findings in my MRI report?
• Can you explain the impression section in non-technical terms?
• What is my RADS category or risk score, and what does it mean for my care?
• Are there any abnormal results that need further testing or follow-up?
• How do these findings change my diagnosis or treatment plan?
• Are any additional scans, biopsies, or specialist consultations recommended?
• How reliable are the MRI findings? Could there be false positives/negatives?
• What symptoms or changes should I watch for going forward?

These questions will help you understand your results, clarify uncertainties, and participate in informed decision-making about your next steps.

Ezra provides a radiologist-reviewed report in a non-technical and easy-to-understand format on your dashboard.

Frequently Asked Questions

Can an MRI detect cancer anywhere in the body?

MRI can detect cancer in many areas, especially soft tissues and organs, but it is not always the best test for every type of cancer and may miss smaller or certain types of tumours.

Can MRI cause cancer?

MRI does not use ionising radiation and has not been shown to cause cancer, making it one of the safest imaging techniques available.

Can you tell if a tumour is cancerous from an MRI?

An MRI can often distinguish between benign and malignant tumours based on certain imaging features, but a definite cancer diagnosis usually requires a biopsy or additional tests.

What colour does cancer show up on MRI?

Cancerous tissue typically appears as a white or bright area compared to the surrounding tissue on standard black-and-white MRI scans, but contrast and colour can vary depending on scan settings or use of special dyes.

Can MRI results be seen immediately?

MRI results are not available immediately after the scan; images must be reviewed by a radiologist, and the final report is usually provided to your doctor within a few hours to a couple of days, unless it is an emergency.

Key Takeaways

• Radiation-Free Precision: MRI uses powerful magnets and radio waves instead of ionising radiation, making it safe for repeated scans and especially suitable for imaging sensitive populations. Its ability to deliver high-contrast, detailed images of soft tissues surpasses many other modalities, revealing cancers that may remain hidden on X-ray or CT scans.
• Multiparametric Edge: By integrating multiple imaging sequences, such as T2-weighted, diffusion-weighted (ADC), and contrast-enhanced MRI, multiparametric MRI increases detection rates for challenging cancers in organs like the breast, prostate, brain, liver, and bones. This combination enables accurate tumour characterisation at early stages, which is crucial for curative treatment and better patient outcomes.
• Future-Proof Reach: Advances like whole-body diffusion MRI empower clinicians to detect and stage metastatic disease throughout the body in a single scan. The integration of AI-powered radiomics enables automated detection, risk stratification, and personalised therapy planning, pushing MRI to the forefront of scalable, precision oncology.

MRI stands out for its safety, diagnostic performance in soft tissue tumours, and adaptability to emerging technologies, making it a cornerstone of modern and future cancer care.