Cancer MRI Scan: A Guide to Imaging and Oncology Diagnosis

What is MRI?

Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that creates detailed images of the organs and tissues inside the body. Unlike X-rays or CT scans, MRI uses powerful magnetic fields and radio waves instead of ionising radiation. This method allows for a safe and accurate way to examine the body’s internal structures.

MRI is especially useful in imaging soft tissues, such as the brain, muscles, organs, and blood vessels. It provides high-resolution images and is non-invasive, making it a valuable tool in diagnosing various diseases, including cancer.

MRI and cancer detection

While MRI cannot directly detect cancer in the way that a biopsy can, it plays an important role in the detection, staging, and monitoring of tumours. Here’s how:

1. Identifying abnormalities:

   • MRI scans are often used to detect abnormalities that might indicate the presence of cancer. 

   • For example, if a patient experiences symptoms like unexplained pain or swelling, an MRI can help identify potential tumours or growths that may be cancerous.

2. Characterising tumours:

   • Once a tumour is detected, MRI can help doctors understand its size, shape, and location. 

   • This information is crucial in determining the type of cancer, its aggressiveness, and its relationship to surrounding tissues.

   • Certain types of tumours, like those found in the brain, prostate, or breast, show up more clearly on MRI scans due to the contrast between the tumour and healthy tissue. 

3. Staging cancer:

   • One of the critical steps in cancer treatment is staging, which refers to determining how far cancer has spread. 

   • MRI scans help assess the extent of the disease, particularly in cases where cancer has spread to soft tissues, such as the liver or lymph nodes. For example, in brain cancer, MRI can provide a clear view of tumours spreading to nearby structures.

4. Monitoring treatment response

   • MRI plays a key role in monitoring a patient’s response to cancer treatments like chemotherapy or radiation therapy. 

   • By comparing pre- and post-treatment scans, doctors can assess whether a tumour is shrinking or if further interventions are necessary.

5. Specialised imaging techniques

   • For certain cancers, specialised MRI techniques can provide more detailed information. For example, breast MRI is often used to assess breast cancer in patients with dense breast tissue or to further evaluate suspicious findings from a mammogram. 

   • Functional MRI (fMRI) and diffusion-weighted imaging (DWI) can provide insights into tumour metabolism and tissue viability.

MRI’s role in specific cancers

While MRI is not the first imaging method used for every cancer type, it is particularly beneficial for certain cancers:

1. Brain cancer: 

   • MRI is considered the gold standard for diagnosing brain tumours. It provides high-resolution images that can reveal tumours' location, size, and relationship to critical brain structures.

2. Breast cancer: 

   • In women with dense breast tissue, MRI is often used in conjunction with mammography for early detection. MRI is also valuable in assessing the extent of breast cancer after diagnosis.

3. Prostate cancer: 

   • MRI is increasingly used to visualise prostate tumours, helping guide biopsy procedures and plan treatment strategies.

4. Liver cancer:

   • For liver cancers, MRI can offer detailed images of the liver and surrounding organs, allowing for better evaluation of liver function and metastasis.

5. Soft tissue cancers: 

   • MRI excels in imaging soft tissues and is commonly used to detect and monitor cancers of the muscles, tendons, and other soft tissues.

Early detection can make a significant difference. Request an appointment with us to find out whether an MRI scan is right for you and get a comprehensive check for cancer and other conditions.

What can’t an MRI detect?

Despite its strengths, MRI has several limitations and may not be suitable for all diagnostic needs:

1. Microscopic tumours:

   • Very small or early-stage tumours may not be visible on MRI images, particularly if they blend in with the surrounding healthy tissue.

2. Lung cancer: 

   • MRI is not ideal for imaging the lungs, as air-filled spaces don’t produce clear images. 

   • CT scans are more commonly used for detecting lung conditions, including cancer.

3. Bone conditions: 

   • MRI is not typically used to assess bone density, fractures, or certain types of bone cancer. These are better evaluated through X-rays, CT scans, or bone scans.

4. Some infections or inflammatory conditions: 

   • While MRI can sometimes show inflammation, other diagnostic tools like PET scans, ultrasound, or blood tests may be more effective depending on the condition.

Because of these limitations, MRI is often used in combination with other imaging modalities such as CT scans, PET scans, or biopsies to obtain a detailed picture of a patient’s health. 

Is a CT or MRI better for cancer?

Both CT and MRI are widely used in cancer detection and diagnosis, but each has its strengths. The choice between them depends on several factors, including the type of cancer, the part of the body being scanned, the clinical urgency, and whether metal implants or devices are present in the body.

Learn more about the differences between an MRI and a CT scan here.

CT scans: Fast and effective for certain areas

CT scans are often the first imaging method used when cancer is suspected, especially for quick assessments. They are particularly useful for detecting cancers in the lungs, abdomen, pelvis, and bones, as they provide clear images of dense structures and can identify tumours, lymph node involvement, or fluid buildup.

CT scans are also widely available, relatively fast, and suitable for emergency situations or when a large area needs to be scanned quickly.

MRI scans: Detailed imaging of soft tissues

MRI offers better image detail for soft tissue structures, making it ideal for detecting and characterising cancers such as brain tumours, breast cancer, spinal cord tumours, liver cancer, prostate cancer, and bladder cancer, as well as other cancers in the pelvic region.

Unlike CT, MRI does not use ionising radiation, making it a safer option for repeated imaging, particularly in younger patients or for long-term monitoring.

Choosing between CT and MRI: Other considerations

If you have metal fragments, implants, surgical clips, cochlear implants, or other medical devices, a CT scan may be recommended instead of an MRI. This is because MRI machines use strong magnetic fields, which can interfere with or be affected by metallic objects in the body.

Even things like body piercings or artificial joints need to be assessed for MRI compatibility.

That said, CT is not always suitable for detailed soft tissue imaging, and your doctor will decide which scan is more appropriate based on the area of concern and the clinical question. In many cancer cases, medical professionals use both CT and MRI scans together to get a full picture.

For example, CT may be used for an initial overview and to check for metastasis, while MRI may provide a closer look at specific soft tissue structures or neurological involvement.

Price of an MRI scan for cancer detection in Singapore

The cost of an MRI scan for cancer detection in Singapore is different depending on various factors, including the physician, if contrast dye is used or not, and if the scan is conducted at a public or private facility.

At subsidised rates in public hospitals, an MRI scan ranges between SGD 300 and SGD 600. The price may be higher in some instances for non-subsidised patients or referrals from private clinics.

Private facilities or hospitals range from about SGD 800 upwards to more than SGD 1,500, depending on the complexity of the scan as well as whether specialist consultation is included or not.

Some important factors that may affect the total cost include:

• Whether the scan includes the use of contrast agents

• The need for specialist interpretation or follow-up consultation

• Urgency of the scan (e.g., same-day vs. scheduled appointment)

• Inclusion of pre- or post-scan services, such as cognitive assessments

Patients may use MediSave to offset part of the cost, especially if the scan is medically indicated. However, coverage amounts and eligibility vary, so it is advisable to check with your healthcare provider or the relevant institution beforehand.

Where to get an MRI scan for cancer detection in Singapore?

MRI scans for cancer detection are available at public hospitals, private hospitals, and imaging centres across Singapore. For subsidised rates, public hospitals mostly require a doctor’s referral, usually from a polyclinic. For faster appointments, private hospitals as well as imaging centres usually offer MRI scans without long waiting times. 

To book an MRI, consult your doctor for a referral or contact a private imaging centre directly. It is recommended to check the cost and MediSave eligibility before proceeding.

Learn more about the differences between Urgent Care Centre, A&E, GP, and 24-Hour Clinics.

At Thomson Medical, we offer advanced MRI scans to support doctors in detecting and evaluating potential signs of cancer. If you’re experiencing unexplained symptoms such as pain, swelling, or persistent fatigue, or if you have risk factors for certain cancers, request an appointment with us to determine if an MRI scan is suitable for further evaluation.

FAQs

Does cancer appear on an MRI?

Yes, cancer can appear on MRI scans, particularly when it involves soft tissues. MRI is highly effective in detecting and evaluating tumours in areas such as the brain, breast, and spinal cord, where it provides detailed images that help distinguish cancerous tissue from surrounding healthy structures.

What cancers can MRI not detect?

MRI may not be as effective in detecting certain types of cancer, particularly those involving areas where it has limited imaging capability.

For example, lung cancer is often better visualised using CT scans due to the air-filled nature of the lungs. Similarly, some types of bone cancer may not be clearly detected with MRI, as it is not the optimal tool for assessing bone structure and density.

Will a full-body MRI show cancer?

Yes, a full-body MRI can show signs of cancer, especially in soft tissues like the brain, liver, or spine. It can help spot abnormal growths or tumours across the body. However, it might miss small cancers or those in the lungs and bones, which are better seen with other scans like CT.

Full-body MRI isn’t usually the first test doctors use, but it can be helpful for people at high risk or those being monitored after treatment.

Can MRI images be wrong?

Yes, MRI images can sometimes be wrong. They may miss very small tumours or show something that looks like cancer but isn’t (called a false positive). Movement during the scan or certain body conditions can also affect the image quality. That’s why MRI results are usually reviewed together with other tests, like CT scans, biopsies, or blood tests, to make a more accurate diagnosis.

What is the best scan to detect cancer?

There’s no one-size-fits-all scan for detecting cancer. The best option depends on the type of cancer and where it’s located in the body. CT scans, MRI scans, PET scans, and even biopsies all play different roles, and doctors choose the most suitable one based on each individual case.

Does MRI have side effects on cancer?

MRI itself does not have harmful effects on cancer or cancerous tissue. It uses strong magnetic fields and radio waves—not ionising radiation—so it doesn’t damage cells like X-rays or CT scans can. However, side effects are rare but may include:

• Mild reactions to contrast dye (if used)

• Discomfort or claustrophobia during the scan

• Risks for those with metal implants

The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.