MRI vs CT Scan for Lung Cancer: What’s the Difference?

Lungs are sponge-like organs located in the chest behind the rib cage. The primary function of the lungs is to give your body oxygen and remove carbon dioxide. 

During inhalation, air filled with oxygen is taken into the lungs. Oxygen passes across the alveoli, the tiny air sacs in the lungs, into the blood. Simultaneously, carbon dioxide, a waste product produced by cells, moves from the blood into the alveoli and is exhaled. This process is known as gas exchange. It ensures the continuous supply of oxygen to tissues and the elimination of carbon dioxide, maintaining the delicate balance of gasses necessary for life.

Lung cancer occurs when cells in the lungs mutate. The primary cause of such mutation is exposure to (and inhalation of) harmful chemicals. However, lung cancer can also affect people without any known exposure to toxic substances. Unlike healthy cells, cancerous cells grow uncontrollably and form a cluster, leading to a tumor that destroys healthy lung tissue around it. Symptoms usually don't appear until the cancer cells spread to other parts of the body, hindering their proper functioning. At this stage, treating lung cancer becomes challenging. 

Lung cancer is diagnosed via imaging tools, including MRI (magnetic resonance imaging) and CT (computed tomography) scans. Read on to learn more about an MRI vs.CT scan for lung cancer and discover the advantages, disadvantages, and applications of each medical imaging technique.

How Common Is Lung Cancer in the United States?

Lung cancer is the leading cause of cancer deaths, accounting for 18% of cancer deaths in 2020, with an estimated 1.8 million deaths.

The latest statistics for lung cancer in the United States, projected for 2024, are as follows:

• 234,580 new cases of lung cancer
• 116,310 cases in men
• 118,270 cases in women
• 125,070 deaths

According to the American Cancer Society, most people diagnosed with lung cancer are at least 65 years of age, with an average age of 70. While it remains the leading cause of cancer death, new lung cancer cases are declining overall thanks to fewer people smoking (or quitting).

MRI vs CT for Lung Cancer: Which One Should You Choose?

While each type of scan offers its advantages, computed tomography or CT scans remain the gold standard for lung cancer imaging. This is due to their superior spatial resolution and ability to detect small pulmonary nodules. However, MRI is a valuable tool in specific scenarios, and its use in lung cancer assessment is evolving. 

Your doctor will recommend the most appropriate imaging test based on your circumstances. Some of the factors they will consider include the reason for the scan (detection, cancer staging, follow-up), suspected location of the cancer, specific information needed, and patient factors, such as allergies to contrast agents (like gadolinium), presence of pacemakers, claustrophobia, etc.

Magnetic Resonance Imaging for Lung Cancer

MRI scans utilize a powerful magnetic field and radio waves to generate detailed images of soft tissues within the body. These scans excel in imaging the brain, spinal cord, joints, and other soft tissues, providing superior soft tissue contrast for visualizing ligaments and other structures.

MRI applications for lung cancer include:

• Evaluating the tumor's extent: MRI scans can help determine the extent of the cancer
• Detecting brain metastases: Excels at detecting metastases (cancer that has spread) to the brain and spine
• Characterizing lesions: Effective in differentiating benign from malignant lesions
• Soft tissue imaging: Useful in examining chest wall invasion by lung tumors

Some advantages of using MRI:

• Superior soft tissue contrast: MRI is excellent for differentiating between soft tissues, making it ideal for detecting brain and spinal cord metastases
• No radiation exposure: Unlike CT scans, MRI machines do not use ionizing radiation, which is better for frequent monitoring
• Multiplanar imaging capabilities: MRI can acquire images in multiple planes without moving the patient, aiding in comprehensive tumor assessment

Some disadvantages of using MRI:

• Susceptibility to motion artifacts: Patient motion can create poor image quality
• Longer scan times: MRI typically takes longer than CT, which can be uncomfortable for some patients
• Expensive and less available: MRI is generally more expensive and less widely available than CT scans

Learn more about the Ezra Full Body Plus Scan, which can screen for cancer in 14 organs (including your lungs) in just one hour.

‍Computed Tomography Scan for Lung Cancer

CT scans use X-ray technology to create cross-sectional images of the body. These types of scans provide exceptional detail of the lungs, abdomen, pelvis, and bones. CT scans are ideal for detecting lung nodules, tumors, and metastases and assessing their size, location, and spread.

CT scan applications for cancer include:

• Initial diagnosis and lung nodule detection: Ideal for identifying lung nodules and initial lung cancer diagnosis
• Staging of lung cancer: Helps assess the size of the tumor, lymph node involvement, and distant metastasis
• Guiding biopsies: Used to guide needle biopsies of lung nodules or masses
• Treatment monitoring and follow-up: Useful for evaluating response to therapy and monitoring for recurrence

Some advantages of CT scans:

• Rapid imaging: CT scans are quick and can minimize motion artifacts
• High resolution for lung structures: Excellent for visualizing lung parenchyma and identifying small nodules
• Widely available and cost-effective: CT scans are accessible in most healthcare settings and are less expensive than MRI

Some disadvantages of CT scans:

• Ionizing radiation: Repeated exposure to this carries a greater cancer risk of cumulative radiation dose
• Less effective for soft tissue: CT is less capable of differentiating between types of soft tissue compared to MRI
• Contrast-induced nephropathy: In cancer patients with renal impairment, contrast agents used in CT can worsen kidney function

Other Imaging Techniques for Diagnosing Lung Cancer

Other imaging modalities that are important for lung cancer include:

• PET/CT scan: This combination scan combines the strengths of positron emission tomography (PET) and CT, showing both structural information and areas of metabolic activity potentially related to cancer
• X-ray: While less sensitive than CT, chest X-rays may still be used to evaluate potential lung abnormalities

Lung Cancer Screening: The Importance of Early-Stage Detection

Early detection is paramount for those at high risk of lung cancer, primarily due to smoking history. Low-dose CT (LDCT) screening has proven to save lives by detecting cancer at its earliest, most treatable stages.

Talk to your doctor about LDCT screening if you meet the following criteria:

• Age 50-80 years old
• Current or former smoker with a 20-pack-year history
• In relatively good overall health

Learn more about lung cancer screening guidelines that aim to lower mortality rates and improve survival rates. 

MRI vs. CT for Lung Cancer: Calculate Your Risk

MRI and CT scans play important roles in finding, evaluating, and managing lung cancer. Your healthcare provider will discuss your options based on your specific clinical scenario, the area of interest, and patient factors. 

CT scans are often the first choice for initial diagnosis and cancer staging due to their speed and effectiveness in lung imaging. MRI, conversely, is more suited for detecting metastases, especially in the brain, central nervous system, and spinal cord, and for detailed assessment of soft tissue involvement. The combined use of these modalities can provide a comprehensive picture of the disease, aiding in optimal patient management.

You can determine your risk for various types of cancer, including lung cancer, by using Ezra's risk calculator. In just a few minutes, you can identify if you are at high risk for any type of cancer. With Ezra, you can opt for a low-dose CT scan to screen for potential lung cancer, which is a quick process of only five minutes.