Medical imaging plays a crucial role in diagnosing, monitoring, and treating various medical conditions. Advances in imaging technologies have enabled doctors to view the inside of the body without invasive procedures, helping to detect abnormalities early and plan effective treatments.
There are several types of scans used in clinical practice, each with its unique characteristics, benefits, and risks. In this article, we will explore common imaging techniques, such as X-ray, ultrasound, CT, MRI, PET, and bone scintigraphy, and discuss their preparation, limitations, and advancements.1,2,3
Types of scans
| Type of scan |
Screening recommendations |
Preparations |
Limitations and risks |
| X-ray |
- Frequent scans for chronic conditions (e.g., arthritis)
|
- Inform healthcare provider if pregnant
- Wear loose clothing
- Remove metal objects
|
- Radiation exposure (small risk)
- Limited in soft tissue imaging
|
| Ultrasound |
- Used to guide minimally invasive procedures
|
- Fast for abdominal ultrasound
- Full bladder for pelvic ultrasound
|
- Limited penetration for deep structures
- Image quality may be affected by obesity or gas in intestines
|
| CT (Computed tomography) |
- Used in emergencies
- Low-dose CT for high-risk smokers (lung cancer screening)
|
- May need to fast for a few hours
- Contrast dye may be injected
- Remove metal objects
|
- Higher radiation exposure compared to X-rays
- Not ideal for pregnant women
|
| MRI (Magnetic resonance imaging) |
- Used for neurological disorders, musculoskeletal injuries, and cancer detection
|
- Remove metal objects
- Possible contrast dye
- Not suitable for people with certain metal implants
|
- Claustrophobia due to narrow scanner
- Not suitable for individuals with specific implants
|
| PET (Positron emission tomography) |
- Often used with CT or MRI for a complete diagnosis
- Recommended for high-risk cancer patients
|
- Fast for several hours
- Avoid vigorous exercise before the scan
|
- Small amount of radiation exposure
- Expensive and not always widely available
|
| Bone scintigraphy (Bone Scan) |
- Used for diagnosing bone infections or cancer
- Recommended for individuals with unexplained bone pain
|
- No special preparation required
- Drink fluids after the scan to clear radioactive material
|
- Less detailed for soft tissues
- Small amount of radiation exposure
|
Which scan is right for you?
The type of scan recommended for you depends on your specific symptoms, medical history, and the condition being investigated. Age, underlying health conditions, and the area of the body being examined also influence the choice of imaging. For example:
X-rays are often the first-line imaging for bone injuries and infections.
MRI is the go-to for soft tissue imaging, particularly for the brain, spine, and muscles.
CT scans are frequently used in emergencies due to their speed and ability to detect internal injuries.
PET scans are often used for cancer diagnosis and monitoring.
Frequency and age to start
The frequency of scans depends on individual health needs and risk factors. For example:
- Women may begin routine mammograms at age 50, or earlier if they have a family history of breast cancer.
- Low-dose CT scans for lung cancer screening are recommended for smokers over 50.
- Children may have fewer scans due to radiation exposure concerns but may undergo ultrasounds or MRI for various conditions.
Advancements in imaging technology
Recent advancements in imaging technologies have significantly improved the accuracy, speed, and safety of diagnoses. Some of the most notable innovations include:
|
Artificial intelligence (AI) integration
AI is increasingly being integrated into imaging systems to assist doctors in interpreting scan results more accurately. AI algorithms can detect patterns that might be missed by the human eye, improving the early detection of conditions like cancer, heart disease, and neurological disorders.
|
|
Functional imaging
Techniques such as functional MRI (fMRI) and PET scans are used to observe metabolic activity and brain function. These have revolutionised research in brain disorders and have provided valuable insights into conditions like Alzheimer's and Parkinson's disease.
|
|
3D imaging
Three-dimensional imaging techniques, particularly in MRI and CT scans, offer highly detailed, multidimensional views of the body, allowing for better planning of surgeries and more accurate diagnoses.
|
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Reduced radiation
Newer CT scanners and X-ray machines are designed to use lower doses of radiation while maintaining high image quality, reducing the long-term risks associated with these procedures.
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DID YOU KNOW?
Artificial intelligence has shown potential for helping radiologists detect cancerous breast tissue more quickly, accurately and predict individual breast cancer risk.
A study in Sweden has shown that mammograms read by an AI before a radiologist helped detect 20% more breast cancers.4
References
- Medical Scans Explained. NIH News in Health. Available at: https://newsinhealth.nih.gov/2019/11/medical-scans-explained.
- Understanding Medical Scans. National Institute of Biomedical Imaging and Bioengineering. Available at: https://www.nibib.nih.gov/Understanding-Medical-Scans-App.
- Different Imaging Tests, Explained. Inside View. Available at: https://blog.radiology.virginia.edu/different-imaging-tests-explained/.
- Lång K, Josefsson V, Larsson AM, et al. Artificial intelligence-supported screen reading versus standard double reading in the Mammography Screening with Artificial Intelligence trial (MASAI): A clinical safety analysis of a randomised, controlled, non-inferiority, single-blinded, screening accuracy study. Lancet Oncol. 2023;24(8):936-944.
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