What Is an Ultrasound?

Ultrasound (sonography) is a medical imaging test that uses high-frequency sound waves to create real-time pictures of organs and tissues inside the body. Unlike X-rays, CT, or PET scans, ultrasound does not use radiation.

A handheld device called a transducer is placed on the skin. It sends sound waves into the body and captures the echoes, which a computer then converts into moving images.

 

How Ultrasound Is Used in Cancer

1. Detection & Diagnosis

• Detects lumps or abnormal masses, especially in breast, thyroid, liver, kidneys, ovaries, and testicles.
• Can help distinguish between solid tumors and fluid-filled cysts.

2. Guidance for Biopsies & Procedures

• Commonly used to guide needle biopsies, ensuring samples are taken from the right area.
• Helps in placing catheters or draining fluid collections.

3. Staging & Monitoring

• Evaluates whether cancer has spread to nearby organs or lymph nodes.
• Monitors tumor changes during and after treatment.

4. Special Types

• Doppler Ultrasound: Shows blood flow to tumors, helping assess aggressiveness.
• Endoscopic Ultrasound (EUS): A probe is inserted into the digestive tract to get detailed images of the pancreas, esophagus, or stomach.

 

What to Expect During the Test

• Usually painless, lasting 15–45 minutes.
• A clear gel is applied to the skin to help transmit sound waves.
• The transducer is moved over the skin, producing images in real time.
• For some types (like transvaginal or endoscopic ultrasound), the probe goes inside the body for better visualization.

 

Benefits

• No radiation exposure — safe for children and pregnant patients.
• Real-time imaging, useful for guiding procedures.
• Portable, widely available, and less expensive than CT or MRI.

 

Risks & Limitations

• Operator-dependent: Image quality varies with technician skill.
• Limited depth: Cannot see through bone or air-filled areas (e.g., lungs, brain).
• Less detailed than CT or MRI for staging or complex anatomy.
• Not always sufficient to confirm cancer — usually combined with other imaging or biopsy.

 

Alternatives & Related Tests

• X-ray / CT Scan: More detail for bones and lungs.
• MRI: Excellent for soft tissues, no radiation.
• PET Scan: Shows cancer activity and spread.
• Mammogram: Often paired with ultrasound in breast cancer evaluation.

 

Questions to Ask Your Doctor

• Why is ultrasound recommended for my situation?
• Will I also need a CT, MRI, or PET scan?
• Can ultrasound alone confirm if the mass is cancer?
• Will contrast (Doppler or contrast-enhanced ultrasound) be used?
• How will the results affect my next steps?

 

Patient Tips

• Wear loose clothing; you may be asked to change into a gown.
• For abdominal ultrasound, fasting 6–8 hours before the test may be required.
• For pelvic ultrasound, you may be asked to drink water and keep a full bladder.
• Relax — the test is painless and generally quick.

 

References

• National Cancer Institute (NCI): Ultrasound and Cancer
• American Cancer Society: Ultrasound Exams
• Radiological Society of North America (RSNA): What is Ultrasound?