Ultrasound technology uses high-frequency sound waves to generate real-time images of internal body structures. A handheld device called a transducer sends sound waves into the body and captures the echoes that bounce back from tissues and organs, which a computer translates into a visual image.
Yes, ultrasound can visualize an abnormal mass or lesion. However, the technology cannot provide a definitive diagnosis of cancer, as it only shows the physical characteristics of a mass. A final determination of malignancy requires further testing.
How Ultrasound Functions in Cancer Screening
Ultrasound is a valuable tool in the initial assessment of many cancers because it is non-invasive, widely accessible, and does not use ionizing radiation. It is often deployed after a lump or abnormality is felt or detected on another screening test, such as a mammogram. The procedure’s strength lies in its ability to quickly distinguish between a fluid-filled sac (cyst) and a solid mass.
Cysts are highly likely to be benign, while solid masses carry a greater potential for malignancy and require closer attention. This imaging technique is frequently used to examine organs and soft tissues near the body’s surface. Key areas where ultrasound is important for cancer detection include the breast, thyroid, testicles, liver, ovaries, and uterus.
Imaging Features That Suggest Cancer
Radiologists look for specific characteristics on the ultrasound image to determine if a mass is suspicious for cancer. Malignant lesions often display an irregular, non-round shape, contrasting with the typically oval or smooth appearance of benign growths. The margins of a cancerous mass are frequently poorly defined, spiculated, or angular, suggesting the lesion is invading surrounding tissue.
Another concerning feature is a vertical orientation (“taller than wide”), which suggests an aggressive growth pattern. Most solid tumors are hypoechoic, appearing darker than the surrounding healthy tissue because they reflect fewer sound waves. Specialized techniques like Doppler ultrasound may also be used to check for increased vascularity, as cancerous tumors often create new, irregular blood vessels.
Limitations of Ultrasound for Definitive Diagnosis
Despite its utility in identifying suspicious masses, ultrasound has limitations that prevent it from confirming a cancer diagnosis. The technology provides a structural picture of tissue density but cannot analyze the cellular makeup of a lesion. This means a mass that appears suspicious may ultimately be a benign finding, known as a false positive.
The quality and interpretation of the scan are highly dependent on the skill and experience of the operator (operator dependence). Furthermore, sound waves cannot effectively penetrate bone or air, limiting the effectiveness of ultrasound for deeply located tumors or those in organs like the lungs. The sensitivity and specificity of ultrasound vary widely depending on the organ and tumor type, requiring confirmation with other methods.
The Path Forward Following an Abnormal Scan
If an ultrasound reveals a highly suspicious mass, the next step is to obtain a tissue sample to confirm the diagnosis. The definitive method for diagnosing cancer is a biopsy, where tissue is removed from the lesion for microscopic examination. Ultrasound is often used to guide the needle precisely into the mass during the biopsy procedure, such as a fine-needle aspiration or a core needle biopsy.
In addition to tissue sampling, complementary imaging tests may be ordered to fully assess the finding and check for spread. These may include Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans. These advanced scans help doctors determine the extent of the disease (staging) and are combined with biopsy results to form a comprehensive treatment plan.