Dr Gonzalo E. Díaz Murillo




Better Breast Cancer Detection with Ultrasound 

X-ray mammography has been the role to detect breast cancer. But it causes cáncer. That gave rise to a "X-rayed way" to look for Cancer. However, there is another good option working since the early 50s: Breast ultrasound or sonomammography.

Ultrasound imaging is based on acoustic impedance (a product of the density of the observed tissue and the ultrasound velocity along that tissue). Mammography imaging is based on accumulated density of the tissues, i.e., we detect shadows. That is why mammography looks for microcalcifications while ultrasound looks for shape and texture, besides microcalcifications.

Ultrasound speckle masks microcalcifications but let us acquire relevant information. Speckle is caused by scattered signals coming from reflectors smaller than the ultrasound wave length. This scattering gives rise to the resulting texture. That constitutes very important diagnostic information. Ultrasound has many advantages over X-rayed mammography, for instance:

  1. Breast Ultrasound can detect whether a lump is a malignant mass or a benign cyst. While there are a few exceptions, ultrasound can do it while mammography cannot.

  2. Ultrasound It is relatively inexpensive and most mammograms must be complemented with ultrasound. As ultrasound is already used for diagnosis, we could skip one step and use it for screening and diagnosis. A portable digital ultrasound scanner with a linear array 7.5 MHz probe costs less than $10.000 while a film-based device for non-digital mammography is about $50.000-$70.000.

  3. Sonomammography is painless. Many patients say mammography hurts

  4. Sonomammography scans the whole breast. Mammography scans almost all the breast

  5. Ultrasound is safer: mechanical waves with very low power and very short exposure time. Mammography uses X-rays whose adverse effects are cumulative

  6. Ultrasound works for dense breast. Mammography does not.

  7. Modern Ultrasound devices are digital and can use computer-aided detection systems very easily. The included images of breast cancer show a working example of ultrasound CAD. This technique enhances the information by increasing the contrast with color. A newer technique, under development - Ultrasound color pre processing, will disclose new information.

One final comment about specificity and breast cancer: Specificity is "a measure of how often a test correctly identifies a woman as not having breast cancer." We can prove something exists but how can we scientifically prove that a disease does not exist? We are detecting things we could not see just a few years ago. Bacteria "did not exist" before the microscope. Light speed was beaten short ago.

Gonzalo E. Díaz M.D.


IARC X-Rays cause cancer

cancer org: X-Rays cause cancer