Mammography is the gold standard for screening in the detection of early breast cancer, since it has proven to reduce mortality by 44%. The efficacy of mammography depends on the technical quality of the mammogram, the expertise of the interpreting radiologist, and proper implementation of a screening program. Mammography relies on the relative densities of breast tissues to differentiate normal from abnormal tissue. Breast density is the most significant independent predictor of sensitivity at any age; fatty breast 98% and very dense breast 48%. The overall mammographic sensitivity is 85% but decreases to 45% in women with dense breast tissue, breast implants or in the post surgical breast. In general, sensitivity is lower in women under 49 years old of age.
Compared to screen film mammography (SFM), digital mammography (DM) exposes patients to slightly lower doses of radiation, while optimizing the image contrast. DM improves the sensitivity of breast cancer detection from 55% to 70% in women less than 50 years (pre or peri-meopausal) with dense breast. However, DM is significantly more expensive than SFM. The equipment costs approximately $400,000 versus $100,000 plus higher expenses for maintenance, storage and retrieval.
Studies have shown that a second mammography reader can increase the number of cancers detected by 4-14% without changing the false positive rates. However, this added cost is not reimbursed and therefore is impractical in most practices. Computed-aided- detection or CAD achieves the same detection rate as two readers and increases the sensitivity (especially for microcalcifications), but is not as effective for masses. However the improved sensitivity with CAD is offset by both an increase in false positives and biopsy rates.
References:
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