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Medical editor Marit Muri Holmen MD
Oslo University Hospital


Mammography can reveal a tumor in the preclinical phase before it is palpable.  The examination renders three-dimensional structures in two dimensions.

Mammography is highly sensitive for revealing tumors in women with normal tissue density or parenchyma atrophy. However, the tumor may in rare cases be missed due to uncharacteristic appearance and growth pattern.

In women with dense tissue structure (abundant fibroglandular tissue/fibroadenomatosis), the sensitivity is lower.

Even if multiple projections are used with good compression, over projection of normal tissue can cause diagnostic difficulties. Ultrasound examinations (ultrasonography) are today a very important supplement to mammography. In very young women, with a probably benign palpable tumor, ultrasound may replace mammography as a primary examination.


  • Symptoms due to malignant disease or an infectious condition
  • Increased breast cancer risk 
  • Woman selected through the mammography screening program
  • Follow-up

In young women, mammography should only be performed for strict indications, for example cancer suspicion or for hereditary cancer risk.


  • Diagnose breast cancer


Clinical mammography

Patients are referred for clinical mammography with breast symptoms and for suspicious result at mammography screening. 

The examination is performed at a diagnostic center for breast cancer with a radiologist present.

The radiologist will decide based on the image diagnostics and/or the clinical profile if there is need for supplementary examinations (supplementary mammography, ultrasound, intervention, MRI).

Mammography screening

Systematic organized mammography examination of women to discover breast cancer at an early stage.

The Norwegian Mammography Programmme became nationwide from February 2004, and offered women between the ages 50-69 two-dimensional mammography of each breast every second year. This program is quality-controlled enforcing European guidelines for mammography screening.

Special conditions for mammography screening

  • Women with implants ( silicone prosthesis) are invited even if the diagnostics are less certain in case of prosthesis.
  • Women with hereditary cancer risk are entitled to mammography every year till 60 years of age according to the national procedures. The department of medical genetics will decide the claim for annual examination.
  • Women operated for breast cancer shall be followed up for 10 years according to the schedule of NBCG. Subsequent to mastectomy the patient may after 50 years of age participate in the Mammography program and be referred to clinical mammography biannualy. After 10 years all patients above 50 years of age should be offered participation in the Mammography program similarly to those without breast cancer. Patients, who after 10 years have not reached the age of screening, should continue with clinical mammography until they may participate in the Mammography program.
  • Ultrasound examination is not included in the mammography program even not for women with implants.


Mammography does not require any special preparation of the patient.


  • The examination is performed standing or sitting if necessary.
  • Under graded compression of the breast, X-ray images are taken in two planes. This is done bilaterally.
  • Compression may be uncomfortable.
  • If necessary, additional pictures are taken.

In women with silicone implants:

  • The breast is fixed, but with less compression.
  • Images are taken with a modified technique.
  • Clinical mammography is most often supplemented with ultrasound.

Examples of mammography images

  Horisontal plane. No pathology.

  Vertical plane. No pathology.

  Horisontal plane. Suspect lesion.

  Vertical plane. Suspect lesion.

Mammography may be supplemented with ultrasound to increase the diagnostic precision, especially with clinically palpable tumors and uncertain mammography findings. Ultrasound alone is not suitable for examination of the whole breast.


The result of an examination is usually available within one week.

In some cases, the patient may need supplementary mammography, possibly also ultrasound.

After breast conservation treatment

  • Follow-up is performed yearly for the first 10 years.
  • Subsequently the patient may participate in the Norwegian Mammography program

Both breasts should be examined. Two images may be taken with enlargement over the scar(s) in one or two dimensions.

After ablation

  • Follow-up is performed yearly for the first 10 years after treatment.
  • Subsequently the patient may participate in the Norwegian Mammography program.

Hereditary breast cancer 

Women with known risk for hereditary breast cancer based on family history (no known gene defect) should be screened annually from age 30. From 60 years, they should be screened every other year.

With a known gene defect, MRI is recommended from 25 years. In addition to MRI,  mammography should be done. Ultrasound is performed if the MRI findings are ambiguous.

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