Understand Mammogram Views

Mediolateral Oblique (MLO) and Craniocaudal (CC) are the two most common mammography views. Statistically, most breast cancers are in the upper outer quadrant of the breast. The MLO view is slightly oblique by 30-60 degrees to best image the upper outer quadrant breast tissue. As a result, deciphering where the lesion is can be tricky. Remember, you will always see the right or left marker on the same side as the axilla.

MLO (Mediolateral Oblique) View- The Posterior Nipple Line (PNL) is a reference line that runs from the nipple at a right angle to the pectoralis muscle. Above the posterior nipple line is the superior region of the breast/above the nipple. Below the posterior nipple line is the inferior region. You cannot know whether the lesion is medial or lateral in the MLO view. Since these are not true lateral views, lesions in the breast's medial portion will be one clock up or slightly higher than predicted. Lesions in the lateral portion of the breast will be one clock lower than anticipated. The further from the nipple the mass lies, the more this may vary.

REMEMBER: MULD--medial up (a clock), lateral down (a clock) or Muffins rise, Lead falls

CC (Craciocaudal) View-From the nipple to the marker in the mammogram image, (R CC, L CC), is lateral. From the nipple away from the marker is medial. You cannot know if the lesion is in the superior or inferior plane in the CC view. With this view, you do not need to adjust the clock for your estimation since it is not taken at an angle.