Which structure must be visualized on the mediolateral oblique (MLO) view to confirm adequate positioning?
- A The nipple in profile in every patient
- B Pectoralis major muscle extending to or below the level of the posterior nipple line ✓
- C Ribs projected behind the breast parenchyma
- D The inframammary fold at the inferior edge
Correct answer: B. Pectoralis major muscle extending to or below the level of the posterior nipple line
Explanation
On a properly positioned MLO, the pectoralis major muscle should be seen extending from the axilla to or below the level of the posterior nipple line, indicating inclusion of deep posterior tissue. The craniocaudal view, not the MLO, is judged by posterior depth of tissue relative to the pectoralis. Ribs are not required on MLO. The nipple may be non-profiled if it does not obscure pathology, so its profile is not mandatory.
Reference: Kopans, Breast Imaging, 3rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.