Mediolateral oblique view
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It is the most important projection as it allows depiction of most breast tissue.
The representation of the pectoral muscle on the MLO view is a key component in assessing the adequacy of patient positioning and therefore, the adequacy of the image.
The amount of visible pectoral muscle determines the amount of breast tissue included in the image, resulting in a decisive quality factor which is very important to limit the number of false negatives and increase the sensitivity of the mammography. Furthermore, as most breast pathology occurs in the upper outer quadrant, it is important that this area is clearly visible on MLO views.
The patient is positioned in front of the mammography arm of the hand in question lying at the top of the table top, usually at 45°. There will be a uniform compression on the breast and armpit, making sure that the skin is flat and that there are no skin folds.
It must be noted that the standard 45° is not always suitable for all women. In certain disease processes, the angle can be altered to between 40° and 60°, to maximize the quality of imaging. Examples of conditions that require angle change includes scapula-humeral disease, kyphosis, scoliosis, pectus.
- nipple well aligned
- pectoral muscle displayed until the level of the posterior nipple line (PNL)
- presence of submammary angle free
- folds and the absence of artifacts
Errors to avoid
- projected behind the line nipple skin
- inframammary fold not lying visible in mammograms
- overlapping structures
- inclusion of other body parts, e.g. nose, chin, ear, shoulders and hair
- 1. Eklund GW, Cardenosa G, Parsons W. Assessing adequacy of mammographic image quality. Radiology. 1994;190 (2): 297-307. Radiology (abstract) - Pubmed citation
- 2. Taplin SH, Rutter CM, Finder C et-al. Screening mammography: clinical image quality and the risk of interval breast cancer. AJR Am J Roentgenol. 2002;178 (4): 797-803. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Vyborny CJ, Schmidt RA. Mammography as a radiographic examination: an overview. Radiographics. 1989;9 (4): 723-64. Radiographics (abstract) - Pubmed citation
- 4. Sardanelli F, Zandrino F, Imperiale A et-al. Breast biphasic compression versus standard monophasic compression in X-ray mammography. Radiology. 2000;217 (2): 576-80. Radiology (full text) - Pubmed citation
- 6. Eklund GW, Cardenosa G. The art of mammographic positioning. Radiol. Clin. North Am. 1992;30 (1): 21-53. - Pubmed citation
- 7. Bassett LW, Hirbawi IA, Debruhl N et-al. Mammographic positioning: evaluation from the view box. Radiology. 1993;188 (3): 803-6. Radiology (abstract) - Pubmed citation
- 8. Paredes ES. Atlas of mammography. Lippincott Williams & Wilkins. (2007) ISBN:0781764335. Read it at Google Books - Find it at Amazon