The value of Ultrasonography as an adjunct to Mammography in evaluating Breast Masses.
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Objectives

To compare the findings of ultrasound and mammography in-order to determine the value of ultrasonography as an adjunct to mammography in evaluating breast masses.

 

Study design

Prospective blinded study.

 

 

Setting of study

Kenyatta National Hospital, (KNH)  Radiology Department and  Department of Diagnostic Imaging and Radiation Medicine of the University of Nairobi.

 

 

Subjects studied

185 patients were studied.

 

 

Results of the study

185 patients were seen, 3 males and 182 two females.  Majority (80%) were aged between 20 and 49 years.  Sixteen patients had no breast mass seen.  33 patients had malignant lesions and 137 had benign lesions.  One patient had both.  Ultrasound detected al the breast masses and categorized accurately all the malignant lesions.

7 masses were missed by mammography, 2 of them malignant.  On ultrasonography, 49 of 169(29%) masses were found suspicious or malignant.  All were biopsied and 33 (63.3%) of them confirmed to be malignant.  On ultrasound benign masses were round or oval.  Malignant masses had various shapes.  Of 74 masses  typed mammographically as benign, 66(89.2%) had their long axis parallel to skin and 8(10.8%) had their long axis perpendicular to skin.

 

64 of these masses (86.5%) had smooth margins while 10 (13.5%) had irregular margins.  All the ten masses with irregular margins were biopsed.  The histological diagnosis in all of them was fibrocystic disease.  52 (70.3%) showed through transmission of sound where as 22 (29.7%) did not.  Of these 22, 2 showed posterior shadowing and 20 had no sound attenuation.  The 2 with posterior acoustic shadowing were fibroadenomas.  Of the 20 with no sound attenuation 10 were fibrocystic disease, 2 were lipomas and 10 were fibroadenomas.  Of 33 malignant masses confirmed histologically 18 (54.5%) had their long axis perpendicular to skin.  8(24%) had equal dimensions, 6(18%) had their long axis parallel to skin and 1(3.5%) was immeasurable this was a large ulcerated carcinoma.

23 (69.7%) of the malignant masses had irregular margins on ultrasound was 10 (30.3%) had smooth margins.  25 of these masses (75.8%) showed posterior acoustic shadowing while eight (24.2%) had no sound attenuation.  Ultrasound picked all the 169(100%) masses where as mammography picked 162( 96%) masses.  Ultrasound picked 33 of 33 (100%) malignant masses whereas mammography picked 31 of 33 (94%) malignancies.

 

Conclusion

 

Ultrasound characteristics of breast masses can be used to categorise a mass as either benign or malignant.  However these must be taken together as no single characteristic is diagnostic of malignancy as shown in our study.  We recommend that breast ultrasound should be used as the first imaging modality for patients presenting with breast lump and mammography be reserved for those patients with equivocal ultrasound results, for screening older patients and for patients presenting with other complaints.