Pre-Operative Breast MRI Predicts Feasibility of Nipple-Sparing Mastectomy

Nipple-sparing mastectomy is a popular option among the 30 percent of breast cancer patients who must undergo mastectomy as part of their treatment. It isn’t possible, though, if the cancer has spread to the nipple.

In a study published July 13 in Radiology, investigators from South Korea demonstrated that pre-operative breast MRI can detect non-mass enhancement extension to the nipple base. In those cases, there’s a good chance the cancer has spread to the nipple, eliminating the nipple-sparing procedure as a feasible option.

“Non-mass enhancement extension to the nipple at breast MRI has a high positive predictive value for tumor involvement of the nipple, a known contraindication for nipple-sparing mastectomy,” said the team led by Joon Jeong, M.D., Ph.D., as associate professor at Yonsei University College of Medicine. “Nipple-sparing mastectomy should be avoided in patients with non-mass enhancement extension to the nipple at breast MRI. Conversely, nipple-sparing mastectomy can be performed if the non-mass enhancement does not extend to the nipple at pre-operative breast MRI considering the low rate of pathologic nipple invasion.”

Images in a 49-year-old woman in the nonmass enhancement (NME) extension group with pathologic nipple invasion. (A) Contrast-enhanced fat-suppressed T1-weighted axial MRI scan obtained in first postcontrast phase shows that linear NME (dashed arrow) extends to the nipple base (solid arrow). (B) Photomicrograph (hematoxylin-eosin stain; original magnification, 35) shows nipple invasion. The lactiferous duct (arrowheads) is observed in the nippleareolar complex (NAC). The ductal carcinoma in situ (DCIS) involves the lactiferous duct beyond the baseline (dotted line). Inset is high-power view (original magnification, 3100) of the ductal carcinoma in situ.

Credit: RSNA

Typically, the team noted, nipple-sparing mastectomy is considered oncologically safe if the tumor-to-nipple distance is at least 2 cm. But, they wanted to know whether relying on findings from these images could effectively and accurately identify which women could undergo the procedure.

For their study, between November 2017 and November 2019, they prospectively enrolled 64 women who had breast cancer and non-mass enhancement extension within the 2-cm threshold at breast MRI who had surgery that included removing the nipple-areolar complex. All women underwent breast MRI on a 3T scanner, and two radiologists reviewed the images.

Images in a 43-year-old woman in the nonmass enhancement (NME) nonextension group without pathologic nipple invasion. (A) Contrast-enhanced fat-suppressed T1-weighted axial MRI scan obtained in first postcontrast phase shows that NME continues to the tumor and extends toward the nipple but does not reach the nipple base (solid arrow). The radiologic distance between the nipple base and the closest NME (dashed arrow) is 1.4 cm. (B) Photomicrograph (hematoxylin-eosin stain; original magnification, 35) shows the pathologic distance between the nipple baseline (dotted line) and the nearest tumor (arrowheads) is 0.7 cm. DCIS = ductal carcinoma in situ, NAC = nipple-areolar complex.

Credit: RSNA

Of the group, 49 women (77 percent) had non-mass enhancement extension, and 15 (23 percent) did not. Additionally, 43 women (67 percent) had nipple invasion at pathologic evaluation, and 21 women (33 percent) did not.

Based on the team’s evaluation, the positive predictive value of non-mass enhancement extension at breast MRI was 86 percent while the nipple invasion rate at pathologic evaluation was only 7 percent among women without any extension. The team also determined that, for identifying nipple involvement at pathologic exam, breast MRI produced 98-percent sensitivity, 67-percent specificity, 93-percent negative predictive value, and 88-percent diagnostic accuracy.

They also found that the distance between the nipple and the closest non-mass enhancement extension correlated well with the distance between the nipple base and the closest tumor cells at pathologic evaluation.

“These results suggest that nipple invasion by non-mass enhancement extension at breast MRI should be considered a contraindication for nipple-sparing mastectomy,” the team concluded. “Furthermore, we identified a positive correlation between the radiologic and pathologic distance, which means that nipple-sparing mastectomy can be safely performed even when the non-mass enhancement extension-to-nipple distance is less than 2 cm if non-mass enhancement extension does not reach the nipple base.”

For more coverage based on industry expert insights and research, subscribe to the Diagnostic Imaging e-Newsletter here.