LASER THERAPY FOR BREAST-CANCER - MR-IMAGING AND HISTOPATHOLOGIC CORRELATION

PURPOSE: To investigate magnetic resonance (MR) imaging guidance of in terstitial laser photocoagulation to treat primary breast cancer. MATE RIALS AND METHODS: Twenty female patients with symptomatic breast canc ers diagnosed at cytologic examination underwent interstitial laser ph otocoagulation by means of a single fiber prior to surgical excision. Gadolinium-enhanced T1-weighted three-dimensional fast low-angle shot (FLASH) MR imaging was performed before and after laser therapy (media n, 48 hours; range, 24-96 hours). Following resection, tumors were map ped in detail histopathologically. The extent of disease, size of lase r burn, and extent of residual tumor were correlated with MR findings. RESULTS: Twenty-seven tumors were detected at histopathologic examina tion in the 20 patients. Five patients had more than one invasive mass . Twenty-five of the 27 tumors were identified as discrete enhancing m asses at MR. The two missed invasive foci were obscured on MR images b y diffuse patchy enhancement that correlated with the presence of an a ssociated extensive intraductal component. Early (4-hour) follow-up im ages failed to depict the laser effect. Later (24-96 hours) follow-up images depicted the laser-induced necrosis as a zone of nonenhancement within the residual enhancing tumor. The correlation coefficients (MR vs histopathologic analysis) for the laser-burn diameter and residual tumor were 0.80 and 0.86, respectively. CONCLUSION: Delayed gadoliniu m-enhanced MR images can help define the extent of laser-induced necro sis and residual tumor after interstitial laser photocoagulation thera py in breast cancer.