E3228. Preoperative MRI-Guided Needle Localization of Breast Lesions: Outcomes and Feasibility
  1. Shannon Yoo; University of California, Los Angeles
  2. Steven Lee; University of California, Los Angeles
  3. Reza Fardanesh; University of California, Los Angeles
MRI-guided needle localization enables localization of lesions not amenable to MRI-guided biopsy or localization by other imaging modalities. We aimed to examine the safety and outcomes of MRI-guided needle localization.

Materials and Methods:
We conducted an IRB-approved retrospective review of MRI-guided localizations performed at UCLA Health System from January 1, 2018 to September 13, 2022. We reviewed patient demographics, preoperative imaging indications, MRI-guided localization indications, and pathology results. MRI enhancement characteristics and kinetic assessment were analyzed. Positive predictive values (PPVs) were calculated, and univariate analysis was performed for the association between the collected parameters and malignancy rates using the Chi-square test.

Seventy-two patients with 78 suspicious findings underwent MRI-guided localization. The median age was 54 years (range 26 - 71). Out of 78 lesions, 33 (42.3%) were masses, and 45 (57.7%) nonmass enhancements (NMEs). Disease extent evaluation identified 47 out of 78 (60.3%), of which 45 out of 47 (95.7%) were for newly diagnosed malignancy, and 2 out of 47 (4.3%) were for positive surgical margins. For new malignancies, 27 out of 45 (60%) were found ipsilateral to the index tumor. Diagnostic workups identified 17 out of 78 (21.8%) lesions, with 5 out of 17 (29.4%) that were diagnostic for palpable abnormalities not seen in other modalities and 4 out of 17 for bloody nipple discharge (23.5%). High-risk screening identified 14 out of 78 (17.9%) lesions localized. MRI-guided biopsy was not performed before localization for 62 out of 78 (79.5%) due to lesion location (26 out of 62; 42%), or to not delay scheduled surgery (21 out of 62; 33.9%) in those with biopsy-proven diagnosis. For the remaining 16 out of 78 (20.5%), MRI-guided localization followed MRI-guided biopsy due to extensive area of enhancement, interval growth, or biopsy marker migration. Surgical pathology yielded 36 (46.2%) malignant, 12 (15.4 %) high-risk, and 30 benign (38.4%) benign results. The extent of the disease evaluation yielded 31 out of 36 (86.1%) malignancies, with the highest PPV (31 out of 47; 66%) for malignancy among preoperative indications with statistical significance (<em>p</em> < 0.05). Two previously biopsied lesions (7.7%) had histopathologic upgrades: one to invasive ductal carcinoma from ductal carcinoma in situ and another to high-risk from benign discordant. The average time for localization ranged from 29-39 minutes. There were no complications. The highest enhancement characteristic PPVs associated with malignant outcomes with statistical significance (<em>p</em> < 0.05) were irregular shape mass (76.9 %) and heterogeneous enhancement (100%).

MRI-guided localization is a safe and feasible technique for lesions not amenable to biopsy or not seen in other modalities, with a significant malignancy detection rate in preoperative imaging, high-risk screening, and diagnostic workups. It can affect patient management and influence patient outcomes.