Specimen PET-CT Imaging for Intraoperative Margin Assessment in Early-Stage Breast Cancer: The BrIMA Nonrandomized Clinical Trial

Abstract

Importance Positive margins occur in 12% to 30% of breast-conserving surgeries and are associated with increased local recurrence risks. Accurate and efficient intraoperative margin assessment, therefore, remains an unmet clinical need. Objective To evaluate the success rate of intraoperative specimen positron emission tomography (PET)–computed tomography (CT) imaging in addressing positive margins in patients with invasive ductal carcinoma. Design, Setting, and Participants This was an interventional, multicenter, nonrandomized clinical trial that recruited patients from June 2022 to March 2025. Patients were followed up 2 weeks after surgery. Six European breast cancer centers participated and integrated specimen PET-CT imaging into their routine surgical flow. The analysis included eligible patients with early-stage breast cancer scheduled for breast-conserving surgery. Interventions Patients received an intravenous injection of low-dose 18F-fluorodeoxyglucose (FDG; 0.8 MBq/kg). After tumor excision, the specimen was imaged intraoperatively using a dedicated specimen PET-CT scanner. Surgeons interpreted PET-CT images intraoperatively, and additional tissue was excised when margins were deemed suspicious to achieve final negative margins. Main Outcomes and Measures The primary outcome was the success rate of specimen PET-CT in addressing positive margins for the invasive component in patients undergoing breast-conserving surgery for invasive ductal carcinoma. Secondary outcomes included success rates in other breast cancer subtypes, final positive margin rates, reoperation rates, and diagnostic performance using histopathology as the reference standard. Results The analysis cohort consisted of 148 female patients with a median (IQR) age of 65 (53-73) years and a median (IQR) preoperative tumor size of 17 (12-22) mm. For the invasive component of invasive ductal carcinoma, success rates increased from 83.3% (70 of 84 patients) without intraoperative margin assessment (IMA) to 86.9% (73 of 84 patients) with routine margin assessment and to 95.2% (80 of 84 patients) with specimen PET-CT (P