Evaluating Multidetector Row CT for Locoregional Staging in Individuals with Locally Advanced Breast Cancer

Purpose To assess the agreement and reliability between multidetector row CT (MDCT) and MRI features for locoregional staging of newly diagnosed breast cancer and to compare these imaging findings with pathologic staging in individuals undergoing upfront surgery. Materials and Methods This prospective single-center study (CAAE: 73328923.1.0000.5432) included participants with breast cancer who underwent breast MRI and contrast-enhanced chest MDCT for staging between September 2019 and September 2021. MDCT was performed in the prone position, using a custom-made device similar to the MRI coil. Agreement between MDCT, MRI, and pathologic results (when available) was expressed as percentages, and reliability was assessed using Fleiss κ and intraclass correlation coefficients (ICCs). Results The study included 111 female participants (mean age ± SD, 48.7 years ± 12.1). MRI depicted all index tumors, and only one (0.1%) was not visible at MDCT. The mean tumor size was 3.3 cm ± 2.2 on MR images and 3.2 cm ± 2.1 on MDCT images (ICC, 0.91; 95% CI: 0.86, 0.93). Multifocality was characterized with both methods in 31 participants and only with MDCT in one participant (agreement, 99%; κ = 0.98; 95% CI: 0.94, 1.00). Although more additional suspicious lesions were detected at MRI, almost all malignant additional lesions (sensitivity, 90%; positive predictive value, 69.2%) were detected at MDCT. In 54 participants who underwent upfront surgery, MRI showed a higher reliability with surgical pathology results for determining the main tumor size (ICC, 0.74; 95% CI: 0.59, 0.84) compared with MDCT (ICC, 0.53; 95% CI: 0.31, 0.70), whereas MDCT was more reliable for determining the number of metastatic nodes (MDCT ICC, 0.69; 95% CI: 0.53, 0.81 vs MRI ICC, 0.56; 95% CI: 0.34, 0.71). Conclusion This study demonstrates that contrast-enhanced MDCT, when performed with a dedicated breast protocol, offers high agreement and reliability with breast MRI for locoregional staging of newly diagnosed breast cancer. Keywords: CT, Breast, Staging Supplemental material is available for this article. © RSNA, 2025.