Contrast-Enhanced Spectral Mammography Versus Magnetic Resonance Imaging: Intra- and Inter-Observer Agreements in Tumour Size Assessment

Introduction:In patients with locally advanced breast carcinomas undergoing neoadjuvant chemotherapy (NAC), imaging monitoring is important for guiding clinical management.Contrast-enhanced spectral mammography (CESM) is a recently introduced modality that may serve this purpose as an alternative to magnetic resonance imaging (MRI).We aimed to investigate intra-and inter-observer agreements in CESM and MRI in assessment of tumour size.Methods: Imaging studies performed between December 2019 and March 2022 for breast cancer patients undergoing NAC were retrospectively reviewed.Two radiologists measured the largest lesion sizes, intra-and inter-observer agreements were measured using the intraclass correlation coefficient.To assess the agreement between CESM and MRI findings, Lin's concordance correlation coefficient (CCC) and Bland-Altman plots were used.Scanning time and reading time were recorded and compared.Results: 12 cases of patients who had undergone a total of 20 CESM studies and 18 MRI studies were assessed.The intra-observer agreement for the two radiologists on CESM was 0.983 and 0.996.The inter-observer agreement on CESM was 0.995.For MRI, the intra-observer agreement was 0.975 and 0.984, while the inter-observer agreement was 0.982.The agreement between the 10 baseline CESM and MRI studies was high (CCC = 0.972).Both the scanning time and reading time were significantly shorter for CESM than MRI (both p < 0.001).Conclusion: Our results provide further evidence of CESM measurement reproducibility before, during, and after NAC.CESM can be considered an alternative assessment modality for monitoring NAC response.