Subtle ground enhancement a new definition for breast magnetic resonance imaging (MRI) after neoadjuvant chemotherapy: is it a marker for microscopic residual disease?

Abstract

AIM: This study aims to describe 'subtle ground enhancement' (SGE) patterns as a new definition and investigate the diagnostic contribution of 'SGE' in magnetic resonance imaging (MRI) evaluation after neoadjuvant chemotherapy (NACT) by correlating with histopathology. MATERIALS AND METHODS: This is a single-centre retrospective study. Breast MRI examinations after NACT were analysed by 2 radiologists and classified according to the Respond Evaluation Criteria In Solid Tumours (RECIST) criteria. Cases with SGE, which is not included in the RECIST criteria, were the study group. On post-NACT, late-phase contrast-enhanced MRI series, areas that showed slightly more intense enhancement than the surrounding parenchyma with visual assessment were recorded. Measurements were made with region of interests, from the region where the SGE was most intense, and from the surrounding adjacent parenchyma, and ratios were calculated. Receiver operating characteristic curve analysis determined cut-off values according to the statistically significant parameters. The diagnostic values and CIs were obtained. RESULTS: SGE was detected in 27 of 332 patients. After surgery, histopathological examination revealed residual invasive tumours in 16 of 27 patients with SGE, a complete response in 11 patients. The optimum cut-off value calculated for the ratio of SGE to normal parenchyma was 1.595 showing a sensitivity and specificity at 87.5% (95% CI: 68.8%-10 0%) and 54.6% (95% CI: 27.3%-81.8%), respectively, in predicting the residual tumour. CONCLUSION: SGE is a new definition, and our studydespite the limited number of cases showed that this finding has the potential to increase the accuracy of MRI after NACT. (c) 2026 The Royal College of Radiologists. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.