Definition and classification of additional lesions
Additional lesions were those identified with CEM and/or MRI, which had not been previously detected with routine clinical examination and conventional breast imaging (as defined above). Additional lesions were assigned an NBCC grade of between 1 and 5 according to the radiologists’ level of concern (1 = benign; 2 = probably benign; 3 = indeterminate/equivocal; 4 = suspicious; 5 = malignant) [Assessment pathway for additional lesions. Based on the CEM and/or MRI imaging findings, lesions classified as NBCC category 1 or 2 were considered negative, and those classified NBCC 3 and above were called positive. A lesion not detected on one or other modality was considered as negative for that modality.