Magnetic Resonance Imaging of Invasive Ductal Carcinoma and Ductal Carcinoma in Situ in Detecting Multifocal/Multicentric and Bilateral Breast Disease: A Pictorial Essay

In accordance with the standard protocol in place, all patients with biopsy-proven breast malignancy (either by ultrasound-guided or stereotactic biopsy), with histology of invasive ductal carcinoma (IDC) and/or ductal carcinoma in situ (DCIS), subsequently undergo preoperative magnetic resonance imaging (MRI) of both breasts to rule out multifocal/multicentric and bilateral disease before considering breastconserving therapy (BCT).Some of the patients are referred from the surgical department to the radiology department for MRI if they do not opt for private imaging.Unlike invasive lobular carcinoma (ILC) which is characteristically associated with multifocal/ multicentric or bilateral disease, 1 primary IDC and DCIS are not known to be linked to a high rate of such involvement, and patients may proceed directly to BCT without preoperative MRI in our locality.This pictorial essay reviews our experience in detecting multifocal/ multicentric and bilateral disease in patients with primary IDC and DCIS using MRI and illustrates the associated MRI features. MAGNETIC RESONANCE IMAGING FEATURESMost primary breast carcinomas present as a palpable mass.By definition, a 'mass' is a three-dimensional lesion that occupies space.Mammography remains the cornerstone of breast cancer screening and is often the first imaging modality used.Ultrasound is useful in characterising palpable masses, especially in dense breast tissue, providing real-time assessment of lesion morphology and vascularity.MRI is generally reserved for problem-solving, preoperative staging, or screening high-risk populations.Any enhancing lesion measuring less than 5 mm on MRI is termed a 'focus', which is too small to characterise.Evaluation of a mass is based on its shape, margins, T1-and T2-weighted signals, and its enhancement pattern. 2 MRI provides valuable functional information regarding masses, including kinetic curves and diffusion restriction, which will be discussed in a subsequent section.MRI often reveals multifocal/ multicentric and bilateral disease in IDC and DCIS that is occult on mammography or ultrasound, commonly presenting as non-mass enhancement (NME).