Abstract
Objective
To determine whether invasive lobular carcinoma (ILC) extent is more accurately depicted with preoperative MRI (pMRI) than conventional imaging (mammography and/or ultrasound).
Methods
After IRB approval, we retrospectively identified women with pMRIs (February 2005 to January 2014) to evaluate pure ILC excluding those with ipsilateral pMRI BI-RADS 4 or 5 findings or who had neoadjuvant chemotherapy. Agreement between imaging and pathology sizes was summarized using Bland-Altman plots, absolute and percent differences, and the intraclass correlation coefficient (ICC). Rates of underestimation and overestimation were evaluated and their associations with clinical features were explored.
Results
Among the 56 women included, pMRI demonstrated better agreement with pathology than conventional imaging by mean absolute difference (1.6 mm versus −7.8 mm, P < 0.001), percent difference (10.3% versus −16.4%, P < 0.001), and ICC (0.88 versus 0.61, P = 0.019). Conventional imaging more frequently underestimated ILC span than pMRI using a 5 mm difference threshold (24/56 (43%) versus 10/56 (18%), P < 0.001), a 25% threshold (19/53 (36%) versus 10/53 (19%), P = 0.035), and T category change (17/56 (30%) versus 7/56 (13%), P = 0.006). Imaging–pathology size concordance was greater for MRI-described solitary masses than other lesion types for both MRI and conventional imaging (P < 0.05). Variability of conventional imaging was lower for patients ≥ to the median age of 62 years than for patients younger than the median age (SD: 12 mm versus 22 mm, P = 0.012).
Conclusion
MRI depicts the size of pure ILC more accurately than conventional imaging and may have particular value for younger women.
Editorial for “Accuracy of Preoperative Breast MRI Versus Conventional Imaging in Measuring Pathological Extent of Invasive Lobular Carcinoma”