Accuracy of 3 T versus 1.5 T breast MRI for pre-operative assessment of extent of disease in newly diagnosed DCIS

• We compared sizes of known ductal carcinoma in situ (DCIS) on pre-operative breast MRI at 3 T and 1.5 T with final pathology sizes.
• DCIS sizes on 3 T MRI correlated better with pathologic sizes than 1.5 T MRI.
• Imaging features of DCIS, including morphology and kinetics, were similar at 3 T and 1.5 T MRI.

ObjectivesWhile 3 T breast magnetic resonance imaging has increased in use over the past decade, there is little data comparing its use for assessing ductal carcinoma in situ (DCIS) versus 1.5 T. We sought to compare the accuracies of DCIS extent of disease measures on pre-operative 3 T versus 1.5 T MRI.MethodsThis institutional review board-approved prospective study included 20 patients with ductal carcinoma in situ diagnosed by core needle biopsy (CNB) who underwent pre-operative breast MRI at both 3 T (resolution = 0.5 mm × 0.5 mm × 1.3 mm) and 1.5 T (0.85 mm × 0.85 mm × 1.6 mm). All patients provided informed consent, and the study was HIPPA compliant. Lesion sizes and imaging characteristics (morphologic and kinetic enhancement) were recorded for the 3 T and 1.5 T examinations. Lesion size measures at both field strengths were correlated to final pathology, and imaging characteristics also were compared.ResultsOf the initial cohort of 20 patients with CNB-diagnosed DCIS, 19 underwent definitive surgery. Median DCIS sizes of these 19 patients were 6 mm (range: 0–67 mm) on 3 T, 13 mm (0–60 mm) on 1.5 T, and 6 mm (0–55 mm) on surgical pathology. Size correlation between MRI and pathology was higher for 3 T (Spearman's ρ = 0.66, p = 0.002) than 1.5 T (ρ = 0.36, p = 0.13). In 10 women in which a residual area of suspicious enhancement was identified on both field strengths, there was agreement of morphologic description (NME vs. mass) in nine, and no significant difference in dynamic contrast enhanced kinetics at 3 T compared to 1.5 T.ConclusionsPre-operative breast MRI at 3 T provided higher correlation with final pathology size of DCIS lesions compared to 1.5 T, and may be more accurate for assessment of disease extent prior to definitive surgery.