UCSF

Objectives

While 3T 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 3T versus 1.5 T MRI.

Methods

This 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 3T (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.

Results

Of the initial cohort of 20 patients with CNB-diagnosed DCIS, 19 underwent definitive surgery. Median DCIS sizes of these 19 patients were 6mm (range: 0-67 mm) on 3T, 13 mm (0-60 mm) on 1.5 T, and 6mm (0-55 mm) on surgical pathology. Size correlation between MRI and pathology was higher for 3T (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 3T compared to 1.5 T.

Conclusions

Pre-operative breast MRI at 3T 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.