MRI phenotype of breast cancer: Kinetic assessment for molecular subtypes.

Abstract

To evaluate the dynamic contrast-enhanced magnetic resonance imaging (MRI) kinetic characteristics of newly diagnosed breast cancer molecular subtypes. Breast MRI examinations of 112 patients with newly diagnosed breast cancer were reviewed. Cases of newly diagnosed invasive ductal carcinoma were sorted by molecular subtype (28 TN, 11 HER2 +, 73 Lum A/B) and MRI field strength, with lesion segmentation and kinetic analyses performed on a dedicated workstation. For kinetic assessment, 50% and 100% thresholds were employed for display of medium and rapid uptake. Kinetic profiles in terms of percent volume for six kinetic types (medium-persistent, medium-plateau, medium-washout, fast-persistent, fast-plateau, fast-washout) relative to the whole volume of the lesion were obtained. Statistical analysis of the kinetic profiles was performed using Welch's t-test. Percent volume of HER2-positive lesions with >100% uptake at early phase on 3T strength MRI exams was significantly greater compared with luminal A/B (93.8 ± 0.92 vs. 77.3 ± 7.2; P < 0.01) and triple negative (93.8 ± 0.92 vs. 81.3 ± 8.2; P < 0.05) subtypes. The >50% early phase uptake for HER2+ lesions was also higher than Lum A/B (99.1 ± 0.73 vs. 93.6 ± 3.05; P < 0.01) at 3T. In the 1.5T subgroup the percent volume of HER2+ tumors with >50% and >100% early phase uptake trended higher than Lum A/B lesions without reaching significance. The percent volume of HER2-positive tumors demonstrating rapid early contrast uptake is significantly increased compared to other molecular subtypes.