Diffusion weighted MRI and spectroscopy in invasive carcinoma of the breast at 3Tesla. Correlation with dynamic contrast enhancement and pathologic findings.

BACKGROUND: The most common histological types of invasive breast carcinomas are the invasive ductal carcinoma (IDC) and the invasive lobular carcinoma (ILC). The purpose of our study was to evaluate the role of the diffusion-weighted imaging (DWI) and the in vivo proton magnetic resonance spectroscopy (1 H-MRS ) at 3 Tesla magnet in invasive breast cancer and correlate them with the dynamic contrast enhancement (DCE) and pathologic findings.

METHODS: We retrospectively studied at 3Tesla magnet the apparent diffusion coefficient (ADC) values, the detection of choline in the 1 H-MRS and the kinetic analyses obtained after DCE in 181 patients with histologically confirmed invasive breast carcinomas. Among these patients, 160 had IDC and 21 ILC. We used the DWI sequence with a b value of 1,000 mm2 /sec for the calculation of the ADC value, the fat-suppressed point-resolved spectroscopy (PRESS) sequence in order to evaluate the existence of a choline peak in the spectrum and the T1 W GRE FAT SAT VIBRANT sequence for the characterization of the kinetic curves. Finally, we correlated the pathologic type of invasive cancer, as well as the type of the kinetic curve with the ADC value and the detectability of choline resonance in the spectrum in each of the 181 patients.

RESULTS: The ADC values in the 158 out of 160 IDC patients, ranged from 0.5 x 10-3 to 1.2 x 10-3 mm2 /sec, with 78.1 % having ADC value of 1 x 10-3 mm2 /sec. Regarding the 1 H-MRS, in 121 out of 160 IDC patients, choline was found in 72.3 %. The ADC values in the 21 ILC patients also ranged from 0.5 x 10-3 to 1.2 x 10-3 mm2 /sec with 57.1 % having ADC value of 1 x 10-3 mm2 /sec. Regarding the 1 H-MRS, in 10 out of 21 ILC patients, detection of choline was positive in 60 % of them. In the 21 ILC patients, the kinetic analysis after the dynamic administration of contrast medium showed type I (persistent) curve in 4.3 %, type II (plateau) curve in 33.3 % and type III (washout) in 52.4 %. In the 158 IDC patients (missing in two cases) type I curve was obtained in 0.63 %, type II in 19.4 % and type III in 80 %. From the correlation analysis of the IDC results using Kruskal-Wallis Test and the non-parametric Kendall's tau-b test, the curve type was positively associated (Kendal tau-b: 0.254, p =0.005) with the presence of choline, while the ADC value was negatively associated (Kendal tau-b: -0.224, p =0.011) with the presence of choline. In the ILC cases, the sample was insufficient for the correlation to become statistically significant. However, the ADC values tended to be lower in IDC patients (78.1 % having ADC value 1 x 10-3 mm2 /sec) compared to ILC (57.1 % having ADC value 1 x 10-3 mm2 /sec). Choline was more commonly detected in the IDC (72.3 %) than ILC (60 %) patients.

CONCLUSION: Our results are consistent with previous findings that both ADC values and choline detection in the spectrum play a significant role in establishing the final diagnosis of malignancy, especially when the kinetic pattern of enhancement is misleading. Hippokratia 2016, 20(3): 192-197.