Multiparametric Magnetic Resonance Imaging in Evaluation of Benign and Malignant Breast Masses with Pathological Correlation

Abstract

Background Dynamic contrast-enhanced (DCE) MRI sequences plays a vital role in diagnosing breast masses with high sensitivity and specificity as compared to other diagnostic modalities. The addition of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values significantly improves diagnostic accuracy. This study aimed to study the breast masses on DCE-MRI, restricted diffusion on DWI, ADC values, and choline peak on spectroscopy in breast cancer diagnosis. Material and methods This study was a prospective observational study which involved subjects with breast lumps. Baseline data was collected from the patients along with pertinent clinical history and relevant laboratory investigations. MR mammography (MRM) was performed on a 1.5 Tesla MR Scanner (MAGNETOM® Avanto, Siemens AG, Munich Germany) using a dedicated double breast coil. Results Forty-one subjects were included with a total of 54 breast masses in them. The mean age of the study population was 47.1±14.7 years. From the MRI final diagnosis, the majority (53.70%) were diagnosed as malignant lesions and 46.30% as benign. Out of 20 lesions diagnosed as benign on histopathology, only five percent had ADC value <1.3 ×10^-3mm²/s, and the majority (95%) had ADC value >1.3 ×10^-3mm²/s. All 20 lesions were circumscribed, ovoid, or round in shape showing no restricted diffusion on DWI, with corresponding ADC value of >1.3×10^-3mm²/s, homogeneous post-contrast enhancement, or with dark internal septations, type I kinetic enhancement curve, and they showed no choline peak on spectroscopy. Out of 34 malignant lesions diagnosed on histopathology, the majority (85.29%) displayed restricted diffusion on DWI and had an ADC value of <1.3×10^-3mm²/s, most of them had spiculated margins, type II/ III kinetic curve with choline peak on spectroscopy. Conclusion Multiparametric MR mammography, which included DCE-MRM, DWI, ADC values, and spectroscopy, correlated well with the histopathological diagnosis of benign and malignant breast masses.

Keywords: adc value; brest cancer; diffusion weighted imaging (dwi); kinetic curve; mr mammography.

Figure 1. Dedicated double breast coil

Figure 2. Shape of breast lesions

(A) oval, (B) round, (C) lobulated, (D) spiculated

Figure 3. Margin of breast lesion on T1 weighted post-contrast images

(A) circumscribed, (B) irregular, (C) spiculated

Figure 4. Five patterns of post-contrast enhancement of breast lesions on contrast-enhanced T1 fat-saturated MR images

(A) non-mass-like enhancement, (B) homogenous enhancement, (C) heterogeneous enhancement, (D) rim enhancement, (E) enhancement of the lesion with dark internal septations

Figure 5. Kinetic curve assessment according to types

(A) Fibroadenoma in left breast showing type I kinetic enhancement curve. (B) Infiltrative ductal carcinoma in right breast showing type II kinetic enhancement curve. (C) Squamous cell carcinoma in right breast showing type III kinetic enhancement curve.

Figure 6. DWI and ADC sequences of a patient with fibroadenoma

(A) DWI and (B) corresponding ADC images showing no restriction of diffusion within the lesion present in the left breast – suggestive of benign etiology. (C) DWI image demonstrating the method of placing multiple ovoid ROIs (each measuring ~25 mm²) throughout the benign lesion for calculation of mean ADC value. DWI - diffusion-weighted imaging; ADC - apparent diffusion coefficient; ROI - region of interest

Figure 7. DWI and ADC sequences of a patient with infiltrative ductal carcinoma

(A) DWI and (B) corresponding ADC images showing the peripheral area of restriction of diffusion within the lesion present in the left breast- suggestive of malignant etiology. (C) DWI image demonstrating the method of placing multiple ovoid ROIs (each measuring ~25 mm²) in the areas of restricted diffusion for calculation of mean ADC value. DWI - diffusion-weighted imaging; ADC - apparent diffusion coefficient; ROI - region of interest

Figure 8. MR spectroscopy image of a malignant breast lesion showing tCho peak at 3.2 ppm

tCho - total choline

Figure 9. DWI and ADC sequences of the axillary lymph node in a patient with infiltrative ductal carcinoma in the left breast

(A) DWI and (B) corresponding ADC images showing a lymph node in the left axilla with restriction of diffusion. (C) DWI image demonstrating method placing a single ovoid ROI on the lymph node for calculation of ADC value. DWI - diffusion-weighted imaging; ADC - apparent diffusion coefficient