Diffusion weighted imaging (DWI) could help differentiate between benign and malignant tumors and predict tumor recurrence in breast cancer patients, according to research published online Oct. 4 in Academic Radiology. The authors noted that DWI may also serve as a beneficial supplement to contrast enhanced breast MRI.
Apparent diffusion coefficient (ADC) value was found to be important in distinguishing malignancy and differentiating tumors with higher Oncotype score and progesterone receptor (PR) negativity, wrote lead author Shima Roknsharifi, MD, a radiologist with Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, and colleagues.
“This study demonstrates that mean ADC values of malignant tumors are significantly lower than benign tumors and are predictive in differentiating malignancy,” Roknsharifi et al. wrote.
A total of 956 patients underwent breast MRI from January to December 2015, with a total of 156 BI-RADS category 4, 5, or 6 lesions detected in 111 patients.
DWI imaging at B0, B100, B600, B1000 was performed with dynamic contrast-enhanced (DCE) MRI and diffusion values were recorded by two breast radiologists.
Additionally, average ADC and signal intensity (SI) values were correlated with histology, tumor grade, hormone receptors (ER, PR, and HER-2) and Oncotype DX scores.
Of 156 lesions detected, 38 percent were benign, 15 percent ductal carcinoma in-situ, 30 percent invasive ductal carcinoma (IDC), ten percent invasive lobular carcinoma (ILC) and two percent mucinous carcinoma (MC), five percent mixed IDC and ILC, and four percent tubular and rare types of malignancy.
Additional findings included the following:
- Mean ADC values for malignancy were significantly lower than for benign lesions;
- Tumors with PR negativity and Oncotype scores less than 18 (intermediate to high risk for recurrence) demonstrated significantly lower ADC values;
- SI at B100 and B600 was helpful in distinguishing benign versus IDC;
- No significant correlation found between ADC values and tumor grade or ER/HER2 status.
The researchers determined that ADC values can help distinguish benign and malignant lesions in BI-RADS category 4, 5, and 6 lesions and help direct clinical care and management of breast cancer patients.
“Higher tumor recurrence based on Oncotype DX score is significantly correlated with lower ADC values, suggesting the benefit of diffusion weighted imaging to guide management," Roknsharifi et al. added. "In addition, this study demonstrates signal intensity at b values of 100 and 600 can represent a satisfactory direct measure for differentiating IDC from benign lesions.”