Use of dynamic phase subtraction (DPS) map in dynamic contrast-enhanced MRI of the breast

The Breast Imaging Reporting and Data System (BI-RADS) of the American College of Radiology recommends careful examination of the region of interest (ROI) in areas that seem to show a washout pattern on time-intensity curve (TIC). However, it is difficult to identify malignancies because many benign lesions also show enhancement, and these include cysts, hemorrhage, fibrosis, and necrosis in the mass.

This study was performed to assess the performance of the dynamic phase subtraction (DPS) map for dynamic contrast-enhanced magnetic resonance imaging (MRI) of the breast. A DPS map is a map image with pixel-by-pixel subtraction of an early-phase image from a delayed-phase image obtained in a dynamic study.

The use of the DPS map was analyzed retrospectively in 53 patients (32-84 years old) who underwent dynamic contrast-enhanced MRI of the breast. Sensitivity and specificity were compared with and without a DPS map for masses diagnosed as malignant lesions by biopsy. In addition, the patterns of time-intensity curves 30 seconds, 90 seconds, and 5 minutes after injection of contrast agent were compared with and without a DPS map.

Sensitivity increased from 0.78 to 0.95, and specificity increased from 0.71 to 0.95 with reference to the DPS map. The pattern of TIC changed from continuous to a plateau in 9 cases, from a plateau to washout in 21 cases, and from continuous to washout in 7 cases.

Use of the DPS map of dynamic contrast-enhanced MRI of the breast results in high detection rates of malignant masses, allows accurate ROI setting of TIC, and reduces operator's task.