Validation of semiautomatic measurement of the extent of breast tumors using contrast-enhanced magnetic resonance imaging

Objectives: The aim of this study was to assess whether the semiautomatic measurement of breast-tumor extent using contrast-enhanced magnetic resonance imaging (CE-MRI) decreases measurement variation compared with manual evaluation and increases precision with respect to tumor extent measured at histopathology. Materials and Methods: Forty-three patients who underwent breast-conserving therapy for 46 tumors were consecutively included. Extended histopathology analysis was performed on the excision specimens. Two experienced breast-MR radiologists independently manually assessed the largest diameter of the tumors at preoperative CE-MRI. Two observers used a semiautomatic segmentation technique to independently obtain the largest diameter and the volume of the tumors. Results: Semiautomatic volumetric measurement of tumor volume was more accurately correlated with histopathology (adjusted R-square 0.84 and 0.81) compared with conventional measurement (adjusted R-square 0.56 and 0.70) and semiautomatic measurement (adjusted R-square 0.63 and 0.60) of the largest diameter of the tumor. The interobserver variability between the volumetric measurements was significantly smaller than the interobserver variability between the largest-diameter measurements of tumor extent obtained by the radiologists (P < 0.001). Conclusions: Semiautomatic volumetric measurement of breast-tumor extent at CE-MRI provides a more accurate assessment of tumor extent with respect to histopathology and reduces measurement variation compared with manual assessment of the largest diameter. Automated volumetric measurement thus provides potential for increased precision in establishing response to treatment.