Contrast-enhanced ultrasound findings with Sonazoid for evaluation of neoadjuvant chemotherapy for breast cancer

Abstract

Purpose: The change in maximum tumor diameter is generally used to evaluate clinical response to neoadjuvant chemotherapy (NAC) for breast cancer. However, there are cases in which accurate evaluation cannot be performed due to internal necrosis or scar tissue. The objectives of this study were to examine whether accurate evaluation can be performed by addition of contrast-enhanced ultrasound (CEUS) using Sonazoid^® and to examine on what types of CEUS findings one should focus. Subjects and Methods: The subjects were 20 breast cancer patients (22 nodules) who had undergone CEUS before and after NAC followed by surgery in our hospital between July 2007 and July 2010. Sonazoid^® suspension (0.0075 ml/kg) was injected intravenously. The nodules were classified into the following five categories based on micro flow images and video taken for 1 min after injection: the tumor interior was not contrast enhanced, had the same enhancement as the non-tumor area, was slightly more enhanced than the non-tumor area, was more strongly enhanced than the non-tumor area, and was non-evaluable. Three categories were used to classify peritumoral contrast enhancement and intratumoral non-contrast enhanced areas: absent, present, and non-evaluable. The results based on these categories were compared with histological responses to NAC. Results and Discussion: Peritumoral and intratumoral contrast enhancement tended to decrease after NAC compared with before NAC. This tendency was stronger in nodules that showed a good histological response. There was no consistent trend between histological responses and intratumoral non-enhanced areas. It suggests the need to evaluate not only absence or presence of non-enhanced areas but also changes in tumor size and the state of enhanced areas. Conclusion: The effectiveness of NAC can be evaluated by the assessment of intratumoral and peritumoral contrast enhancement using CEUS.