Role of imaging in evaluating the response after neoadjuvant treatment for pancreatic ductal adenocarcinoma

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy. Despite the development of multimodality treatments, including surgical resection, radiotherapy, and chemotherapy, the long-term prognosis of patients with PDAC remains poor. Recently, the introduction of neoadjuvant treatment (NAT) has made more patients amenable to surgery, increasing the possibility of R0 resection, treatment of occult micro-metastasis, and prolongation of overall survival. Imaging plays a vital role in tumor response evaluation after NAT. However, conventional imaging modalities such as multidetector computed tomography have limited roles in the assessment of tumor resectability after NAT for PDAC because of the similar appearance of tissue fibrosis and tumor infiltration. Perfusion computed tomography, using blood perfusion as a biomarker, provides added value in predicting the histopathologic response of PDAC to NAT by reflecting the changes in tumor matrix and fibrosis content. Other imaging technologies, including diffusion-weighted imaging of magnetic resonance imaging and positron emission tomography, can reveal the tumor response by monitoring the structural changes in tumor cells and functional metabolic changes in tumors after NAT. In addition, with the renewed interest in data acquisition and analysis, texture analysis and radiomics have shown potential for the early evaluation of the response to NAT, thus improving patient stratification to achieve accurate and intensive treatment. In this review, we briefly introduce the application and value of NAT in resectable and unresectable PDAC. We also summarize the role of imaging in evaluating the response to NAT for PDAC, as well as the advantages, limitations, and future development directions of current imaging techniques.

Keywords: Pancreatic ductal adenocarcinoma, Neoadjuvant treatment, Imaging, Resectability, Tumor response, Prognosis

Core Tip: The timely and accurate evaluation of tumor response in patients with pancreatic ductal adenocarcinoma (PDAC) after neoadjuvant therapy (NAT) is of great significance to increase the probability of tumor R0 resection and prolong survival. Ultrasound and conventional computed tomography imaging features show limited roles in the evaluation of NAT response for PDAC. Novel imaging biomarkers extracted from functional imaging technologies show promise in providing further important information for the assessment of tumor resectability and survival prediction. We reviewed the application and value of NAT in PDAC, as well as the advantages, limitations, and future development directions of current imaging techniques in tumor response assessment of PDAC after NAT in this article.