Copyright ©The Author(s) 2021.
World J Gastroenterol. Jun 14, 2021; 27(22): 3037-3049
Published online Jun 14, 2021. doi: 10.3748/wjg.v27.i22.3037
Table 1 Role of current imaging in the response assessment after neoadjuvant treatment for pancreatic ductal adenocarcinoma
Imaging technologies
Imaging parameters
Pathological basis
Roles and advantages
USConventional US imaging featuresIso-/low-attenuating pancreatic massesNon-radiation and high economy; a tool for PDAC early detection and staging; detection of systemic therapies associated adverse events in metastatic PDACPlay the limited role for tumor response of PDAC after NATFurther exploration
EUSTumor size Change in tumor size after NATProvides additional information for response assessment and survival predictionInvasive procedure, preliminary research, lack of credible resultsFurther large-scale research is needed in the future
Tumor stiffness (EUS elastography)Decrease of change in tumor stiffness after NATPotential marker for NAT response and tumor resectability assessmentPoor objectivity and low reproducibility; the pressure of the probe on the lesion area is not easily controlled Technology Optimization; further investigation is needed
CTMDCT conventional imaging features Tumor size; Enhancement; Tumor-vessel contact Size or enhancement reduction; changes in tumor-vessel contactHigh-density resolution; speed of data acquisition; multiplanar reconstruction ability Low specificity and sensitivity (53%-80% of patients are in a stable state on MDCT after NAT)Further quantification, exploration and evaluation of imaging indicators on MDCT conventional imaging features
Perfusion CT; Blood flow; Blood volume Permeability–surface area productChanges in extracellular matrix causing changes in the tumor blood flowPre-treatment perfusion CT can be helpful to predict the histopathologic response of PDAC to NATPreliminary research, lack of credible resultsFurther studies are needed to evaluate the value of perfusion imaging in a large number of patients
Texture analysis; Texture featuresCT texture features after NAT can reveal the heterogeneity in PDACProviding additional value for judging tumor heterogeneity; judging tissue changes and tumor downstaging in those cases with no significant alteration in tumor size after NATTime consuming segmentation and non-robustness conclusionFurther large-scale research is needed in the future
Radiomics; Radiomics features and delta radiomics features combined with common clinical index (e.g., CA-199)Radiomics features after NAT can reveal the heterogeneity change of PDACIncreasing the possibility for response-based treatment adaptation; has a broad prospect in the management of PDAC after NATThe lack of enough research; time consuming segmentation and non-robustness conclusion
MRIADC value of DWICellularity and potential fibrotic changes of PDAC after NATImprove the prediction possibility of R0 resection rate (75% accuracy) in resectable PDAC; pre-treatment ADC can be used to distinguish responding patients from non-responding patients after NATFew related studies and inconsistent conclusions; no unified standard for the selection of DWI scanning technology and parameters; large motion artifacts, time-consuming and high costLarge-scale studies to validate the role of DWI in PDAC to NAT; establish a unified scanning standard; reduce motion artifacts and scan time; reduce costs by optimizing sequences
PET imagingSUVmaxChanges in glucose metabolism of tumors before and after NATAid in monitoring the clinical outcome of patients with locally advanced PDAC treated with NAT; distinguish responding patients from non-responding patients after NAT; plays a significant role in the clinical decision-making of patientsLack of relevant research and high cost of inspectionApplication of PERCIST criteria and comparison with the accuracy of traditional evaluation criteria will be the future research direction