Progress of quantitative prediction of the pathologic complete response after neoadjuvant chemoradiotherapy for locally advanced rectal cancer with functional MRI
Neoadjuvant chemoradiotherapy (nCRT) could reduce the local recurrence rate and improve the anus-preserving rate in patients with locally advanced rectal cancer (LARC). Some patients can achieve pathologic complete response (pCR) after nCRT,who will be take "watch and wait" strategy,and the patients could be avoid the complications caused by surgery. Functional magnetic resonance imaging (fMRI) can more accurately assess patients' response to nCRT than conventional MRI by reflecting changes in the structure and function of the tumor microenvironment at the cellular level. In this paper,we review the research progress on the quantitative evaluation of pCR after nCRT by diffusion-weighted imaging (DWI) and its derived sequences and perfusion imaging in patients with LARC,compare the advantages and disadvantages of DWI,intravoxel incoherent motion (IVIM),stretched exponential model (SEM),diffusion kurtosis imaging (DKI),dynamic contrast-enhanced MRI (DCE-MRI),and artificial intelligence-based prediction models in the current research,and provide clues and ideas for future research directions,aiming to provide relative reliable quantitative indicators for accurately identifying patients with LARC who achieve pCR.