Published online Oct 28, 2018. doi: 10.4329/wjr.v10.i10.116
Peer-review started: June 24, 2018
First decision: July 19, 2018
Revised: August 2, 2018
Accepted: August 2, 2018
Article in press: August 26, 2018
Published online: October 28, 2018
Gastrointestinal tumors (GTs) are among the most common tumors of the digestive system and are among the leading causes of cancer death worldwide. Functional magnetic resonance imaging (MRI) is crucial for assessment of histopathological changes and therapeutic responses of GTs before and after chemotherapy and radiotherapy. A new functional MRI technique, intravoxel incoherent motion (IVIM), could reveal more detailed useful information regarding many diseases. Currently, IVIM is widely used for various tumors because the derived parameters (diffusion coefficient, D; pseudo-perfusion diffusion coefficient, D*; and perfusion fraction, f) are thought to be important surrogate imaging biomarkers for gaining insights into tissue physiology. They can simultaneously reflect the microenvironment, microcirculation in the capillary network (perfusion) and diffusion in tumor tissues without contrast agent intravenous administration. The sensitivity and specificity of these parameters used in the evaluation of GTs vary, the results of IVIM in GTs are discrepant and the variability of IVIM measurements in response to chemotherapy and/or radiotherapy in these studies remains a source of controversy. Therefore, there are questions as to whether IVIM diffusion-weighted MRI is feasible and helpful in the evaluation of GTs, and whether it is worthy of expanded use.
Core tip: In general, the gastrointestinal tumors (GTs) can be diagnosed by routine computed tomography/magnetic resonance imaging (MRI) and biopsy, but the intravoxel incoherent motion (IVIM), a new emerging MRI technique, plays a important role in the tumor evaluation before and after surgery, and provides more useful information in tumor properties, stage and chemoradiotherapy (CRT) response. What’s more, the quantitative parameters derived from IVIM, including D, D* and f, can gain an insight into tumor tissue physiology changes and simultaneously reflect the microenvironment, microcirculation in the capillary network and diffusion in tumor tissues, thus, new imaging biomarkers for monitoring and evaluating the tumor and the CRT response in GTs.