Motivation: To evaluate the mesorectal microenvironment. Goal(s): To assess the mesorectal microstructure and microcirculation of rectal cancer by IVIM-MRI. Approach: 42 patients with semicircular rectal tumors underwent IVIM-MRI with 14 b values before surgery. ROIs were depicted in the mesorectum that surrounded the tumor (MT) and normal rectal wall (MN) respectively. D, D* and f values of ROIs were estimated based on the bi-exponential model. Histopathology served as standard reference. Results: The MT showed lower D but higher D* and f than the MN (P<0.001). A higher D* of MT was observed in patients with pT3 tumors than in patients with pT1~2 tumors (P=0.001). Impact: The mesorectum that surrounded the rectal tumor had a more complex microstructure and a higher microvascular prefusion than that close to the normal rectal wall. The mesorectal microenvironment might be an interesting point for further MRI study in rectal cancer.
Yang et al. (Tue,) studied this question.