Morphometric assessment of the mesorectal fat in Chinese Han population: A clinical MRI study

Abstract

The study aimed to analyze morphometric assessment of the mesorectal fat thickness and its correlation with body mass index in Chinese Han population. The anterior, posterior, right lateral, and left lateral mesorectal fat thickness were measured using MRI T2-weighted images. The mean distance from the rectal wall to the mesorectal fascia were 3.8, 8.4, 11.3, and 11.7 mm in anterior, posterior, right lateral, and left lateral portion, respectively. The mesorectal area, rectal area, mesorectal fat thickness area, and rectal height were 2395.3 ± 691.1 mm2, 709.6 ± 403.5 mm2, 1685.7 ± 525.3 mm2, and 9.1 ± 0.8 cm. BMI was found to be directly proportional to and statistically significant to the mesorectal fat area ( p = 0.01). Since the mean mesorectal fat thickness was found to be <12 mm, T3d staged rectal cancer is less likely to be found in an average Chinese population that may affect the overall-survival and progression-free survival in rectal cancer patients. Anterior portion of the rectum was least thick compared to all other sides. Therefore, extra-caution should be taken in handling tumors on the anterior part of the rectum.

Role of Perirectal Fat in the Carcinogenesis and Development of Early-Onset Rectal Cancer

“…It was reported that viscerally obese patients with rectal cancer were more likely to be male [ 37 ], which was consistent with our results. Two other studies measured PFA using pelvic CT/MR images and found that PFA positively correlated with BMI [ 23 , 40 ], which was consistent with our results. Both BMI and VAT were prognostic factors for OS and DFS in CRC patients [ 17 , 41 , 42 ].…”

“…PFA, as the closest part of the VAT surrounding the rectum, was speculated to play an active role in the carcinogenesis and progression of rectal cancer. Tripathi et al reported that the mean PFA in a Chinese Han population, measured using pelvic MR images, was 24:0 ± 6:9 cm [23], which was higher than the mean PFA (20:4 ± 6:9 cm 2 ) in our study. This may have been caused by the difference in the series of MR images selected for measurement; they selected T2weighted images, and we selected the fat series images.…”

“…Perirectal fat, a part of the visceral fat surrounding the rectum within the mesorectal fascia (MRF), is speculated to play a part in the progression of rectal cancer by secreting multiple cytokines and adipokines and having direct contact with the rectum. MRI has been widely used in the preoperative evaluation of rectal cancer [ 23 ]. MRI outweighs CT in measuring perirectal fat, as adipose tissues have a specific signal on MRI compared to the neighboring tissue [ 24 ].…”

Better prognostic determination of cT3 rectal cancer through measurement of distance to mesorectal fascia: A multicenter study

“…One possible reason may be that EMD is limited by the tumor’s location (high or low rectal cancer), actually by the mesorectum thickness. A clinical MRI study of 183 Chinese reported that the mean mesorectum thickness was found to be <12 mm, suggesting that the existing EMD-based T3 substage including 15 mm may not suitable for Chinese population because of relatively thin mesorectum thickness ( 26 ). In this study, 55.6% (160/288) of T3a/b tumors were located at the lower rectum, while only 46.2% (122/264) of T3c/d tumors were located at the lower rectum.…”