Quantitative MRI of colonic mural enhancement: segmental differences exist in endoscopically proven normal colon

Abstract

Objectives: Abnormal contrast enhancement on MRI is advocated as a biomarker for inflammation in colitis, although the enhancement kinetics of normal colon are poorly described. Our purpose was to quantitatively assess mural enhancement in normal colon and test for intersegmental differences.

Methods: Eight patients without prior history of inflammatory bowel disease underwent standard MRI colonography followed by normal same-day colonoscopy. Acquired sequences included a volumetric interpolated breath-hold examination (VIBE) to encompass the whole colonic volume, performed at 5°, 10° and 35° flip angles for T(1) quantitation and then at a fixed 35° flip angle three times prior to and every 30 s following intravenous gadoterate meglumine for 220 s. Ascending colon, descending colon and rectal R(1) (1/T(1)) was plotted against time. Mean pre-contrast R(1), initial change of R(1) (ΔR(1)), early and late "plateau phase" enhancement and the area under the R(1)-time (AUC-R(1)) curve were compared between segments using the Student's paired t-test.

Results: There was no significant difference of pre-contrast R(1) between segments (p=0.49 to 0.62). ΔR(1) was higher for ascending colon compared with descending colon (0.0023±0.0012 ms(-1) vs 0.0010±0.0011 ms(-1), p=0.03). There was no significant difference for early or late plateau phase R(1) between colonic segments (p=0.08 to 1.00). AUC-R(1) was greater for ascending than descending colon (0.54±0.19 vs 0.30±0.14, p=0.03).

Conclusions: Intersegmental differences in colonic enhancement are present and should be considered when interpreting differential segmental enhancement.

Figure 1

Region of interest (ROI) placement was performed using OsiriX (www.osirix-viewer.com). (a) Pre-contrast coronal T₁ weighted fat-saturated three-dimensional fast low-angle shot examination image of the ascending colon with a linear mural ROI (length 4.4 cm, signal intensity 109). (b) Matched post-contrast 10, 40, 70, 100, 130, 160, 190 and 220 s (1–8, respectively) images demonstrating the linear ROI on successive acquisitions (length 4.4 cm for each ROI, signal intensity values of 116, 179, 188, 181,192, 151, 156 and 134 for ROIs 1 to 8, respectively).

Figure 2

R₁–time curve for the (a) ascending colon, (b) descending colon and (c) rectum. Error bars represent standard error of the mean. Pre-con., pre-contrast injection.