Purpose: To assess dark lumen MR colonography (MRC), a technique based on a rectal enema with water in combination with the intravenous injection of Gd-DOTA for the detection of polyps in a rodent model.
Methods and Materials: 14 male Wistar rats were subjected to carcinogenic N-methyl-N-nitro-N-nitrosoguanidine (MNNG) at the age of 4 months in order to induce colon neoplasms. MR imaging was performed after a time interval of 1 year. Preparation and data acquisition was performed with the animals under full anesthesia. Following a body-warm saline enema MR imaging was performed on a clinical 1.5-T whole-body MR system using a standard extremity coil. Plain and contrast-enhanced (0.1 mmol/kg; Gd-DOTA; Dotarem, Guerbet, France) 3D T1-w GRE (VIBE) images were acquired. Two radiologists analysed the MR data sets in consensus for lesion depiction. Contrast uptake in colonic wall and polyps was quantitatively assessed by signal-to-noise (SNR), and contrast-to-noise ratio (CNR) measurements. Finally, all animals were euthanized and the imaging results were compared with histology.
Results: By histology, a total of 15 polyps were found in 9 of 14 rats. MRC detected 8/9 polyps resulting in a sensitivity/specifity of 0.89/1.0. Compared to the pre-contrast data, all polyps showed a statistically significant increase in SNR (78.2 ± 6.3 to 167.4 ± 17.7) and CNR (45.4 ± 5.2 to 124.6 ± 11.2), respectively.
Conclusion: Contrast-enhanced MRC based on a dark colonic lumen and a bright, contrast-enhanced colonic wall appears well suited for the detection of colonic polyps. Marked contrast uptake in polyps facilitates their detection. (P.R., J.B., C.L., X.V., C.C. are employees of Guerbet.)
Questions about this event email: firstname.lastname@example.org