High-resolution MR imaging appearance of colonic tissue in rabbits using an endoluminal coil

This study assessed the value of high-resolution magnetic resonance imaging (MRI) of the distal colon by means of a dedicated endoluminal magnetic resonance receiver coil on a 1.5-T clinical scanner.

To this end, single-loop, receive-only radio-frequency coils, housed in 18 F sheaths, were built. A 1.5-T clinical imager was used. A 18 French diameter internal MRI receiver coil was inserted into the distal colon in 15 New Zealand rabbits to obtain high-resolution magnetic resonance images by using T1-weighted Flash sequences with and without Fat Saturation (FS), T2-weighted True-Fisp, turbo spin-echo, and T1-weighted Flash FS after contrast media injection. Images were compared to histological sections.

An adequate image quality was obtained in all specimens without significant artefacts. Based on histological reports, a five-layer structure of the wall was considered normal. On different MR sequences, only two layers were identified on the images of all rabbits specimens. The nearest layer to the mucosal surface was usually seen as a hyper intense layer and likely corresponds to the mucosa. The highest difference of signal value between internal and external layers was performed on 2D Fat saturation T1 weighted gradient echo. Comparison of mean signal value between the internal and external layers was statistically different in for each sequence used in our protocol (P < 0.05).

Dedicated endoluminal RF coil provides good spatial resolution at the region of interest. On this prospective study of in vivo rabbit, evaluation of colon walls allowed to provide detailed information.