Oral contrast makes MR enteroclysis more palatable

Several problems hamper Crohn's disease diagnosis, including the need for repetitive diagnostic assessment and the possibility of incomplete diagnostic information.

Because of the necessity for repeat exams, particularly for pediatric patients, radiologists want to use low or no ionizing radiation and a minimally invasive method to increase patient acceptance.

Dr. Boris C. Bassler and colleagues in the department of diagnostic and interventional radiology at the Klinikum Ludwigshafen, Germany, assessed the use of kaolin, an oral contrast agent, for MR in the diagnosis of chronic inflammatory bowel disease. This method is cost-effective and requires no invasive jejunal tube, Bassler said.

The protocols used in the study were T1-weighted sequences with fat saturation before and after gadolinium enhancement and coronal T2-weighted TSE half-Fourier single-shot sequences.

Three radiologists assessed images from 25 confirmed and 13 suspected Crohn's disease patients for quality and artifacts, intestinal distention and wall differentiation, and diagnostic significance in comparison to endoscopy and histology.

Additionally, as an objective qualitative parameter, they measured the signal-to-noise ratio of the wall and the contrast between the wall and cavity.

The researchers found stable and reproducible image quality without artifacts, good distention of the intestinal loops, and an excellent differentiability between cavity and small bowel wall, Bassler said. MR showed 92% sensitivity in endoscopy and histology.

In another study, Greek researchers experimented with a methylcellulose-barium oral contrast for small bowel MR imaging. They found it to be a feasible imaging technique providing high-quality images in patients with Crohn's disease.

Dr. Nickolas Papanikolaou and colleagues in the departments of radiology and gastroenterology at the University Hospital of Iraklion in Crete, evaluated 12 consecutive patients with suspected or known Crohn's disease. The patients underwent both conventional enteroclysis as the reference standard and MRI.

"MR imaging of the small bowel has attracted much interest in the last couple of years," Papanikolaou said. "The most important aspect to consider when dealing with these diseases is adequate luminal distention."

Sequence protocol included True FISP, HASTE, and postgadolinium 3D FLASH with fat saturation, all applied in the coronal and axial planes. Radiologists evaluated the homogeneity of luminal opacity, bowel distention, and intestinal wall conspicuity.

They found greater than 80% homogeneity of opacification in most cases, and adequate luminal distention occurred in 91.6% of cases. Intestinal wall conspicuity ranked as excellent in 75% of cases.

MR images accurately disclosed all nine involved segments seen on conventional enteroclysis and demonstrated deep ulcers, wall thickening, and luminal narrowing when present. Infiltration of the mesentery was seen in four of nine involved segments.

"This agent can be used when internal intubation cannot be performed," Papanikolaou said.