Methodological aspects of performing MR-enterography for Crohn's disease: what is important for a diagnostician?

Abstract

The purpose: to determine the influence of various aspects of the MR-enterography technique on the quality of the obtained images.Materials and methods. MR-enterography was performed in 634 patients for verified Crohn's disease and suspected inflammatory and tumor diseases of the small intestine. The following drugs containing polyethylene glycol (PEG) were used as an oral contrast agent in 573 patients, mannitol in 32 patients, pineapple juice in 16 patients, water in 11 patients, milk in 2 patients. Oral administration of 1500 ml of contrast agent was carried out fractional for an hour in 3 stages of 15 minutes with an interval of 10 minutes. Each patient underwent programs: T2-FIESTA mode in three planes, diffusion-weighted images with a slice thickness of 5 mm through 1 mm.Results. There were no significant differences in the severity of filling of the loops of the small and large intestine in patients taking polyethylene glycol (n = 573) and mannitol (n = 32) as an oral agent. Adequate stretching of the loops of the small intestine was achieved in 94% of patients, the expansion of the loops was considered moderate or unsatisfactory in 11 patients (4%), which is associated with poor tolerance of the contrast agent or individual characteristics of peristalsis. After coloprotectomy in 14 patients, the volume of the contrast agent was reduced to 1000 ml and the time of its administration to 30–40 minutes due to the rapid passage. MR-enterography could not be performed in 27 patients due to intolerance to PEG and mannitol drugs, which caused a pronounced gag reflex. In these cases, we resorted to alternative options in the form of water (n = 11) and pineapple juice (n = 16).Conclusions. A qualitative assessment of the condition of the small intestine is possible only with the exact observance of all aspects of the research methodology in the form of: an interval between the last meal and MR-enterography of at least 8 hours, the volume of oral contrast agent (mannitol or PEG) 1200–1500 ml, taken 60 minutes before the study. When performing MR-enterography in patients after coloprotectomy, we recommend reducing the volume of oral contrast agent to 1000 ml and the preparation time for the study to 30–40 minutes.