Optimization of a contrast medium suitable for conventional enteroclysis, MR enteroclysis, and virtual MR enteroscopy.

Abstract

The purpose of the current study was to optimize a gadolinium-barium sulfate solution suitable for performing conventional and MR enteroclysis examinations in the same session. Eighteen vials of 20% barium sulfate and various gadolinium concentrations (lower 0 ml/lt, higher 45 ml/lt) were prepared and placed in the magnet. The imaging protocol was consisted of the following sequences: true FISP, HASTE with fat saturation and 3d FLASH with fat saturation in various flip angles. Ten patients underwent conventional enteroclysis with 1.2 lt of 20% barium sulfate enema and 18 ml of gadolinium. MR enteroclysis was performed afterwards using true FISP, fat suppressed 3d FLASH and fat suppressed HASTE sequences. The lowest gadolinium concentration in the barium sulfate solution generating low intraluminal signal on HASTE and high intraluminal signal on true FISP and 3d FLASH sequences was 15 ml/lt. The presence of gadolinium did not influence the lumen opacification in conventional enteroclysis examination. In all patients the proposed contrast medium acted as positive in 3d FLASH (T1w), true FISP (T2/T1 w) and as a negative in HASTE (T2w). Bowel wall conspicuity, lumen opacification and distention were ranked as very good to excellent on MR enteroclysis images while artifacts level did not downgraded the overall image quality. High quality virtual MR endoluminal views of the small bowel, based on 3d FLASH images, were obtained in all cases. A 20% barium sulfate enema with 15 ml/lt gadolinium is appropriate for conventional and MR enteroclysis examinations.