Oral administration of a low-cost negative contrast agent: a three-year experience in routine practice.

A low cost, well tolerated, and effective gastrointestinal contrast agent is needed for abdominal MRI. The authors tested, in vitro and in routine practice, a mixture of 192 g of barium sulfate (Micropaque HD oral, Guerbet, France) diluted in 500 ml of gastric antacid (Maalox, Rohrer, Fort Washington, PA). Its T1 and T2 relaxation times were 324 and 14 msec, respectively (.2 T). This contrast agent was used in routine practice in 789 patients (.5 T). It had a low signal intensity in 86% and 82% of the cases on T1- and T2-weighted sequences, respectively. No side effect due to magnetic susceptibility was seen, even with gradient-echo sequences. The dilution of barium sulfate in gastric antacid, instead of water, causes a low signal intensity on all sequences for a low barium sulfate concentration (38% w/v). This product is an effective and low cost contrast agent in routine practice.