[A comparison of positive and negative enteral contrast media for the magnetic resonance tomography of the abdomen].

Following oral administration of a buffered gadopentetate-dimeglumine solution (Magnevist enteral, 1 mmol/l, 6-17 ml/kg) T1-, proton-density- and T2-weighted spin-echo images of abdominal and retroperitoneal lesions were acquired (0.5 T). Gadopentetate is a signal-enhancing, positive MR contrast agent, intraluminal air served as a model of a signal-free, negative agent. In 21 patients contrast/noise ratios of gadopentetate and air versus lesions and fat were compared quantitatively (t-test). In T1- and T2-weighted images contrast/noise ratios of gadopentetate versus lesions were significantly higher than those of air. In proton-density images there was no significant difference. In T1- and proton-density images contrast/noise ratios of air versus abdominal fat were significantly higher than those of gadopentetate, in T2-weighted images gadopentetate had a significantly higher contrast/noise ratio than air. Signal-enhancing positive contrast agents seem advantageous over signal-free negative enteral MR contrast agents.