Abdominal pseudotumors and simulated lymphadenopathy in MRI: differential features with the use of retrograde air insufflation.

In order to evaluate the contribution of retrograde air insufflation in decreasing the occurrence of pseudotumor appearance and mimicked lymphadenopathy due to nonair-distended bowel loops, we retrospectively compared two groups of magnetic resonance (MR) examinations. In the group receiving retrograde air insufflation, 10.8% (67 of 619) of images showed a tumor-like lesion due to nonair-distended bowel loop(s), whereas in the group not receiving air introduction, a tumor-like lesion was simulated in 45.6% (140 of 307) of images. Furthermore, a collapsed bowel loop(s) mimicking an enlarged lymph node close to the aorta, inferior vena cava, or bilateral iliac vessels was found in 9.5% (24 of 252) of images of the latter group, in contrast to only 1.8% (9 of 505) of images of the former group. This study shows that retrograde air insufflation greatly reduces the occurrence of pseudotumor appearance and false impression of paraaortic, paracaval, or parailiac lymphadenopathy secondary to nonair-distended bowel loop(s).