The MRI of extraadrenal pheochromocytoma in the abdominal cavity.

The purpose of this study was to summarize the MR appearances of extraadrenal pheochromocytoma in the abdominal cavity and evaluate the capabilities of MRI in diagnosis of the tumor. Eleven consecutive patients with an extraadrenal pheochromocytoma in abdominal cavity who underwent preoperative 0.5 T (n=5) or 1.5 T (n=6) superconductor MRI and had a surgical resection were enrolled in the study. The MR scanning protocol included axial T(2)-weighted imaging with or without fat-suppressed sequences, axial and coronal uncontrast and contrast T(1)-weighted sequences with or without fat suppression. The extraadrenal pheochromocytomas were found in retroperitoneum (n=5), the urinary bladder (n=1), the pelvis (n=1), the right prerenal area (n=1), the renal hilus (n=1), the left paramusculus psoas major (n=1) and liver (n=1). The mean maximal diameter of tumors was 55.9 mm (range 17.8-162.2 mm). The high signal intensity was seen on T(2)-weighted imaging in all tumors compared to muscle or liver, especially with fat suppression. The intratumoral septa and capsules were shown in 63.6% and 72.7% of cases, respectively, which had low signal intensity on T(2)-weighted imaging. These relative characteristics may be helpful for qualitative diagnosis of extraadrenal pheochromocytomas with MRI. Other usefulness of MRI was to locate the position, to decide the range of tumors and to show well the relationship between the tumor and near structures.