[A Case of Ureteroarterial Fistula Successfully Treated with Endovascular Stent Graft].

We report a case of right uretero-external iliac artery fistula. A 46-year-old woman diagnosed with left ovarian cancer with peritoneal dissemination underwent simple hysterectomy, bilateral adnexal removal, partial omentectomy and appendectomy. Sixteen months after the operation, a computed tomography scan showed right hydronephrosis due to the development of tumor within the pelvis. A ureteral stent was placed into the right ureter in order to preserve renal function. The ureteral stent was replaced at regular intervals. Five months after the ureteral stent placement, the patient was hospitalized urgently with gross hematuria. She was diagnosed with right uretero-external iliac artery fistula based on the angiographic examination that was conducted to detect the source of hemorrhage. She was treated successfully with endovascular stent grafting in the right external iliac artery. She has since shown no episode of hematuria.

Bright pituitary stalk on MR T1-weighted image: damming up phenomenon of the neurosecretory granules.

Characteristic findings of the pituitary stalk on magnetic resonance (MR) imaging, which suggest a damming-up phenomenon of neurosecretory granules, were reported. Neurosecretory granules containing vasopressin influence the signal intensity on MR T1-weighted image (T1WI). The normal posterior lobe of the pituitary gland appears as a bright signal on T1WI. The bright signal of the posterior lobe represents the normal content of neurosecretory granules and disappears in patients with central diabetes insipidus. The normal pituitary stalk appears as a low-intermediate intensity signal on sagittal and coronal T1WIs with 3 mm-slice thickness. The pituitary stalk appeared as a bright signal in 20 patients; 13 with pituitary adenoma, 4 with an intrasellar cystic lesion, one with cavernous sinus mass, and 2 with no abnormal MR findings. The pituitary stalk was not severed in any of the cases. The normal bright signal of the posterior lobe disappeared in 17 patients. No patients suffered from symptoms of central diabetes insipidus when the bright pituitary stalk appeared. It is suggested that the origin of the bright signal in the pituitary stalk is the damming up and accumulation of neurosecretory granules in the nerve fibers of the hypothalamohypophyseal tract obstructed by adenoma, postoperative scarring, cystic mass and so on. Probably, the damming-up phenomenon on MR imaging represents the functional integrity of the hypothalamo-neurohypophyseal system, and should be distinguished from an ectopic posterior lobe formation which is caused by stalk transection.