Evaluation of MR-angiography for pre-operative assessment of living kidney donors.

INTRODUCTION: Pre-operative magnetic resonance tomography (MR) and MR-angiography (MRA) have rendered favorable results for the assessment of renal anatomy preceding living-related kidney transplantation. However, limited value of MRA in the detection of accessory renal vasculature is reported. METHODS: We compared the results of pre-operative contrast-medium-enhanced MRA of the last 30 consecutively performed nephrectomies in living kidney donors with the intraoperative findings of vascular, parenchymal, and ureteral anatomy. RESULTS: Pre-operative MRA diagnosed a solitary renal artery in 24 cases (80%) and a normal venous, ureteral and parenchymal anatomy in all cases. Intraoperatively, the surgeon confirmed the normal pre-operative MRA findings of ureter and parenchyma. Yet, in 6 out of 30 patients (20%) vascular architecture differed from the pre-operative imaging: four of them, who had a radiologically regular anatomy, were found to have accessory vessels upon surgical preparation. In the fifth patient, MRA revealed an accessory lower polar artery, which was confirmed during surgery. An undiagnosed third arterial vessel, located behind the renal vein, led to an aortic bleeding. In the sixth case, the adrenal gland artery was misinterpreted as an accessory superior polar artery of the kidney in MRA. Additionally, a radiologically undetected inferior polar artery was dissected during nephrectomy and led to partial hypoperfusion of the graft. Subsequent retrospective reevaluation of the MRA by experienced radiologists was unable to identify the intraoperative anatomical discrepancies. Hence, sensitivity of MRA was 60% (6 out of 10 cases) for accessory renal vessel detection and 80% (24 out of 30 cases) for overall sensitivity in determining renal vessel number. DISCUSSION: MRA is a reliable method for the non-invasive investigation of living kidney donors and provides valuable information required by the surgeon. But, as the technique misses small diameter vessels, it cannot be recommended as sole diagnostic tool in unclear cases.

A new abdominal cavity chamber to study the impact of increased intra-abdominal pressure on microcirculation of gut mucosa by using video microscopy in rats.

OBJECTIVE: In experimental studies of capillary blood flow that use intravital video microscopy, organs are exposed in observation chambers implanted into the animal. In this article we describe an abdominal cavity chamber for intravital video microscopy of gut mucosa microcirculation during increased intra-abdominal pressure. DESIGN: Prospective, experimental animal study. SETTING: Research laboratory at a university hospital. SUBJECTS: Male Wistar rats. INTERVENTIONS: The abdominal cavity chamber was designed for implantation into the abdominal wall of rats after laparotomy, thus creating an expanded hermetic, abdominal cavity volume. Animals were assigned to three levels of intra-abdominal pressure: controls (group 1), 10 mm Hg (group 2), and 15 mm Hg (group 3). Intra-abdominal pressure was increased by intra-abdominal insufflation of gas. By using a fluorescent marker, we quantitatively assessed mucosa perfusion index, functional capillary density, red blood cell velocity, capillary diameters, and flow motion during increased intra-abdominal pressure by intravital video microscopy. Results were expressed as mean +/- SEM. Significance of differences was determined by analysis of variance and multiple comparison of means with post hoc test (*p <.05 groups vs. control;p <.05 group 3 vs. group 2). MEASUREMENTS AND MAIN RESULTS: When compared with controls, animals subjected to an intra-abdominal pressure of 10 and 15 mm Hg showed a significant stepwise decrease in mucosa perfusion index (88%, 71%*, 22%*), functional capillary density (665.4 +/- 71.7, 461.6 +/- 71.9*, 375.1 +/- 2.0*cm(-1)), and red blood cell velocity (0.50 +/- 0.04, 0.33 +/- 0.03*, 0.04 +/- 0.06*mm/sec), indicating a stepwise impairment of mucosal microcirculation. Capillary diameters and flow motion did not change with respect to intra-abdominal pressure. CONCLUSIONS: This novel animal model of intravital intestinal video microscopy that uses an abdominal cavity chamber is a feasible and sensitive experimental tool to study intestinal microcirculation during increased intra-abdominal pressure. Intra-abdominal pressure likely results in a severe impairment of mucosal microcirculation.