IMAGING

Multidetector CT angiography for preoperative evaluation of living laparoscopic kidney donors
Kawamoto S (1), Montgomery RA (2), Lawler LP (1), Horton KM (1), Fishman EK (1)
(1) The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Hospital, 601 N. Caroline St., Rm. 3254, Baltimore, MD, (2) Department of Surgery, Johns Hopkins Hospital, 600 N. Wolfe St., Baltimore, Maryland, USA
AJR Am J Roent. 2003; 180: 1633-8

• Purpose: The purpose of this study was to determine the accuracy of multidetector CT (MDCT) angiography as the primary imaging technique in the evaluation of living kidney donors.
• Material and Methods: Seventy-four consecutive living kidney donors (30 men, 44 women; mean age, 41.7 years) who underwent MDCT were evaluated. CT examination was performed with 120 mL of IV contrast material at an injection rate of 3 mL/sec and a pitch of 6. In every case, arterial and venous phase volumetric data sets were acquired at 25 and 55 sec, respectively. Scans were reconstructed at 1-mm intervals for three-dimensional (3D) imaging using a volume-rendering technique. Axial CT images and 3D CT angiography were evaluated prospectively by one reviewer and retrospectively by two reviewers who had no knowledge of surgical results. Surgical correlation for the location of primary and accessory renal arteries, early branching of the renal arteries, and renal vein anomalies was made.
• Results: Seventy-two subjects underwent left nephrectomy, and two subjects underwent right nephrectomy because supernumerary left renal arteries were detected on preoperative CT angiography. Eighteen supernumerary renal arteries (two arteries to 16 kidneys and three arteries to one kidney) to 74 kidneys underwent nephrectomy. CT and surgical findings agreed in 93% of subjects (the average of three reviewers; range, 89–97%). Two small accessory renal arteries were missed by all three reviewers. Those arteries were diminutive and were thought to be insignificant by the surgeons. Early branching of the renal arteries was shown in 14 arteries, and CT and surgical findings agreed in 96% (the average of three reviewers; range, 93–97%). Renal vein anomalies were present in eight subjects, and CT and surgical findings agreed in 99% of the cases (range, 96–100%).
• Conclusions: MDCT angiography is highly accurate for detecting vascular anomalies and providing anatomic information for laparoscopic living donor nephrectomy.
  
• Editorial Comment
  Radiological imaging plays an important role in the evaluation of potential living related kidney donors since anatomical and functional assessment of the donor kidney is mandatory. This is particularly critical when laparoscopic donor nephrectomy is performed. As we know, arterial and venous anomalies are more frequently found in the left kidney. Since this kidney is usually preferred for laparoscopic nephrectomy, the demonstration of arterial or venous anomalies is essential for the success of the surgical procedure. Single-slice helical CT angiography with advanced 3-D techniques provides detailed description of the vascular, parenchymal, and collecting system and is considerately a method with high accuracy for detecting vascular anomalies and provides anatomical information. It may be used as the primary tool for donor evaluation since additional useful information can be obtained: cortical cysts, duplex collecting system, hydronephrosis and renal stone. Recently several reports have shown high accuracy of single-slice CT angiography in demonstrating accessory arteries (78-98%), early arterial branching (89-99%), and renal / perirrenal venous anatomy (90–99%) as pointed out in this manuscript. These rates are not significantly different from those obtained with MDCT, 89–97%, 93–97% and 96–100%, respectively. The use of the recent technology of multi-slice CT known also as multi-detector CT, has several advantages over single-slice technology (better vascular opacification and higher spatial resolution) and few but important drawbacks (higher dose of ionizing radiation and potentially nephrotoxic contrast agents). In order to avoid such problems one might consider using MR angiography, which is also very important method for the preoperative evaluation of living kidney donors. Preoperative CT and MR angiography of the renal arteries in renal donors demonstrate substantial agreement and similar high rates of accuracy. MR angiography has the advantage of avoiding ionizing radiation and potentially nephrotoxic contrast agents.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil