DOI: 10.1148/radiol.2373041303
(Radiology 2005;237:973-980.)
© RSNA, 2005
Assessment of 100 Live Potential Renal Donors for Laparoscopic Nephrectomy with Multi–Detector Row Helical CT1
Andrew Holden, MBChB, FRANZCR,
Andrew Smith, MBChB,
Paul Dukes, MBChB, FRANZCR,
Helen Pilmore, MBChB, MD, FRACP and
Motohiko Yasutomi, MD, PhD
1 From the Departments of Radiology (A.H., A.S., P.D.), Renal Medicine (H.P.), and Transplantation Surgery (M.Y.), Auckland City Hospital, Park Rd, Grafton, Auckland, New Zealand. Received August 12, 2004; revision requested October 27; revision received December 14; accepted January 14, 2005.
Address correspondence to A.H. (e-mail: andrewh{at}adhb.govt.nz).
 |
ABSTRACT
|
|---|
PURPOSE: To retrospectively review the authors' experience with multi–detector row helical computed tomography (CT) in assessing 100 consecutive live potential renal donors.
MATERIALS AND METHODS: Hospital ethical committee approval was obtained; informed patient consent was not required. One hundred potential renal donors underwent multi–detector row CT assessment. Nonenhanced, arterial phase, and nephrographic phase examinations were performed. Delayed topograms were acquired to visualize the collecting system anatomy. A vascular radiologist prospectively interpreted the multi–detector row CT images. A second vascular radiologist, blinded to the initial results, retrospectively reviewed the images. Eighty candidates subsequently underwent donor nephrectomy, including 70 laparoscopic donor nephrectomies (LDNs) and 10 open donor nephrectomies (ODNs). Surgical findings served as the reference standard for 80 kidneys. The imaging findings in all 100 candidates (200 kidneys) were reviewed, although these findings were considered observational data only because there was no reference standard for 120 kidneys.
RESULTS: Multi–detector row CT findings predicted uncomplicated LDN in 67 of 70 patients. Small upper-pole capsular arteries arising from the distal main renal artery in two patients were not described in the multi–detector row CT report: In one patient, the arising vessels resulted in conversion to ODN because of bleeding; in the other patient, arterial reconstruction was performed. In another patient, conversion to ODN was necessary because of ongoing bleeding from an avulsed large lumbar venous tributary to the left renal vein. Observational data revealed that multiple renal arteries—most of which were accessory renal arteries—were seen in 52 (26%) kidneys. Early branching of the main renal artery was seen in 24 (12%) kidneys, and main renal arterial abnormalities were identified in six (3%). Capsular arteries were detected in 10 (5%) kidneys. Major variations in the anatomy of the main renal veins—including multiple right renal veins, a retroaortic left renal vein, and a circumaortic left renal vein—were seen in 28 (14%) kidneys. Large (>5 mm in diameter) systemic tributaries to the left renal vein were seen in 25 (25%) kidneys. There was no significant interobserver disagreement between the vascular radiologists.
CONCLUSION: Multi–detector row CT findings can predict successful LDN in live potential renal donors.
© RSNA, 2005
|
INTRODUCTION
|
|---|
Live donor renal grafts survive longer than do cadaveric grafts (1). Laparoscopic donor nephrectomy (LDN) performed in a living person has a number of advantages over open donor nephrectomy (ODN), including reduced postoperative pain, blood loss, narcotic requirements, and hospital stay and a more rapid return to regular activities (2–9). The graft survivals after LDN and ODN have been similar in most studies (6,7).
Traditionally, live potential renal donors have undergone preoperative evaluation with intravenous urography and angiography (10,11). These modalities enable excellent visualization of renal arterial and collecting system anatomic detail but not of the renal venous anatomy. Venous variants and systemic venous tributaries can usually be managed during ODN. However, owing to the limited surgical visibility and surgical exposure during LDN, preoperative visualization of the renal venous anatomy greatly assists the laparoscopic surgeon.
The use of single-section helical computed tomography (CT) in the examination of live potential renal donors has been described by a number of authors (10–16). The purpose of our study was to retrospectively review our experience with multi–detector row CT in the assessment of 100 live potential renal donors.
|
MATERIALS AND METHODS
|
|---|
Renal Donor Candidates
One hundred consecutive live potential renal donors (52 men, 48 women) underwent CT evaluation at Auckland City Hospital between December 2000 and March 2004. A four-channel multi–detector row CT unit (Somatom Volume Zoom; Siemens, Erlangen, Germany) was used to examine the first 75 patients. The remaining 25 patients were imaged with use of a 16-channel multi–detector row CT unit (Somatom Sensation; Siemens). The mean age of the potential donors was 43 years (range, 23–65 years).
Informed patient consent was obtained before the multi–detector row CT examinations were performed; this is a hospital-wide policy for patients who receive iodinated contrast material. The hospital ethical committee approved our retrospective study, for which informed patient consent was not required.
Imaging Examinations
A triple-phase protocol was used. The patients were instructed not to eat or drink anything for 3 hours before the CT examination; no oral contrast material was administered. A 20-gauge venous line was placed, usually in an antecubital fossa vein. The acquisition parameters used to perform the four-channel multi–detector row CT examinations were 4 x 1-mm detector collimation, 120 kVp, 170 effective mAs, and a 0.5-second rotation time. The reconstruction parameters used were a 1.25-mm section width and a 1-mm reconstruction increment. The acquisition parameters used to perform the 16-channel multi–detector row CT examinations were 16 x 0.75-mm detector collimation, 120 kVp, 260 effective mAs, and a 0.5-second rotation time. The reconstruction parameters used were a 1.0-mm section width and a 0.8-mm reconstruction increment.
After an initial topogram was obtained, nonenhanced imaging of the area from the diaphragm to the iliac crests was performed. Arterial phase and nephrographic phase imaging of an area ranging from the celiac artery to the iliac arterial bifurcations (approximately 200 mm) was then performed. The imaging time for these acquisitions varied a little, depending on the scanning range but was on the order of 20 seconds for four-channel multi–detector row CT and 15 seconds for 16-channel multi–detector row CT. In all cases, 120 mL of iodinated contrast material (iopromide, 370 mg of iodine per milliliter [Ultravist 370]; Schering, Berlin, Germany) was injected intravenously at 4 mL/sec. Automated timing (CARE Bolus; Siemens) was used, with the sample volume positioned in the aorta at the level of the celiac artery and an attenuation threshold of 80 HU used for arterial phase imaging. The nephrographic phase commenced 35 seconds after the completion of arterial phase scanning, approximately 75 seconds after the commencement of the contrast material injection. A 5-minute contrast material–enhanced topogram was then obtained to visualize the upper urinary tract collecting system. If the anatomy was not well depicted, the topogram acquisition was repeated with the patient positioned prone.
Image and Surgical Evaluations
The volumetric CT data sets were displayed as 1-mm original transverse images and 3-mm reconstructed transverse images. In addition, volumetric reconstructions were performed at the CT workstation, and all images were downloaded to a picture archiving and communication system (PACS-Impax; Agfa-Gevaert, Morstel, Belgium) for soft-copy review and reporting. Initially, a full range of volumetric reconstructions—including surface rendering, maximum intensity projection (MIP), multiplanar reconstruction, and volume rendering—were performed. However, later in the series, the number of volumetric reconstructions was reduced to an edited three-dimensional MIP reconstruction of the arterial phase and overlapping oblique coronal thin MIP reconstructions of the arterial and nephrographic phases, with the reconstruction plane parallel to the renal hilar vessels. These thin MIP images had a section thickness of 20 mm, were reconstructed at 2-mm overlapping intervals, and were obtained at soft-tissue windows.
All multi–detector row CT images were initially reviewed and interpreted by a vascular radiologist (A.H., with 12 years experience in vascular CT), and the results were presented at a multidisciplinary renal transplant clinicoradiologic meeting. For the purposes of this study, a second vascular radiologist (P.D., with 6 years experience in vascular CT) who was blinded to the initial results retrospectively reviewed the multi–detector row CT images. Both radiologists assessed the renal arterial imaging findings, including multiple equal-sized renal arteries, accessory renal arteries, arterial abnormalities, and aberrant arterial courses. The two radiologists also assessed major variations in the systemic venous anatomy, large (>5 mm in diameter) systemic tributaries to the left renal vein, and extrahilar confluence of the left renal vein. Other findings assessed by both radiologists included the presence of solid or cystic renal masses, renal scarring or calcification, a duplicate collecting system, and/or extrarenal abnormalities. In the retrospective review (conducted by P.D.), the presence of capsular arteries and large lumbar tributaries to the left renal vein also were assessed. These findings were not reported prospectively (by A.H.) early in the series. The radiologists reached a final decision regarding the discrepant findings by consensus.
After discussion among the radiologists, renal transplant physicians, and transplant surgeons, the donor candidates were judged to be suitable for LDN, suitable for ODN, or unsuitable for donor nephrectomy. Exclusion criteria for laparoscopic surgery included the presence of a renal artery abnormality, accessory renal arteries, early main renal artery branching, multiple right renal veins, and/or a duplicate collecting system. Before undergoing multi–detector row CT, the potential donors had been judged by a nephrologist to be medically suitable for nephrectomy and had undergone full hematologic, biochemical, and viral serologic examinations; urinalysis; and psychologic evaluation.
Initially, right LDN was not performed at our hospital, but it was performed subsequently (for the first time in July 2002). In the candidates who underwent nephrectomy, comparisons between the imaging and surgical findings were performed (by A.H. and H.P., with 12 years experience as renal transplant physicians; and M.Y., with 10 years experience as a transplant surgeon). The surgical findings were considered the reference standard.
Statistical Analyses
The level of interobserver disagreement between the two radiologists (A.H., P.D.) was assessed in terms of their reporting of normal anatomic variants and incidental abnormalities. The assessed data included renal arterial, renal venous, renal collecting system, and renal parenchymal imaging findings, as well as extrarenal abnormalities. Differences between the observers' assessments were evaluated by using the McNemar test. This test is appropriate for analyzing paired data—both observers viewed the same data samples—but requires the assumption of independent samples. We believe that this assumption was valid in our study because the assessment of each variant was in no way affected by the other variants in any given patient or kidney.
|
RESULTS
|
|---|
Of the 100 assessed candidates, 70 underwent LDN (49 left kidney, 21 right kidney) and 10 underwent ODN (seven left kidney, three right kidney). In seven candidates, right ODN was performed before the use of right LDN had been established in our transplantation program. ODN was performed in two candidates owing to the donors' renal arterial anatomy and in one candidate because of the donor's body mass index of less than 30. In two patients who were scheduled for LDN, the procedure was converted to ODN. In one of these patients, the nephrectomy was converted to an open procedure to manage bleeding from an upper-pole capsular artery that was injured during laparoscopic access to the renal hilum in a typical anterosuperior laparoscopic approach. This occurred early in the series, and the capsular artery was evident at multi–detector row CT. However, this event was not reported because the capsular branch arose from the distal main renal artery and therefore did not represent an accessory renal artery or an early main renal artery branch. Another similar event occurred early in the series, but LDN was still possible; however, arterial reconstruction of the capsular artery was necessary. After these events, all capsular arteries were described in our radiology reports. The second conversion to ODN occurred owing to bleeding from a large lumbar venous tributary to the left renal vein that was avulsed during graft retrieval.
Of the 100 candidates assessed, 20 did not undergo surgery. Six candidates were judged to be unsuitable for nephrectomy because of their renal anatomy, and seven were judged to be unsuitable because CT depicted renal (renal artery fibromuscular dysplasia, renal artery atherosclerosis, three renal parenchymal scars) and extrarenal (rectal dysplastic adenoma, retroperitoneal mass) abnormalities. Six candidates could not undergo nephrectomy because of a change in the recipient's status (three spontaneous renal recoveries, three general medical deteriorations), and one could not undergo the procedure owing to personal reasons.
Renal Arteries and Veins
The renal arterial imaging findings in all 100 candidates (200 kidneys) are summarized in Table 1. Accessory renal arteries (Fig 1) were seen in the upper and lower poles of the kidney at approximately the same frequency. Capsular arteries were detected in 10 (5%) kidneys; four of these arteries were distal main renal artery branches (Fig 2 ), and two required arterial reconstruction. The remaining vessels appeared as accessory renal arteries (Fig 3) or early arising branches of the main renal artery (Fig 4). Arterial abnormalities were detected in six (3%) kidneys: There were two cases of unilateral fibromuscular dysplasia and four cases of atheroma in the main renal artery. An aberrant course of the main renal artery was seen in three cases: one renal artery arising from the distal abdominal aorta, immediately above the bifurcation; one right renal artery passing anteriorly to the inferior vena cava (Fig 5); and one left renal artery arising above the celiac artery, behind the median arcuate ligament.
View larger version (162K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2a. Left upper-pole capsular artery arising as a distal main renal artery branch. (a) Arterial phase oblique coronal MIP image shows the capsular artery (arrow). (b) Transverse multi–detector row CT image shows the capsular artery (arrow) penetrating the parenchyma directly at the upper renal pole.
|
|
View larger version (135K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2b. Left upper-pole capsular artery arising as a distal main renal artery branch. (a) Arterial phase oblique coronal MIP image shows the capsular artery (arrow). (b) Transverse multi–detector row CT image shows the capsular artery (arrow) penetrating the parenchyma directly at the upper renal pole.
|
|
Major variations in the anatomy of the main renal veins were seen in 28 (14%) kidneys. Multiple right renal veins were seen in 17 candidates (Fig 6), a retroaortic left renal vein was seen in three (Fig 7), and a circumaortic left renal vein was seen in seven. One candidate had a double inferior vena cava. The prevalences of large (>5 mm in diameter) systemic tributaries to the left renal vein are summarized in Table 2. Most of these large tributaries—with the exception of the first lumbar (Fig 8) and adrenal veins—joined the inferior surface of the left renal vein (Fig 9). Extrahilar confluence of the left renal vein was seen in seven candidates (Fig 10).
View larger version (149K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8a. Lumbar venous tributary to the left renal vein. (a) Transverse multi–detector row CT image shows a first lumbar vein (arrow) joining the posterior surface of the left renal vein. This tributary is not well visualized with the laparoscopic approach. (b) Sagittal CT image reconstruction findings confirm the posterior course of the lumbar tributary (arrow).
|
|
View larger version (150K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 8b. Lumbar venous tributary to the left renal vein. (a) Transverse multi–detector row CT image shows a first lumbar vein (arrow) joining the posterior surface of the left renal vein. This tributary is not well visualized with the laparoscopic approach. (b) Sagittal CT image reconstruction findings confirm the posterior course of the lumbar tributary (arrow).
|
|
View larger version (157K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9a. Systemic venous tributaries to the left renal vein during the nephrographic phase, when they are best depicted. (a) Coronal thin MIP arterial phase reconstruction clearly shows the left main renal artery (arrow) owing to the rapid renal circulation time. However, the systemic left renal vein tributaries are not well seen. (b) Coronal thin MIP reconstruction obtained during the nephrographic phase confirms the presence of a 7-mm-diameter gonadal vein joining the left renal vein. Note the extrahilar confluence of the left renal vein branches.
|
|
View larger version (158K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 9b. Systemic venous tributaries to the left renal vein during the nephrographic phase, when they are best depicted. (a) Coronal thin MIP arterial phase reconstruction clearly shows the left main renal artery (arrow) owing to the rapid renal circulation time. However, the systemic left renal vein tributaries are not well seen. (b) Coronal thin MIP reconstruction obtained during the nephrographic phase confirms the presence of a 7-mm-diameter gonadal vein joining the left renal vein. Note the extrahilar confluence of the left renal vein branches.
|
|
View larger version (190K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 10. Coronal thin MIP reconstruction obtained during the nephrographic phase shows extrahilar confluence (arrows) of the left renal vein tributaries, immediately to the left of the aorta.
|
|
Other Findings
A duplicate collecting system was seen in one kidney (Fig 11). Simple renal cysts were seen in 25 (12.5%) kidneys; most of these cysts were smaller than 10 mm in diameter. Renal parenchymal scars were detected in three kidneys. A renal calculus was seen in only one kidney. Renal ectopia was seen in one candidate, who had a ptotic right kidney lying high in the right iliac fossa. Extrarenal abnormalities included simple hepatic cysts in 3% of patients, hepatic cavernous hemangioma in 3%, and cholelithiasis in 5%.
Statistical Parameters
Levels of interobserver agreement are summarized in Table 3. With regard to the 200 kidneys assessed, 1400 possible observations of anatomic variants or incidental abnormalities could be made. These observations included the presence or absence of the anatomic variants described earlier, such as accessory renal arteries, capsular arteries, early main renal artery branching, and/or major venous variants. There were six discrepant observations between the two radiologists, including single discrepant cases of early main renal artery branching, distal main renal artery capsular branching, and multiple right renal veins. There were three discrepant cases of large tributaries to the left renal vein. With the assumption that the variants were independent, there were no significant differences in the proportions of variants observed by the two radiologists (
2 = 0.7, df = 1, P = .40).
In this series, multi–detector row CT enabled the correct prediction of uncomplicated LDN in 67 of 70 cases; hence, we estimated that multi–detector row CT enabled the correct prediction of 96% of the uncomplicated LDN procedures (95% confidence interval: 88%, 99%). After the early experiences of two conversions to ODN, all capsular arteries and large lumbar venous tributaries were described in the CT reports. None of the remaining 58 consecutive LDNs was converted to ODN.
|
DISCUSSION
|
|---|
The limited surgical visibility and surgical exposure during LDN make preoperative demonstration of the renal vascular anatomy important.
CT Technique
Helical CT assessment of live potential renal donors, including nonenhanced and arterial phase examinations, has been described by a number of authors (10–16). Nonenhanced CT is used to localize the kidneys, detect urolithiasis, and obtain baseline measurements of renal mass attenuation. In this series, a renal calculus was seen in only one candidate, but it was evident at arterial and nephrographic phase imaging. No solid renal masses that required attenuation measurements were depicted, so it could be argued that the nonenhanced CT phase was noncontributory in this series of 100 potential renal donors.
Arterial phase CT is used to identify arterial variants such as multiple renal arteries or early arterial branching, as well as arterial abnormalities such as fibromuscular dysplasia and atherosclerosis. The main renal veins are usually well demonstrated during this phase owing to the rapid arteriovenous circulation time (17). Most authors have used a fixed delay from the onset of intravenous contrast material injection to the arterial phase image acquisition (10–13,16), although this delay has varied from 15 seconds (10) to 30 seconds (11,16). The hemodynamic variability of peak contrast enhancement means that the use of this approach will not always facilitate optimized first-pass CT angiography. Use of an automated bolus-timing technique avoids the need for a contrast material test dose while optimizing the data acquisition during the first arterial pass of contrast material.
Although the use of arterial phase CT has been universal, not all authors have included a delayed phase (15,16). The venous phase is said to occur 40–50 seconds after the contrast material injection (10), although the arterial-venous transit time is considerably shorter than this (4–11 seconds) (17). Systemic tributaries to the renal veins often are not well opacified during the venous phase, so we have preferred the more delayed nephrographic phase (10,11,13,14). During the nephrographic phase, the renal cortex and medulla are uniformly enhanced, but contrast material has not yet reached the collecting system. Renal parenchyma (including parenchymal scars), masses (eg, cysts), and systemic venous tributaries are better visualized during the nephrographic phase than during the arterial phase. The contrast material volumes and injection rates reported in the literature vary from 130 mL (14) to 190 mL (10) and from 3 to 5 mL/sec (10,11,13,16), respectively, and the agents are usually injected through an antecubital fossa vein.
Original 1-mm transverse arterial phase CT images are helpful for identifying small (1–3 mm in diameter) accessory renal arteries (18). Among the postprocessing options available, we found two types of MIPs to be most useful. Thick MIP reconstruction of the entire arterial phase data set (with windowing and editing performed to remove bone and mesenteric arterial branches) facilitated excellent demonstration of the arterial anatomy for presurgical planning. In addition, thin MIP reconstructions during the arterial and nephrographic phases yielded a sliding or overlapping appearance because the images were reviewed at a workstation (19). The 20-mm thickness of each thin MIP, as compared with the thicknesses of standard thin-section MIPs or multiplanar images, allowed the considerable lengths of each vessel depicted on each image to be viewed with greater "persistence" of vessel length when the overlapping images were reviewed at a workstation. The nearly isotropic spatial resolution of multi–detector row helical CT meant that the reconstructed thin MIP images often depicted variants such as early arterial branching or systemic venous tributaries better than the original transverse images. The quality of volumetric reconstructions is likely to improve with use of 16-channel multi–detector row CT, although the number of cases in this series was too small for a valid comparison.
Arterial Findings
In this study, all renal arteries that had an aortic ostium separate from the main renal artery were defined as accessory renal arteries. The reported prevalence of accessory renal arteries is 25%–40% (10,13,15,20). Supplementary arteries are defined as arteries that have a separate aortic ostium but pass directly into the renal hilum (10,13). We did not differentiate supplementary accessory arteries from other types of accessory arteries. Although the presence of an accessory renal artery may be considered a contraindication to LDN, kidneys with this variant have been retrieved at ODN (21) and LDN (22), which yielded similar reported warm ischemic times, serum creatinine levels, and 1-year graft survival rates. An increased incidence of posttransplantation hypertension has been described in association with accessory renal arteries (21), probably because of the presence of segmental infarcts. Lower kidney pole accessory renal arteries often provide a substantial blood supply to the renal pelvis and upper ureter (23), and right lower-pole accessory renal arteries may be precaval (24).
Early renal arterial branching (ie, prehilar branching) is defined as a branch arising within 15 mm of the main renal artery ostium (13) and has a reported prevalence of 10% (8,15). This finding has surgical implications because 10–15 mm of an artery's length may be used during arterial ligation and anastomosis with the recipient iliac artery (25–28). Polar arteries are arteries that arise from the main renal artery but do not enter the renal hilum (13). Capsular arteries are arteries that perfuse the renal capsule and may arise from the main renal artery or smaller branches (13). We used the term capsular artery to describe small arteries that pierced the renal capsule directly, above or below the renal hilum. Capsular arteries may appear as accessory renal arteries or early branches of the main renal artery, or they may arise from the distal main renal artery, close to the renal hilum. Left upper-pole capsular arteries may need ligation to allow access to the renal hilum.
The most common arterial abnormality described in the conventional angiographic assessment of potential renal donors is fibromuscular dysplasia, which has a reported prevalence of 4.4% (24). However, most cases of fibromuscular dysplasia are mild (20), and this anomaly may not be detected at CT. Atherosclerosis may be a more prevalent arterial abnormality in older renal donors, as was the case in our series.
Venous Findings
The most common main renal venous anatomic variants are multiple right renal veins, which have a prevalence of 15%–28% (8,10,11,13), and circumaortic left renal veins, which have a prevalence of 8%–17% (2,11,13,25). Multiple right renal veins are a contraindication to donor nephrectomy because this variant is associated with a higher incidence of graft renal venous thrombosis (29). The right LDN procedures performed in kidneys with a single renal vein have evolved such that the lengths of the renal veins retrieved by using either retrocaval (30) or aortocaval (31) exposure have improved and results comparable to those achieved with left LDN (32) are possible. The prevalence of the appearance of a circumaortic left renal vein depends on the size of the retroaortic venous component (16).
Other main renal vein variants include retroaortic left renal vein, which has a prevalence of 3% (11,13), and extrahilar confluence of the renal venous branches. Occasionally, extrahilar confluence occurs immediately lateral to the aorta. In this situation, the smallest vessel can be ligated because renal venous tributaries can be anastomosed at several levels (23) and the ligation of one small vessel results in excellent diversion to other vessels.
Systemic tributaries to the left renal vein include adrenal, gonadal, and lumbar veins (10,11). Gonadal and adrenal veins can be ligated relatively easily during LDN, but it is more important to recognize large lumbar tributaries (usually at the L1 vertebral level) because they cannot be visualized by using an anterior laparoscopic approach and may be avulsed during renal vein mobilization (13,33).
Collecting System Findings
Topograms obtained at delays of 5–10 minutes after contrast material injection have been widely used (11,12,14,15) to visualize the upper urinary tract collecting system. When the collecting system anatomy was not well depicted on the 5-minute topogram, we found that a topogram obtained immediately after contrast material injection with the patient prone showed improved detail. However, repeat topogram acquisition was necessary on only two occasions. In several studies, a plain abdominal radiograph rather than a topogram has been used to visualize the collecting system anatomy (10,13,16). The resultant improved spatial resolution is reportedly more sensitive for the detection of medullary sponge kidney and papillary necrosis (10), both of which are contraindications to donor nephrectomy.
Incidental Findings
The incidental findings commonly described in most series are renal and hepatic cysts, renal angiomyolipoma, and cavernous hemangioma (10,13,15). None of these findings is considered a contraindication to donor nephrectomy. However, CT has the potential to depict important incidental abnormalities in donors that would not be identified with use of the conventional imaging modalities of excretory urography and angiography.
We were pleased that there was close agreement between the independent observers and close concordance between the multi–detector row CT and surgical findings in the 80 kidneys that were resected. A greater than 95% concordance between the CT and surgical findings has been described by other authors who used single-section helical CT (15,18). Small accessory renal arteries and veins, as well as early main renal artery branching, have been overlooked by using single-section helical CT. Similar vascular variants have also been overlooked at multi–detector row CT (34).
In this series, multi–detector row CT enabled the accurate prediction of uncomplicated LDN. However, the two conversions to open procedures emphasize the importance of two anatomic variants that have not, to our knowledge, been discussed in detail in the previous literature: Although an upper-pole capsular artery arising as a branch from the distal main renal artery may not be recognized as an important finding, this vessel may need to be ligated during LDN to gain access to the renal hilum. This vessel may perfuse a substantial area of renal parenchyma and require reconstruction. In addition, a large first lumbar tributary to the left renal vein cannot be easily visualized with an anterior laparoscopic approach and may be avulsed during LDN. Bleeding from this vessel may be difficult to control.
Magnetic resonance (MR) angiography has been shown to have sensitivities similar to those of CT angiography for donor nephrectomy assessment (16); however, there is a lack of published studies in which state-of-the-art MR angiography is compared with multi–detector row CT angiography in this setting. The absence of ionizing radiation and iodinated contrast material makes MR angiography appealing. Imaging assessment of potential renal donors places demands on the spatial and temporal resolution of the imaging modality. It is unclear if modern MR angiographic systems can compete with multi–detector row CT units in terms of these resolution parameters.
A limitation of this study was the lack of a reference standard for many of the imaged kidneys. The multi–detector row CT imaging findings could be confirmed in only the 80 kidneys that were removed at donor nephrectomy, and this limitation prevented us from performing any useful statistical analysis of multi–detector row CT in the remaining 120 kidneys. The prospective finding evaluations were performed by only one vascular radiologist, and the multi–detector row CT equipment used changed from a four-channel unit to a 16-channel unit during the study period.
In conclusion, multi–detector row CT enables highly accurate assessment of the renal anatomy in LDN candidates. Review of the original arterial phase 1-mm transverse CT images facilitates the identification of small accessory renal arteries, and the oblique coronal thin MIP reconstructions obtained during this phase best depict early main renal artery branching. Major variations in the main renal venous anatomy are also well depicted during the arterial phase, but optimal opacification of the large systemic venous tributaries is achieved during the nephrographic phase. It is important to identify these tributaries in the confined laparoscopic field. A thorough understanding of the renal vascular anatomy enables appropriate case selection and optimizes the technical success of donor nephrectomy.
|
ACKNOWLEDGMENTS
|
|---|
The authors acknowledge the contributions made to the Renal Transplant Program at Auckland City Hospital by the following individuals: Alan List, FRANZCR, Ian Dittmer, FRACP, John McCall, FRACS, Stephen Munn, FRACS, John Windsor, FRACS, Richard Harman, FRACS, John Collins, FRACP, Ian Simpson, FRACP, Laurie Williams, FRACP, and Peter Christie, FRACS. The authors also thank Alistair Stewart, of the School of Population Health, University of Auckland, for statistical analysis and support.
|
FOOTNOTES
|
|---|
Abbreviations: LDN = laparoscopic donor nephrectomy • MIP = maximum intensity projection • ODN = open donor nephrectomy
Authors stated no financial relationship to disclose.
Author contributions: Guarantor of integrity of entire study, A.H.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; approval of final version of submitted manuscript, all authors; literature research, A.H., A.S., H.P., M.Y.; clinical studies, all authors; statistical analysis, A.H., A.S., P.D.; and manuscript editing, A.H., A.S., H.P.
|
References
|
|---|
- Nicholson ML, Bradley JA. Renal transplantation from living donors. BMJ 1999;318:409–410.[Free Full Text]
- Ratner LE, Ciseck LJ, Moore RG, et al. Laparoscopic live donor nephrectomy. Transplantation 1995;60(9):1047–1049.[Medline]
- Flowers JL, Jacob S, Cho E, et al. Comparison of open and laparoscopic live donor nephrectomy. Ann Surg 1997;226:483–489.[CrossRef][Medline]
- Odland MD, Ney AL, Jacobs DM, et al. Initial experience with laparoscopic live donor nephrectomy. Surgery 1999;126(4):603–607.[Medline]
- Ratner LE, Montgomery RA, Kavoussi LR. Laparoscopic live donor nephrectomy: the four year Johns Hopkins University experience. Nephrol Dial Transplant 1999;14:2090–2093.[Free Full Text]
- Philosophe B, Kuo PC, Schweitzer EJ, et al. Laparoscopic versus open donor nephrectomy: comparing ureteral complications in the improving laparoscopic technique. Transplantation 1999;68:497–502.[CrossRef][Medline]
- Ratner LE, Kavoussi LR, Sroka M, et al. Laparoscopic assisted live donor nephrectomy: a comparison with the open approach. Transplantation 1997;63:229–233.[CrossRef][Medline]
- Sasaki TM, Finelli F, Burgarin E, et al. Is laparoscopic donor nephrectomy the new criterion standard? Arch Surg 2000;135:943–947.
- Leventhal JR, Deeik RK, Joehl RJ, et al. Laparoscopic live donor nephrectomy: is it safe? Transplantation 2000;70:602–606.
- Rydberg J, Kopecky KK, Tann M, et al. Evaluation of prospective living renal donors for laparoscopic nephrectomy with multisection CT: the marriage of minimally invasive imaging with minimally invasive surgery. RadioGraphics 2001;21(Spec Issue):S223–S236.[Abstract/Free Full Text]
- Smith PA, Ratner LE, Lynch FC, Corl FM, Fishman EK. Role of CT angiography in the preoperative evaluation for laparoscopic nephrectomy. RadioGraphics 1998;18:589–601.[Abstract]
- Dachman AH, Newmark GM, Mitchell MT, Woodle ES. Helical CT examination of potential kidney donors. AJR Am J Roentgenol 1998;171:193–200.[Abstract/Free Full Text]
- Pozniak MA, Balison DJ, Lee FT, Tambeaux RH, Uehling DT, Moon TD. CT angiography of potential renal transplant donors. RadioGraphics 1998;18:565–587.[Abstract]
- Halpern EJ, Mitchell DG, Wechsler RJ, Outwater EK, Moritz MJ, Wilson GA. Preoperative evaluation of living renal donors: comparison of CT angiography and MR angiography. Radiology 2000;216:434–439.[Abstract/Free Full Text]
- Patil UD, Ragavan A, Nadaraj, et al. Helical CT angiography in evaluation of live kidney donors. Nephrol Dial Transplant 2001;16(9):1900–1904.[Abstract/Free Full Text]
- Rankin SC, Jan W, Koffman CG. Non-invasive imaging of living related kidney donors: evaluation with CT angiography and gadolinium-enhanced MR angiography. AJR Am J Roentgenol 2001;177:349–355.[Abstract/Free Full Text]
- Rutland MD. A comprehensive analysis of renal DTPA studies: theory and normal values. Nucl Med Commun 1985;6:11–20.[Medline]
- Platt JF, Ellis JH, Korobkin M, Reige K. Helical CT evaluation of potential kidney donors: findings in 154 subjects. AJR Am J Roentgenol 1997;169:1325–1330.[Abstract/Free Full Text]
- Remy-Jardin M, Bonnel F, Masson P, Remy J. Reconstruction techniques in spiral CT angiography. J Radiol 1999;80(9):988–997.[Medline]
- Neymark E, LaBerge JM, Hirose R, et al. Arteriographic detection of renovascular disease in potential renal donors: incidence and effect on donor surgery. Radiology 2000;214:755–760.[Abstract/Free Full Text]
- Makiyama K, Tanabe K, Ishida H, et al. Successful renovascular reconstruction for renal allografts with multiple renal arteries. Transplantation 2003;75:828–832.[CrossRef][Medline]
- Oh HK, Hawasli A, Cousins G. Management of renal allografts with multiple renal arteries resulting from laparoscopic living donor nephrectomy. Clin Transplant 2003;17(4):353–357.
- Dworkin LD, Brenner BM. The renal circulations. In: Brenner BM, Rector FC, eds. The kidney. 5th ed. Philadelphia, Pa: Saunders, 1996; 247–285.
- Andreoni KA, Weeks SM, Gerber DA, et al. Incidence of donor renal fibromuscular dysplasia: does it justify routine angiography? Transplantation 2002;73(7):1112–1116.[CrossRef][Medline]
- Rubin GD, Alfrey EJ, Dake MD, et al. Spiral CT for the assessment of living renal donors. Radiology 1995;195:457–462.[Abstract/Free Full Text]
- Cochran ST, Krasny RM, Danovitch GM, et al. Helical CT angiography for examination of living donors. AJR Am J Roentgenol 1997;168(6):1569-1730.
- Alfrey EJ, Rubin GD, Kuuo PC, et al. The use of spiral computed tomography in the evaluation of living donors for kidney transplantation. Transplantation 1995;59:643–645.[Medline]
- Platt JF, Ellis JH, Korobkin M, Reige KA, Konak JW, Leichtman AB. Potential renal donors: comparison of conventional imaging with helical CT. Radiology 1996;198:419–423.[Abstract/Free Full Text]
- Mandal AK, Cohen C, Montgomery RA, Kavoussi LR, Ratner LE. Should the indications for laparoscopic live donor nephrectomy of the right kidney be the same as for the open procedure? anomalous left renal vasculature is not a contraindication to laparoscopic left donor nephrectomy. Transplantation 2001;71(5):660–664.[Medline]
- Buell JF, Hanaway MJ, Woodle ES. Maximizing renal artery length in right laparoscopic donor nephrectomy by retrocaval exposure of the aortorenal junction. Transplantation 2003;75:83–85.[CrossRef][Medline]
- Chow GK, Chan DY, Ratner LE, et al. Interaortocaval renal artery dissection for laparoscopic donor nephrectomy. Transplantation 2001;72:1458–1460.[CrossRef][Medline]
- Lind MY, Hazebroek EJ, Hop WC, Weimar W, Jaap BH, Ijzer JN. Right-sided laparoscopic live-donor nephrectomy: is reluctance justified? Transplantation 2002;74(7):1045–1048.[CrossRef][Medline]
- Nicholson ML, Veitch PS. Laparoscopic live-donor nephrectomy. Nephrol Dial Transplant 2000;15:1124–1126.[Free Full Text]
- Kawamoto S, Montgomery RA, Lawler LP, Horton KM, Fishman EK. Multidetector CT angiography for preoperative evaluation of living laparoscopic kidney donors. AJR Am J Roentgenol 2003;180:1633–1638.[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
B YAGCI, B TAVASLI, N KARABULUT, and Y KIROGLU
Clinical significance and renal haemodynamics of incidentally detected retroaortic left renal vein: assessment with venous Doppler sonography
Br. J. Radiol.,
March 1, 2008;
81(963):
187 - 191.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
