Helical CT examination of potential kidney donors

Evaluation of renal vascular variations with computed tomography

Background

It is important to know the renal vascular variations before renal surgeries and invasive procedures. The aim of this study is to evaluate the prevalence and types of variation of renal arteries and veins.

Methods

The abdominal CT images of 460 patients, taken between 2019 and 2021, were retrospectively analyzed in axial and coronal planes. The presence and number of accessory renal arteries and early branching in the main renal artery were evaluated. Then, bilateral renal vein variations were investigated. Finally, the compression of the left renal vein by different anatomical structures was evaluated.

Results

Of the 450 patients included in the study, the mean age was 53 years. No variations were detected in 378 renal arteries on the right side (84%) and 392 renal arteries on the left side (87.1%). The most common variation in renal arteries was an accessory inferior hilar artery in 7.5% and 6% rates on the right and left, respectively. An accessory inferior renal polar artery was observed at an overall rate of 1.3%. An accessory superior renal hilar artery was found at 3.3% and 2% rates on the left and the right, respectively. An accessory superior renal polar artery was found at an overall rate of 3.5%. Multiple variations in the renal arteries were observed at a rate of 6.4%. Early branching was observed at a rate of 4.9% on the right and 2.2% on the left. The presence of two and three right renal veins was observed at rates of 13.1% and 0.6%, respectively. Retroaortic and circumaortic left renal veins were found at 3.5% and 4.4% rates, respectively. The compression on the anterior and posterior left renal veins was observed at 4.6% and 0.9% rates, respectively.

Conclusion

Considering that variations in renal arteries and veins are too many and of different types to underestimate, a CT examination for the renal vascular anatomy before and at the planning phase of renal surgery or interventional procedures will be of great benefit to avoid potential complications.

Accessory renal arteries in a Caribbean population: a computed tomography based study

INTRODUCTION

The commonest variation to the classic anatomic description of renal arterial supply is the presence of accessory renal arteries. The incidence varies widely according to ethnicity. There is no data on the prevalence of these anomalies in persons of Caribbean ethnicity.

METHODS

All CT scans done over two years from July 1, 2010 to June 30, 2012 were retrospectively evaluated. The anatomy of the renal arterial supply was reported from these studies and the anatomy of accessory renal arteries was documented.

RESULTS

There were 302 CT scans evaluated and accessory renal arteries were present in 109/302 (36.1%) CT scans, 95% confidence interval 30.6%, 41.4%. There were 71/309 (23.5%) patients with accessory arteries on the left and 54/309 (17.9%) had them on the right (p 0.087). Of these, 16 (14.7%) patients had bilateral accessory renal arteries present. The most common origin for the accessory arteries was the abdominal aorta in 108 (99.1%) cases and in 1 case the accessory artery arose from the coeliac trunk. There were 80 left sided accessory renal arteries: 17 (21.3%) upper polar and 27 (33.8%) lower polar arteries. Of 62 right sided accessory arteries, 14 (22.6%) were upper polar and 26 (42%) were lower polar arteries.

CONCLUSION

This is the first population-based report of anatomic anomalies in renal arterial supply in a Caribbean population. These are important findings that may affect vascular and urologic procedures on persons of Caribbean ethnicity.

Role of multidetector computed tomography for evaluation of living kidney donors

Background

Kidney transplantation from living donors has been increased recently. Preoperative evaluation of living donor is important to select the appropriate kidney for transplantation and to decrease donor surgical complications.

Objectives

The aim of this study was to compare the accuracy of the use of multidetector computed tomography (MDCT) to evaluate vascular anatomy in living kidney donors with traditional angiography.

Patients and Methods

A total number of 60 living kidney donors who underwent open surgical approach for transplantation were selected: Kidney anatomy of donors evaluated by CT angiography (group 1) or traditional angiographic examination (group 2). Renal vessels anatomy was compared with surgical findings in both groups.

Results

The accuracy for detecting number of main renal arteries were not different in both groups which were 96.7% in CT angiography group and 90% in traditional angiography group (P = 0.15). The accuracy for detection of main renal veins were 100% in group 1 and 96.7% in group 2 (P = 0.31).

Conclusions

MDCT has the same accuracy as traditional angiography to detect renal abnormalities in living kidney donors.

Assessment of glomerular filtration rate with dynamic computed tomography in normal Beagle dogs

The objective of our study was to determine individual and global glomerular filtration rates (GFRs) using dynamic renal computed tomography (CT) in Beagle dogs. Twenty-four healthy Beagle dogs were included in the experiment. Anesthesia was induced in all dogs by using propofol and isoflurane prior to CT examination. A single slice of the kidney was sequentially scanned after a bolus intravenous injection of contrast material (iohexol, 1 mL/kg, 300 mgI/mL). Time attenuation curves were created and contrast clearance per unit volume was calculated using a Patlak plot analysis. The CT-GFR was then determined based on the conversion of contrast clearance per unit volume to contrast clearance per body weight. At the renal hilum, CT-GFR values per unit renal volume (mL/min/mL) of the right and left kidneys were 0.69 ± 0.04 and 0.57 ± 0.05, respectively. No significant differences were found between the weight-adjusted CT-GFRs in either kidney at the same renal hilum (p = 0.747). The average global GFR was 4.21 ± 0.25 mL/min/kg and the whole kidney GFR was 33.43 ± 9.20 mL/min. CT-GFR techniques could be a practical way to separately measure GFR in each kidney for clinical and research purposes.

Are multiplanar reconstructions necessary in routine body computed tomography practice?: what is the published evidence?

OBJECTIVE

During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume.

CONCLUSIONS

Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

CT angiography for living kidney donors: accuracy, cause of misinterpretation and prevalence of variation

Objective

To determine the accuracy of the use of multi-detector row CT (MDCT) to predict vascular anatomy in living kidney donors and to reveal the prevalence of vascular variations in a Korean population.

Materials and Methods

A total of 153 living kidney donors that had undergone preoperative CT and nephrectomy, either with open or laparoscopic surgery, were selected retrospectively. The initial CT results were compared with the surgical findings and repeated review sessions of CT scans were performed to determine the causes of mismatches in discordant cases.

Results

The accuracy of CT angiography was 95% to predict the number of renal vessels. Four arteries and two veins were missed during the initial CT interpretation due to perception errors (for two arteries and two veins) and technical limitations (two arteries). The prevalence of multiple renal arteries and veins, early branching of a renal artery and late confluence of a renal vein were 31%, 5%, 12%, 17%, respectively. The circumaortic renal vein and the bilateral inferior vena cava were found in two cases each (1.3%). One case (0.7%) each of a retroaortic renal vein and a supradiaphragmatic originated renal artery were found.

Conclusion

MDCT provides a reliable method to evaluate the vascular anatomy and variations of living kidney donors.

Evaluation of renal arteries in living renal donors: comparison between MDCT angiography and gadolinium-enhanced 3D MR angiography

PURPOSE

The purpose of this study was to clarify and compare the accuracy of contrast-enhanced computed tomography (CT) angiography using multidetector-row helical CT (MDCT angiography) and gadolinium-enhanced MR angiography using three-dimensional Fourier transformation gradient-echo sequence (3D MR angiography) for preoperative evaluation of renal arteries in living renal donors.

MATERIALS AND METHODS

A total of 42 living renal donor candidates underwent both MDCT angiography and 3D MR angiography before digital subtraction angiography (DSA). Each MDCT angiogram and 3D MR angiogram was prospectively interpreted, and the findings were compared with the DSA results.

RESULTS

MDCT angiography identified all of the 12 supernumerary arteries detected by DSA, whereas 3D MR angiography identified only 8. MDCT angiography identified all of the 19 proximal arterial branches detected by DSA, whereas 3D MR angiography identified only 16.

CONCLUSION

A more accurate depiction of renal arteries in living renal donors can be achieved with MDCT angiography than with 3D MR angiography.

Noninvasive method using multidetector CT for calculating the relative blood supply ratio of duplicated renal arteries in renal donors

PURPOSE

The aim of this study was to evaluate the correlation between the renal artery cross-sectional area measured by multidetector computed tomography (MDCT) and the nephrogram area calculated by renal arteriography in potential living renal donors with duplicated renal arteries.

MATERIALS AND METHODS

Medical records of 18 patients with duplicated renal arteries who underwent both MDCT angiography and renal arteriography between 2001 and 2003 were retrospectively reviewed. All 20 kidneys were evaluated. Renal artery cross-sectional areas were measured using the workstation to which the CT data were transferred; the nephrogram areas on the digitized angiographic images were calculated using public domain software. Bland-Altman analysis was performed to compare the cross-sectional area ratio of the accessory arteries to the main renal arteries, with the ratios obtained from the nephrogram areas calculated from the arteriograms.

RESULTS

The mean cross-sectional areas of the accessory and main renal arteries were 6.78 and 20.9 mm2, respectively. The ratio of the nephrogram areas calculated from the arteriograms ranged from 0.094 to 0.809. Bland-Altman analysis showed no significant difference.

CONCLUSION

It is possible to predict the supply volume of accessory renal arteries by measuring the cross-sectional area of the accessory and main renal arteries in potential living renal donors.

MDCT angiography of living laparoscopic renal donors

Laparoscopic donor nephrectomy has become the accepted method of harvesting the kidney at many institutions because of multiple advantages over open donor nephrectomy. Spiral computed tomographic (CT) angiography provides accurate information of renal vascular anatomy and has become an accepted method of preoperative evaluation of potential laparoscopic renal donors. More recently, multidetector CT (MDCT) provides more detailed datasets compared with single-detector spiral CT and has been used for preoperative evaluation of laparoscopic donor nephrectomy to provide accurate anatomic information. MDCT (especially 16- and 64-slice MDCT) angiography has advantages over single-detector helical CT due to rapid scan time that allows coverage of a large volume of interest with higher spatial and temporal resolutions. In this article, we review the current status of MDCT angiography in the evaluation of laparoscopic renal donors and potential advantages of using this technology.

Assessment of 100 Live Potential Renal Donors for Laparoscopic Nephrectomy with Multi–Detector Row Helical CT

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.

Preoperative evaluation of live renal donors using multislice CT angiography

AIM

To determine the accuracy of multidetector row CT renal angiography in the preoperative evaluation of live kidney donors, and to identify potential pitfalls when reporting.

METHODS

Between July 1998 and June 2003, 74 consecutive live renal donors underwent contrast-enhanced multidetector row CT renal angiography before donor nephrectomy. The operative notes and radiological reports of all cases were reviewed retrospectively. Where a significant discrepancy was identified, the archived images were reviewed by two radiologists in the light of the intraoperative findings.

RESULTS

A total of 12 discrepancies were identified in 11 of the 74 cases (15%). In the preoperative CT angiography reports, 4 accessory arteries, 6 early-branching renal arteries, 1 duplicated renal vein and 1 accessory ureter were not identified; 9 of these were evident on review, but were not detected at the time of reporting. In 3 cases (1 accessory artery, the duplicated renal vein and the accessory ureter), the anomaly was not visible on review of the CT angiographic data, even with the benefit of hindsight. Surgical feedback during the study period resulted in modifications to CT technique and improved performance.

CONCLUSION

In the majority of cases, there was good correlation between preoperative CT renal angiography and operative findings. Most discrepancies were due either to an oversight by the reporting radiologist, or failure to fully appreciate the potential surgical significance of certain findings. Regular surgical feedback plays a valuable role in improving reporting accuracy and maintaining imaging standards.

Evaluation of the Renal Venous System on Late Arterial and Venous Phase Images with MDCT Angiography in Potential Living Laparoscopic Renal Donors

OBJECTIVE

The objective of our study was to assess whether both renal arteries and renal veins can be evaluated using single-phase MDCT data sets alone to eliminate the need for both arterial and venous phase data sets.

MATERIALS AND METHODS

One hundred consecutive potential living renal donors who underwent 4-MDCT were evaluated. CT was performed with 120 mL of IV contrast material at an injection rate of 3 mL/sec. Both late arterial and venous phase acquisitions were obtained at 25 and 55 sec from the start of IV contrast injection, respectively. The number of the right and left renal veins and its anatomic variations were assessed by two reviewers. Late arterial phase images were evaluated initially, and then venous phase images were analyzed to assess opacification of the renal vein and to see whether venous phase data sets changed or added information about the venous anatomy as seen on late arterial phase images.

RESULTS

The retroaortic left renal vein was found in two subjects, and the circumaortic left renal vein was detected in three subjects. The renal veins were adequately opacified on late arterial phase images in all subjects. There were six subjects who had a normal left renal vein with a small posterior branch coursing posterior to the aorta and draining into the inferior vena cava, which were difficult to differentiate from the lumbar vein or ascending lumbar vein; in three of these six subjects, the small posterior branch was opacified only on venous phase images.

CONCLUSION

Late arterial phase images obtained at 25 sec after the start of contrast injection can reveal the renal vein anatomy except for a small posterior branch of the left renal vein difficult to differentiate from the lumbar or ascending lumbar vein, as seen in three subjects. The data suggest that venous phase imaging is not necessary for the evaluation of renal vein anatomy.

Kidney transplantation: evaluation of donors and recipients

MR imaging provides a comprehensive method for noninvasive evaluation of renal donor anatomy. Although multidetector helical CT can provide similar information, MR imaging has the advantage of avoiding exposure to ionizing radiation and potentially nephrotoxic contrast material. These are important considerations in screening a generally healthy donor population. MR imaging also can provide complete evaluation of the kidney after transplantation, where avoidance of potentially nephrotoxic agents and preservation of maximal renal function are critical.

Magnetic resonance angiography for preoperative evaluation of potential kidney donors1

BACKGROUND

Careful evaluation of the renovascular anatomy for living kidney donors is essential to optimize donor and recipient outcomes. Arteriography has been the standard for delineating the renovascular anatomy. However, this procedure is invasive. Magnetic resonance angiography (MRA) is an attractive, noninvasive alternative. The aim of this study was to evaluate the accuracy of MRA in potential living kidney donors.

METHODS

A retrospective comparison of the preoperative MRA results with the intraoperative anatomy was performed in 189 living kidney donors.

RESULTS

MRA interpretations correctly identified the vascular anatomy of the donor kidneys in 173 donors (91.5%). In the remaining 16 patients (8.5%), the MRA interpretation was inaccurate. In 10 patients, the MRA reported fewer arteries than the number encountered during the donor operation, whereas in six patients MRA reported more arteries than what found during operation. In seven patients, MRA supplied additional important anatomical information, including kidney size disparity, the presence of nephrolithiasis, the presence of a renal cyst, and renal artery stenosis. All kidneys were successfully transplanted. The misinterpretation of the MRA did not adversely affect the recipient outcome.

CONCLUSION

The noninvasive MRA evaluation of donor renovascular anatomy is an acceptable substitute for traditional angiography.

CT Angiography for Evaluation of Living Renal Donors: Comparison of Four Reconstruction Methods

OBJECTIVE

We sought to compare various reconstruction methods for CT angiographic images in evaluating living renal donors.

MATERIALS AND METHODS

In 76 patients who underwent donor nephrectomy, vascular phase CT data were obtained using an MDCT scanner (detector array, 1.25 mm x 4; beam pitch, 1.5). Two radiologists independently reconstructed CT angiographic images using thick-slab volume rendering, thick-slab maximum intensity projection (MIP), sliding thin-slab volume rendering, and sliding thin-slab MIP. The radiologists counted the number of renal arteries, early branching arteries, and renal veins. We compared the accuracy rates for the detection of vessels achieved with the four types of reconstructed images, using the surgical findings as the gold standard. Agreement between the two observers and between the surgical and CT angiographic findings was evaluated.

RESULTS

The sensitivity for detecting the supernumerary artery was significantly greater with sliding thin-slab volume rendering and sliding thin-slab MIP (97%) than with thick-slab volume rendering (59%) (p = 0.039). No significant difference between the other comparison pairs of reconstruction methods was found. The interobserver agreement for detecting supernumerary and early branching arteries with sliding thin-slab volume rendering and MIP was excellent (kappa = 0.820-0.859) and good for renal veins (kappa = 0.698-0.724), whereas the agreement of thick-slab volume rendering and MIP was good for arteries (kappa = 0.706-0.791) and moderate for veins (kappa = 0.443-0.579). The agreement between CT angiographic reconstructed images and surgical findings for detection of vessels was better with sliding thin-slab volume rendering and MIP (kappa = 0.793-1.000) than in thick-slab volume rendering and MIP (kappa = 0.306-0.613).

CONCLUSION

For CT angiographic evaluation of living renal donors, sliding thin-slab reconstruction is superior to thick-slab reconstruction.

Multispiral computed tomographic angiography of renal arteries of live potential renal donors: a review of 118 cases

OBJECTIVES

Review of the angiographic data of 118 live kidney donors was performed to assess the renal vessel anatomy; compare the findings with the perioperative findings using multislice spiral (MS) computed tomographic angiography (CTA) with the use of 50 mL of intravenous contrast; determine the sensitivity of this technique in the workup of live potential renal donors; and finally to discuss and compare the results of the present study with the reported results using single-slice spiral (SS) CTA, magnetic resonance angiography (MRA), and conventional angiography (CA).

METHODS

Retrospective analysis of the angiographic data of 118 of prospective live kidney donors was performed. All donors underwent renal angiography on MSCTA scanning using 50 mL of intravenous contrast with 1.25-mm slice thickness followed by maximum intensity projection and virtual rendering techniques postprocessing algorithms. Analysis was made on imaging and intraoperatively for the number of renal arteries as well as their bifurcation pattern, location, vessel caliber, length, and venous anatomy, and these were then compared with each other.

RESULTS

MSCTA showed clear delineation of the main renal arteries in all the donors with detailed vessel morphology. The study also revealed a 100% sensitivity in the detection of accessory renal vessels, which had an overall incidence of 26.67%, with the most common distribution in the perihilar region.

CONCLUSIONS

The present study showed a 100% sensitivity and specificity in the visualization and detection of main and accessory renal vessels with the use of only 50 mL of intravenous contrast with similar results seen with CA which has so far been considered the "gold standard." The results on MSCTA were also better than those with the use of SSCTA and MRA in the workup of liver renal donors, with the above technique also proving to be more cost effective. The overall incidence of supernumerary vessels was the same as reported in the literature; however, a higher incidence of single aberrant vessels was seen on the right side, contrary to what has been suggested so far and was attributable to improved detection of accessory vessels less then 2 mm in diameter.

Multi-detector row CT evaluation of living renal donors prior to laparoscopic nephrectomy

Since its introduction in 1995, laparoscopic nephrectomy has become the preferred technique at many medical centers for the harvesting of kidneys from living donors for transplantation. Because the field of view at laparoscopic surgery is limited, preoperative radiologic evaluation of the donor's anatomy---the renal veins and arteries, collecting system, and parenchyma--is critical. Spiral computed tomographic (CT) angiography is a fast, safe, minimally invasive, and generally accepted method for preoperative evaluation of the renal vessels. Multi-detector row CT scanners offer shorter image acquisition time, narrower collimation, better spatial resolution, and less tube heating than do single-detector row CT scanners. Multi-row scanners also provide more complete anatomic coverage, increased contrast enhancement of the arteries, and greater longitudinal spatial resolution--all of which are important both for accurate imaging of the renal vasculature and for three-dimensional postprocessing of image data. Dual-phase multi-detector row CT angiography combined with three-dimensional postprocessing enables minimally invasive and highly accurate depiction of the preoperative donor anatomy. To make the most effective use of this method, radiologists must be familiar with its technical aspects, advantages, and potential pitfalls. They also must be able to identify variations in vasculature and in renal and extrarenal anatomy that are important for laparoscopic donor nephrectomy.

Contrast Enhanced Spiral Computerized Tomography in Live Kidney Donors:: A Single Session for Anatomical and Functional Assessment

PURPOSE

We evaluated contrast enhanced spiral computerized tomography (CT) as a single session for anatomical and functional assessment of potential live kidney donors.

MATERIALS AND METHODS

The study included 80 consecutive kidney donors. In addition to routine donor evaluation, radiological imaging of the kidneys was performed with spiral CT, which was also used for selective determination of the glomerular filtration rate (GFR) of each kidney. All donors underwent 99mTc-mercaptoacetyltriglycine renal scan as a gold standard for GFR determination. Anatomical results of spiral CT were compared to operative findings at donor nephrectomy. Moreover, the results of CT GFR were compared with those of standard 99mTc-mercaptoacetyltriglycine GFR.

RESULTS

Spiral CT detected major renal abnormalities that might be potentially significant for safe renal donation in 4 of the 80 donors (5%). Spiral CT had 100% sensitivity, 85.7% specificity and 97.2% overall accuracy for detecting the number of renal arteries. To identify the number of renal veins spiral CT had 100% sensitivity, 92.3% specificity and 98.6% overall accuracy. A comparison between the isotope GFR of each kidney with the corresponding CT GFR showed a perfect correlation (r = 0.54, p <0.001). For the right and left kidneys mean isotope clearance was not significantly different from that of mean CT clearance.

CONCLUSIONS

Multidetector row spiral CT with contrast medium can provide accurate information regarding the anatomy of the urinary tract and vasculature of the kidney. Moreover, it can detect renal and vascular abnormalities that might be potentially significant for safe renal donation. In addition, it can accurately demonstrate selective GFR of each kidney. Therefore, we recommend spiral CT with contrast material as a single radiological diagnostic modality for the assessment of potential live kidney donors.

Living donor kidneys: usefulness of multi-detector row CT for comprehensive evaluation

PURPOSE

To evaluate in living renal donors the usefulness of multi-detector row computed tomography (CT) in the assessment of renal vasculature and the upper urinary tract.

MATERIALS AND METHODS

Four-channel multi-detector row CT scans were obtained in 77 patients. Vascular phase scans were used for CT angiography; excretory phase scans, for CT urography. At CT angiography, two independent observers evaluated the number of arteries and veins and the presence of early-branching arteries. CT urographic images were evaluated with regard to the opacification of the urinary tract and for abnormalities. Findings of CT angiography and urography were compared with surgical findings. Interobserver agreement between CT angiographic and surgical findings was quantified with weighted kappa statistics. Sensitivity and specificity of CT angiography in identifying supernumerary vessels and early-branching arteries were also evaluated. To evaluate the radiation dose to patients, weighted CT dose index (DI) was assessed for each scan.

RESULTS

Agreement between CT angiographic and surgical findings was excellent for the number of renal arteries (kappa = 0.896) and veins (kappa = 0.843). Detection rate of CT angiography was 98% (89 of 91) for arteries and 98% (83 of 85) for veins. The respective sensitivity and specificity of CT angiography were 86% (12 of 14) and 100% (65 of 65) for supernumerary arteries, 100% (11 of 11) and 100% (66 of 66) for early-branching arteries, and 75% (six of eight) and 100% (69 of 69) for supernumerary veins. At CT urography, collecting systems and proximal ureters were well opacified in all patients; two patients had underrotated kidneys without obstruction. The weighted CT DI was 10.19 mGy for unenhanced and excretory phase scans and 12.88 mGy for the vascular phase scan.

CONCLUSION

Multi-detector row CT can help assess well the renal vasculature and the urinary tract of living renal donors.

Multidetector CT angiography for preoperative evaluation of living laparoscopic kidney donors

OBJECTIVE

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.

SUBJECTS 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%).

CONCLUSION

MDCT angiography is highly accurate for detecting vascular anomalies and providing anatomic information for laparoscopic living donor nephrectomy.

Living renal donors: optimizing the imaging strategy--decision- and cost-effectiveness analysis

PURPOSE

To determine the most cost-effective strategy for preoperative imaging performed in potential living renal donors.

MATERIALS AND METHODS

In a decision-analytic model, the societal cost-effectiveness of digital subtraction angiography (DSA), gadolinium-enhanced magnetic resonance (MR) angiography, contrast material-enhanced spiral computed tomographic (CT) angiography, and combinations of these imaging techniques was evaluated. Outcome measures included lifetime cost, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. A base-case analysis was performed with a 40-year-old female donor and a 40-year-old female recipient.

RESULTS

For the donor, MR angiography (24.05 QALYs and 9,000 dollars) dominated all strategies except for MR angiography with CT angiography, which had an incremental ratio of 245,000 dollars per QALY. For the recipient, DSA and DSA with MR angiography yielded similar results (10.46 QALYs and 179,000 dollars) and dominated all other strategies. When results for donor and recipient were combined, DSA dominated all other strategies (34.51 QALYs and 188,000 dollars). If DSA was associated with a 99% specificity or less for detection of renal disease, MR angiography with CT angiography was superior (34.47 QALYs and 190,000 dollars).

CONCLUSION

For preoperative imaging in a potential renal donor, DSA is the most cost-effective strategy if it has a specificity greater than 99% for detection of renal disease; otherwise, MR angiography with CT angiography is the most cost-effective strategy.

Comprehensive MR imaging in the preoperative evaluation of living donor candidates for laparoscopic nephrectomy: initial experience

PURPOSE

To evaluate the accuracy of magnetic resonance (MR) imaging in the preoperative evaluation of potential living renal donors who are candidates for laparoscopic nephrectomy.

MATERIALS AND METHODS

Twenty-eight donor candidates who underwent subsequent laparoscopic nephrectomy were examined by using a torso phased-array coil at 1.5 T. Gadolinium-enhanced MR angiograms, MR venograms, and MR urograms were obtained in all patients by using an interpolated three-dimensional T1-weighted spoiled gradient-echo sequence (3.4-6.8/1.2-2.3 [repetition time msec/echo time msec], 25 degrees -40 degrees flip angle). Interpretation of the MR images was used to assess the arterial, venous, and ureteral anatomy, as well as parenchymal masses and scarring, and findings were compared with the surgical findings in all patients. Statistical evaluation was performed, with the surgical findings as the reference standard.

RESULTS

At MR imaging, 31 of 32 renal arteries and one of three early-branching arteries were identified correctly. The correct venous anatomy was identified in 23 of 28 patients, including a single left renal vein anterior to the aorta (n = 16), retroaortic left renal vein (n = 2), circumaortic left renal vein (n = 2), and single right renal vein (n = 3). A single collecting system in all harvested kidneys was identified correctly with MR urography. Overall, MR imaging correctly depicted vascular, ureteral, and parenchymal anatomy in 21 of 28 patients. Twenty-seven of 28 patients underwent successful laparoscopic donor nephrectomy on the basis of the MR findings. One procedure was converted to open nephrectomy on the basis of complex venous anatomy not prospectively identified on the MR images. The sensitivity and positive predictive value of MR imaging in correctly determining the combined vascular, ureteral, and parenchymal anatomy in the harvested kidney were 75% (21 of 28) and 95% (21 of 22), respectively.

CONCLUSION

Comprehensive gadolinium-enhanced MR imaging can depict the vascular anatomy, collecting system, and renal parenchyma preoperatively in patients who are candidates for laparoscopic living-donor nephrectomy.

Multiple renal arteries do not pose an impediment to the routine use of laparoscopic donor nephrectomy

Since the first description by Ratner and collegues in 1996, laparoscopic live-donor nephrectomy is gaining wide acceptance in an attempt to minimize the donor morbidity, length of hospital stay and length of time to return to work. It is unknown whether multiple renal arteries pose additional problems with laparoscopic donor nephrectomy. In November 1998, our institution initiated laparoscopic donor nephrectomy program. In the ensuing 19 months, we performed 25 living donor renal transplants, 24 of them using laparoscopic donor nephrectomy. The left kidney was procured in all cases. Eight donor candidates (33%) had two or more renal arteries (two arteries in five patients and three patients).

RESULTS

In six cases (25%), findings at surgery differed from the CT angography results (in four cases, CT angiogram reported fewer arteries than were found at surgery and in two cases it reported more). We found no significant differences in both donor outcomes and recipient, based on the presence or absence of multiple renal arteries. Among donor outcomes, we found equivalent results for donor warm ischemia time total donor operating time, and donor length of stay. For recipient outcomes, we found no significant differences between groups for the incidence of acute tubular necrosis (ATN), graft survival and most recent serum creatinine. In one case, we constructed two arteries into a single conduit on the backtable prior to transplantation. However, in most cases with multiple arteries, we implanted the arteries separately into the recipient external iliac artery. Based on this experience, we do not find the presence of multiple renal arteries to be a barrier to the successful use of kidney grafts procured by laparoscopic donor nephrectomy.

Noninvasive imaging of living related kidney donors: evaluation with CT angiography and gadolinium-enhanced MR angiography

OBJECTIVE

This study was performed to determine whether noninvasive imaging with CT angiography and MR angiography in the preoperative investigation of living, related kidney donors provides sufficient information for the surgeon.

MATERIALS AND METHODS

Eighty consecutive potential living kidney donors were investigated. Fifty patients underwent CT angiography and 30 underwent MR angiography before donor nephrectomy. CT was performed using 3-mm collimation with a pitch of 1.6 after the injection of 150 mL of nonionic contrast medium. The axial data, multiplanar reconstructions, and maximum intensity projections were reviewed. MR angiography was performed on a 1-T magnet using a contrast-enhanced three-dimensional gradient echo technique. Maximum intensity projections and axial reformations were reviewed. Imaging findings were compared with the surgical results in 54 patients.

RESULTS

CT angiography and MR angiography were 100% sensitive in identifying the main renal arteries and renal veins. CT angiography visualized 37 of the 40 arteries identified at surgery, for a detection rate of 93%. MR angiography visualized 18 of the 20 arteries identified at surgery, a detection rate of 90%.

CONCLUSION

CT angiography and MR angiography are suitable for the noninvasive investigation of living kidney donors and provide all the information required by the surgeon. Both methods may miss small accessory renal arteries. MR angiography does not use potentially toxic contrast material or radiation and is the preferred investigation, with CT angiography reserved for patients unable to tolerate MR imaging.

Three-dimensional volume-rendered CT angiography of the renal arteries and veins: normal anatomy, variants, and clinical applications

Three-dimensional volume-rendered computed tomographic (CT) angiography represents an increasingly important clinical tool that, in many institutions, is replacing conventional angiography in the depiction of normal vascular anatomy and the diagnosis of vascular disorders. Evaluation of conditions affecting the renal vasculature constitutes a major focus of volume-rendered CT angiography, which has documented utility for demonstrating both arterial and venous disease. Arterial disorders include renal artery stenosis, renal artery aneurysms, and dissection. Venous disorders include splenorenal shunts, thrombosis, and intravascular tumor extension. In addition, volume-rendered CT angiography accurately displays the normal and variant renal vascular anatomy, which is crucial to detect before surgery, especially partial nephrectomy and laparoscopic nephrectomy. CT angiography is also useful in the evaluation of the renal vasculature following renal transplantation. Familiarity with proper CT protocols and data acquisition techniques are crucial for accurate diagnosis.

Three-dimensional CT of the genitourinary tract

The applications of three-dimensional (3D) CT techniques encompass a spectrum from calculus disease to preoperative planning. With proper selection of display windows and levels, accurate measurement of stone size can be achieved, along with volumetric information. A CT scan with reconstruction may help guide the direction of an endopyelotomy incision away from crossing vessels. The benefits of 3D CT in the evaluation of living renal donors include lower cost and decreased patient morbidity. In renal allograft recipients and other patients, the study may be used to investigate hypertension. Also, 3D CT is invaluable in planning nephron-sparing surgery for renal masses. The ultimate role of this modality rests in the hands of clinicians who can benefit from them and the radiologists who must provide the high-quality images and the interpretive expertise.

Preoperative evaluation of living renal donors: comparison of CT angiography and MR angiography

PURPOSE

To compare computed tomographic (CT) angiography and magnetic resonance (MR) angiography for preoperative evaluation of living renal donors.

MATERIALS AND METHODS

Thirty-five living renal donors underwent preoperative contrast material-enhanced CT angiography and gadolinium-enhanced MR angiography. Each study was interpreted by two independent radiologists blinded to all other studies and to interpretations provided by other reviewers. Eighteen kidneys had surgical correlation.

RESULTS

CT demonstrated 33 supernumerary arteries in 19 patients, bilateral solitary arteries in 16 patients, and 18 proximal arterial branches in 16 patients. MR demonstrated 26 supernumerary arteries in 15 patients, bilateral solitary renal arteries in 20 patients, and 21 proximal arterial branches in 16 patients. Interobserver agreements for MR (kappa = 0. 74) and CT (kappa = 0.73) were similar to the agreement between MR and CT (kappa = 0.74). Among the kidneys chosen for nephrectomy, one small accessory artery and one proximal arterial branch were missed with CT and MR. Two of the accessory arteries suggested at CT were not found at nephrectomy. By averaging data for both modalities, supernumerary arteries were present in 49% of kidney donors and were bilateral in approximately 17%. Proximal arterial branches were present in 46% of kidney donors.

CONCLUSION

Preoperative CT and MR angiography of the renal arteries in renal donors demonstrate substantial agreement. Interobserver disagreement in the interpretation of CT and MR angiograms is related to 1-2-mm-diameter vessels.

Magnetic resonance imaging and magnetic resonance angiography before postchemotherapy retroperitoneal lymph node dissection

OBJECTIVES

Retroperitoneal lymph node dissection (RPLND) after primary chemotherapy is an accepted therapeutic approach for metastatic nonseminomatous germ cell testicular cancer. Because of the intense desmoplastic reaction and adherence to venous and arterial walls, accurate imaging of the retroperitoneal vasculature and its relation to residual tumor is essential. We report our experience with magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA), including the recently developed technique of bolus-contrast MRA, in patients undergoing postchemotherapy RPLND.

METHODS

Eighteen patients underwent MRI of the retroperitoneal region before RPLND. In addition to routine sequences, MRA was performed in 10 patients, including 8 with a three-dimensional technique using bolus intravenous MR contrast. Results were compared with intraoperative and pathologic findings.

RESULTS

MRI and MRA provided detailed information on retroperitoneal vasculature and its relation to tumor, including multiple renal vessels (n = 5), duplex inferior vena cava (n = 1), left retroaortic renal vein (n = 2), and common iliac vein thrombus (n = 1). In all cases, bolus-contrast MRA provided unique information on the location and number of renal and lumbar arteries, in addition to information on the aorta and the mesenteric and iliac vessels. The origin and number of renal arteries were accurately identified in all patients by bolus-contrast MRA; 2 patients had supernumerary renal arteries discovered at RPLND that had not been identified on non-bolus-contrast MRI.

CONCLUSIONS

Bolus-contrast three-dimensional MRA provides unique information on renal and lumbar vessels. The potential benefit of avoiding vascular injury during dissection should be prospectively evaluated.

Helical computerized tomography arteriography for evaluation of live renal donors undergoing laparoscopic nephrectomy

PURPOSE

Traditionally, live renal donors are evaluated with excretory urography and renal arteriography. Helical computerized tomography (CT) arteriography offers a less invasive alternative for demonstrating necessary anatomical information before laparoscopic allograft harvest. We evaluate the accuracy of helical CT arteriography in depicting renal vascular anatomy with an emphasis on the detection of arterial and venous anomalies.

MATERIALS AND METHODS

Imaging studies were done on 175 patients according to a standard CT arteriography protocol with early arterial phase scanning (14 to 20-second delay), and 1 mm. axial and 3-dimensional maximum intensity projection reconstructions. Renal vascular anatomy was mapped with attention to aberrant arterial and venous anatomy. Intraoperative findings were correlated at laparoscopic donor nephrectomy.

RESULTS

There was overall agreement between CT arteriography and laparoscopic findings in 163 cases (93%). Supernumerary renal arteries were identified in 40 cases (23%). Sensitivity, specificity and accuracy of CT arteriography for arterial anatomy were 91, 98 and 96%, respectively. Cases with less than 2 mm. accessory arteries or early branching single vessels simulating dual arteries were misdiagnosed. Venous anomalies occurred in 11 patients (6.3%). Sensitivity, specificity and accuracy of CT arteriography for venous anatomy were 65, 100, and 97%, respectively. Misdiagnoses included early venous bifurcations and supernumerary tributary veins, which were poorly opacified.

CONCLUSIONS

Helical CT is highly accurate and specific for the demonstration of renal arterial anatomy. Poor opacification resulted in a lower sensitivity for venous anatomy. Overall, helical CT provides essential anatomical information, and is an alternative to standard urography and arteriography.

Living donor nephrectomy

The need for more organs for kidney transplantation is increasing. Cadaver sources for these organs are stable, therefore living donation must increase if the need is to be met. Less perfect kidneys are now being transplanted. The pool of potential donors is being expanded. The process of kidney donation is being made easier in an effort to increase the number of donors. The donor work-up is being streamlined. Laparoscopic donor nephrectomy has been introduced, and appears to be promising as a technique of lessening donor pain and suffering, while maintaining excellent graft results.

Computed tomographic angiography in the preoperative evaluation of potential renal transplant donors

The preoperative screening of potential renal transplant donors has undergone a major evolution with the introduction of computed tomographic angiography. With computed tomographic angiography, the radiologist is able to provide the surgeon with precise and valuable preoperative details of renal arterial and venous anatomy. In addition, computed tomographic angiography provides valuable information regarding the renal parenchyma and adjacent organs. This helps reduce the risks and complications associated with transplant surgery and improves the chances of a successful outcome. Helical computed tomographic angiography is rapidly replacing intravenous urography and conventional angiography as the imaging modality of choice for evaluating renal donors.