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

Anatomical Variants of the Renal Veins and Their Relationship with Morphofunctional Alterations of the Kidney: A Systematic Review and Meta-Analysis of Prevalence

Background: Variations in renal veins are quite common, and most people do not experience issues due to them. However, these variations are important for healthcare professionals, especially in surgical procedures and imaging studies, as precise knowledge of vascular anatomy is essential to avoid complications during medical interventions. The purpose of this study was to expose the frequency of anatomical variations in the renal vein (RV) and detail their relationship with the retroperitoneal and renal regions. Methods: A systematic search was conducted in the Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS databases from their inception until January 2024. Two authors independently carried out the search, study selection, and data extraction and assessed methodological quality using a quality assurance tool for anatomical studies (AQUA). Ultimately, consolidated prevalence was estimated using a random effects model. Results: In total, 91 studies meeting the eligibility criteria were identified. This study included 91 investigations with a total of 46,664 subjects; the meta-analysis encompassed 64 studies. The overall prevalence of multiple renal veins was 5%, with a confidence interval (CI) of 4% to 5%. The prevalence of the renal vein trajectory was 5%, with a CI of 4% to 5%. The prevalence of renal vein branching was 3%, with a CI of 0% to 6%. Lastly, the prevalence of unusual renal vein origin was 2%, with a CI of 1% to 4%. Conclusions: The analysis of these variants is crucial for both surgical clinical management and the treatment of patients with renal transplant and hemodialysis.

Renal venous density in the arterial phase of contrast-enhanced CT predicts prognosis in septic shock

OBJECTIVE

To evaluate a series of vascular parameters derived from abdominal dual-phase contrast-enhanced CT as predictors of 14-day mortality and AKI within 7 days in septic shock.

METHODS

144 patients with septic shock and 60 negative cases were included. The vascular parameters from CT were measured and calculated, including aortic density in arterial (Dena-A) and venous phase (Dena-V), renal vein density in arterial (Denrv-A) and venous phase (Denrv-V), and renal vein-to-aortic density ratio in arterial (DenRrv/a-A) and venous phase (DenRrv/a-V). The parameters were compared between patients and controls, and between patients with different clinical outcomes, and assessed for predictive value of 14-day mortality and AKI within 7 days.

RESULTS

Patients with septic shock presented significantly lower Denrv-A (p < 0.001) and DenRrv/a-A (p = 0.002) levels than the controls. In the septic shock group, patients who died had significantly lower Denrv-A (p = 0.001) and lower DenRrv/a-A (p < 0.001) than those who survived. Patients who developed AKI had significantly lower Denrv-A (p < 0.001) and DenRrv/a-A (p = 0.011) than those who did not. Multivariate analysis suggested DenRrv/a-A as an independent predictor of 14-day mortality (OR 0.012; 95% confidence interval [CI]:0.002,0.086; p < 0.001) and Denrv-A as an independent predictor of AKI (OR 0.989;95% CI:0.982,0.997; p = 0.006).

CONCLUSION

In septic shock, significant decreases in Denrv-A and DenRrv/a-A were associated with the onset of AKI and predicted higher 14-day mortality.

ADVANCES IN KNOWLEDGE

The renal vein density and renal vein-aortic density ratio in arterial phase of dual-phase contrast-enhanced CT may serve as good predictors of AKI and mortality in septic shock.

Anatomical variants of renal veins: A meta-analysis of prevalence

The main aim of this article is to establish the actual prevalence of renal vein variations (circumaortic renal vein, retroaortic renal vein, double renal vein), and to increase awareness about them. To this purpose, we have performed a meta-analysis of prevalence, using the MetaXL package, We included 105 articles in the final analysis of prevalence, of which 88 contained data about retroaortic renal vein, 84 - about circumaortic renal vein, and 51 - about multiple renal veins. The overall prevalence for retroaortic renal vein was 3% (CI:2.4-3.6%), for circumaortic renal vein - 3.5% (CI:2.8-4.4%), and for multiple renal veins - 16.7% (14.3-19.2%), much higher on the right 16.6 (14.2-19.1%) than on the left side 2.1 (1.3-3.2%). The results were relatively homogenous between studies, with only a minor publication bias overall.

A Case Study of Malrotated Kidneys with Asymmetric Multiple Renal Arteries, Variant Venous Drainage, and Unilateral Ureteral Duplication

Variations in the arterial, venous, and ureteral patterning of the right (r) and left (l) kidneys are common; however, concomitant involvement with all three systems is rare. Specimens that demonstrate anatomic variation across multiple systems provide an opportunity to illustrate links between anatomic concepts, embryologic development, clinical practice, and education. During anatomic study of the abdominal cavity, a total of five major arteries (3l and 2r) emerged from the aortic and common iliac axes in a cadaveric donor. Through continued study, multiple contributing veins, of different caliber, coalesced into four major renal veins (2l and 2r) that returned blood from the kidneys to the inferior vena cava (IVC) at different locations. In addition, unilateral duplication of the kidney with concomitant ureters was evident on the right side. Both ureters continued inferiorly and independently entered the bladder, each with an observable orifice adjacent to the bladder trigone. Most evident in the specimen was the anteriorly directed hilum for both kidneys. Reported measures for each of the observed anatomic variations suggest that the current specimen has an estimated incidence of less than 0.3%. This comparatively rare specimen provides an example of important anatomic concepts that are relevant to educational and clinical practices.

Evaluation of Vascular Structures of Living Donor Kidneys by Multislice Computed Tomography Angiography before Transplant Surgery: Is Arterial Phase Sufficient for Determination of Both Arteries and Veins?

Objectives

The aim of our study was to determine the efficacy of preoperative early arterial Computed tomography angiography (CTA) in donor nephrectomy, to assess the renal arterial and venous structures of donor kidneys.

Materials and Methods

Seventy living donor candidates were included to this study, who had CTA for the assessment of their renal vessels in our hospital between January 2011 and January 2015. Only early arterial phase images were obtained to avoid exposing the patients from high dose of radiation. Scans were reported by two radiologists independently. The number of renal arteries, veins and their tributaries were documented. The donor kidneys were removed by two consultant surgeons, and after back-table perfusion the same details were recorded and taken as the reference findings for the operation side.

Results

A total of 70 potential live kidney donors underwent renal CTA, among them fifty five patients had donor nephrectomy. A total of 140 kidneys were evaluated by CTA and the vessels of 55 harvested kidneys were compared with CTA findings. There were 40 kidneys that had at least one accessory or polar artery. There were 5 early branching renal arteries, two retroaortic and two circumaortic renal veins. Three kidneys had multiple renal veins. Operation findings were totally consistent with CTA findings in patients who underwent donor nephrectomy.

Conclusion

Arterial phase CTA is sufficient for evaluation of both arterial and venous vessels of kidneys, and precontrast, venous or late phase imaging should be preserved only for chosen circumstances to avoid high radiation exposure.

The use of multi detector computed tomography in assessing the retroaortic left renal vein and accompanying vessel anomalies

OBJECTIVE

Because renal venous variations possess potential hazards during abdominal aortic surgery or laparoscopic donor nephrectomy, the detailed preoperative evaluation of the renal vessels with angiography should be performed to avoid vascular injuries. We present multidetector row computed tomography (MDCT) findings of the retroaortic left renal vein (RLRV) with other vascular variations.

MATERIALS AND METHODS

Twenty-two patients with RLRV were evaluated with MDCT using multiplanar images, MIP images, and 3D volume rendering.

RESULTS

The RLRVs with accessory renal vessels and other variant veins draining into the left renal vein were effectively evaluated in all patients.

CONCLUSIONS

MDCT angiography is an effective technique for evaluating abdominal vessels, and it presents adequate images of renal vessels and vascular variations, which pose importance before abdominal surgery.

Experiences with the use of iteratively reconstructed dose-modified MDCT angiography examinations of living renal donors

PURPOSE

To evaluate the performance of iteratively reconstructed (IR) dose-modified (DM) multidetector computed tomography (MDCT) angiography (CTA) examinations of renal donors in comparison to standard dose filtered back projection (FBP) images.

MATERIALS AND METHODS

Eighty-five potential donors who underwent dual-phase CTA on 16-/64-MDCT scanners were retrospectively reviewed. Images from a 16-MDCT scanner were reconstructed with filtered back projection (group A, 47) and examinations from 64-MDCT with IR (group B, 38). Scan parameters were constant for both groups except for higher noise index (× 1.3) in group B. Images were interpreted for the relevant anatomy and IQ by 2 readers. Surgical report served as reference standard for operated kidneys, whereas for nonoperated kidneys, interobserver agreement was evaluated.

RESULTS

Radiation dose was 36% lower in group B compared to group A. All CTA examinations were rated for diagnostic quality with comparable IQ scores. In 48 operated kidneys, 10 surgically confirmed vascular anomalies were correctly identified by both readers. In the remaining 122 nonoperated kidneys, there was an excellent interobserver agreement.

CONCLUSIONS

Iteratively reconstructed technique preserves high image quality and diagnostic performance at significantly lower radiation doses in DM kidney donor CTA examinations.

Diagnostic accuracy of 64-MDCT angiography in the preoperative evaluation of renal vessels and compared with laparotomy findings in living donor kidney

INTRODUCTION

Multidetector-row computed tomography (MDCT) angiography is a reliable technique in preoperative renal anatomy evaluation in live renal donors.

OBJECTIVES

To investigate the accuracy of early arterial phase findings and compares them with intraoperative findings.

METHODS

In this prospective study, 100 potential live donors undergoing preoperative MDCT and nephrectomy during 2010-2013 were included. The examination was performed with a 64-detector scanner including early arterial and venous phase. MDCT angiography started by bolus tracking and venous phase was acquired 9 s after arterial phase. Anatomical findings and vein and artery attenuation values were recorded and arterial phase findings were compared with intraoperative findings.

RESULTS

All anatomical findings reported by MDCT in early arterial phase were confirmed by intraoperative findings with sensitivity of 100%. Right renal vein was supernumerary in 17 cases and left renal vein was circumaortic in 3 and retroaortic in 5 cases. Renal arteries had early branching in 13, two arteries in 12 and accessory in 8 cases. Vein and artery attenuation values had significant difference between early arterial and venous phase (p < 0.001).

CONCLUSION

Early arterial phase has similar results to venous phase in preoperative evaluation and intraoperative findings and could be used alone to reduce radiation dose.

Low-radiation-dose dual-phase MDCT protocol with split contrast media dose and time optimization: protocol design for renal donors evaluation

BACKGROUND

A routine, multiphase, computed tomography (CT) protocol is associated with high radiation exposure to potential kidney donors. To reduce radiation exposure, several authors have suggested a reduction in the number of phases.

PURPOSE

To evaluate a low-radiation-dose, dual-phase protocol (i.e. a protocol with an unenhanced phase and combined vascular and excretory phase) for the preoperative evaluation of potential renal donors.

MATERIAL AND METHODS

Sixty-five potential renal donors were divided into two groups. The first group was scanned with a routine quadric-phase protocol (non-contrast, arterial, venous, and delayed), and the second group was scanned with a triple-phase protocol (dual phase protocol + venous phase). In the second group, we replaced CT angiography with a routine abdominal CT technique. In addition to the evaluation of renal arteries, veins, and excretory systems, the radiation dose of the suggested protocol was compared to that of the routine quadric-phase protocol.

RESULTS

The suggested protocol was efficient in the evaluation of renal arteries, veins, and excretory systems in all studied potential renal donors. Renal arteries were well visualized in the combined vascular excretory phase using the routine abdominal CT technique; no significant difference was noted when these results were compared to those obtained from the CT angiography used in the quadric-phase protocol. The mean effective radiation dose of our suggested dual-phase protocol was only 34% of the dose resulting from the routine quadric-phase protocol.

CONCLUSION

Use of a low-radiation, dual-phase, CT protocol, which relied on both an unenhanced phase and a combined vascular and excretory phase, significantly reduced radiation dose. Furthermore, the proposed protocol provides adequate visualization of renal arteries and veins, and affords sufficient opacification of the urinary tract using improved acquisition triggering.

[Pre-kidney-transplant evaluation of donors and recipients]

The pretransplant imaging evaluation of recipients is mainly achieved with CT and has two objectives: detection of iliac artery calcifications that may have an impact on the site of the transplant and the type of arterial anastomosis; detection of a primary malignancy that would be a contraindication to transplantation. The pretransplant imaging evaluation of living donors relies on noninvasive techniques. CT angiography and MR angiography both allow the simultaneous evaluation of arteries, excretory tract and renal parenchyma. The goal is to achieve anatomical and functional renal evaluation in order to select the best donor and plan the surgical procedure.

Role of multidetector-row computed tomography in evaluation of living renal donors

OBJECTIVES

To assess the value of multidetector-row computed tomography (MDCT) in evaluation of the anatomy of living kidney donors and to reveal the prevalence of renal vascular variations in a Chinese population.

PATIENTS AND METHODS

One hundred four potential donors underwent MDCT, and the data sets were postprocessed for reformatted images using maximum intensity projection, a volume-rendering technique, and multiplanar re-formation. Nephrectomy was performed in 97 donors, which enabled correlation of MDCT evaluation with the actual anatomy at surgery as the standard of reference.

RESULTS

The MDCT images accurately demonstrated the anatomical structure of the main renal arteries and veins and the upper part of the ureters. The prevalence of accessory arteries was 41.7% (43 of 103), and of early branching was 12.6% (13 of 103). Compared with findings during surgery, the detection rate of accessory arteries on MDCT images was 91.3% (21 of 23), of larger accessory arteries (>1.5 mm in diameter) was 100%, and of early branching was 100%.

CONCLUSION

Multidetector-row computed tomography is helpful in accurately evaluating the renal anatomy of potential donors, thus facilitating planning of surgery.

Multidetector computed tomography with triple-bolus contrast medium administration protocol for preoperative anatomical and functional assessment of potential living renal donors

OBJECTIVE

To evaluate multidetector computed tomography (MDCT) with a triple-bolus contrast administration protocol for preoperative anatomical and functional assessment of living renal donors.

METHODS

Fifty-five potential living renal donors underwent MDCT of which 27 proceeded to donor nephrectomy. A triple-bolus contrast administration protocol was used for simultaneous acquisition of arterial, nephrographic, and excretory phases. MDCT images were independently reviewed in random order by two radiologists blinded to surgical anatomy findings. Diagnostic accuracy for anatomical variants was quantified by sensitivity and specificity. Differential renal function (DRF) was derived from MDCT for 54 patients and compared with technetium-99 m dimercaptosuccinic acid renography (Tc-99 m DMSA).

RESULTS

All triple-bolus MDCT examinations were technically adequate. Accessory renal arteries and veins were identified at surgery in 33% (n = 9/27) and 22% (n = 6/27) of donor kidneys. The mean difference between MDCT-derived DRF and DMSA was 0.8% (95% CI 0.1-1.6) with 95% limits of agreement of -4.6% (95% CI -3.3 to -5.9) to 6.3% (95% CI 5.0-7.6). MDCT delivered a mean (SD, range) radiation dose of 9.5 (3.6, 3.6-17.3) mSv.

CONCLUSION

MDCT with a triple-bolus contrast administration provides accurate anatomical and functional evaluation of living renal donors.

The utility of 64 channel multidetector CT angiography for evaluating the renal vascular anatomy and possible variations: a pictorial essay

The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

Single-phase 16-slice multidetector computed tomographic angiography in the evaluation of the venous system in potential laparoscopic renal donors

OBJECTIVE

Our objective was to assess the efficacy of single-arterial-phase, 16-slice multidetector computed tomographic (16-MDCT) angiography in the evaluation of both the renal arterial and venous systems in prospective renal donors with surgical (laparoscopic) correlation.

METHODS

Fifty-one consecutive renal donors (age range, 20-62 years; 12 men and 39 women) underwent 16-MDCT angiography followed by laparoscopic donor nephrectomy. Approval from institutional review board was obtained with waiver of consent. The arterial-phase image data set was reviewed independently by 2 abdominal radiologists for the number of renal arteries and veins, anomalies, and degree of opacification of the renal veins. Computed tomographic angiography results were compared with the surgical findings. Interobserver agreement was assessed using kappa statistics.

RESULTS

The sensitivity, specificity, and accuracy for identifying the number of renal veins in the arterial phase on 16-MDCT angiography were 96.3%, 96.07%, and 96.2% for reviewer 1 and 94.44%, 94.11%, and 94.3% for reviewer 2, respectively. Both reviewers correctly identified all venous anomalies and had substantial interobserver agreement (kappa coefficient = 0.68).

CONCLUSIONS

A single-arterial-phase image data set is sufficient for evaluation of both the renal arterial and venous anatomy in potential renal donors before laparoscopic nephrectomy. Venous-phase acquisition is not necessary, thereby substantially reducing the radiation burden on the donor.

Vascular renal anatomy and the ureteropelvic junction: preoperative multidetector CT scanning with split-bolus injection as a predictor of laparoscopic findings

PURPOSE

To compare multidetector CT scan (MDCT) results with intraoperative findings in the detection of an inferior-pole pedicle crossing the ureteropelvic junction.

PATIENTS AND METHODS

Over the 2-year study period, 35 patients receiving laparoscopic pyeloplasty underwent preoperative investigation with a novel MDCT protocol in order to detect crossing vessels. Postprocessing, including maximum intensity projection, volume-rendering technique, and multiplanar reconstruction, was used in addition to standard axial views.

RESULTS

All the arteries found during laparoscopic surgery were detected by MDCT, but one radiologic false-positive was noted at the beginning of the series. Seven veins were not detected with MDCT. In the only case featuring an isolated inferior-pole vein, the aberrant vessel was identified by MDCT.

CONCLUSION

Multidetector CT scanning is a highly accurate way of providing all the information necessary preoperatively concerning renal parenchymal anomalies, urinary stones, and collecting system and vessel anatomy. It helps physicians make appropriate therapeutic decisions and gives surgeons information about what they can expect during laparoscopic procedures.

Imaging of the renal donor and transplant recipient

Renal transplant remains the mainstay of the treatment of end-stage renal disease. With improvement in management strategies and the diverse imaging options, the yearly survival of recipients with functional kidneys has improved significantly. This improved survival is attributed to factors such as immunosuppressive therapy planning in recipients, human leukocyte antigen matching, surgeon experience, and recipient's age. Transplantation offers the closest thing to a normal state if the transplanted kidney can replace the failed kidneys. Living-donor kidney transplants are playing a vital role in bridging the gap between decreased supply of, and increased demand for, kidneys for transplant. Early detection and characterization of complications in the recipient are of immense clinical relevance, allowing timely intervention to prevent graft failure.

Preoperative assessment of thymic veins on multidetector row CT: optimization of contrast material volume

PURPOSE

Preoperative localization of the thymic veins is considered important to prevent intraoperative severe bleeding prior to video-assisted thoracoscopic thymectomy. The purpose of this study was to determine the optimal dose of contrast material for preoperative CT imaging for the detection of thymic veins on the basis of patient weight.

MATERIALS AND METHODS

The records of 31 patients who underwent thymectomy were examined retrospectively. All patients were scanned using an eight-channel multidetector-row computed tomography (CT) scanner at 1.25 mm collimation and a 0.625-mm reconstruction interval. CT scans were obtained after injection of 300 mg I/ml nonionic contrast material at a rate of 2 ml/s. A 90-ml contrast bolus was used for the first 16 consecutive patients (group I), and a 150-ml bolus was used for the following 15 patients (group II). The scan delay was 60 s and 90 s in groups I and II respectively. Two independent radiologists who were blinded to the surgical results evaluated the number of thymic veins observed on preoperative CT, which was later correlated with the actual number of thymic veins clipped during surgery. The responses were analyzed with respect to contrast amount by single bolus and per kilogram of body weight.

RESULTS

Thymic veins were correctly detected in 9 of 16 (56%) patients in group I and 14 of 15 (93%) patients in group II. Thymic vein detection was significantly better in patients who received the >or=2.0 ml/kg contrast medium compared to those who received the 1.00-1.99 ml/kg medium (P < 0.05).

CONCLUSION

An intravenous contrast material volume of 2 ml/kg (300 mg I/ml) is appropriate for the identification of thymic veins on prethymectomy CT.

Surgically Relevant Normal and Variant Renal Parenchymal and Vascular Anatomy in Preoperative 16-MDCT Evaluation of Potential Laparoscopic Renal Donors

OBJECTIVE

Using 16-MDCT, we describe and quantify the frequency and types of renal anatomic variants and findings relevant for preoperative evaluation and surgical planning for potential laparoscopic renal donors.

MATERIALS AND METHODS

On 16-MDCT, 126 consecutive potential donors underwent scanning before contrast administration and after i.v. power injection of nonionic contrast material during the arterial, nephrographic, and excretory phases. On a 3D workstation, CT images were evaluated retrospectively in consensus by three abdominal imagers. The number and branching pattern of bilateral renal arteries and veins, including anomalies of the inferior vena cava and lumbar-gonadal axis, were categorized along with the frequency of incidental findings of the renal parenchyma and collecting system.

RESULTS

Major arterial variants including supernumerary and early branching arteries were present in 16% and 21%, respectively, of left kidneys and 22% and 15%, respectively, of right kidneys. Major and minor venous variants were detected in 11% and 58% of left kidneys and 24% and 3% of right kidneys. Late confluence of the venous trunk was identified in 17% of left kidneys and 10% of right kidneys. Incidental parenchymal and urothelial abnormalities, most commonly cysts and calyceal calcifications, were identified in 30% of the kidneys. Other relevant incidental findings included focal infarcts, cortical scars, atrophic scarred kidney, and bilateral papillary necrosis. Urothelial variants included bilateral simple ureteroceles and rightsided complete duplicated collecting system.

CONCLUSION

16-MDCT angiography and urography allow confident detection and classification of a variety of anatomic and incidental anomalies relevant to the preoperative selection of potential laparoscopic renal donors and to surgical planning.

Multidetector Computerized Tomography Angiography to Predict Lumbar Venous Anatomy Before Donor Nephrectomy

PURPOSE

Multidetector computerized tomography angiography has been used to predict renal anatomy before donor nephrectomy. Unrecognized lumbar veins represent a significant risk during laparoscopic surgery but to our knowledge no previous group has attempted to predict lumbar veins with multidetector computerized tomography angiography before laparoscopic donor nephrectomy. We evaluated the ability of multidetector computerized tomography angiography to preoperatively predict the size and location of anomalous left lumbar veins.

MATERIALS AND METHODS

A prospective study was performed in patients undergoing left hand assisted laparoscopic donor nephrectomy from January 2003 to September 2004. All patients were imaged using 4-phase computerized tomography, including computerized tomography angiography with 1.25 mm collimation of the arterial and venous phases. Each multidetector computerized tomography angiogram was prospectively reviewed by a radiologist and operating surgeon, and retrospectively reviewed by a second blinded radiologist.

RESULTS

A total of 70 patients underwent left hand assisted laparoscopic donor nephrectomy between January 2003 and September 2004. Five patients underwent imaging elsewhere and were excluded from study. Of the remaining 65 patients 54 (83%) had at least 1 anomalous lumbar vein of any size recognized at surgery. Additionally, 33 of these 65 patients (51%) had an anomalous lumbar vein that was 3 mm or greater. These 3 mm or greater vessels carry a significant risk of bleeding and they were used in further calculations. As read by a radiologist and surgeon, the sensitivity and specificity of multidetector computerized tomography angiography compared to surgical identification were 97% and 91%, respectively. Positive and negative predictive values, and accuracy were 91.4%, 97% and 94%, respectively.

CONCLUSIONS

Multidetector computerized tomography angiography accurately predicts lumbar venous anatomy before donor nephrectomy with high sensitivity, specificity and accuracy.

Multidetector row computed tomography evaluation of potential living laparoscopic renal donors: the story so far

Renal transplantation is the treatment of choice for end-stage renal disease. Living related kidney donation is the major source of renal grafts due to limited availability of cadaveric kidneys. Open nephrectomy was used to harvest donor kidneys. However, the laparoscopic approach is associated with less postoperative pain and quick recovery. So, most centers now prefer a laparoscopic approach to explant donor kidneys. Laparoscopic approach is technically challenging due to limited operative visibility. Hence, accurate preoperative detection of renal arterial and venous anomalies is imperative to avoid inadvertent vascular injury and bleeding. The preoperative workup of renal donors includes clinical evaluation, laboratory tests, and imaging. Traditionally, the renal donors were evaluated with conventional imaging techniques, which included renal catheter angiography and intravenous urography. However, conventional imaging is invasive, expensive, and less accurate for evaluation of complex renal venous anomalies, small calculi, and diffuse or focal renal parenchymal lesions. The introduction of multidetector row computed tomography (MDCT) revolutionized the CT technology by enabling isotropic resolution with faster scan coverage in a single, short breath-hold. Consequently, MDCT has now replaced conventional imaging for comprehensive imaging of potential living renal donors. MDCT is a minimally invasive technique that can accurately detect urolithiasis, renal arterial and venous anomalies, renal parenchymal lesions, and urinary tract anomalies. Renal vascular anomalies detected by MDCT can help the surgeon in planning donor nephrectomy. MDCT with three-dimensional CT angiography enables accurate preoperative renal vascular mapping. This article reviews the role of MDCT in preoperative evaluation of potential laparoscopic renal donors.

Multidetector-row CT angiography for preoperative evaluation of potential laparoscopic renal donors: how accurate are we?

The purpose of this study was to evaluate multidetector-row computed tomography (MDCT) angiography in preoperative evaluation of renal donors for renal vascular abnormalities. Eighty-one patients underwent renal MDCT angiography and laparoscopic donor nephrectomy. MDCT angiographic findings were compared with surgical findings. The sensitivity and specificity of MDCT angiography for detection of accessory arteries, prehilar renal artery branching, and renal venous anomalies were 88% and 98%, 100% and 97%, and 100% and 97%, respectively. CT findings agreed with surgical findings for accessory renal arteries, prehilar renal artery branching, and renal venous anomalies in 94%, 93%, and 98% of patients, respectively.

Utility of 16-MDCT angiography for comprehensive preoperative vascular evaluation of laparoscopic renal donors

OBJECTIVE

Our objective was to determine the efficacy of 16-MDCT angiography in preoperative evaluation of vascular anatomy of laparoscopic renal donors.

METHODS AND MATERIALS

Fifty-five consecutive renal donors (25 men and 30 women) underwent 16-MDCT angiography followed by donor nephrectomy. In the arterial and nephrographic phases, images were acquired with 60% overlap and 0.6-mm reconstruction in both phases after 120 mL of iohexol was injected at 4 mL/sec. On a 3D workstation, images were evaluated retrospectively by two abdominal imagers blinded to surgical results with respect to number and branching pattern of renal arteries and major and minor renal veins. These CT angiography results were compared with surgical findings.

RESULTS

The surgically confirmed sensitivity of both reviewers (1 and 2) using the MDCT data for detection of renal arteries was 98.5% (65 of 66), and accuracies were 97.0% for reviewer 1 and 95.5% for reviewer 2. Sensitivity and accuracy detection of renal veins was 97% (61 of 63) and 98% (62 of 63) for reviewer 1 and reviewer 2, respectively. Sensitivity and accuracy detection of early arterial bifurcation (< 2 cm from aorta) was 100% (14 of 14), and sensitivity in detection of late venous confluence (< 1.5 cm from aorta) was 100% (8 of 8). All major renal venous variants were identified; reviewer 1 identified 78% (18 of 23) minor venous variants, and reviewer 2 identified 83% (19 of 23) minor venous variants. There were no hemorrhagic complications at surgery. Excellent agreement between reviewers (kappa = 0.92-0.97) was achieved for detection of normal and variant anatomy.

CONCLUSION

16-MDCT angiography enabled excellent preoperative detection of arterial anatomy and venous laparoscopic donor nephrectomy.

[Living donor kidney transplantation: helical CT evaluation of candidates]

OBJECTIVES

Computed tomography (CT) is a diagnostic tool that has won acceptance in the past years for the vascular evaluation of living renal donor (LRD) candidates. We show the findings observed in a series of 102 candidates consecutively evaluated in our centre and present the correlation with the surgical data obtained in those individuals finally operated.

METHODS

From May 1995 to June 2005, 102 LRD candidates were evaluated with CT. Eighteen were also studied with digital subtraction angiography (DSA). Fifty-eight donors underwent nephrectomy. Prevalence of arterial and venous variants found on CT exams were analyzed, as well as the correlation with surgical and DSA data when they were obtained.

RESULTS

Forty-four percent candidates showed multiple renal arteries at least in one kidney. Seventy-one percent of right kidneys and 76% of left kidneys had a single arterial pedicle. Early branching was observed in 7.8% and 15.7% in right and left kidneys respectively. Venous variants were present in 17.5% and the 13.7% in right and left sides respectively. Sensitivity, specificity and accuracy of CT to detect accessory arteries were 89%, 100% and 97% respectively when it was compared to DSA. Correlation with surgical data raised 93% for the presence of arterial variants.

CONCLUSIONS

Vascular variants in renal pedicle showed a high prevalence. Helical CT can effectively achieve all the information required prior to surgery as a sole imaging procedure in LRD candidates.

Multidetector row CT angiography of living related renal donors: is there a need for venous phase imaging?

OBJECTIVE

To prospectively evaluate whether renal venous anatomy can be detected from arterial phase images of multidetector row CT (MDCT) of renal donors.

MATERIAL AND METHODS

Institutional review board approved our study protocol with waiver of consent. Forty-eight consecutive renal donors (age range, 21-56 years; M:F, 20:28) referred for MDCT evaluation were included. Two sub-specialty radiologists performed an independent and separate evaluation of renal venous anatomy in arterial and venous phase images. Opacification of renal venous structures was scored on a five-point scale (1-not seen; 3-minimal opacification; 5-excellent opacification). Arterial and venous phase opacification scores were compared by Wilcoxon signed rank test.

RESULTS

Both readers detected all renal venous anomalies in arterial as well as venous phase images. Each reader detected accessory right renal veins (n=14), retroaortic left renal vein (n=2), circumaortic left renal vein (n=1), and left renal hilar arteriovenous malformation (n=1) in arterial phase images. Retroaortic left renal venous branch was difficult to differentiate from lumbar vein (reader-1, n=1; reader-2, n=2) in both arterial and venous phase images. Sensitivity of detection of renal veins, left adrenal, gonadal and lumbar veins in arterial phase images was 100, 83-88, 100, and 85-90%, respectively. As expected, venous phase images showed significantly greater opacification of renal veins, left gonadal, adrenal and lumbar veins (p<.05). However, this did not substantially limit the evaluation of renal venous anatomy in arterial phase images. Both readers had substantial interobserver agreement (kappa coefficient, 0.7; p<0.05).

CONCLUSIONS

Arterial phase MDCT images alone can be used to detect renal venous anomalies, and to identify small left renal venous branches namely, the left gonadal, adrenal and lumbar veins in renal donors. Venous phase MDCT acquisition is not necessary for evaluation of renal venous anatomy in 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.

Multidetector CT Angiography of the Abdomen

Multidetector CT angiography (MDCTA) is redefining traditional imaging strategies of the vascular structures of the abdomen. Angiographic depiction of normal and variant anatomy is becoming the standard for evaluation and has a significant impact in transplant and oncologic surgery. MDCTA is increasingly being used for assessing diseases affecting the vasculature of the abdominal organs, including the abdominal aorta for treatment planning and post therapy follow-up.