Assessment of living renal donors with spiral CT

Standardized Reporting on the Preoperative CT Assessment of Potential Living Renal Transplant Donors: Can We Create a Universal Report Standard to Meet the Needs of Transplant Urologists?

Purpose: Determine whether standardized template reporting for the preoperative assessment of potential living renal transplant donors improves the comprehensiveness of radiology reports to meet the needs of urologists performing renal transplants. Methods: Urologist and radiologist stakeholders from renal transplant centres in our province ratified a standardized reporting template for evaluation of potential renal donors. Three centres (A, B, and C) were designated "intervention" groups. Centre D was the control group, given employment of a site-specific standardized template prior to study commencement. Up to 100 consecutive CT scan reports per centre, pre- and post-implementation of standardized reporting, were evaluated for reporting specific outcome measures. Results: At baseline, all intervention groups demonstrated poor reporting of urologist-desired outcome measures. Centre A discussed 5/13 variables (38%), Centre B discussed 6/13 variables (46%), and Centre C only discussed 1/13 variables (8%) with ≥90% reliability. The control group exhibited consistent reporting, with 11/13 variables (85%) reported at ≥90% reliability. All institutions in the intervention group exhibited excellent compliance to structured reporting post-template implementation (Centres A = 95%, B = 100%, and C = 77%, respectively). Additionally, all intervention centres demonstrated a significant improvement in the comprehensiveness of reports post-template implementation, with statistically significant increases in the reporting of all variables under-reported at baseline (P > .01). Conclusion: Standardized templates across our province for CT scans of potential renal donors promote completeness of reports. Radiologists can reliably provide our surgical colleagues with needed preoperative anatomy and incidental findings, helping to determine suitable transplant donors and reduce potential complications associated with organ retrieval.

Vascular Variations and Incidental Pathologies in Potential Living Renal Donors Using 160-Slice Multidetector Computed Tomography Angiography

INTRODUCTION

The aim of the study is to evaluate the vascular variations and incidental pathologies in potential living renal donors using 160-slice multidetector computed tomography (MDCT) angiography.

METHODS

This is an observational study conducted at the Department of Radiology from January 2017 to May 2022. In this study, we performed retrospective data analysis of 61 CT renal angiograms, totaling 122 kidneys of potential renal donors, using a Toshiba 160 slice MDCT scanner with a four-phase CT image acquisition protocol, performed for pre-transplant workup. All patients had normal renal functions.

RESULTS

Of our 61 patients, 34 (55.7%) were male and 27 (44.3%) were female, and their mean age was 31.2 ± 9.4 years. We have found 31 (50.8%) variations in the right renal arteries and 21 (34.4%) in the left renal arteries. Of these patients, 13 had bilateral renal arterial variations. The late confluence of the renal vein was found in 3.3% of males, multiple right renal veins in 7 (11.5%), and left renal veins in 2 (3.3%). By distributing the data according to gender, we noticed more diversity in the renal vessels of male patients. Left renal artery variations were more frequent in males (16, 76.2%) than in females (5, 23.8%), and they were statistically significant (p=0.02). Likewise, variations in the right renal arteries were also more frequently found in males (19, 61.3%) as compared to females (12, 38.7%). Right renal vein variations were more common in males (9, 81.8%) as compared to females (2, 18.2%) (p=0.05).

CONCLUSION

Frequent renal vascular variations and incidental pathologies in potential living donors were found by MDCT examination, and these vascular variations should be analyzed before renal transplant.

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.

Quantitative analysis of renal arterial variations affecting the eligibility of catheter-based renal denervation using multi-detector computed tomography angiography

Catheter-based renal denervation (RDN) was introduced to treat resistant hypertension. However, the reduction in blood pressure after the RDN was modest. Catheter-based RDN was performed only at main renal arteries, except for accessory and branch arteries due to the diameter being too small for the catheter to approach. Here, we retrospectively analyzed the anatomy of diverse renal arteries via 64-channel multi-detector computed tomography angiograms of 314 consecutive donors who underwent living donor nephrectomy from January 2012 to July 2017. Occurrence rates of one or more accessory renal arteries in donors were 25.3% and 19.4% on the left and right sides, respectively. Early branching rates before 25 mm from the aorta to the right and left renal arteries were 13.7% and 10.5%, respectively. Overall, 63.1% and 78.3% of donors had no accessory artery bilaterally and no branched renal artery, respectively. As a result, 47.1% had only main renal arteries without an accessory artery and early-branching artery. Approximately half of the donors had multiple small renal arteries bilaterally, for which catheter-based denervation may not be suitable. Thus, preoperative computed tomography angiography requires careful attention to patient selection, and there is a need for improved methods for denervation at various renal arteries.

Morphological and clinical aspects of the occurrence of accessory (multiple) renal arteries

Renal vascularization variants vastly differ between individuals due to the very complex embryogenesis of the kidneys. Moreover, each variant may have implications for clinical and surgical interventions. The number of operating procedures continues to grow, and includes renal transplants, aneurysmorrhaphy and other vascular reconstructions. In any surgical technique, unawareness of the presence of multiple renal arteries may result in a fatal outcome, especially if laparoscopic methods are used. The aim of this review is to comprehensively identify the variation within multiple renal arteries and to highlight the connections between the presence of accessory renal arteries and the coexistence of other variants of vascularization. Another aim is to determine the potential clinical implications of the presence of accessory renal arteries. This study is of particular importance for surgeons, intervention radiologists, nephrologists and vascular surgeons.

Does the type of renal artery anatomic variant determine the diameter of the main vessel supplying a kidney? A study based on CT data with a particular focus on the presence of multiple renal arteries

Background

An in-depth knowledge of renal vascular anatomy is essential when planning many surgical procedures; however, a few data exists regarding renal artery diameter. The aim of this study was to assess this morphological feature and to investigate whether a correlation exists between renal artery diameter and the type of arterial supply, with a particular emphasis on variant anatomy and the presence of multiple renal arteries.

Materials and methods

Computed tomography angiography (CTA) studies of 248 patients, i.e., a total of 496 kidneys, were evaluated. The mean age of the patients was 66.4 ± 15.01 years. Renal artery diameter was measured based on the type of arterial blood supply.

Results

The frequency of occurrence of three anatomic variants of renal arterial supply was established: single renal artery (RA) 43.35%, single artery with prehilar branching (pRA) 37.30%, and multiple renal artery (mRA) 19.35%. The diameter of single renal arteries, with either prehilar or hilar branching, was significantly larger than when multiple arteries were present. A detailed analysis of just the mRA variant demonstrated that the diameter of the renal arteries in men was larger (p = 0.012) than those in women and that there was no difference in diameter with regard to the side of the body (p = 0.219).

Conclusions

The classification described in our study containing a detailed description of renal artery diameter. It may be helpful in clinical practice, especially for transplantologists, surgeons, and vascular surgeons.

Optimal scan delay depending on contrast material injection duration in abdominal multi-phase computed tomography of pancreas and liver in normal Beagle dogs

This study was conducted to establish the values for optimal fixed scan delays and diagnostic scan delays associated with the bolus-tracking technique using various contrast material injection durations in canine abdominal multi-phase computed tomography (CT). This study consisted of two experiments employing the crossover method. In experiment 1, three dynamic scans at the porta hepatis were performed using 5, 10 and 15 sec injection durations. In experiment 2, two CT scans consisting of five multi-phase series with different scan delays of 5 sec intervals for bolus-tracking were performed using 5, 10 and 15 sec injection duration. Mean arrival times to aortic enhancement peak (12.0, 15.6, and 18.6 sec for 5, 10, and 15 sec, respectively) and pancreatic parenchymal peak (17.8, 25.1, and 29.5 sec) differed among injection durations. The maximum mean attenuation values of aortas and pancreases were shown at the scan section with 0 and 5, 0 and 10 and 5 and 10 sec diagnostic scan delays during each injection duration, respectively. The optimal scan delays of the arterial and pancreatic parenchymal phase in multi-phase CT scan using fixed scan delay or bolus-tracking should be determined with consideration of the injection duration.

Accessory (multiple) renal arteries - Differences in frequency according to population, visualizing techniques and stage of morphological development

The aim of this paper is to comprehensively analyze the literature focused on frequency of the presence of the accessory renal arteries in the human body. A systematic analysis of papers has been made. With regard to ethnicity, the incidence of accessory renal arteries fluctuates from 4% in a Malaysian population to 61.5% in a Brazilian population. The frequency is lowest in eastern and southern Asia (from 4% to 18.4%). In some, not ethnically homogenous populations, wide span of occurrence of accessory renal arteries is described (e.g. American - averaging from 18% to 28.8%). A higher frequency of accessory renal arteries was observed in fetuses compared to adults. Moreover, differences in the presence and number of accessory renal arteries reported in different papers are a consequence of type of visualizing technique used in research - especially when computed tomography and anatomical dissection were compared. The increasing number of surgical interventions, especially where laparoscopic methods are concerned, underlines the importance of such knowledge especially to surgeons, interventional radiologists, nephrologists, and vascular surgeons.

Evaluation of Renal Arteries of 286 Living Donors by Multidetector Computed Tomography Angiography: A Single-Center Study

OBJECTIVES

In living renal donors, digital subtraction angiography and intravenous pyelogram techniques developing traditional evaluation before transplant have started to give place to more modern and less-invasive methods such as multidetector computerized tomography angiography, and magnetic resonance angiography via the developments in the imaging technology. We aimed to evaluate the renal arteries of living-renal donors by multidetector computerized tomography angiography and to compare the findings with the surgical results.

MATERIALS AND METHODS

In our renal transplant center, 286 living-donor candidates to whom multi-detector computerized tomography angiography was applied, were evaluated retrospectively and the findings were compared with the surgical operation notes.

RESULTS

In 180 of 286 living donor candidates to whom computerized tomography angiography was applied, bilateral single renal artery was deter-mined. In 79 renal donor candidates, unilateral multiple renal artery; and in 27 renal donor candidates, bilateral multiple renal artery were found. In 58 renal donor candidates, at least 1 polar artery was specified; in 32 renal donor candidates, a unilateral single renal artery; in 10 renal donor candidates, a bilateral double renal artery was determined. When computerized tomography angiography and operative notes were compared, we observed that the findings in 280 donor candidates were the same. In 6 renal donor candidates, differences in the findings were present. Our accuracy rate was 97% and according to the operative notes, our sensitivity and specificity ratios in determining multiple renal arteries were calculated as 98% and 95%.

CONCLUSIONS

Multidetector computerized tomography angiography can be used rapidly and efficiently in living-donor renal candidates with high specificity and sensitivity ratios.

Atherosclerotic renal artery stenosis and revascularization

Atherosclerotic renovascular disease is the most common cause of secondary hypertension. The patients with renovascular disease are at increased risk for adverse cardiac outcomes. Recent trials comparing medical therapy alone to medical therapy with stenting are flawed, but lay to rest any existing debate that unselected revascularization is unwarranted; however, revascularization may be appropriate in high-risk populations. Defining an appropriate population for revascularization is an area of ongoing study. Furthermore, delivery of optimal medical therapy in this population is inadequate. This review describes recent developments in renal artery revascularization.

CT angiography after 20 years: a transformation in cardiovascular disease characterization continues to advance

Through a marriage of spiral computed tomography (CT) and graphical volumetric image processing, CT angiography was born 20 years ago. Fueled by a series of technical innovations in CT and image processing, over the next 5-15 years, CT angiography toppled conventional angiography, the undisputed diagnostic reference standard for vascular disease for the prior 70 years, as the preferred modality for the diagnosis and characterization of most cardiovascular abnormalities. This review recounts the evolution of CT angiography from its development and early challenges to a maturing modality that has provided unique insights into cardiovascular disease characterization and management. Selected clinical challenges, which include acute aortic syndromes, peripheral vascular disease, aortic stent-graft and transcatheter aortic valve assessment, and coronary artery disease, are presented as contrasting examples of how CT angiography is changing our approach to cardiovascular disease diagnosis and management. Finally, the recently introduced capabilities for multispectral imaging, tissue perfusion imaging, and radiation dose reduction through iterative reconstruction are explored with consideration toward the continued refinement and advancement of CT angiography.

CT angiography in potential living kidney donors: 80 kVp versus 120 kVp

OBJECTIVE

The purpose of this article is to retrospectively investigate the diagnostic accuracy, image quality, and radiation dose of renal artery CT angiography (CTA), at 80 kVp compared with 120 kVp, in adult kidney donors.

MATERIALS AND METHODS

CTA examinations of 258 consecutive potential kidney donors were retrospectively evaluated; 189 patients were scanned using 64-MDCT scanners (higher maximal tube current), and 69 patients were scanned using 16-MDCT scanners (lower maximal tube current). On the basis of the tube potential and scanners, the study population was divided into four groups. Qualitative and quantitative analysis include vascular attenuation measurements, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Volume CT dose index (CTDIvol) was recorded, and size-specific dose estimate was also estimated.

RESULTS

Using 80 kVp for the 16-MDCT scanner, there was a 64.9% reduction in size-specific dose estimate (66.1% reduction in CTDIvol), increased noise, and tube current saturation in all cases. Axial image quality was significantly lower compared with that obtained at 120 kVp (p = 0.02), but image quality and visibility of renal artery branch order were comparable. Using 80 kVp for the 64-MDCT scanner, there was a 40.5% reduction in size-specific dose estimate (43.6% reduction in CTDIvol) and increased SNR and CNR (p < 0.001). No significant differences in 3D image quality and branch order visibility were observed. Tube current saturation was reached in 31% of cases. One hundred fifty-one patients (86 imaged at 80 kVp and 65 imaged at 120 kVp) underwent donor nephrectomy; CTA diagnostic accuracy was 100%.

CONCLUSION

Renal artery CTA using 80 kVp combined with limiting the tube current results in a significant reduction in radiation dose and improved SNR and CNR, without deterioration of image quality.

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.

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.

Clinical insight into the precaval right renal artery: a multidetector row computed tomography angiographic study

Variations of course and number of renal vessels are not so uncommon and their knowledge is important for planning of minimally invasive renal surgeries. The earlier literature reports a prevalence of precaval right renal artery between 0.8% and 5%. Normally, the right renal artery passes posterior to the inferior vena cava, but it can also be precaval where it passes anterior to inferior vena cava. The multidetector row contrast enhanced computed tomography angiography allows precise evaluation of renal vasculature. The aim of this retrospective study is to determine the prevalence of precaval right renal artery. Amongst 73 MDCT scans studied, we identified 4 cases of precaval right renal artery with the prevalence being 5.48%, more than what is reported in the earlier literature. We also report a single and dominant precaval right renal artery in one of the cases, which is a rare finding. On the basis of these results, we conclude that precaval right renal artery appears to be more common and so the knowledge of this variant holds a major clinical implication in preventing misinterpretation of radiological images and proper planning of interventional procedures and minimally invasive surgeries.

Imaging evaluation of kidney using multidetector computerized tomography in living-related renal transplantation

BACKGROUND

Multidetector computerized tomography (MDCT) is lesser invasive than conventional angiography and has the advantage of assessment of vessels and surrounding anatomic variants before laparoscopic nephrectomy.

METHODS

From May 2005 to March 2011, 62 consecutive living kidney donors of mean age 45.3 ± 12.7 years (range 24-70 y, male:female 26:36) underwent laparoscopic nephrectomy to paired recipients of mean age 44.8 ± 14.0 years (range 17-74 y, male:female 38:24). The clinical characteristics and laboratory data of donors and recipients were collected for analysis. Graft function as indicated by estimated glomerular filtration rate (eGFR) was obtained from the last stable visit of the donors and the best value displayed by the recipients.

RESULTS

There was no significant correlation between CT kidney volume and and eGFR. By univariate analysis, donor age was associated with worse graft function (-0.51 mL/min lower eGFR per 1 year of donor age; P < .0001). Female sex and higher effective renal plasma flow/body mass index ratio were associated with better graft function; conversely, body weight and BMI were associated with poor graft function upon univariate and multivariate analysis. An ERPF of <220 mL/min and a donor age >45 y showed significantly lower eGFR. There was no effect of CT kidney volume <100 mL.

CONCLUSIONS

Our preliminary data suggest that CT kidney volume does not predict posttransplantation graft function, but MDCT is still important for analysis of anatomy before laparoscopic nephrectomy among living donors.

Multidetector computed tomographic angiography evaluation of micropig major systemic vessels for xenotransplantation

Due primarily to the increasing shortage of allogeneic donor organs, xenotransplantation has become the focus of a growing field of research. Currently, micropigs are the most suitable donor animal for humans. However, no standard method has been developed to evaluate the systemic vascular anatomy of micropigs and standard reference values to aid in the selection of normal healthy animals as potential organ donors are lacking. Using 64-channel multidetector row computed tomographic angiography (MDCTA), we evaluated morphological features of the major systemic vessels in micropigs and compared our results to published human data. The main vasculature of the animals was similar to that of humans, except for the iliac arterial system. However, diameters of the major systemic vessels were significantly different between micropigs and humans. Specifically, the diameter of the aortic arch, abdominal aorta, external iliac artery, and femoral artery, were measured as 1.50 ± 0.07 cm, 0.85 ± 0.06 cm, 0.52 ± 0.05 cm, and 0.48 ± 0.05 cm, respectively, in the micropigs. This MDCTA data for micropig major systemic vessels can be used as standard reference values for xenotransplantation studies. The use of 64-channel MDCTA enables accurate evaluation of the major systemic vasculature in micropigs.

Estudo do padrão arterial de 200 pedículos renais por meio de angiotomografias

OBJETIVO: Verificar a prevalência e a distribuição das artérias renais e de seus ramos in vivo, relacionando as particularidades encontradas nas artérias renais com o sexo e sua lateralidade. MÉTODO: Duzentos pedículos renais foram estudados por meio de angiotomografias e suas artérias analisadas de acordo com número, posição de origem, calibre, comprimento e trajeto em relação aos segmentos renais. Sua frequência e lateralidade foram pesquisadas quanto ao sexo e idade. RESULTADOS: Foram observadas múltiplas artérias em 61,5% dos pedículos (56% à direita e 67% à esquerda), ocorrendo em 65% dos homens e 58% das mulheres. A origem aórtica para as múltiplas artérias foi mais frequente à direita e, com maior frequência, as artérias renais se originaram entre as vértebras L1 e L2 como divisões pré-hilares da artéria principal. O comprimento médio da artéria principal foi maior em rins direitos com artéria única. Não houve diferença entre o diâmetro da artéria renal principal. CONCLUSÃO: Existe maior prevalência das múltiplas artérias renais do que aquela descrita na literatura, sem diferença entre os sexos ou lateralidade. As artérias renais originaram-se com maior frequência entre as vértebras L1 e L2, como divisões pré-hilares da artéria principal e com trajeto ao hilo do rim. O comprimento médio da artéria principal é maior à direita e nos rins com artéria única. Não houve diferença no diâmetro da artéria renal principal entre rins com artérias únicas e múltiplas.

Prospective Evaluation of the Accuracy of MDCT Angiography for Living Kidney Donor

PURPOSE

In donor nephrectomy, it is important to understand the exact anatomy of the blood vessels during minimally invasive surgery. We prospectively analyzed the accuracy of the vessel structures obtained by use of 64-row multi-detector computed tomography (MDCT) angiography compared with the actual vessel structure observed during surgery.

MATERIALS AND METHODS

We analyzed 238 patients who underwent donor nephrectomy from July 2007 to August 2010. Before the operation, MDCT angiography was performed, and after the operation, the surgeons themselves wrote the protocol. The ipsilateral artery, the number of veins, the association with the run of the hilar vessel, and other vascular anomalies in computed tomography (CT) angiography and in the donor protocol were summarized.

RESULTS

Among 238 patients, nephrectomy was performed on the left side in 199 patients. The accuracy of MDCT for the artery and the vein was 93.3% and 92.4%, respectively. Accuracy did not differ significantly on the left and right sides (artery: p=0.124; vein: p=0.174). In 199 patients, the CT findings for the lumbar vein were compared with the surgical findings. The overall accuracy was shown to be 84.9%, and the accuracy of the group drained to the inferior vena cava (54%) was significantly different (p<0.01) from that of the group drained to the renal vein (98.6%). Thus, it may be necessary to pay close attention to the interpretation of the findings for the lumbar vein.

CONCLUSIONS

MDCT angiography is important for understanding the exact anatomy of blood vessels before minimally invasive surgery. We showed that 64-channel MDCT has high accuracy in the main vessel and hilar vessels. However, close attention to the interpretation of the CT findings for the lumbar vein may be required.

Intravenous contrast medium administration and scan timing at CT: considerations and approaches

The continuing advances in computed tomographic (CT) technology in the past decades have provided ongoing opportunities to improve CT image quality and clinical practice and discover new clinical CT imaging applications. New CT technology, however, has introduced new challenges in clinical radiology practice. One of the challenges is with intravenous contrast medium administration and scan timing. In this article, contrast medium pharmacokinetics and patient, contrast medium, and CT scanning factors associated with contrast enhancement and scan timing are presented and discussed. Published data from clinical studies of contrast medium and physiology are reviewed and interpreted. Computer simulation data are analyzed to provide an in-depth analysis of various factors associated with contrast enhancement and scan timing. On the basis of basic principles and analysis of the factors, clinical considerations and modifications to protocol design that are necessary to optimize contrast enhancement for common clinical CT applications are proposed.

Prevalence of renal artery and kidney abnormalities by computed tomography among healthy adults

BACKGROUND AND OBJECTIVES

Management of incidental renal artery and kidney abnormalities in patients undergoing computed tomography scans is a clinical challenge because their frequency in healthy subjects has not been precisely estimated. Therefore, the prevalence and management of these abnormalities were determined among a large cohort of potential kidney donors undergoing protocol evaluations.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All patients at the Mayo Clinic who underwent computed tomographic angiography and urography as part of their kidney donor evaluation between 2000 and 2008 were identified. Radiographic reports were abstracted for abnormalities of the renal arteries and kidneys. The prevalence of radiographic abnormalities was stratified by age and gender, and the effect on approval for kidney donation was determined.

RESULTS

Among 1957 potential kidney donors, the mean +/- SD age was 43 +/- 12 years, and 58% were women. The most common abnormalities were kidney stones (11%), focal scarring (3.6%), fibromuscular dysplasia (2.8%), and other renal artery narrowing or atherosclerosis (5.3%). Fibromuscular dysplasia, focal scarring, parenchymal atrophy, and upper tract dilation were more common in women. Renal artery narrowing, focal scarring, and indeterminate masses increased with age. Overall, 25% of potential donors had at least one abnormality. However, these incidental radiographic abnormalities contributed to exclusion from donation in only 6.7% of potential donors.

CONCLUSIONS

Incidental radiographic abnormalities of the renal arteries and kidneys are common. The majority of imaging findings are not perceived to be harmful enough to prevent kidney donation, but future studies are needed to determine their clinical relevance.

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.

Origination angle of renal artery has no role in renal artery pattern

INTRODUCTION

Renal artery (RA) anatomy plays a critical role in selecting donors. During the present study, we sought to evaluate the physiological role of RA origination angle for the presence of an accessory RA or its early branching.

METHODS

During the present cross-sectional study (August 2005-October 2007), 143 candidates for kidney donation underwent RA angiography by 64 multidetector computed tomographic angiography. We assessed the RA diameter, distance to first branching, presence of accessory RA, and early branching, as well as the origination angle of RA from aorta in coronal plane (alpha angle).

RESULTS

The male-to-female ratio was 96:47 with an overall mean age of 27.42 +/- 4.55 years. The alpha angle, sine, cosine of the alpha angle and the deviation factor were not significantly different between kidneys with versus without an accessory artery or between the RA with versus without an early branching. Only the RA diameter (P = .047) and the distance of RA to the branching (P < .001) in kidneys with an accessory RA were significantly lower and higher than those without an accessory RA, respectively. Also the distance of the RA to the branching was significantly less in kidneys with an early branching (P < .001). The RA diameter directly correlated with the RA origination angle (r = .191, P = .001), while there was no correlation between the distance to RA branching and the RA origination angle (r = -.060, P = .311).

CONCLUSION

The origination angle of the RA from aorta has no role in the early branching or accessory RA development. There was a direct correlation between the RA diameter and the RA origination angle.

Diagnosis and management of atherosclerotic renal artery stenosis: improving patient selection and outcomes

Renal artery stenosis (RAS) is common among patients with atherosclerosis, and is found in 20-30% of individuals who undergo diagnostic cardiac catheterization. Renal artery duplex ultrasonography is the diagnostic procedure of choice for screening outpatients for RAS. Percutaneous renal artery stent placement is the preferred method of revascularization for hemodynamically significant RAS, and is favored over balloon angioplasty alone. Stent placement carries a class I recommendation for atherosclerotic RAS according to ACC and AHA guidelines. Discordance exists between the very high (>95%) procedural success rate and the moderate (60-70%) clinical response rate after renal stent placement, which is likely to be a result of poor selection of patients, inadequate angiographic assessment of lesion severity, and the presence of renal parencyhmal disease. Physiologic lesion assessment using translesional pressure gradients, and measurements of biomarkers (e.g. brain natriuretic peptide), or both, could enhance the selection of patients and improve clinical response rates. Long-term patency rates for renal stenting are excellent, with 5-year secondary patency rates greater than 90%. This Review will outline the clinical problem of atherosclerotic RAS and its diagnosis, and will critically assess treatment options and strategies to improve patients' outcomes.

Preoperative evaluation of living kidney donors with multidetector computed tomography angiography

OBJECTIVE

The purpose of this study was to determinate the accuracy of multidetector computed tomography (MDCT) angiography for imaging evaluation of renal anatomic variants among potential living renal donors for surgical planning.

MATERIALS AND METHODS

Two hundred twenty-three living kidney donors underwent MDCT angiography (MDCTA) in our institution over the last 2 years. The examination was performed with a 4-detector scanner, including scanning before and after power injection of nonionic contrast material during the arterial, nephrographic, and excretory phases. Scans were reconstructed for three-dimensional (3D) images using MIP, MPR, VRT, and CPR techniques.

RESULTS

Arterial variants, including supernumerary renal arteries, were present in 140 subjects: 11 presented luminal stenosis; 10 had calcifications within the vessel wall; 3 had renal artery aneurysms; 2 had obstructions; and 1 had angulation of the renal artery. Calcifications were associated with luminal stenosis (4 subjects) or no pathology (6 subjects). Venous variants were present in 4 subjects, including 3 retroaortic renal veins and 1 left renal vein draining into the retrohepatic portion of the IVC. Incidental findings were 3 renal infarcts.

CONCLUSION

MDCTA and urography are a minimally invasive, fast method to detect and classify a variety of anatomic anomalies among potential living renal donors relevant to surgical planning.

Normal renal arterial anatomy assessed by multidetector CT angiography: are there differences between men and women?

The purpose of this study was to determine renal arterial anatomy and gender differences in adults without renovascular disease using multidetector computed tomography angiography (MDCTA). MDCTA datasets of 399 patients were retrospectively reviewed. Measurements of the aortorenal diameters, the angulation of the renal ostia and pedicles as well as the distance between the origins of the renal arteries were measured. Differences in measurements between genders were tested for statistical significance using analysis of variance (ANOVA) and Pearson's Chi-Square tests. A total of 798 renal arteries were available for analysis in 207 female (mean age = 52.91 years) and 192 male patients (mean age = 53.04 years). Female patients were found to have smaller aortae (at the level of the right renal ostium) and bilateral renal arteries than males (mean aortic diameter M/F = 18.33/15.89 mm, mean right renal artery ostial diameter M/F = 5.06/4.59 mm, mean left ostial renal diameter M/F = 5.14/4.66 mm) (p < .001). There was no statistical significance for the renal ostia level in relation to the vertebrae and the majority of renal arteries originated at the L1 and L2 levels. The longitudinal distance between right and left renal artery ostia ranged from 0 to 32 mm (mean = 4,6 mm, median = 5mm). The mean anteroposterior orientation of the right renal ostia was M/F = 29.45 degrees/28.20 degrees , and M/F = -7.96 degrees/-11.14 degrees for left renal artery ostia. The mean anteroposterior orientation of the right renal pedicle was M/F = 41.37 degrees/44.34 degrees and M/F = 42.31 degrees/43.95 degrees for the left pedicle. There are some differences in normal renal arterial anatomy between genders. Normal renal arterial information is useful not only for planning and performing of endovascular and laparoscopic urologic procedures, but also for medical device development.

[Laparoscopic nephrectomy in a living donor]

Kidney transplantation is the therapeutic option of choice for patients with end-stage renal disease. With the advent of safer harvesting techniques and immunosuppression, both donor and recipient outcomes have markedly improved in recent years. Kidney donation from Living donors remains the single most important factor responsible for improving patient and graft survival. The laparoscopic donor nephrectomy has revolutionized renal transplantation, allowing expansion of the donor pool by diminishing surgical morbidity while maintaining equivalent recipient outcome. This technique is now becoming the gold-standard harvesting procedure in transplant centres worldwide, despite its technical challenge and ongoing procedural maturation, especially early in the learning curve. Previous contraindications to laparoscopic donor nephrectomy are no longer absolute. In the following analysis, the procedural aspects of the laparoscopic donor nephrectomy are detailed including pre-operative assessment, operative technique and a review of the current literature delineating aspects of both donor and recipient morbidity and mortality compared with open harvesting techniques.

Volume-rendered three-dimensional spiral computed tomographic angiography as a planning tool for microsurgical reconstruction in patients who have had operations or radiotherapy for oropharyngeal cancer

Three-dimensional spiral computed tomographic angiography (3D-SCTA) is a minimally invasive method of delineating vessels in three-dimensional detail. Our aim was to evaluate the clinical usefulness of volume-rendered three-dimensional SCTA for planning microsurgical reconstruction. Eighteen patients had a spiral computed tomogram (CT) of the extracranial carotid arteries. The volume rendering technique (VRT) was used to visualise the cervical vessels, and the three-dimensional SCTA images evaluated by a staff radiologist. Radiographic and operative findings were correlated in 13 of 18 patients. The anatomical and pathological alterations of vascular anatomy identified by three-dimensional SCTA correlated exactly with operative findings and led to a successful microsurgical reconstruction. Oropharyngeal reconstruction with microvascular free flaps requires accurate evaluation of the vascular system of the carotid arteries, and improves the accuracy of diagnostic decisions. Three-dimensional SCTA enables the surgeon to establish an appropriate treatment plan.

[Multislice CT arteriography in the pre-surgical evaluation of patients with ureteropelvic junction stenosis]

INTRODUCTION

The current treatment of choice for ureteropelvic stenosis is endopyelotomy, but the presence of vessels in contact with the stenotic area of the ureteropelvic junction reduces the success of these interventions and increases vascular and hemorrhagic complications. The aim of our study was to use multislice CT arteriography to evaluate patients prior to surgery for ureteropelvic junction stenosis.

PATIENTS AND METHODS

16 patients with ureteropelvic junction stenosis underwent multislice CT arteriography; multidirectional images and three-dimensional reconstructions were used to identify and characterize vessels in contact with the stenotic area of the ureteropelvic junction.

RESULTS

A total of eight vessels (four arteries and four veins) in six (38%) patients were found in contact with or passing within 2 mm of the ureteropelvic junction. The vessels were located anterior to the junction in four cases; it was posterior in one case, and anteromedial in the other. Endopyelotomy was contraindicated in the six patients in whom vessels were found in contact with the ureteropelvic junction. The presence of the vessels was confirmed during surgery in five of these patients; the remaining patient did not undergo surgery).

CONCLUSION

Multislice CT arteriography allows adequate presurgical evaluation of ureteropelvic junction stenosis, detecting the presence of crossing vessels and facilitating the planning of the surgical approach in these patients.

Economic and ethical impact of extrarenal findings on potential living kidney donor assessment with computed tomography angiography

To determine the prevalence and spectrum of extrarenal findings in a screening population of potential living kidney donors undergoing renal Computed tomography angiography (CTA) and evaluate their impact on subsequent patient management and imaging costs. Two radiologists retrospectively reviewed 175 consecutive renal CTA's performed for assessment of potential living kidney donors. Extrarenal radiological findings were recorded and classified according to high, medium, or low importance based on clinical relevance and the need for further investigations and/or treatment. The cost of additional imaging examinations was calculated using 2002 Canadian (British Columbia) reimbursements. There were 73 extrarenal findings in 71/175 (40.6%) of the potential kidney donors in the study population. Findings were categorized as of high clinical importance in 18 (10.3%) cases, including lung lesions, bowel tumors, and liver tumors and as medium importance in 31 (17.7%). Twenty-two (12.6%) individuals had findings categorized as low importance, probably of no clinical significance and requiring no follow-up. Further potential evaluation of the 49 patients (28%) with highly and moderately significant extrarenal findings may require an additional $6137 (mean $35.1 per each case of all the screened patients). Transplantation of a kidney from a living donor is an excellent alternative to cadaveric allografts. Potential living kidney donors are a highly selected population of healthy individuals, screened for significant past or current medical conditions before undergoing CTA. Despite this screening, potentially significant extrarenal findings (classified as high or medium importance) were revealed in 28% of patients. These patients may require further investigations and/or treatment. The referring physician and patient should be aware of such potentially high probability, which may require further nontransplant related evaluation and treatment. This has medical, legal, economic, and ethical implications.

Improved Detection of Renal Vascular Anatomy Using Multidetector CT Angiography: Is 100% Detection Possible?

BACKGROUND AND PURPOSE

Multidetector CT angiography (MDCTA) is being used increasingly to evaluate vascular anatomy prior to donor nephrectomy. To improve the ability of MDCTA to predict donor renal anatomy, a novel protocol including four-phase imaging with three-dimensional reconstruction and maximum intensity projections (MIPs) was incorporated into the standard donor evaluation. The purpose of this study was to determine the results of this protocol.

PATIENTS AND METHODS

Seventy consecutive patients who underwent hand-assisted laparoscopic donor nephrectomy between January 2003 and September 2004 were reviewed. All MDCTA studies were examined initially by a radiologist alone, after which, a second preoperative reading was performed by a radiologist and the operating surgeon together. The two reviews were compared with the operative findings.

RESULTS

Using this protocol to detect the total number of renal arteries, veins, and ureters, the sensitivity of the initial radiologist was 97%, 100%, and 96%, respectively. These values increased to 100%, 100%, and 99% when the films were reviewed by a radiologist together with the surgeon who would operate on the donor. The sensitivity, specificity, and accuracy in predicting supernumerary arteries, including early (< or =1-cm) arterial branching was 89%, 100%, and 97%, respectively after the single reading but increased to 100%, 100%, and 100% with the combined reading.

CONCLUSIONS

An MDCTA study with this protocol provides excellent anatomic detail prior to donor nephrectomy. Its ability to predict renal-arterial and ureteral anatomy is enhanced when the films are reviewed simultaneously by a radiologist and the operating surgeon.

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.

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.

Multidetector computed tomography arteriography in the preoperative assessment of patients with ureteropelvic junction obstruction

BACKGROUND

Nowadays, endoscopic management of ureteropelvic junction (UPJ) obstruction is the treatment of choice. However, in the presence of crossing vessels, the success rate of endoscopic management decreases and the risk of hemorrhagic and vascular complications rises. The purpose of this study is to evaluate patients with UPJ obstruction using contrast enhanced multidetector computed tomography (CT) angiography to aid in surgical planning and management.

PATIENTS AND METHODS

Between 2001 and 2005, 27 patients (mean age: 43 years; age range: 17-75 years) with UPJ obstruction were studied with multidetector CT angiography. Identification and characterization of crossing vessels was performed with multidirectional images and three-directional reconstructions.

RESULTS

12 patients (44%) were found to have 16 crossing vessels (vessels in contact with the UPJ or within a vicinity of less than 2 mm). Nine of these vessels were arteries and seven were veins. Nine vessels crossed anteriorly, two posteriorly, and one anteromedially. Endopyelotomy was contraindicated in these 12 patients due to the presence of crossing vessels. Eleven out of the 12 patients underwent a pyeloplasty by open surgery or laparoscopy, where the presence of crossing vessels was confirmed. One of the 12 patients did not undergo surgery.

CONCLUSION

Multidetector CT angiography permits an adequate preoperative assessment of patients with UPJ obstruction as it is able to identify the presence and location of crossing vessels. Furthermore, it allows to study in detail the anatomy of the renal area and its vascular variants.

Maximizing clinical information obtained by CT

CT scanning is an integral part of the urologist's practice today. It is the most commonly used imaging modality and the one with which urologists are most familiar. CT urography, CT angiography, and 3D reconstruction enable the urologist to perform comprehensive evaluations of patients who have different urologic diseases, using a single imaging modality. It is thus prudent that urologists become familiar with CT applications, to maximize the clinical information available from them.

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.