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The two primary nephron-sparing interventions for treating renal masses such as renal cell carcinoma are surgical partial nephrectomy (PN) and image-guided percutaneous thermal ablation. Nephron-sparing surgery, such as PN, has been the standard of care for treating many localized renal masses. Although uncommon, complications resulting from PN can range from asymptomatic and mild to symptomatic and life-threatening. These complications include vascular injuries such as hematoma, pseudoaneurysm, arteriovenous fistula, and/or renal ischemia; injury to the collecting system causing urinary leak; infection; and tumor recurrence. The incidence of complications after any nephron-sparing surgery depends on many factors, such as the proximity of the tumor to blood vessels or the collecting system, the skill or experience of the surgeon, and patient-specific factors. More recently, image-guided percutaneous renal ablation has emerged as a safe and effective treatment option for small renal tumors, with comparable oncologic outcomes to those of PN and a low incidence of major complications. Radiologists must be familiar with the imaging findings encountered after these surgical and image-guided procedures, especially those indicative of complications. The authors review cross-sectional imaging characteristics of complications after PN and image-guided thermal ablation of kidney tumors and highlight the respective management strategies, ranging from clinical observation to interventions such as angioembolization or repeat surgery. Work of the U.S. Government published under an exclusive license with the RSNA. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Quiz questions for this article are available in the Online Learning Center. See the invited commentary by Chung and Raman in this issue.

Background: Preterm birth impairs nephrogenesis, leading to a reduced nephron endowment which is inextricably linked to hypertension and chronic kidney disease in adults. The aim of this study was to compare nephron endowment between preterm infants to that of intrauterine fetuses at the same gestational age (GA) using a novel indirect ultrasound measurement of the renal parenchymal thickness. We hypothesized that extrauterine and intrauterine renal parenchymal thickness would differ based on altered renal growth environments., Methods: In this observational study, appropriately grown preterm infants (birth weight of between the 5th and 95th percentile) born <32 weeks, admitted to the neonatal department were eligible to participate. Renal parenchymal thickness of the infants was measured at 32- and 37-weeks postmenstrual age (PMA). These measurements were compared to the intrauterine renal parenchymal thickness of appropriately grown fetuses (control)., Results: At 32-weeks PMA, the preterm infants had a significantly thinner renal parenchyma compared to fetuses at 32-weeks GA suggesting they had less nephrons, however by 37-weeks there was no significant difference in renal parenchymal thickness., Conclusions: We propose that the differences in the extrauterine growth of the renal parenchyma in preterm infants may be due to a reduced number of nephrons and compensatory hyperfiltration., Impact: This article provides insight into the effects of prematurity on nephrogenesis by comparing extrauterine renal parenchymal growth of born preterm infants to the ideal intrauterine fetal growth. Renal parenchyma thickness measurement using ultrasonography is a novel non-invasive measurement of renal development for the determination of nephron endowment. Differences in the renal parenchymal thickness of the preterm infants may be due to a deficit in nephron number and compensatory hyperfiltration., (© 2022. The Author(s).)

Background: Accumulating evidence supports an association between nephron number and susceptibility to kidney disease. However, it is not yet possible to directly measure nephron number in a clinical setting. Recent clinical studies have used glomerular density from a single biopsy and whole kidney cortical volume from imaging to estimate nephron number and single nephron glomerular filtration rate. However, the accuracy of these estimates from individual subjects is unknown. Furthermore, it is not clear how sample size or biopsy location may influence these estimates. These questions are critical to study design, and to the potential translation of these tools to estimate nephron number in individual subjects., Methods: We measured the variability in estimated nephron number derived from needle or virtual biopsies and cortical volume in human kidneys declined for transplantation. We performed multiple needle biopsies in the same kidney, and examined the three-dimensional spatial distribution of nephron density by magnetic resonance imaging. We determined the accuracy of a single-kidney biopsy to predict the mean nephron number estimated from multiple biopsies from the same kidney., Results: A single needle biopsy had a 15% chance and virtual biopsy had a 60% chance of being within 20% of the whole-kidney nephron number. Single needle biopsies could be used to detect differences in nephron number between large cohorts of several hundred subjects., Conclusions: The number of subjects required to accurately detect differences in nephron number between populations can be predicted on the basis of natural intrakidney variability in glomerular density. A single biopsy is insufficient to accurately predict nephron number in individual subjects., (Copyright © 2022 by the American Society of Nephrology.)

Background: Renal-cell carcinoma is the most common kidney cancer and the 13th most common cause of cancer death worldwide. Partial nephrectomy and percutaneous ablation, increasingly utilized to treat small renal masses and preserve renal parenchyma, require precise preoperative imaging interpretation. We sought to develop and evaluate a convolutional neural network (CNN), a type of deep learning (DL) artificial intelligence (AI), to act as a surgical planning aid by determining renal tumor and kidney volumes through segmentation on single-phase CT. Materials and Methods: After Institutional Review Board approval, the CT images of 319 patients were retrospectively analyzed. Two distinct CNNs were developed for (1) bounding cube localization of the right and left hemiabdomen and (2) segmentation of the renal parenchyma and tumor within each bounding cube. Training was performed on a randomly selected cohort of 269 patients. CNN performance was evaluated on a separate cohort of 50 patients using Sorensen-Dice coefficients (which measures the spatial overlap between the manually segmented and neural network-derived segmentations) and Pearson correlation coefficients. Experiments were run on a graphics processing unit-optimized workstation with a single NVIDIA GeForce GTX Titan X (12GB, Maxwell Architecture). Results: Median Dice coefficients for kidney and tumor segmentation were 0.970 and 0.816, respectively; Pearson correlation coefficients between CNN-generated and human-annotated estimates for kidney and tumor volume were 0.998 and 0.993 ( p  < 0.001), respectively. End-to-end trained CNNs were able to perform renal parenchyma and tumor segmentation on a new test case in an average of 5.6 seconds. Conclusions: Initial experience with automated DL AI demonstrates that it is capable of rapidly and accurately segmenting kidneys and renal tumors on single-phase contrast-enhanced CT scans and calculating tumor and renal volumes.

Chronic kidney disease continues to be under recognised and is associated with a significant global health burden and costs. An adverse intrauterine environment may result in a depleted nephron number and an increased risk of chronic kidney disease. Antenatal ultrasound was used to measure the foetal renal parenchymal thickness (RPT), as a novel method to estimate nephron number. Foetal renal artery blood flow was also assessed. This prospective, longitudinal study evaluated the foetal kidneys of 102 appropriately grown and 30 foetal growth-restricted foetuses between 20 and 37 weeks gestational age (GA) to provide vital knowledge on the influences foetal growth restriction has on the developing kidneys. The foetal RPT and renal artery blood flow were measured at least every 4 weeks using ultrasound. The RPT was found to be significantly thinner in growth-restricted foetuses compared to appropriately grown foetuses [likelihood ratio (LR) = 21.06, P ≤ 0.0001] and the difference increases with GA. In foetuses with the same head circumference, a growth-restricted foetus was more likely to have a thinner parenchyma than an appropriately grown foetus (LR = 8.9, P = 0.0028), supporting the principle that growth-restricted foetuses preferentially shunt blood towards the brain. No significant difference was seen in the renal arteries between appropriately grown and growth-restricted foetuses. Measurement of the RPT appears to be a more sensitive measure than current methods. It has the potential to identify infants with a possible reduced nephron endowment allowing for monitoring and interventions to be focused on individuals at a higher risk of developing future hypertension and chronic kidney disease.

The mammalian kidney is a complex organ, requiring the concerted function of up to millions of nephrons. The number of nephrons is constant after nephrogenesis during development, and nephron loss over a life span can lead to susceptibility to acute or chronic kidney disease. New technologies are under development to count individual nephrons in the kidney in vivo. This review outlines these technologies and highlights their relevance to studies of human renal development and disease.

Renal imaging is widely used in the assessment of surrogate markers of nephron mass correlated to renal function. Autopsy studies have tested the validity of various imaging modalities in accurately estimating "true" nephron mass. However, in vivo assessment of nephron mass has been largely limited to kidney volume determination by ultrasonography (US) in pediatric populations. Practical limitations and risks create challenges in incorporating more precise 3D volumetric imaging, like magnetic resonance imaging (MRI), and computed tomography (CT) technologies, compared to US for routine kidney volume assessment in children. Additionally, accounting for structural anomalies such as hydronephrosis when estimating renal parenchymal area in congenital anomalies of the kidney and urinary tract (CAKUT) is important, as it correlates with chronic kidney disease (CKD) progression. 3D imaging using CT and MRI has been shown to be superior to US, which has traditionally relied on 2D measurements to estimate kidney volume using the ellipsoid calculation. Recent innovations using 3D and contrast-enhanced US (CEUS) provide improved accuracy with low risk. Indexing kidney volume to body surface area in children is an important standard that may allow early detection of CKD progression in high-risk populations. This review highlights current understanding of various imaging modalities in assessing nephron mass, discusses applications and limitations, and describes recent advances in the field of imaging and kidney disease. Although renal imaging has been a long-standing, essential tool in assessing kidney disease, innovation and new applications of established technologies provide important tools in the study and management of kidney disease in children.

A horseshoe kidney is a congenital kidney malformation commonly associated with complications such as hydronephrosis, renal calculi, and infections of the renal pelvis. Renal cell carcinoma is extremely rare in a horseshoe kidney; once it occurs, however, it is intractable because of vascular abnormalities. This is especially true in laparoscopic nephron-sparing surgery, even for tumors of <4 cm in diameter. We herein report a case involving an asymptomatic 65-year-old man with an incidental finding of a 4-cm solid mass near the isthmus of a horseshoe kidney on B-mode ultrasonography. Preoperative computed tomography of the renal artery revealed six arterial vessels supplying the affected kidney. Laparoscopic partial nephrectomy was performed. The outcome of this case suggests that laparoscopic nephron-sparing surgery might be a successful treatment method for a horseshoe kidney but that preoperative vessel evaluation and experienced laparoscopic skills are needed.

There are limited reports of laparoscopic nephron sparing surgery (LNSS) in children and none where a 3D model facilitated oncological resection. There are also limited reports discussing the use of cis-retinoic acid in bilateral diffuse hyperplastic perilobar nephrogenic rests (DHPLNR). We report the first case of a 3D model facilitated zero-ischemia LNSS in children and the first following treatment with cis-retinoic acid. The patient was a 3-year-old girl with bilateral DHPLNR who had recurrent disease following standard therapy. She had suspicious lesions in the upper pole of the left kidney. Both were completely excised and histologically described as hyperplastic nephrogenic rests., (Crown Copyright © 2019. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: Nowadays, kidney cancer surgery has been focusing on a patient-tailored management, expanding the indication to nephron-sparing surgery (NSS). Starting from computer tomography images, 3D models can be created, allowing a never experienced before understanding of surgical anatomy. Once obtained the models can be printed or virtually visualized with the aid to assist the surgeon in preoperative planning and simulation or intraoperative navigation. The aim of this systematic review is to assess the preoperative and intraoperative impact of 3D printed and virtual imaging for robotic NSS., Recent Findings: Ten articles were found to meet the inclusion criteria and reviewed. An 'intermediate' score was assessed to the overall articles' quality. A moderate/high risk of bias was recorded for all the studies., Summary: 3D-printed models were considered to be more useful during both preoperative simulations and patients' counseling. These models guaranteed a better comprehension of anatomical structures and surgical procedure. Costs and quality of the materials available represent the two main limits of this developing technology.Instead, in a virtual reality setting the preoperative planning was enhanced by using 3D virtual models in a mixed reality environment. Intraoperatively, the possibility to overlap the 3D model to real anatomy allowed augmented reality procedures. This technology is still a 'newborn' and is constantly evolving, expanding day by day the range of its potential applications.

We give an overview of mathematical models of renal physiology and anatomy with the clinician in mind. Beyond the past focus on issues of local transport mechanisms along the nephron and the urine concentrating mechanism, recent models have brought insight into difficult problems such as renal ischemia (oxygen and CO 2 diffusion in the medulla) or calcium and potassium homeostasis. They have also provided revealing 3D reconstructions of the full trajectories of families of nephrons and collecting ducts through cortex and medulla. The recent appearance of sophisticated whole-kidney models representing nephrons and their associated renal vasculature promises more realistic simulation of renal pathologies and pharmacological treatments in the foreseeable future., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Purpose of Review: Many studies have suggested low nephron endowment at birth contributes to the risk of developing hypertension and chronic kidney disease (CKD) later in life. Loss of nephrons with age and disease is largely a subclinical process. New technologies are needed to count nephrons as glomerular filtration rate (GFR) is a poor surrogate for nephron number., Recent Findings: Cortical volume, glomerular density, and percent globally sclerotic glomeruli are imperfect surrogates for nephron number. The disector-fractionator method is the most accurate method to count nephrons but is limited to autopsy settings. Glomerular density combined with kidney imaging and ultrafiltration coefficient-based methods require a kidney biopsy, and have been applied in living humans (kidney donors). Low nephron number predicts a higher postdonation urine albumin. Contrast-enhanced MRI has detected glomeruli without a biopsy, but so far, not in living humans., Summary: Currently, there is no accurate and well tolerated method for determining nephron number in living humans. A clinically useful method may allow GFR to be replaced by its more relevant determinants: nephron number and single nephron GFR. This could revolutionize nephrology by separating the measurement of chronic disease (nephron loss) from more reversible hemodynamic effects (nephron hyperfiltration/hypofiltration).

Methods for estimating nephron number in a clinical setting may be useful for predicting renal outcomes. This study aimed to establish such a method using unenhanced computed tomography (CT) and biopsy-based stereology. Patients or living kidney donors simultaneously subjected to enhanced and unenhanced CT examinations were randomly assigned to development and validation groups. The enhanced CT-measured arterial phase and the venous phase images of kidneys were regarded as the true values for cortical volume and parenchymal volume, respectively. Linear multiple regression analysis was used to create models for estimating cortical volume using explanatory variables including unenhanced CT-measured parenchymal volume. Nephron number was determined as the product of cortical volume and the glomerular density in biopsies of donors. Five equations for estimating cortical volume were created and verified. In donors, estimated nephron number by unenhanced CT was consistent with that by enhanced CT, with minimal errors in all models (636-655 ± 210-219 vs. 648 ± 224 × 10 3 /kidney). Clinical characteristics combined with parenchymal volume did not improve the equation over parenchymal volume alone. These results support the feasibility of estimating nephron number by a combination of unenhanced CT and biopsy-based stereology, with a possible application for renal disease patients who are often not suitable for contrast media.

Objective: To evaluate the significance of sonographic perinephric fluid collection on the emergent management of patients with acute urinary stone obstruction., Methods: We conducted a prospective study with retrospective analysis. Since January 2016 through July 2017, patients admitted to our tertiary hospital's emergency department (ED) with suspected symptomatic urinary stones underwent ultrasound evaluation. Images were prospectively interpreted by experienced radiologist who analyzed each case for the following imaging features: hydronephrosis, perinephric fluid and urethral stone identification. The presence and measurements of perinephric fluid were re-evaluated by second radiologist who was blinded for the first reader's measurements. Retrospective analysis was conducted to evaluate for an association between perinephric fluid collection and the following outcome variables: need for analgesics, the number of doses of analgesics and the amount of morphine (mg) in the ED, elevation of creatinine levels, hospitalization and need for urological interventions., Results: The need for analgesics, the number of doses of analgesics and the amount of morphine were significantly associated with the presence of perinephric fluid (p < 0.05). The odds ratio for the need for analgesics was 3.8 in the presence of any perinephric fluid, and 8.9 in the presence of moderate/severe perinephric fluid. No other patient outcome variables were found to be significantly associated with the presence of perinephric fluid (p > 0.05)., Conclusions: This study shows a correlation between sonographic evidence of perinephric fluid and more severe pain. Therefore, an emergency physician can consider the evidence of perinephric fluid, in acute urethral stone obstruction, a predictor for more severe pain., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: One major objective of currently available morphometric scores (MS) for renal masses, i.e., R.E.N.A.L., PADUA classification, Centrality-Index, is the prediction of type of surgery (nephron-sparin surgery [NSS] or radical nephrectomy [RN])., Methods: Based on a prospective study protocol, various MS were assigned and calculated for 108 patients undergoing surgical treatment for renal masses at a single academic center. MS calculation was based on preoperative computed-tomography or magnet-resonance-imaging and performed by two independent readers blinded for surgical approach and outcome. Multivariable logistic-regression- and ROC-analyses were performed to assess the predictive value of various MS for surgical approach and the correlation of clinical parameters with nephrectomy type. Furthermore, the association with perioperative outcome parameters was evaluated., Results: None of the tested MS was significantly superior to tumor size alone (area under the curve [AUC]=0.82) in predicting RN, with Centrality-Index showing the best association (AUC=0.88). Based on these findings, a simplified and optimized R.E.N.A.L. Score (optR.E.N.A.L.) was developed with different weightings of included parameters, which did not only show a significantly enhanced association with surgery type (AUC=0.93) than tumor size, but also outperformed all 1st and 2nd generation MS tested in the study cohort. Besides a modest correlation with postoperative change in renal function, no association with perioperative outcome variables was found for all MS including optR.E.N.A.L., Conclusions: optR.E.N.A.L. represents a promising improvement of the preexisting R.E.N.A.L. Score with higher predictive ability for nephrectomy type than established MS and may serve as a benchmarking tool for nephrectomy assessment and comparison of surgical strategies.

Drug-induced kidney toxicity is a significant contributor to acute kidney injury. Nephrotoxic drugs need to be identified during nonclinical testing to highlight potential risk translatable to the intended patient population. When nonclinical kidney toxicity signals arise, scientists and physicians affiliated with clinical trials need to be familiar with commonly encountered drug-induced perturbations in the kidney, terminology, and how these changes relate to clinical risk. Mechanistic and translational toxicologic studies beyond routine histopathology and clinical pathology approaches may be needed to elucidate the pathogenesis and human relevance to inform clinical risk assessment. Investigational studies may help elucidate specific sites of injury within the nephron, the presence of reactive metabolites, mechanisms of membrane transport or tissue distribution, potential drug-drug interactions, or the ability to recover function after drug withdrawal. Cutting-edge techniques such as in vitro alternative platforms, humanized animal models, translational imaging/microscopy or circulating/secretory biomarkers, omics platforms at the interface of genes, proteins, metabolites, or advanced molecular and biochemical approaches provide toxicologists and pathologists with a wide variety of potential experimental modalities to investigate mechanisms of kidney toxicity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To investigate the association of renal elasticity to microscopic findings of nephron hypertrophy and nephrosclerosis., Methods: Patients who underwent renal biopsy were enrolled. Renal elasticity was measured by acoustic radiation force impulse, and nephron size (glomerular volume, non-sclerotic glomerular density, and mean profile tubular area) and nephrosclerosis (globally sclerotic glomeruli and interstitial fibrosis) were estimated. Nephron hypertrophy was indicated by larger glomerular volume, larger tubular area, and lower non-sclerotic glomerular density. Nephrosclerosis was indicated by a higher percentage of globally sclerotic glomeruli and higher severity of fibrosis., Results: Renal elasticity was negatively correlated with glomerular volume (r = - 0.480, P = 0.024) and mean tubular area (r = - 0.469, P = 0.028), but it was not correlated with non-sclerotic glomerular density (r = 0.205, P = 0.359), percentage of globally sclerotic glomeruli (r = 0.057, P = 0.800), and severity of fibrosis (r = 0.014, P = 0.950). In a multiple linear regression analysis, glomerular volume and mean tubular area were independently associated with renal elasticity (std β = - 0.454, P = 0.015 and std β = - 0.577, P = 0.007, respectively)., Conclusion: Renal elasticity was correlated with microstructural findings of nephron hypertrophy. Measuring renal elasticity could help in detecting kidney disease.

Background: Xanthogranulomatous pyelonephritis (XGP) is an uncommon infectious disease of the kidney known to mimic other renal maladies. A rare presentation of this uncommon disease is spontaneous renal hemorrhage (SRH)., Case Presentation: We report a case of XGP in a 58 year old woman who presented with abdominal pain, hematuria, and radiating left flank pain. CT scan was felt to be consistent with perirenal hemorrhage abutting a fat-containing renal mass. The patient was eventually taken to surgery for left partial nephrectomy. Pathology report returned as XGP, and the patient has no complications from this disease process at 8 month follow up., Conclusion: Our search of the literature shows XGP presenting as SRH to be a rare clinical entity. Furthermore, this is the first such case managed with a nephron-sparing approach. The "great imitator" XGP should be added to the differential for patients presenting with spontaneous renal hemorrhage.

Nephron-sparing surgery, especially through a minimally invasive approach, is increasingly being performed for incidentally detected renal masses with excellent outcomes. Tumors in central location remain a surgical challenge during nephron-sparing surgery. In this chapter, we discuss the minimally invasive management of these tumors, which include complex hilar tumors and endophytic central tumors, with a focus on surgical technique. The key to management of these tumors is to maintain good preoperative hydration, achieving adequate exposure of tumor, and the use of intraoperative ultrasound to plan the resection plane. Individual vessels may be ligated as they enter close to the tumor. Careful renorrhaphy is essential, especially in hilar tumors, which have major blood vessels at the base of the tumor. Selective use of near infrared fluorescence imaging, on-demand ischemia, early unclamping, enucleoresection techniques, and intracorporeal hypothermia may help minimize, or reduce the effect of warm ischemia.

Low nephron number has been shown to be a risk factor for hypertension (HTN) in adulthood. Kidney volume may serve as a surrogate marker for nephron mass. The relationship between kidney volume and ambulatory blood pressure (BP) in the pediatric population is not known. A retrospective chart review of children younger than 21 years who were evaluated for HTN was performed. Twenty-four-hour BP and ultrasonography data were obtained. Multiple regression was used to examine associations between BP and kidney volume. Of 84 children (mean age 13.87 years, 72.6% males), 54 had HTN. Systolic BP index during the awake, sleep, and 24-hour periods (all P≤.05) was found to be positively correlated with total kidney volume. Greater total kidney volume was found to be a positive predictor of 24-hour and sleep systolic index (P≤.05). It failed to serve as a predictor of HTN, pre-HTN, or white-coat HTN. Contrary to expectation, total kidney volume was positively associated with systolic BP indices., (©2016 Wiley Periodicals, Inc.)

Background No non-invasive method of observing renal microcirculation in vivo has been established as yet. Although angiography is considered to be ideally suited for the purpose, conventional X-rays cannot be used to image structures smaller than 100 µm. Purpose To develop a method for visualizing the renal arterioles, glomeruli, and proximal tubules of rats in vivo making use of synchrotron radiation. Material and Methods Male Wistar rats were anesthetized, and a catheter was inserted via laparotomy into the abdominal aorta with its tip placed above the renal arteries. The rats were paralyzed with a neuromuscular blocking agent and mechanically ventilated. An inorganic iodine contrast medium was injected via the catheter. The SR derived X-rays transmitted through the subjects were recorded with a CCD camera. Two-dimensional images with a pixel size of 9 µm were obtained. The exposure time was fixed at 50 ms, with a maximum acquisition rate of three images/s. Results Renal arterioles as small as 18 µm in diameter, glomeruli with an average diameter of 173 ± 21 µm, as well as proximal tubules, were clearly visualized. In addition, glomerular density at the peripheral renal cortex was measurable. Conclusion Rat renal microcirculation could be successfully observed in real-time, without exteriorization of the kidney in this study.

Background: Premature and/or intrauterine growth-restricted neonates have an increased risk of developing postnatal renal injuries in later life. Studies on renal physiology in these neonates at a corrected age of 30-40 days are scarce and mostly relate to preterm infants. The data from these studies often lack the results of correlation analyses between biochemical parameters and nephron number-data which could provide additional insight and/or improve recognition of individuals at higher risk of renal failure., Methods: Urinary total protein and albumin levels and N-acetyl-β-D-glucosaminidase and cathepsin B activity were evaluated in preterm and intrauterine growth-restricted infants at a corrected age of 30-40 days and compared to data from a healthy control neonate population. The data were then associated with predominant susceptibility factors of renal damage related to low nephron number, such as gestational age, birth weight, total renal volume and renal cortex volume., Results: Compared to the control neonate population, we found significantly increased levels of all biochemical parameters tested in the intrauterine growth-restricted neonates, whereas in the preterm infants we observed a significant increase in cathepsin B activity, total protein level and, to a lesser extent, albumin level. Cathepsin B activity showed a significant, strong and inverse correlation with all surrogate markers of nephron number and was also strongly and positively correlated with urinary albumin level., Conclusions: At this postnatal age, we found that lower nephron number in low birth weight neonates was associated to tubular impairment/injury that could be concurrent with a dysfunction of glomerular permeability. Urinary cathepsin B activity may be a candidate marker for the early prediction of renal susceptibility to damage in low birth weight neonates.

MRI can provide excellent detail of renal structure and function. Recently, novel MR contrast mechanisms and imaging tools have been developed to evaluate microscopic kidney structures including the tubules and glomeruli. Quantitative MRI can assess local tubular function and is able to determine the concentrating mechanism of the kidney noninvasively in real time. Measuring single nephron function is now a near possibility. In parallel to advancing imaging techniques for kidney microstructure is a need to carefully understand the relationship between the local source of MRI contrast and the underlying physiological change. The development of these imaging markers can impact the accurate diagnosis and treatment of kidney disease. This study reviews the novel tools to examine kidney microstructure and local function and demonstrates the application of these methods in renal pathophysiology., (Copyright © 2016 the American Physiological Society.)

Minimally invasive partial nephrectomy (MIPN) is now considered the procedure of choice for small renal masses largely based on functional advantages over traditional open surgery. Lack of haptic feedback, the need for spatial understanding of tumor borders, and advanced operative techniques to minimize ischemia time or achieve zero-ischemia PN are among factors that make MIPN a technically demanding operation with a steep learning curve for inexperienced surgeons. Surgical simulation has emerged as a useful training adjunct in residency programs to facilitate the acquisition of these complex operative skills in the setting of restricted work hours and limited operating room time and autonomy. However, the majority of available surgical simulators focus on basic surgical skills, and procedure-specific simulation is needed for optimal surgical training. Advances in 3-dimensional (3-D) imaging have also enhanced the surgeon's ability to localize tumors intraoperatively. This article focuses on recent procedure-specific simulation models for laparoscopic and robotic-assisted PN and advanced 3-D imaging techniques as part of pre- and some cases, intraoperative surgical planning.

The progression to 7 Tesla (7 T) magnetic resonance imaging (MRI) yields promises of substantial increase in signal-to-noise (SNR) ratio. This increase can be traded off to increase image spatial resolution or to decrease acquisition time. However, renal 7 T MRI remains challenging due to inhomogeneity of the radiofrequency field and due to specific absorption rate (SAR) constraints. A number of studies has been published in the field of renal 7 T imaging. While the focus initially was on anatomic imaging and renal MR angiography, later studies have explored renal functional imaging. Although anatomic imaging remains somewhat limited by inhomogeneous excitation and SAR constraints, functional imaging results are promising. The increased SNR at 7 T has been particularly advantageous for blood oxygen level-dependent and arterial spin labelling MRI, as well as sodium MR imaging, thanks to changes in field-strength-dependent magnetic properties. Here, we provide an overview of the currently available literature on renal 7 T MRI. In addition, we provide a brief overview of challenges and opportunities in renal 7 T MR imaging.

The increased use of abdominal cross-sectional imaging has contributed to a greater detection of incidental small renal masses. Treatment options for localized disease renal cell carcinoma include radical nephrectomy or partial nephrectomy (PN), the former being preferred for treatment of early-stage tumors. The most adopted technique for follow-up imaging is contrast-enhanced computed tomography (CT), whose findings can cause uncertainty and unnecessary repetition of examinations. Our purpose is to describe CT findings after PN and to describe evolution in time of such images.

This review examines studies of intra-operative contrast-enhanced ultrasound (CEUS) and its emerging role and advantages in robotic-assisted nephron-sparing surgery. Contrast-enhanced ultrasound is a technology that combines the use of second-generation contrast agents consisting of microbubbles with existent ultrasound techniques. Until now, this novel technology has aided surgeons with procedures involving the liver. However, with recent advances in the CEUS technique and the introduction of robotics in nephron-sparing surgery, CEUS has proven to be efficacious in answering several clinical questions with respect to the kidneys. In addition, the introduction of the microbubble-based contrast agents has increased the image quality and signal uptake by the ultrasound probe. This has led to better, enhanced scanning of the macro and microvasculature of the kidneys, making CEUS a powerful diagnostic modality. This imaging method is capable of further lowering the learning curve and warm ischemia time (WIT) during robotic-assisted nephron-sparing surgery, with its increased level of capillary perfusion and imaging. CEUS has the potential to increase the sensitivity and specificity of intra-operative images, and can significantly improve the outcome of robotic-assisted nephron-sparing surgery by increasing the precision and diagnostic insight of the surgeon. The purpose of this article is to review the practical and potential uses of CEUS as an intra-operative imaging technique during robotic-assisted nephron-sparing surgery.

Background: Transplanted nephron mass is an important determinant of long-term allograft survival, but accurate assessment before organ retrieval is challenging. Newer radiologic imaging techniques allow for better determination of total kidney and cortical volumes., Methods: Using volume measurements reconstructed from magnetic resonance or computed tomography imaging from living donor candidates, we characterized total kidney (n=312) and cortical volumes (n=236) according to sex, age, weight, height, body mass index (BMI), and body surface area (BSA)., Results: The mean cortical volume was 204 mL (range 105-355 mL) with no significant differences between left and right cortical volumes. The degree to which existing anthropomorphic surrogates predict nephron mass was quantified, and a diligent attempt was made to derive a better surrogate model for nephron mass. Cortical volumes were strongly associated with sex and BSA, but not with weight, height, or BMI. Four prediction models for cortical volume constructed using combinations of age, sex, race, weight, and height were compared with models including either BSA or BMI., Conclusions: Among existing surrogate measures, BSA was superior to BMI in predicting renal cortical volume. We were able to construct a statistically superior proxy for cortical volume, but whether relevant improvements in predictive accuracy could be gained needs further evaluation in a larger population.

Introduction: The main problem in nephron sparing surgery (NSS) is to preserve renal tumors oncological purity during the removal of the tumor with a margin of macroscopically unchanged kidney tissue while keeping the largest possible amount of normal parenchyma of the operated kidney. The development of imaging techniques, in particular IGT (Image Guided Therapy) allows precise imaging of the surgical field and, therefore, is essential in improving the effectiveness of NSS (increase of nephron sparing with the optimal radicality)., Aim: The aim of this study was to develop a method of the three-dimensional (3D) imaging of the kidney tumor and its lodge in the operated kidney using 3D laser scanner during NSS procedure. Additionally, the animal model of visualization was developed., Material and Methods: The porcine kidney model was used to test the set built up with HD cameras and linear laser scanner connected to a laptop with graphic software (David Laser Scanner, Germany) showing the surface of the kidney and the lodge after removal the chunk of renal parenchyma. Additionally, the visualization and reconstruction was performed on animal porcine model. Moreover, 5 patients (3 women, 2 men) aged from 37 to 68 years (mean 56), diagnosed with kidney tumors in CT scans with a diameter of 3.7-6.9 cm (mean 4.9) were operated in our Department this year, scanning the surface during the treatment with the kidney tumor and kidney tumor after it is removed with a margin of renal tissue. In one case, the lodge of removed tumor was scanned. Dimensions in 3D reconstruction images of laser scans in the study of animal model and the images obtained intraoperatively were compared with the dimensions evaluated during preoperative CT scans, intraoperative measurements., Results: Three-dimensional imaging laser scanner operating field loge resected tumor and the tumor on the kidney of animal models and during NSS treatments for patients with kidney tumors is possible in real time with an accuracy of -2 mm do +9 mm (+/- 3 mm). The duration of data acquisition by laser scanner and obtain three-dimensional image of the operating field takes an average of 13 seconds +/- 2 seconds. Movements associated with breathing and heart rate did not affect on the quality of the reconstruction. The imposition of the scanned surface texture occurs in real time, allowing you to identify renal parenchymal structures such as renal cortex, pyramids, pyelo-calices complex., Conclusions: Imaging control of NSS procedures is possible in animal models and in real time intraoperatively. The comparison of tumor size and the tumor lodge obtained in preoperative CT scans with the measurements during NSS procedure provide the surgeon to assess the extent of macroscopic estimation of the resection. This procedure helps the surgeon in obtaining oncological radicality with saving as much normal tissue kidney as possible. Performance of the imaging methods should be evaluated on a larger group of patients with kidney tumors eligible for NSS treatment.

Objective: To determine by meta-analysis whether serum procalcitonin (PCT) is a useful marker of acute renal parenchymal involvement (RPI) in children with culture-proven urinary tract infection (UTI), as diagnosed by acute-phase DMSA (Tc-99m dimercaptosuccinic acid) renal scintigraphy., Study Design: We searched PubMed and the Cochrane Central Register of Controlled Trials for prospective studies involving children with culture-proven UTIs. Additional eligibility criteria were measurement of serum PCT at presentation and performance of DMSA scintigraphy within 14 days., Results: Overall, 10 studies eligible for inclusion, involving a total of 627 children, were identified. Half of these studies evaluated children with a first episode of UTI; 8 involved children with febrile UTIs. Using a cutoff value of 0.5 to 0.6 ng/mL, the pooled diagnostic odds ratio of serum PCT for UTI with RPI was 14.25 (95% confidence interval, 4.70 to 43.23). High statistical between-study heterogeneity that could mainly be attributed to 2 studies was observed. The remaining 8 studies uniformly favored PCT use., Conclusions: In children with culture-proven UTI, a serum PCT value >0.5 ng/mL predicts reasonably well the presence of RPI, as evidenced by DMSA scintigraphy. PCT may aid in the identification of children with UTI, necessitating more intense evaluation and management.

Objective: The purpose of this article is to show the CT findings of the various postoperative changes, surgical complications, and tumor recurrence after nephron-sparing surgery for the treatment of renal tumors., Conclusion: Familiarity with the various postoperative changes after nephron-sparing surgery may help radiologists in differentiating these changes from tumor recurrence or surgical complications.

Objectives: To compare changes in renal function following nephron-sparing surgery (NSS) using tissue adhesive only versus NSS using standard suturing technique, as measured by quantitative SPECT of 99m Tc-dimercaptosuccinic acid uptake by the kidney (QDMSA)., Materials and Methods: QDMSA was done before and 3-6 mo after the operation in 32 patients who underwent standard suturing technique and in 24 patients in whom tissue adhesive sealant (19 with albumin glutaraldehyde tissue adhesive [BioGlue]; 5 with CoSeal) was used to close the parenchymal defect. Individual kidney uptake was measured and retrospectively compared between the two groups., Results: Average tumor diameter was 3.4cm (range: 2.2-6) in the suture group and 3.56 (range: 1.7-6) in the tissue sealant group. In the tissue sealant group following surgery, we observed an average individual renal function loss of 11.49% compared with the suture group in whom an average individual renal function loss of 20.36% (p = 0.02) was measured by 99m Tc-DMSA., Conclusions: The use of tissue sealant to close the parenchymal defect during NSS demonstrated a statistically significant advantage in reducing functioning renal loss as measured by the absolute uptake of QDMSA. Further clinical studies are required to establish the role of tissue sealants in NSS., (European Association of Urology.)

Recent advances in molecular genetics and immunocytochemistry have clarified the cell of origin in many renal disorders. Several renal disorders are thought to involve specific segments of the nephron. Renin-secreting tumours arise from juxtaglomerular cells. Clear cell and papillary renal cell carcinoma (RCC) recapitulate the epithelium of the proximal tubules. Oncocytoma and chromophobe RCC differentiate towards Type A and Type B intercalated cells of the cortical collecting duct, respectively. Medullary collecting ducts are the target sites for the development of autosomal recessive polycystic kidney disease, collecting duct carcinoma and medullary carcinoma. Renal papillae are susceptible to unique changes such as necrosis or papillitis. The purpose of our article is threefold: to illustrate the imaging findings of renal disorders that show segmental involvement of the nephron, to describe proximal and distal nephron disorders and to correlate imaging findings of some entities with histopathological features.

The three-dimensional architecture of nephrons in situ and their interrelationship with other nephrons are difficult to visualize by microscopic methods. The present study uses microcomputed X-ray tomography (micro-CT) to visualize intact nephrons in situ. Rat kidneys were perfusion-fixed with buffered formalin and their vasculature was subsequently perfused with radiopaque silicone. Cortical tissue was stained en bloc with osmium tetroxide, embedded in plastic, scanned, and reconstructed at voxel resolutions of 6, 2, and 1 microm. At 6 microm resolution, large blood vessels and glomeruli could be visualized but nephrons and their lumens were small and difficult to visualize. Optimal images were obtained using a synchrotron radiation source at 2 microm resolution where nephron components could be identified, correlated with histological sections, and traced. Proximal tubules had large diameters and opaque walls, whereas distal tubules, connecting tubules, and collecting ducts had smaller diameters and less opaque walls. Blood vessels could be distinguished from nephrons by the luminal presence of radiopaque silicone. Proximal tubules were three times longer than distal tubules. Proximal and distal tubules were tightly coiled in the outer cortex but were loosely coiled in the middle and inner cortex. The connecting tubules had the narrowest diameters of the tubules and converged to form arcades that paralleled the radial vessels as they extended to the outer cortex. These results illustrate a potential use of micro-CT to obtain three-dimensional information about nephron architecture and nephron interrelationships, which could be useful in evaluating experimental tubular hypertrophy, atrophy, and necrosis.

The aim of this study was to evaluate the potential of multiphasic multidetector-row CT (MDCT) in the detection and staging of transitional cell carcinomas (TCC) of the upper urinary tract. We performed a retrospective chart review of 39 consecutive patients with 41 histologically verified TCC of the renal pelvis and/or the ureter. The urinary tract was examined using MDCT performing unenhanced and contrast-enhanced scans during the corticomedullary (CMP), nephrographic (NP) and pyelographic phase (PP). Tumors were staged according to the TNM classification. MDCT and histopathological findings were correlated. The attenuation of the lesions was documented in Hounsfield units (HU). In MDCT, all 41 TCC--including two multicentric TCC--were detected. TCC confined to the organ (stage 0a-II) was correctly staged in 28/29 tumors (96.6%). Stage III-IV tumors were correctly staged in 8/12 patients (66.6%). Overall, MDCT was accurate in predicting pathologic TNM stage in 36/41 upper urinary tract TCC (87.8%). There was no significant difference of mean attenuation of TCC between CMP, NP and PP (P > 0.05). MDCT with its high spatial and temporal resolution is an accurate tool for detection TCC of the upper urinary tract, with 87.8% accuracy in predicting its stage.

Purpose: Partial nephrectomy for hilar tumors represents a technical challenge not only for laparoscopic, but also for open surgeons. We report the technical feasibility and perioperative outcomes of laparoscopic partial nephrectomy (LPN) for hilar tumors., Materials and Methods: Between January 2001 and September 2004, 25 of 362 patients (6.9%) undergoing LPN for tumor, as performed by a single surgeon, had a hilar tumor. We defined hilar tumor as a tumor located in the renal hilum that was demonstrated to be in actual physical contact with the renal artery and/or renal vein on preoperative 3-dimensional computerized tomography. En bloc hilar clamping with cold excision of the tumor, including its delicate mobilization from the renal vessels, followed by sutured renal reconstruction was performed routinely., Results: Laparoscopic surgery was successful in all cases without any open conversions or operative re-interventions. Mean tumor size was 3.7 cm (range 1 to 10.3), 4 patients (16%) had a solitary kidney and the indication for LPN was imperative in 10 patients (40%). Pelvicaliceal repair was performed in 22 patients (88%), mean warm ischemia time was 36.4 minutes (range 27 to 48), mean blood loss was 231 cc (range 50 to 900), mean total operative time was 3.6 hours (range 2 to 5) and mean hospital stay was 3.5 days (range 1.5 to 6.7). Histopathology confirmed renal cell carcinoma in 17 patients (68%), of whom all had negative margins. In 2002 or earlier hemorrhagic complications occurred in 3 patients (12%). No kidney was lost for technical reasons., Conclusions: LPN can be performed in select patients with a hilar tumor. The technical feasibility reported further extends the scope of LPN. To our knowledge the initial experience in the literature is reported.

Objective: To evaluate selective intra-arterial 3-dimensional computed tomography (3D-CT) angiography as a tool for the preoperative evaluation of nephron-sparing surgery (NSS)., Methods: Twenty-three patients with renal cell carcinoma indicating NSS underwent selective intrarenal 3D-CT angiography. The time-lapse dual-phase technique was used for simultaneous vascular and urographic visualization. The 3D images were created by the shaded volume-rendering method. The CT attenuation of target structures was measured for quantitative evaluation. The 3D images were visually evaluated for the renal artery, vein, and collecting system using a grading system. Results were statistically analyzed., Results: The 3D-CT angiography depicted the intrarenal branches of the renal artery and vein and the whole collecting system in most patients. Visualization of the renal artery was significantly correlated to its CT attenuation. Visualization of the renal vein was correlated to its CT attenuation adjusted by the surrounding renal parenchyma., Conclusion: Selective intra-arterial 3D-CT angiography allows the detailed visualization of intrarenal structures.

Rationale and Objectives: Acute cyclosporine (CsA) nephrotoxicity cannot be easily differentiated from other renal parenchymal complications, such as acute tubular necrosis (ATN), that cause renal function impairment at the early posttransplantation period. The purpose of this study was to differentiate acute CsA nephrotoxicity from ATN using enalaprilat renal scintigraphy in rats., Methods: Twenty-six rats were divided into 4 experimental groups: CsA group, who were treated with CsA (50 mg/kg/d) for 2 days; ATN group, who received clamping of both renal arteries for 45 minutes; vehicle group, who were treated with olive oil (1 mL/kg/d) for 2 days; and sham-operated group, who received the same surgical procedure as ATN group without clamping of renal arteries. The baseline study was performed with 300 microCi of technetium-99m diethylenetriaminepentaacetic acid and enalaprilat scintigraphy with 2 mCi of technetium-99m diethylenetriaminepentaacetic acid 5 minutes after intravenous enalaprilat injection (30 microg/kg). The changes of renogram grade and the renal function indices such as T(max), T(1/2), residual cortical activity, and mean transit time between 2 studies were analyzed. Immediately after renal scintigraphy, blood urea nitrogen and serum creatinine levels were measured and renal tissues stained by periodic acid Schiff reaction were examined in each group., Results: Blood urea nitrogen and serum creatinine levels in the CsA and ATN groups were higher than their control groups (P < 0.05). Histologic study revealed severe ischemic necrosis of tubular epithelium in ATN group, but the other groups remained with essentially normal morphology. After enalaprilat injection, renal function indices became improved in CsA group, whereas they deteriorated in ATN group. The renogram grade was decreased in CsA group and increased or unchanged in ATN group after enalaprilat injection. The T(max), residual cortical activity, and mean transit time ratio were statistically different between the 2 groups on enalaprilat study (P < 0.05)., Conclusions: These results suggest that enalaprilat renal scintigraphy could be used clinically in differentiating acute CsA nephrotoxicity from ATN after renal transplantation.

We report on a 17-year-old white woman with multiple bilateral renal angiomyolipomas (AMLs) in the absence of tuberous sclerosis. Multiple hyperdense lesions were detected in both kidneys by sonography. A computed tomography (CT) scan confirmed mainly fatty tissue. Sparing as much functional tissue as possible, eight AMLs of the right kidney were resected. The largest removed tumour measured 7 x 4 x 2.4 cm. Renal function was completely preserved. An AML is a benign, generally unilateral renal tumour. Treatment is necessary in cases of flank pain, spontaneous bleeding, obstruction by tumour growth and tumours exceeding 4 cm in diameter. Patients who present are often symptomatic due to pain, retroperitoneal bleeding or haematuria. An AML occurs either sporadically or in association with tuberous sclerosis. Bilateral or unilateral multiple AMLs are rare.

The feasibility of deconvolution depends on many factors, but the technique cannot provide accurate results if the maximal transit time (MaxTT) is longer than the duration of the acquisition. This study evaluated whether, on the basis of a 20 min renogram, it is possible to predict in which cases the MaxTT will exceed 20 min. Renograms of various shapes were simulated by convolution of a plasma disappearance curve and various created retention functions with a mean transit time (MTT) ranging from 3 to 23 min. The values of MaxTT were then derived from the created curves and compared to three parameters of transit measured on the renograms: the time to reach the maximum of the curve (Tmax), the output efficiency at 20 min (OE20), and the normalized residual activity at 20 min (NORA20). The proportion of retention functions (n=390) with MaxTT>20 min increased with increasing Tmax (e.g. 9% for 6< or =Tmax<10 min, and 34% for 11< or =Tmax<15 min), increasing NORA20 (e.g. 20% for 1.4< or =NORA20<3.0, and 84% for 3.0< or =NORA20<5.0) and decreasing OE20 (19% for 50%

Purpose: To correlate the enhancement pattern of double-phase helical computed tomography (CT) of small renal parenchymal neoplasms with pathologic findings and tumor angiogenesis, and evaluate whether the enhancement pattern would be useful in differentiating the histomorphologic types of small renal parenchymal neoplasms., Materials and Methods: Double-phase helical CT (5 mm slice) of the corticomedullary phase (CMP) and late nephrographic phase (NP) was performed in 40 surgically resected renal neoplasms <3.5 cm. The patterns of CT attenuation value and homogeneity were correlated with the subtypes of neoplasms, microvessel density, and the existence of intratumoral necrosis or hemorrhage., Results: Clear cell renal cell carcinomas (RCC) (n = 29) showed a peak attenuation value in the CMP of >100 HU [Hounsfield units]. Chromophobe cell RCC (n = 2) showed a peak attenuation value in the CMP of <100 HU. Papillary RCC (n = 5) showed a gradual enhancement with the attenuation value in the CMP of <100 HU. However oncocytomas (n = 2) and metanephric adenomas (n = 2) also showed patterns similar to these subtypes of RCC. The degree of enhancement in the CMP correlated with microvessel density (r = 0.87). All tumors with an homogeneous enhancement pattern did not show necrosis or hemorrhage on histologic specimen., Conclusion: The enhancement pattern in double-phase helical CT was different among the subtypes of RCC, and correlated with microvessel density or the existence of intratumoral necrosis or hemorrhage. However it did not differentiate between RCC and other solid tumors.

Purpose: To evaluate progressive US changes in the kidneys of patients with familial juvenile nephronophthisis (NPH), an autosomal recessive progressive kidney disease with polyuria, polydipsia, anemia and growth retardation., Material and Methods: The data from 29 US investigations of 5 boys and 2 girls comprised findings relating to kidney size, echogenicity of the kidney parenchyma, visualization of the corticomedullary junction, and the parameters of renal cysts., Results: In the early stages of NPH, when the serum creatinine values were between 134 and 370 micromol/l, the corticomedullary differentiation was weak in 6 patients, the echogenicity of the kidney parenchyma was equal to or greater than that of the liver in 5 patients, and 6 patients had developed renal cysts. The findings became more intensive with the progression of NPH. The size of the kidneys remained normal in 4 patients., Conclusion: Renal US reveals characteristic changes already in the early stages of NPH and should therefore be an important part of the diagnostics of NPH because no specific diagnostic test is as yet available.

De novo renal cell carcinoma in a renal allograft is rare and has special implications in renal transplant recipients. We describe a patient with a renal allograft who developed a de novo renal cell carcinoma in the functioning renal allograft 258 months after transplantation. The patient underwent enucleation of the tumor because preoperative MRI showed it was well-encapsulated. A DNA banding study showed that the tumor originated from the donor. Indications for conservative renal surgery in renal cell carcinoma have been increasing. Accordingly, 1 option in the treatment of de novo renal cell carcinoma in a functioning renal allograft is enucleation as a method of nephron sparing surgery.

Autosomal recessive polycystic kidney disease, autosomal dominant polycystic disease, and glomerulocystic disease may all appear in the perinatal period as bilaterally enlarged echogenic kidneys. Current ultrasonographic equipment can better demonstrate the underlying pathologic state and assist in the differentiation of these conditions. The primary abnormality in autosomal recessive polycystic kidney disease is at the level of the collecting ducts, which are dilated and saccular. The nephrons remain normal. These dilated ectatic tubules are seen in their usual distribution as a radial array, with major ducts being perpendicular to the renal capsule, in both the renal cortex and the medulla. The peripheral renal cortex does not normally contain collecting ducts and remains unaffected in patients with mild disease. Autosomal dominant polycystic disease is characterized by cystic changes involving both the nephron and the collecting ducts. The nephron may become cystic at any point. Multiple discrete cysts of varying sizes are seen in both the renal cortex and the medulla in the severely affected infant. Subcapsular cysts are seen regularly. Glomerulocystic disease is an unusual sporadic condition characterized by the cystic dilation of the space of Bowman and the proximal convoluted tubule. On ultrasonographic examination tiny, isolated cysts, usually smaller than those occurring in autosomal dominant polycystic kidney disease, are seen in the echogenic renal cortex and may extend to the periphery of the kidney. No cysts are seen in the renal medulla. Correlation between pathologic findings and sonographic images is of value in correctly diagnosing these conditions.

Renal involvement in von Hippel-Lindau (VHL) disease has emerged as the most prevalent cause of death in this hereditary disorder. In a group of 43 VHL patients (23 unrelated families) with renal lesions we examined whether severity of renal disease is affected by parental inheritance and VHL subtype (1, without pheochromocytoma; 2, with pheochromocytoma). We also tested whether and how nephron-sparing surgery could be applied. Renal involvement comprised multiple cysts and bilateral and multifocal carcinomas (RCC) which were detected by screening in 38 patients, at 30.5 (14 to 62) years of age. The severity of the renal disease was similar in VHL type 1 (79% of the pedigrees) and 2 (21%). It was not influenced by the sex of the carrier. Twenty-nine patients were operated on at a mean age of 33.6 years: 21 patients (28 kidneys or 61% of all operated kidneys) underwent nephron-sparing surgery, 4 had complete ablation of involved kidneys and thus required dialysis, 3 had uninephrectomy and 1 had cyst fenestration. Vascular thrombosis was the most severe early complication. It occurred in 4 of 9 kidneys treated by ex vivo surgery. During a median follow-up of 29 months, local recurrence occurred in 5 of 21 (24%) patients treated by nephron-sparing surgery, whereas 2 developed metastasis. Chronic renal failure (creatinine > 120 mumol/liter) affected 11 patients; in 9 of them, it was due to sequelae of surgery. In conclusion, screening of RCC and nephron-sparing surgery are of value in VHL patients. However, indications of ex vivo surgery should be drastically restricted and renal sequelae are not uncommon. Renal followup is required because of the risk of recurrence.

In 50 patients with obstructive uropathy, nuclear imaging supplementary to excretory urography did not improve the detection of obstruction or the determination of the site or etiology of the lesion. However, rapid sequential radionuclide images showed decreased renal perfusion in 64%, more frequently than did an obstructive nephrogram (40%); this finding appeared to occur with more severe degrees of obstruction. Functional impairment of the obstructed kidney was demonstrated more often with 131I Hippuran (o-iodohippurate sodium) (91%) than with 99mTc glucoheptonate (68%) or excretory urography (66%). Neither nuclear nor urographic studies could predict the degree of functional recovery of the kidney until the increased intrapelvic pressures was relieved.