[Imaging after kidney transplantation in childhood and adolescence]. / Bildgebung nach Nierentransplantation im Kindes- und Jugendalter.

The ultrasound (US) examination is the most important imaging procedure in the clinical care of children with chronic kidney disease, the assessment before kidney transplantation and in the acute and chronic phase after successful kidney transplantation. In trained hands, particularly with experience in Doppler sonography, US ensures that vascular complications, such as occlusions, thrombosis, stenosis as well as non-vascular complications, e.g., urinary tract dilatation, abscesses, hematomas, urine leaks or lymphoceles, are cost-effectively and rapidly diagnosed at any time. For the diagnosis of acute rejection, the US signs in the intraindividual course are only suggestive, but not specific. The gold standard for the diagnosis of acute rejection is a kidney biopsy. In these cases, US serves to exclude other causes. The use of multimodal techniques, various Doppler techniques and microvascular procedures, such as superb microvascular imaging (SMI) or B­flow and contrast-enhanced ultrasonography (CEUS), optimizes the imaging in the context of transplantations in children. Magnetic resonance imaging with diffusion-weighed imaging (DWI), magnetic resonance angiography (MRA) and magnetic resonance urography (MRU) as well as functional MRU (fMRU) performed with the administration of gadolinium-containing contrast agents, are part of the extended diagnostics and possibly necessary for surgical planning in the early phase after kidney transplantation and for long-term assessment after transplantation. Excretory urography is associated with ionizing radiation and intravenous administration of iodine-containing contrast medium and is obsolete in children. Computed tomography (CT) using age-adapted and weight-adapted dose protocols is an alternative in emergencies if MRI is not available.

Primary URECs: a source to better understand the pathology of renal tubular epithelia in pediatric hereditary cystic kidney diseases.

BACKGROUND: In pediatric hereditary cystic kidney diseases, epithelial cell defects mostly result from rare, autosomal recessively inherited pathogenic variants in genes encoding proteins of the cilia-centrosome complex. Consequences of individual gene variants on epithelial function are often difficult to predict and can furthermore depend on the patient's genetic background. Here, we studied urine-derived renal tubular epithelial cells (URECs) from genetically determined, pediatric cohorts of different hereditary cystic kidney diseases, comprising autosomal recessive polycystic kidney disease, nephronophthisis (NPH) and the Bardet Biedl syndrome (BBS). UREC characteristics and behavior in epithelial function-related 3D cell culture were compared in order to identify gene and variant-specific properties and to determine aspects of epithelial (cell) dysfunction. RESULTS: UREC preparations from patients (19) and healthy controls (39) were studied in a qualitative and quantitative manner using primary cells cultured for up-to 21 days. In patients with biallelic pathogenic variants in PKHD1 or NPHP genes, we were able to receive satisfactory amounts of URECs of reproducible quality. In BBS patients, UREC yield was lower and more dependent on the individual genotype. In contrast, in UREC preparations derived from healthy controls, no predictable and satisfactory outcome could be established. Considering cell proliferation, tubular origin and epithelial properties in 2D/3D culture conditions, we observed distinct and reproducible epithelial properties of URECs. In particular, the cells from patients carrying PKHD1 variants were characterized by a high incidence of defective morphogenesis of monolayered spheroids-a property proposed to be suitable for corrective intervention. Furthermore, we explored different ways to generate reference cell lines for both-patients and healthy controls-in order to eliminate restrictions in cell number and availability of primary URECs. CONCLUSIONS: Ex vivo 3D cell culture of primary URECs represents a valuable, non-invasive source to evaluate epithelial cell function in kidney diseases and as such helps to elucidate the functional consequences of rare genetic disorders. In combination with genetically defined control cell lines to be generated in the future, the cultivation of primary URECs could become a relevant tool for testing personalized treatment of epithelial dysfunction in patients with hereditary cystic kidney disease.

The diagnostic value of Doppler ultrasonography after pediatric kidney transplantation.

Ultrasonography (US) plays a major diagnostic role in the pre- and post-transplant evaluation of recipient and donor. In most cases, US remains the only necessary imaging modality. After pediatric kidney transplantation, US can ensure immediate bedside diagnosis of vessel patency and possible postoperative non-vascular complications. Criteria for US diagnosis of kidney vessel thrombosis and stenosis in the transplant will be presented. Non-vascular complications after kidney transplantation include hydronephrosis, hematoma, lymphocele, and abscess. US can detect suggestive, but nevertheless non-specific, acute signs (sudden increase in volume and elevated resistive index), and chronic rejection, which therefore remains a histological diagnosis. US is of little or no help in detection of tubular necrosis or drug toxicity, but it can exclude other differential diagnoses. This educational review provides a practical and systematic approach to a multimodal US investigation of the kidney transplant. It includes a short overview on possible indications for contrast-enhanced ultrasonography (CEUS) in children after kidney transplantation.

Contrast-enhanced ultrasound of the spleen, pancreas and gallbladder in children.

Gray-scale and color/power Doppler ultrasound (US) are the first-line imaging modalities to evaluate the spleen, gallbladder and pancreas in children. The increasing use of contrast-enhanced ultrasound (CEUS) as a reliable and safe method to evaluate liver lesions in the pediatric population promises potential for imaging other internal organs. Although CEUS applications of the spleen, gallbladder and pancreas have been well described in adults, they have not been fully explored in children. In this manuscript, we present an overview of the applications of CEUS for normal variants and diseases affecting the spleen, gallbladder and pancreas. We highlight a variety of cases as examples of how CEUS can serve in the diagnosis and follow-up for such diseases in children. Our discussion includes specific examination techniques; presentation of the main imaging findings in various benign and malignant lesions of the spleen, gallbladder and pancreas in children; and acknowledgment of the limitations of CEUS for these organs.

Contrast-enhanced ultrasound of transplant organs - liver and kidney - in children.

Ultrasound (US) is the first-line imaging tool for evaluating liver and kidney transplants during and after the surgical procedures. In most patients after organ transplantation, gray-scale US coupled with color/power and spectral Doppler techniques is used to evaluate the transplant organs, assess the patency of vascular structures, and identify potential complications. In technically difficult or inconclusive cases, however, contrast-enhanced ultrasound (CEUS) can provide prompt and accurate diagnostic information that is essential for management decisions. CEUS is indicated to evaluate for vascular complications including vascular stenosis or thrombosis, active bleeding, pseudoaneurysms and arteriovenous fistulas. Parenchymal indications for CEUS include evaluation for perfusion defects and focal inflammatory and non-inflammatory lesions. When transplant rejection is suspected, CEUS can assist with prompt intervention by excluding potential underlying causes for organ dysfunction. Intracavitary CEUS applications can evaluate the biliary tract of a liver transplant (e.g., for biliary strictures, bile leak or intraductal stones) or the urinary tract of a renal transplant (e.g., for urinary obstruction, urine leak or vesicoureteral reflux) as well as the position and patency of hepatic, biliary and renal drains and catheters. The aim of this review is to present current experience regarding the use of CEUS to evaluate liver and renal transplants, focusing on the examination technique and interpretation of the main imaging findings, predominantly those related to vascular complications.

Contrast-enhanced ultrasound of benign and malignant liver lesions in children.

Contrast-enhanced ultrasound (CEUS) is increasingly being used in children. One of the most common referrals for CEUS performance is characterization of indeterminate focal liver lesions and follow-up of known liver lesions. In this setting, CEUS is performed with intravenous administration of ultrasound contrast agents (UCAs). When injected into a vein, UCA microbubbles remain confined within the vascular network until they dissipate. Therefore, visualization of UCA within the tissues and lesions corresponds to true blood flow. CEUS enables continuous, real-time observation of the enhancement pattern of a focal liver lesion, allowing in most cases for a definite diagnosis and obviating the need for further cross-sectional imaging or other interventional procedures. The recent approval of Lumason (Bracco Diagnostics, Monroe Township, NJ) for pediatric liver CEUS applications has spurred the widespread use of CEUS. In this review article we describe the role of CEUS in pediatric liver applications, focusing on the examination technique and interpretation of main imaging findings of the most commonly encountered benign and malignant focal liver lesions. We also compare the diagnostic performance of CEUS with other imaging modalities for accurate characterization of focal liver lesions.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB): An Update on the Pediatric CEUS Registry on Behalf of the "EFSUMB Pediatric CEUS Registry Working Group".

The European Federation of Ultrasound in Medicine and Biology (EFSUMB) created the "EFSUMB Pediatric Registry" (EFSUMB EPR) with the purpose of collecting data regarding the intravenous application of pediatric contrast-enhanced ultrasound (CEUS). The primary aim was to document the current clinical practice and usefulness of the technique and secondarily to assess CEUS safety in children. We issue the preliminary results of this database and examine the overall practice of CEUS in children in Europe.

Imaging of Kidney Cysts and Cystic Kidney Diseases in Children: An International Working Group Consensus Statement.

Kidney cysts can manifest as focal disease (simple and complex kidney cysts), affect a whole kidney (eg, multicystic dysplastic kidney or cystic dysplasia), or manifest as bilateral cystic disease (eg, autosomal recessive polycystic kidney disease [ARPKD] or autosomal dominant polycystic kidney disease [ADPKD]). In children, as opposed to adults, a larger proportion of kidney cysts are due to genetic diseases (eg, HNF1B nephropathy, various ciliopathies, and tuberous sclerosis complex), and fewer patients have simple cysts or acquired cystic kidney disease. The purpose of this consensus statement is to provide clinical guidance on standardization of imaging tests to evaluate kidney cysts in children. A committee of international experts in pediatric nephrology, pediatric radiology, pediatric US, and adult nephrology prepared systematic literature reviews and formulated recommendations at a consensus meeting. The final statement was endorsed by the European Society of Pediatric Radiology, the European Federation of Societies for Ultrasound in Medicine and Biology, the European Society of Pediatric Nephrology, and reviewed by the European Reference Network for Rare Kidney Diseases. Main recommendations are as follows: US is the method of choice when assessing pediatric kidney cysts, with selected indications for MRI and contrast-enhanced US. CT should be avoided whenever possible because of ionizing radiation. Renal US yields essential diagnostic information in many cases. In patients with ARPKD or other ciliopathies, abdominal US is needed for diagnosis and screening of portal hypertension. US is usually sufficient for follow-up kidney imaging, but MRI can be valuable for clinical trials in patients with ADPKD or in older children with tuberous sclerosis complex to evaluate both kidney cysts and angiomyolipomas.

Role of Contrast-Enhanced Ultrasound (CEUS) in Paediatric Practice: An EFSUMB Position Statement.

The use of contrast-enhanced ultrasound (CEUS) in adults is well established in many different areas, with a number of current applications deemed "off-label", but the use supported by clinical experience and evidence. Paediatric CEUS is also an "off-label" application until recently with approval specifically for assessment of focal liver lesions. Nevertheless there is mounting evidence of the usefulness of CEUS in children in many areas, primarily as an imaging technique that reduces exposure to radiation, iodinated contrast medium and the "patient-friendly" circumstances of ultrasonography. This position statement of the European Federation of Societies in Ultrasound and Medicine (EFSUMB) assesses the current status of CEUS applications in children and makes suggestions for further development of this technique.

Kidney transplantation fails to provide adequate growth in children with chronic kidney disease born small for gestational age.

BACKGROUND: Children with chronic kidney disease are frequently born small for gestational age (SGA) and prone to disproportionately short stature. It is unclear how SGA affects growth after kidney transplantation (KTx). METHODS: Linear growth (height, sitting height, and leg length) was prospectively investigated in a cohort of 322 pediatric KTx recipients, with a mean follow-up of 4.9 years. Sitting height index (ratio of sitting height to total body height) was used to assess body proportions. Predictors of growth outcome in KTx patients with (n = 94) and without (n = 228) an SGA history were evaluated by the use of linear mixed-effects models. RESULTS: Mean z-scores for all linear body dimensions were lower in SGA compared with non-SGA patients (p < 0.001). SGA patients presented with higher target height deficit and degree of body disproportion (p < 0.001). The latter was mainly due to reduced leg growth during childhood. Pubertal trunk growth was diminished in SGA patients, and the pubertal growth spurt of legs was delayed in both groups, resulting in further impairment of adult height, which was more frequently reduced in SGA than in non-SGA patients (50 % vs 18 %, p < 0.001). Use of growth hormone treatment in the pre-transplant period, preemptive KTx, transplant function, and control of metabolic acidosis were the only potentially modifiable correlates of post-transplant growth in SGA groups. By contrast, living related KTx, steroid exposure, and degree of anemia proved to be correlates in non-SGA only. CONCLUSIONS: In children born SGA, growth outcome after KTx is significantly more impaired and affected by different clinical parameters compared with non-SGA patients.

Benign liver tumors in pediatric patients - Review with emphasis on imaging features.

Benign hepatic tumors are commonly observed in adults, but rarely reported in children. The reasons for this remain speculative and the exact data concerning the incidence of these lesions are lacking. Benign hepatic tumors represent a diverse group of epithelial and mesenchymal tumors. In pediatric patients, most benign focal liver lesions are inborn and may grow like the rest of the body. Knowledge of pediatric liver diseases and their imaging appearances is essential in order to make an appropriate differential diagnosis. Selection of the appropriate imaging test is challenging, since it depends on a number of age-related factors. This paper will discuss the most frequently encountered benign liver tumors in children (infantile hepatic hemangioendothelioma, mesenchymal hamartoma, focal nodular hyperplasia, nodular regenerative hyperplasia, and hepatocellular adenoma), as well as a comparison to the current knowledge regarding such tumors in adult patients. The current emphasis is on imaging features, which are helpful not only for the initial diagnosis, but also for pre- and post-treatment evaluation and follow-up. In addition, future perspectives of contrast-enhanced ultrasound (CEUS) in pediatric patients are highlighted, with descriptions of enhancement patterns for each lesion being discussed. The role of advanced imaging tests such as CEUS and magnetic resonance imaging, which allow for non-invasive assessment of liver tumors, is of utmost importance in pediatric patients, especially when repeated imaging tests are needed and radiation exposure should be avoided.

Patterns of growth after kidney transplantation among children with ESRD.

BACKGROUND AND OBJECTIVES: Poor linear growth is a frequent complication of CKD. This study evaluated the effect of kidney transplantation on age-related growth of linear body segments in pediatric renal transplant recipients who were enrolled from May 1998 until August 2013 in the CKD Growth and Development observational cohort study. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Linear growth (height, sitting height, arm and leg lengths) was prospectively investigated during 1639 annual visits in a cohort of 389 pediatric renal transplant recipients ages 2-18 years with a median follow-up of 3.4 years (interquartile range, 1.9-5.9 years). Linear mixed-effects models were used to assess age-related changes and predictors of linear body segments. RESULTS: During early childhood, patients showed lower mean SD scores (SDS) for height (-1.7) and a markedly elevated sitting height index (ratio of sitting height to total body height) compared with healthy children (1.6 SDS), indicating disproportionate stunting (each P<0.001). After early childhood a sustained increase in standardized leg length and a constant decrease in standardized sitting height were noted (each P<0.001), resulting in significant catch-up growth and almost complete normalization of sitting height index by adult age (0.4 SDS; P<0.01 versus age 2-4 years). Time after transplantation, congenital renal disease, bone maturation, steroid exposure, degree of metabolic acidosis and anemia, intrauterine growth restriction, and parental height were significant predictors of linear body dimensions and body proportions (each P<0.05). CONCLUSIONS: Children with ESRD present with disproportionate stunting. In pediatric renal transplant recipients, a sustained increase in standardized leg length and total body height is observed from preschool until adult age, resulting in restoration of body proportions in most patients. Reduction of steroid exposure and optimal metabolic control before and after transplantation are promising measures to further improve growth outcome.

Birth parameters and parental height predict growth outcome in children with chronic kidney disease.

BACKGROUND: We analyzed the impact of birth parameters and parental height on long-term growth outcome in children with chronic kidney disease (CKD) stage 3-5. METHODS: Linear growth was prospectively investigated in 509 children, with a mean follow-up of 4.1 years. Growth outcome was categorized in (i) poor growth (PG): height standard deviation score (SDS) during follow-up < -2.0 and/or actual or previous growth hormone (GH) treatment, and (ii) good growth (GG): height SDS ≥ -2.0 and no need for GH. A multivariate binary logistic regression model was constructed for predictors of PG outcome. RESULTS: PG was observed in 55 % of patients. The rate of pre-term and small for gestational age birth was significantly higher in children with PG compared to GG (43.2 vs. 25.6 % and 36.8 vs. 18.9 %; p < 0.001). Children with PG had significantly lower average values for gestational age, birth weight, length, and head circumference, umbilical cord pH, Apgar scores, and parental height than children with GG. Birth length, umbilical cord pH, and parental height were significant independent predictors of PG outcome (sensitivity 72.8 %, specificity 69.3 %). CONCLUSIONS: Birth parameters and parental height are independent predictors of growth outcome in children with CKD.

Growth and maturation improvement in children on renal replacement therapy over the past 20 years.

BACKGROUND: The attainment of normal growth and maturation remains a major challenge in the management of children and adolescents requiring renal replacement therapy (RRT). METHODS: We compared growth and maturation in 384 German children with RRT who were followed between 1998 and 2009 with 732 children who were enrolled in the European Dialysis and Transplant Association (EDTA) Registry from 1985 to 1988; of these children, 78 and 88 %, respectively, were transplanted. RESULTS: The data on the German patients included in the EDTA registry did not differ significantly from those of the patients from other European countries. Overall, the mean height standard deviation score (SDS) has improved over the past 20 years from -3.03 to -1.80 (p < 0.001). Until the age of 6 years, the difference in height SDS was not significant, whereas it improved significantly in adolescence (-3.40 vs. -1.52; p < 0.001). Significant improvements in the delay of the pubertal growth spurt, age at menarche, bone maturation and body mass index (BMI) were noted in the recent German group compared to the EDTA group (each p < 0.001). CONCLUSIONS: Our findings demonstrate a marked improvement of growth and maturation in paediatric patients on RRT during the past 20 years.

The influence of low donor age, living related donation and pre-emptive transplantation on end-organ damage based on arterial hypertension after paediatric kidney transplantation.

BACKGROUND: To date, no study has described the pre-transplant and transplant risk factors for end-organ damage based on arterial hypertension in children after kidney transplantation (KTX). METHODS: A retrospective chart review was performed of 206 children with KTX between 1991 and 2007. Patients<120 cm were excluded as no validated percentiles for 24-h ambulant blood pressure monitoring (ABPM) exist. Complete data sets were available for 116 patients. Data were recorded at 12, 24 and 36 months post- KTX. We analysed the influence of donor age, age at transplantation, pre-emptive transplantation, living or deceased transplantation and glomerular filtration rate (GFR) on the presence of end-organ damage, ABPM, ABPM standard deviation score and the numbers of anti-hypertensives used. RESULTS: Lower donor age and the decade of transplantation were associated with less detection of end-organ damage (P=0.001). A lower need for anti-hypertensive medication (P=0.001) was detected in children who received organs from living donors and from deceased donors with a donor age<35 years and who were transplanted pre-emptively. Low recipient age was the only factor associated with lower ABPM (P=0.001). In our study, the type of immunosuppressive regimen and the GFR had no influence on the blood pressure. CONCLUSIONS: It may be speculated that the risk of arterial hypertension and associated end-organ damage in children after KTX could be reduced by using organs from young donors with an advantage for living related and pre-emptive donation.

Prematurity, small for gestational age and perinatal parameters in children with congenital, hereditary and acquired chronic kidney disease.

BACKGROUND: Low birth weight has been identified as a risk factor for chronic kidney disease (CKD). METHODS: We analysed perinatal parameters taken from the National Birth Certificates of 435 children with CKD stages 3-5 of different aetiology and time of onset of CKD. Diseases were classified as congenital with onset of renal disease during fetal life (n = 260; 60%), hereditary as genetically determined with onset after 3 months of life (n = 93; 21%) and acquired CKD (n = 82; 19%). RESULTS: The rates of prematurity and small for gestational age (SGA) were elevated in children with congenital (39.3% and 29.2%), hereditary (24.7% and 22.6%) and acquired CKD (15.5% and 29.3%); these compared to 8% (for both) in the normal population. Newborns with congenital CKD had a significantly lower gestational age [median 38 weeks, interquartile range (IQR) 36-40 weeks] than those with hereditary (39.9 weeks, IQR 37.5-40 weeks) or acquired CKD (40 weeks, IQR 38-40 weeks; P < 0.001). Median birth weight and length were lower in newborns with congenital than in hereditary and acquired diseases [2975 g (IQR 2460-3420 g) versus 3250 g (IQR 2740-3580 g) and 3260 g (IQR 2858-3685 g) (P < 0.01); 49 cm (IQR 47-52) versus 50 cm (IQR 48-52.8) and 51 cm (IQR 49-53) (P < 0.01)]. Head circumference was smaller (P < 0.05), and Apgar scores were lower (P < 0.005) in newborns with congenital diseases than in hereditary and acquired diseases. CONCLUSIONS: Children with congenital CKD had the highest rate of prematurity, a significantly lower birth weight, length, head circumference and Apgar score than newborns with hereditary or acquired CKD. Irrespective of the aetiology of CKD, all of the children had a significantly higher rate of SGA and prematurity than the reference population. We conclude that both SGA and prematurity predispose for advanced renal disease in childhood and that fetal kidney disease impairs fetal growth.

Growth hormone treatment of renal growth failure during infancy and early childhood.

Despite major progress in dialysis, nutrition and drug treatment in the past 20 years, growth of infants and toddlers with chronic kidney disease (CKD) remains a major challenge in paediatric nephrology. Our hypothesis is that early growth deficit is one of the most important factors for impaired final height in children with CKD, and we conclude that early implementation of recombinant human growth hormone (rhGH) therapy should be offered to infants with growth failure. Infants with delayed growth, adequate caloric intake and stable parameters of bone metabolism are candidates for rhGH therapy. One predictive factor for the selection of infants for rhGH treatment may be growth retardation at birth. Our conclusion from the limited published data is that the use of rhGH in young children with CKD is effective and safe. Compared with its use in older children, the early use of growth hormone requires lower absolute dosages of rhGH, which therefore reduce the annual treatment costs and allow earlier renal transplantation. Furthermore, an early start on rhGH improves the psychosocial situation later in childhood and may lead to a further improvement in adult height. A multi-centre randomised controlled study should be initiated to analyse the short-term and long-term effects of early rhGH therapy on infants with CKD.

SMARCAL1 mutations: a cause of prepubertal idiopathic steroid-resistant nephrotic syndrome.

UNLABELLED: Schimke immuno-osseous dysplasia (SIOD) is a rare autosomal-recessive multisystem disorder with disproportionate growth failure, impaired T cell function, and steroid-resistant nephrotic syndrome. Recently, we presented the typical anthropometric features of SIOD. We now present data on two siblings who were initially classified as suffering from familial steroid-resistant nephrotic syndrome of unknown genetic origin. Apart from growth failure, no syndrome-specific symptoms were found until the age of 10 y. However, serial anthropometric examinations showed the development of a SIOD-like pattern with a decreased ratio of trunk to leg length in early adolescence. The growth pattern was significantly different from that seen in children with chronic renal failure of other origins. In prepuberty the siblings had proportionate short stature but developed disproportion only during adolescence. Molecular genetic analysis revealed compound heterozygosity for a known and a new mutation in the SMARCAL1 gene. CONCLUSION: the disease spectrum associated with SMARCAL1 mutations includes previously undescribed milder phenotypes that may be clinically overlooked, particularly before puberty. Serial anthropometric assessment can eventually identify patients with a growth pattern similar to that of SIOD. These patients should be tested for SMARCAL1 mutations to avoid overtreatment with immunosuppressive agents.