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Objectives: (1) Determine inter-observer reproducibility and test-retest repeatability of 4D flow parameters in renal allograft vessels; (2) determine if 4D flow measurements in the renal artery (RA) and renal vein (RV) can distinguish between functional and dysfunctional allografts; (3) correlate haemodynamic parameters with estimated glomerular filtration rate (eGFR), perfusion measured with dynamic contrast-enhanced MRI (DCE-MRI) and histopathology., Methods: Twenty-five prospectively recruited renal transplant patients (stable function/chronic renal allograft dysfunction, 12/13) underwent 4D flow MRI at 1.5 T. 4D flow coronal oblique acquisitions were performed in the transplant renal artery (RA) (velocity encoding parameter, VENC = 120 cm/s) and renal vein (RV) (VENC = 45 cm/s). Test-retest repeatability (n = 3) and inter-observer reproducibility (n = 10) were assessed by Cohen's kappa, coefficient of variation (CoV) and Bland-Altman statistics. Haemodynamic parameters were compared between patients and correlated to the estimated glomerular filtration rate, DCE-MRI parameters (n = 10) and histopathology from allograft biopsies (n = 15)., Results: For inter-observer reproducibility, kappa was > 0.99 and 0.62 and CoV of flow was 12.6% and 7.8% for RA and RV, respectively. For test-retest repeatability, kappa was > 0.99 and 0.5 and CoV of flow was 27.3% and 59.4%, for RA and RV, respectively. RA (p = 0.039) and RV (p = 0.019) flow were both significantly reduced in dysfunctional allografts. Both identified chronic allograft dysfunction with good diagnostic performance (RA: AUC = 0.76, p = 0.036; RV: AUC = 0.8, p = 0.018). RA flow correlated negatively with histopathologic interstitial fibrosis score ci (ρ = - 0.6, p = 0.03)., Conclusions: 4D flow parameters had better repeatability in the RA than in the RV. RA and RV flow can identify chronic renal allograft dysfunction, with RA flow correlating with histopathologic interstitial fibrosis score., Key Points: • Inter-observer reproducibility of 4D flow measurements was acceptable in both the transplant renal artery and vein, but test-retest repeatability was better in the renal artery than in the renal vein. • Blood flow measurements obtained with 4D flow MRI in the renal artery and renal vein are significantly reduced in dysfunctional renal transplants. • Renal transplant artery flow correlated negatively with histopathologic interstitial fibrosis score.

Objectives: To assess whether spatial labeling with multiple inversion pulses (SLEEK) sequence can be employed as a one-stop assessment method for evaluating renal function and displaying renal artery in hypertensive patients with suspected renal dysfunction., Methods: A total of 78 patients with suspected hypertensive renal damage were enrolled in this retrospective study. All patients underwent MRI examinations, and both SLEEK and DWI sequences were performed simultaneously. According to estimated glomerular filtration rate (eGFR), patients were divided into three groups (Group 1, eGFR> 90; Group 2, eGFR = 60-90; Group 3, eGFR< 60). Twenty-two of these patients also underwent CT angiography (CTA) examination. Comparison between CTA, DWI, and eGFR was performed to assess the value of SLEEK in evaluating renal function and displaying renal artery., Results: The performance of SLEEK to display renal artery was highly consistent with the results of CTA (kappa = 0.713). The corticomedullary contrast ratio positively correlated with eGFR (p = 0.004, r = 0.322) and was significantly higher in SLEEK images than in DWI images in all three groups (p < 0.001). There was no significant difference in corticomedullary contrast ratio in SLEEK images between Group 1 and Group 2 (p = 0.285). However, the minimal renal cortical thickness, which significantly correlated with eGFR (p < 0.001, r = 0.866), was significantly different between Group 1 and Group 2 (p < 0.001). ROC analysis showed good diagnostic performance when differentiating patients with eGFR> 60 from those with eGFR< 60., Conclusions: The SLEEK sequence could evaluate simultaneously renal function through corticomedullary differentiation and renal arteries, enabling one-stop assessment in hypertensive patients with suspected renal dysfunction., Key Points: • Spatial labeling with multiple inversion pulses (SLEEK) improves renal corticomedullary differentiation in hypertensive patients with renal dysfunction compared with DWI. • SLEEK clearly displays renal artery in hypertensive patients with renal dysfunction. • SLEEK could be utilized as a one-stop assessment method for evaluating renal function and renal artery in hypertensive patients.

Psoriatic arthritis (PsA) patients are at a higher risk of systemic inflammatory sequelae, leading to microalbuminuria, cardiovascular (CVD) and neuropsychiatric (NPD) disease. Our aim is to present the existing literature about the relationship between CVD, kidney and NPD in PsA. The literature evaluation of PsA revealed that chronic T-cell activation and increased levels of circulating immune complexes can cause glomerular injury leading to microalbuminuria, which predicts CVD and all-cause mortality in both diabetic and non-diabetic patients. Furthermore, it is a marker of preclinical brain damage and identifies patients at higher risk of NPD/CVD events. Among the currently used imaging modalities in PsA, magnetic resonance imaging (MRI) maintains a crucial role, because it is ideal for concurrent evaluation of brain/heart involvement and serial follow up assessment. There is increasing evidence regarding the relationship between kidneys, heart and brain in PsA. Although currently there are no official recommendations about a combined brain/heart MRI in PsA, it could be considered in PsA with microalbuminuria, arrhythmia, HF, cognitive dysfunction and/or depression.

Purpose: To prospectively characterize computed tomography (CT)-indeterminate renal masses (CTIRM) using acoustic radiation force impulse (ARFI) elastography and contrast-enhanced ultrasound (CEUS) and to correlate quantitative imaging findings with histopathology or interim follow-up (FU)., Methods: 123 patients with CTIRM (longest diameter < 4 cm) underwent ARFI and CEUS with CT image fusion (IF). Exclusion criteria included all contraindications for CEUS and IF. Shear wave velocity (SWV), shear wave ratio (SWR), peak intensity (PE), time to peak (TTP) and wash-in rate (Wi) were quantified. In case of a cystic lesion classified as ≤ Bosniak 2F, follow-up imaging was performed., Results: 77 out of 123 patients underwent surgical resection of a lesion due to suspect imaging findings, whereas 46 patients underwent FU, which did not show upgrading in Bosniak category. Histopathology revealed 58 renal cell carcinomas [five chromophobe (chRCC), 18 papillary (pRCC) and 35 clear cell (ccRCC)], ten oncocytomas and nine non-malignant renal lesions (one minimal fat AML, three focal nephritis and five infected cysts). SWV and SWR differed significantly between ccRCC, pRCC, chRCC (p = 0.0024, F = 13.94) and in SWR also for oncocytoma (p < 0.0001, F = 14.35). In CEUS, oncocytoma and ccRCC showed significant higher PE values (p < 0.0001, F = 77.31) as well as higher Wi and lower TTP compared to all other solid lesions., Conclusions: Quantitative CEUS and ARFI imaging can provide relevant information to further characterize CT-indeterminate renal masses to guide urological decision making and offer the possibility of differentiation between ccRCC from less malignant RCC subtypes and from oncocytoma.

Objectives: To develop a convenient and rapid single-kidney CT-GFR technique., Methods: One hundred and twelve patients referred for multiphasic renal CT and 99mTc-DTPA renal dynamic imaging Gates-GFR measurement were prospectively included and randomly divided into two groups of 56 patients each: the training group and the validation group. On the basis of the nephrographic phase images, the fractional renal accumulation (FRA) was calculated and correlated with the Gates-GFR in the training group. From this correlation a formula was derived for single-kidney CT-GFR calculation, which was validated by a paired t test and linear regression analysis with the single-kidney Gates-GFR in the validation group., Results: In the training group, the FRA (x-axis) correlated well (r = 0.95, p < 0.001) with single-kidney Gates-GFR (y-axis), producing a regression equation of y = 1665x + 1.5 for single-kidney CT-GFR calculation. In the validation group, the difference between the methods of single-kidney GFR measurements was 0.38 ± 5.57 mL/min (p = 0.471); the regression line is identical to the diagonal (intercept = 0 and slope = 1) (p = 0.727 and p = 0.473, respectively), with a standard deviation of residuals of 5.56 mL/min., Conclusion: A convenient and rapid single-kidney CT-GFR technique was presented and validated in this investigation., Key Points: • The new CT-GFR method takes about 2.5 min of patient time. • The CT-GFR method demonstrated identical results to the Gates-GFR method. • The CT-GFR method is based on the fractional renal accumulation of iodinated CM. • The CT-GFR method is achieved without additional radiation dose to the patient.

Objective: We carried out a study to determine the impact of prematurity on renal development. The primary outcomes measured were nephrinuria and albuminuria; renal volume and glomerular filtration rate were the secondary outcomes., Methods: Preterm neonates born at less than 28 weeks of gestation, with birth weight between 10th and 90th centile (appropriate for gestational age), were recruited and underwent assessments at 28, 32 and 37 weeks postmenstrual age (PMA)., Results: Fifty-three premature neonates and 31 term neonates (control) were recruited. The median gestational age of the premature neonates was 26.4 [24.7-27.4] weeks, with a mean birth weight of 886 (179) g. The mean gestational age of term neonates was 39.1 (1.2) weeks and the mean birth weight was 3406 (406) g. The median age of the term neonates was 6.5 [3.0-12.5] days. The total kidney volume (TKV) almost doubled from 10.3 (2.9) cm 3 at 28 weeks PMA to 19.2 (3.7) cm 3 at 37 weeks PMA (P = 0.0001). TKV at 37 weeks PMA was significantly smaller compared to term neonates (19.2 (3.7) vs 26.3 (7.0) cm 3 ; P = 0.0001). However, there was no significant difference in estimated glomerular filtration rate (eGFR) between premature neonates (at 37 weeks PMA) and term neonates (control) (43.5 [39.7-48.9] vs. 42.0 [38.2-50.0] mL/min/1.73 m 2 ; P = 0.75). There was a statistically significant decline in nephrin-creatinine ratio and albumin-creatinine ratio from 32 to 37 weeks PMA., Conclusions: Despite having a smaller renal volume (and fewer nephrons), extremely premature neonates achieve similar eGFRs at corrected term as term-born neonates, likely through single nephron hyperfiltration. Extremely premature neonates also show evidence of glomerular injury.

Background: Our objective was to analyze the evolution of kidney damage over time in small children with urinary tract infection (UTI) and factors associated with progression of renal damage., Methods: From a cohort of 1003 children <2 years of age with first-time UTI, a retrospective analysis of 103 children was done. Children were selected because of renal damage at index 99m Tc-dimercaptosuccinic acid (DMSA) scintigraphy at least 3 months after UTI, and a late DMSA scan was performed after at least 2 years. Damage was classified as progression when there was a decline in differential renal function (DRF) by ≥4%, as regression when there was complete or partial resolution of uptake defects., Results: Of 103 children, 20 showed progression, 20 regression, and 63 remained unchanged. There were no differences between groups regarding gender or age. In the progression group, 16/20 (80%) children had vesicoureteral reflux (VUR) grade III-V and 13 (65%) had recurrent UTI. In multivariable regression analysis, both VUR grade III-V and recurrent UTI were associated with progression. In the regression group, 16/20 (80%) had no VUR or grade I-II, and two (10%) had recurrent UTI., Conclusions: Most small children with febrile UTI do not develop renal damage and if they do the majority remain unchanged or regress over time. However, up to one-fifth of children with renal damage diagnosed after UTI are at risk of renal deterioration. These children are characterized by the presence of VUR grades III-V and recurrent febrile UTI and may benefit from follow-up.

Objectives: To assess the added-value of systematic unenhanced abdominal computed tomography (CT) on emergency department (ED) diagnosis and management accuracy compared to current practice, in elderly patients with non-traumatic acute abdominal symptoms., Methods: Institutional review board approval and informed consent were obtained. This prospective study included 401 consecutive patients 75 years of age or older, admitted to the ED with acute abdominal symptoms, and investigated by early systematic unenhanced abdominal CT scan. ED diagnosis and intended management before CT, after unenhanced CT, and after contrast CT if requested, were recorded. Diagnosis and management accuracies were evaluated and compared before CT (clinical strategy) and for two conditional strategies (current practice and systematic unenhanced CT). An expert clinical panel assigned a final diagnosis and management after a 3-month follow-up., Results: Systematic unenhanced CT significantly improved the accurate diagnosis (76.8% to 85%, p=1.1x10 -6 ) and management (88.5% to 95.8%, p=2.6x10 -6 ) rates compared to current practice. It allowed diagnosing 30.3% of acute unsuspected pathologies, 3.4% of which were unexpected surgical procedure requirement., Conclusions: Systematic unenhanced abdominal CT improves ED diagnosis accuracy and appropriate management in elderly patients presenting with acute abdominal symptoms compared to current practice., Key Points: • Systematic unenhanced CT improves significantly diagnosis accuracy compared to current practice. • Systematic unenhanced CT optimizes appropriate hospitalization by increasing the number of discharged patients. • Systematic unenhanced CT allows detection of about one-third of acute unsuspected abdominal conditions. • It should allow boosting emergency department management decision-making confidence in old patients.

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.

Objectives: Evaluate a potential association between Wilms' tumour (WT) and renal cystic lesions., Methods: Digital records and imaging files of consecutive patients diagnosed with WT between 2004 and 2014 were retrospectively reviewed under an Institutional Review Board waiver of informed consent. The locations of renal cysts seen on US, CT, and/or MRI were recorded and compared with the locations of newly developed WT., Results: A total of 48 patients (mean age 3 years 9 months) presented with newly diagnosed WT in the study period. Mean follow-up was 4.5 (range 1-10) years. WT was unilateral in 40 children, bilateral in 8. Renal cysts were identified in only one of the forty patients (2.5 %) with unilateral disease - in the contralateral kidney. In contrast, renal cysts were found in seven of eight patients with bilateral WT (87.5 %), in two of whom, new tumours developed in the same location where cysts had been seen on previous imaging studies., Conclusions: Renal cystic lesions in patients with Wilms' tumour should be regarded as potential tumour precursors, and followed with frequent imaging., Key Points: • Cortical renal cystic lesions have a high association with bilateral Wilms' tumour. • In children with Wilms' tumour renal cysts are possible tumour precursors. • MRI appears to be the best modality in depicting the cortical cysts.

The purpose of this article is to describe the imaging appearance of the "renal cortical rim sign" and review the clinical significance of this sign.

Herlyn-Werner-Wunderlich syndrome (HWWS) is a rare congenital anomaly of the female urogenital tract that associates Müllerian duct anomalies with mesonephric duct anomalies. The triad of uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis characterizes this syndrome. Patients generally present with non-specific symptoms after menarche. Pelvic pain, dysmenorrhea, and palpable mass due to hematocolpos or hematometra are the most common findings. Pyohematocolpos and pyosalpinx may appear as acute complications, while endometriosis and pelvic adhesions constitute potential long-term complications. When a prenatal diagnosis of unilateral renal agenesis in newborn girls is known, a gynecological imaging study should be performed to exclude uterine and vaginal abnormalities. These patients should be followed up to ensure that a timely surgical correction is performed. The diagnosis of HWWS is difficult due to the lack of specific symptoms or findings upon physical examination. An accurate imaging description of these congenital anomalies is crucial to guide patients toward surgical treatment, relieving acute complications, and preserving the normal fertility. The authors provide a pictorial review of the magnetic resonance imaging and ultrasonography findings of the HWWS with correlation to embryological, clinical, and surgical features.

This article reviews the clinical applications of current ultrasound elastography methods in non-hepatic conditions including thyroid nodules, prostate cancer, chronic kidney disease, solid renal lesions, pancreatic lesions, and deep vein thrombosis. Pathophysiology alters tissue mechanical properties via ultrastructural changes including fibrosis, increased cellularity, bleeding, and necrosis, creating a target biomarker, which can be imaged qualitatively or quantitatively with US elastography. US elastography methods can add information to conventional US methods and improve the diagnostic performance of conventional US in a range of disease processes.

Objective: The aim of this study was to assess the accuracy of Ultrasound (US) and contrast-enhanced ultrasound (CEUS) in the characterization of renal nodules indeterminate on CT by identifying benign cystic lesions not requiring further examination., Methods: 72 patients with 83 indeterminate renal nodules on CT underwent baseline US and CEUS that classified lesions as benign (Bosniak I, II or IIF cysts) or potentially malignant (Bosniak III or IV cysts, solid nodules). The accuracy of US and CEUS in the differentiation between benign cysts and potentially malignant nodules was analyzed and compared with the final diagnosis obtained by histology or follow-up of at least 23 months with CEUS ± a conclusive CT/MR study., Results: Final diagnoses comprised 50 benign complex cysts, 1 focal nephritis, 1 multilocular cystic nephroma, 3 oncocytomas, 1 transitional cell carcinoma and 27 renal cell carcinomas. Unenhanced US correctly classified 18/50 (36%) benign cysts and 17/33 (51.5%) of the potentially malignant lesions obtaining a sensitivity of 36%, specificity of 51.5%, and overall accuracy of 42.2%. The addition of CEUS allowed a correct diagnosis of 48 /50 (96%) benign cysts and of 31/33 (93.9%) nodules as potentially malignant, with a sensitivity of 96%, specificity of 93.9%, and overall accuracy of 95.2%., Conclusion: CEUS is very useful in the differentiation between benign complex cysts and other lesions that require further investigation in non-conclusive renal nodules detected on CT, improving the accuracy of baseline US from 42.2 to 95.2%.

Background: Nephron number in humans is determined during fetal life. The objective of this study was to investigate the effects of preterm birth on nephron number using renal volume as a surrogate for nephron number., Methods: This observational study was conducted over 12 months in a tertiary perinatal center. Preterm babies less than 32 weeks of gestation were recruited and followed until discharge. Term infants were recruited for comparison. The babies underwent renal sonography and renal function measurements at 32 and 38 weeks corrected age. The primary outcome measurement was total kidney volume at 38 weeks and the secondary outcome was estimated glomerular filtration rate (eGFR)., Results: Forty-four preterm infants and 24 term infants were recruited. At 38 weeks corrected age, premature infants had lower total kidney volume than term infants (21.6 ± 5.7 vs. 25.2 ± 5.7 ml; p = 0.02) and a significantly lower eGFR (73.6 [IQR 68.1-77.6] vs. 79.3 [IQR 72.5-86.6] ml·min(-1)·1.73 m(-2); p = 0.03). There was a significant correlation between total kidney volume and eGFR in premature and term babies., Conclusions: Premature infants have smaller kidney volume and likely decreased nephron number and lower estimated glomerulofiltration rate relative to infants born at term.

Background: Limited data exist on the performance of cystatin C-based glomerular filtration rate (GFR) equations in pediatric transplant recipients and other high-risk patients. The aim of our study was therefore to evaluate the performance of current cystatin C-based equations in this population., Methods: This was a retrospective, cross-sectional study of 141 consecutive patients (58 % post-transplant) who received a nuclear medicine GFR (NucGFR) examination using (99m)Tc- diethylenetriaminepentaacetic acid at our institution. Subjects included children receiving liver, kidney or hematopoietic stem cell transplants and patients with oncologic or urologic disease. GFR estimates using published GFR estimating equations, including those based on cystatin C (Filler, Zappitelli, Larsson, Hoek, Rule and Le Bricon equations, respectively) and on both cystatin C and creatinine (Zappitelli, Bouvet and Schwartz equations, respectively), were evaluated and compared to the NucGFR measurement using Bland-Altman analysis., Results: The mean NucGFR was 95 (interquartile range 76-111) ml/min/1.73 m(2). Of the cystatin C-based equations, the Rule, Hoek, Zappitelli and Schwartz (2009 CKiD equation) formulas provided the closest agreement to the NucGFR estimate. All other formulas overestimated the GFR in our cohort., Conclusion: Cystatin C-based GFR formulas can provide an accurate estimation of NucGFR in a pediatric population with a high proportion of transplant recipients and oncology patients.

Imaging is required if complication is suspected in acute pyelonephritis to assess the nature and extent of the lesions, and to detect underlying causes. The current imaging modality of choice in clinical practice is computed tomography. Because of associated radiation and potential nephrotoxicity, CEUS is an alternative that has been proven to be equally accurate in the detection of acute pyelonephritis renal lesions. The aims of this study of 48 patients are to describe in detail the CEUS findings in acute pyelonephritis, and to determine if abscess and focal pyelonephritis may be distinguished. Very characteristic morphologic and temporal patterns of enhancement are described. These allow differentiation of focal pyelonephritis from renal abscess, and detection of tiny suppurative foci within focal pyelonephritis. The detection of abscesses is important because follow-up in 25 patients revealed a longer clinical course. Typical pyelonephritis CEUS features permit distinction from other renal lesions. As a whole, CEUS is an excellent tool in the work-up of complicated acute pyelonephritis, so it may be considered as the imaging technique of choice in the evaluation and follow-up of these patients who frequently are very young, so as to minimise radiation exposure.

Objectives: To evaluate Estimated Glomerular Filtration Rate (eGFR), using the Modification of Diet in Renal Disease equation, and compare with radionuclide GFR (rGFR) in a Radiology setting to assess renal function prior to contrast administration., Methods: Five hundred and sixteen retrospective rGFR studies from a mixed referral population were selected and the eGFR calculated. Regression and Bland-Altman analysis was performed. The percentage of rGFR and eGFR studies below 30 ml/min/1.73 m² and 60 ml/min/1.73 m² were calculated; these are important thresholds for classifying renal insufficiency., Results: A significant correlation between eGFR and rGFR (R² = 0.62, p < 0.0001) and significant differences in the medians (p < 0.0001) were found. eGFR overestimated rGFR with a bias (mean difference) of 10.8 ml/min/1.73 m² over the whole range of rGFR. Studies with an rGFR of under 30 ml/min/1.73 m² had a mean bias of 4.6 ml/min/1.73 m² (difference range -5.9 to 26.3 ml/min/1.73 m²). The bias over the range 30 to 60 ml/min/1.73 m² was 13.2 ml/min/1.73 m² (difference range -16.8 to 88.3 ml/min/1.73 m²). In 25.4% of studies, eGFR was less than 60 ml/min/1.73 m² compared with 40.5% of rGFR studies., Conclusions: Awareness of the bias between eGFR and rGFR is important when assessing Radiology patients for risks of nephrotoxicity and Nephrogenic Systemic Fibrosis from contrast medium.

Background: By using a microbubble contrast agent and contrast-specific imaging software, the contrast-enhanced ultrasound (CEUS) is able to depict the micro and macrocirculation of the target organ., Methods: A review of the peer reviewed literature was done regarding the current role of ultrasound CEUS imaging in the evaluation of renal pathology with reference to the diagnosis of renal ischaemia, in the characterization of complex cystic lesions and in those with equivocal enhancement at CT., Results: CEUS provides information on tissue perfusion and may play a role in kidney mass characterization similar to the role of contrast-enhanced CT and MRI. In this context, the characterization of cystic lesions is probably the most consolidated field of application of contrast agents on kidney ultrasound imaging. Finally, CEUS provides a good alternative to CT, especially in patients with contraindications to iodinated contrast agents., Conclusions: The usefulness of CEUS in these applications is confirmed by extensive literature production and this article focuses on the potential clinical applications of recent advances in CEUS technology in urology.

We assessed the long-term renal complications in a regional cohort of extremely low birth weight (ELBW) children born in 2002-2004. The study group, comprising 78 children born as ELBW infants (88% of the available cohort), was evaluated with measurement of serum cystatin C, urinary albumin excretion, renal ultrasound, and 24-h ambulatory blood pressure measurements. The control group included 38 children born full-term selected from one general practice in the district. Study patients were evaluated at a mean age of 6.7 years, and had a median birthweight of 890 g (25th-75th percentile: 760-950 g) and a median gestational age of 27 weeks (25th-75th percentile: 26-29 weeks). Mean serum cystatin C levels were significantly higher (0.64 vs. 0.59 mg/l; p = 0.01) in the ELBW group. Hypertension was diagnosed in 8/78 ELBW and 2/38 of the control children (p = 0.5). Microalbuminuria (>20 mg/g of creatinine) was detected only in five ELBW children (p = 0.17). The mean renal volume was significantly lower in the ELBW group (absolute kidney volume 81 ml vs. 113 ml; p < 0.001, relative kidney volume 85 vs. 97%; p < 0.001). Abnormally small kidneys (<2/3 of predicted size) were detected in 19 ELBW and four control children (p = 0.08). Multivariate logistic regression revealed that the only independent risk factor for renal complications was weight gained during neonatal hospitalization (odds ratio: 0.67; 95% confidence interval: 0.39-0.94). Serum cystatin C and kidney volume are significantly lower in school-age ELBW children. It is important to include systematic renal evaluation in the follow-up programs of ELBW infants.

Background: To evaluate feasibility and reproducibility of quantification of perinephric hematoma volume on multidetector-row CT (MDCT)., Methods: Perinephric hematomas in 63 patients (42 males, 21 females, median age: 49 years) imaged with contrast-enhanced MDCT of the abdomen were evaluated. A semi-automated segmentation software was applied to quantify hematoma volume. Reproducibility for quantification of hematoma volume was evaluated by repeated measurements in 20 patients. Statistical analyses were performed by using Student's t test. Interobserver and intraobserver variability was evaluated by Bland-Altman plots. P < 0.05 denoted statistical significance, Results: Quantification of hematoma volume was feasible in all cases. One step, direct quantification of volume was possible in 21 patients (33.33%) with small hematomas that did not reach upper and lower renal poles (range: 3.12-183.98 mL; mean: 39.92 mL). Quantification of hematoma size was performed indirectly in 42 patients (66.67%) with larger hematomas that extended beyond the renal poles by subtracting the ipsilateral renal volume from the combined kidney and hematoma volumes (range: 27.08-2431.3 mL; mean: 435.31 mL). Mean quantification time was 45 and 71 s for small and large hematomas, respectively (P < 0.05). Mean intraobserver and interobserver variability for determination of hematoma volume was 0.14% (95% CI, -1.57% to 1.85%) and 2.04% (95% CI, -1.77% to 5.85%), respectively. There was no significant difference in renal volume between ipsilateral and contralateral kidneys (P > 0.05)., Conclusion: Quantification of perinephric hematoma was feasible from MDCT data in all patients and was reproducible.

Background: In acute unilateral renal obstruction, calculated divided renal uptake following injection of tracer may be normal. Divided renal function as measured by uptake may be insensitive to fall in renal plasma flow (RPF) to the obstructed kidney. This study analyses afferent flow rate parameters of optimised models of renogram time activity curves (TAC). Afferent flow rate parameters may have differing sensitivity to altered RPF from divided renal tracer uptake and may be more sensitive to changes in cortical function in renal obstruction., Method: Twenty-four background-corrected renogram TACs using 99mTc-labelled mercapto-acetyl-triglycine (MAG3) with a unilateral obstructive pattern and six normal control renograms TACs were studied. Optimised computed models of each curve were constructed using specialised software (ModelMaker, Cherwell Scientific) and using the Marquardt Least Squares method. Following optimisation to the TAC of each target renogram, the afferent flow rate parameters were calculated., Results: Following optimisation of models, afferent flow rate parameters, expressed as arbitrary units, (mean 0.15, SD 0.06) in acutely obstructed kidneys, were typically reduced in comparison with those of normal kidneys (mean 0.44, SD 0.04). (Paired t test; P<0.005). By contrast, this reduction in afferent flow rate parameter was greater than the reduction in differential tracer uptake for the obstructed kidney (divided renal function of the obstructed group; mean 0.3, SD 0.14 compared with the control group; mean 0.45, SD 0.05 (P<0.05)., Conclusion: Optimised modelling of TACs of obstructed renograms is feasible and may provide a more sensitive index of parenchymal dysfunction in early obstruction than comparing divided renal tracer uptake.

Percutaneous biopsy has long been used to diagnose malignancies of the kidney. It is an established technique with multiple indications. Percutaneous biopsy now can be used to diagnose benign conditions that may mimic a malignancy and lead to unnecessary treatments. Advances in cytological techniques such as immunocytochemistry and cytogenetics have allowed for an increased diagnostic yield. In this review, various benign entities that may present as a renal mass are discussed and the vital role of percutaneous biopsy detailed.

Background: To determine if the pathology of small (< or = 4 cm) solid renal tumors can be predicted from findings on multidetector CT., Methods: This retrospective study included 46 patients (median age, 60 years; range, 32-91 years; 27 males, 19 females) with 47 tumors who underwent triphasic renal CT with pathology correlation. Two radiologists reviewed CT studies blinded to pathology results and recorded the morphologic and enhancement features of the tumors., Results: The 47 tumors (median diameter, 2.5 cm; range, 0.6-4.0 cm) included: 26 (55%) clear cell renal cell carcinomas; 9 (19%) oncocytomas; 7 (15%) papillary renal cell carcinomas; 2 (4%) chromophobe renal cell carcinomas; 2 (4%) inflammatory pseudotumors; and 1 (2%) angiomyolipoma with minimal fat. Amongst the three commonest tumors, heterogeneity was seen in 23/26 (88%) clear cell renal cell carcinomas, 6/9 (67%) oncocytomas, and 2/7 (29%) papillary renal cell cancer. Median (minimum-maximum) absolute nephrographic phase enhancement (nephrographic minus unenhanced phase) was: clear cell renal cell carcinomas 65 HU (34-120), oncocytomas 80 HU (51-111), and papillary renal cell carcinomas 16 HU (7-32)., Conclusion: Absolute nephrographic phase enhancement of < or = 32 HU distinguished papillary renal cell carcinomas from clear cell renal cell carcinomas and oncocytomas.

Objectives: To analyse 80-kVp 16-MDCT in patients with clinically suspected pulmonary embolism (PE) and diminished renal function after a reduction in dose of contrast medium (CM) from 200 to 150 mg I/kg., Methods: Fifty patients with suspected PE and glomerular filtration rate (GFR) less than 50 mL/min underwent 80-kVp 16-MDCT with 150 mg I/kg. Mean density/image noise (1 standard deviation) was measured in a region of interest in the left pulmonary artery (LPA) and a lower lobe segmental artery (LLSA), and the contrast-to-noise ratio (CNR) was calculated. The values of LPA and LLSA were averaged., Results: Median values/2.5-97.5 percentiles were: age 84/67-96 years, weight 65/43-84 kg, GFR 36/21-45 mL/min, CM dose 9.6/6.4-12 g of iodine, PA density 353/164-495 HU and CNR 11/4.4-20. PE incidence was 16%, and 8% and 12% of the examinations were regarded suboptimal by observer 1 and 2, respectively. Density/CNR values were within ranges reported for common 120-kVp MDCT protocols. None of 32 patients with plasma-creatinine follow-up within 1 week experienced a rise of more than 44.2 mumol/L and none of 50 patients had oliguria/anuria or dialysis. None of 40 patients with a negative CT/no anticoagulation had thromboembolism during follow-up., Conclusion: 80-kVp MDCT combined with individualised ultralow CM doses may provide satisfactory diagnostic quality, which should be to the benefit of patients at risk of contrast medium-induced nephropathy.

Infants with mild postnatal renal dilatation but without vesicoureteral reflux pose a challenge. For how long and in what way should they be followed? From May 1989 to December 2006, we prospectively followed 1,795 pregnancies in which the foetal renal pelvis measured 4 mm or greater. Voiding cystourethrography (VCUG) and renal ultrasound were performed on 1,315 infants at 6 weeks of age. Our study group comprised 208 (167 male) infants with normal VCUG findings who had a renal pelvis of 6-11 mm. We followed them for 1-17 years (mean 11 years). Medical and radiological records were reviewed to determine any urinary symptoms and final outcome. They underwent, on average, four further imaging tests. The renal dilatation had resolved by 24 months in approximately 70%. Urinary tract infection (UTI) developed in 16 (8%). Calyceal dilatation was more likely in those developing UTI (P=0.02). Twenty-two (10.6%) had a radiologically demonstrated urinary tract abnormality. Of the five who had renal scarring or severe obstruction, four became symptomatic. Most infants with mild postnatal renal dilatation can be investigated with only one further sonogram at 24 months of age. Mild postnatal renal dilatation is associated with subsequent UTI or renal tract abnormality in 18%. Severe renal abnormality occurred in 2.4%.

A 3-year-old girl with Alport syndrome presented with decompensated heart failure from hypertension-induced cardiomyopathy 6 months following renal biopsy. Selective renal angiography revealed a large left renal arteriovenous fistula (AVF) with poor perfusion to the left renal parenchyma. The AVF was treated by transcatheter embolization using an Amplatzer vascular plug. Her blood pressure normalized after embolization, and her cardiac function normalized over the following 4 months.

The aim of the investigation reported here was to assess the intraobserver and interobserver variability of renal measurements in children. The study comprised 56 paired measurements in 28 children (median age 7.5 years, range 3.0-15.0 years) without renal or ureterovesical anomalies. Intraobserver and interobserver reproducibility was assessed by repeated measurements of the left and right renal length, width, and thickness. Intraclass correlation coefficients (ICCs) with the corresponding 95% confidence interval (CI) were calculated. Bland and Altman plots were computed to assess the agreement of the measurements. Limits of agreement +/- 2 standard deviations (SD) for the mean differences in renal measurements were derived. Intraobserver ICCs ranged from 0.93 (left and right renal width and right renal thickness) to 0.99 (left renal length), and interobserver ICCs ranged from 0.64 (right renal thickness) to 0.90 (right renal length). Limits of agreement in the Bland and Altman plots ranged from -8.0 to 9.2% (intraobserver left renal width) to the widest limit from -18.0 to 19.2% (interobserver left renal length). Overall, this study demonstrated the good reproducibility and agreement of most renal dimensions in children measured by ultrasound (US). Based on these results, we conclude that US is an appropriate measure to assess renal dimensions in both clinical and epidemiological studies.

Objective: The necrosis rate is low when ablating kidney tissues with extracorporeal high intensity focused ultrasound (HIFU), and this drawback has been limiting the application of ultrasonic therapy. The aim of the present study was to determine whether microbubbles increased the ablation efficiency in vivo., Methods: Goat kidneys were exposed to HIFU (control group) or microbubble-assisted HIFU (experimental group). Microbubbles were intravenously injected before focused ultrasound exposure. The linear scan was employed and tissue ablation was performed in manner of a clinical regime. The necrosis rate was determined 24 h after HIFU. Pathological examinations were performed to confirm tissue necrosis and to determine whether there were unaffected tissues within the exposed volume., Results: The necrosis rate was increased in experimental group (4.17 +/- 1.33 vs. 9.32 +/- 2.27 mm(3)/s, P = 0.0007). Ablated tissues formed a hemorrhagic volume on gross examinations, and the boundary between treated and untreated areas was sharp. There was no intact tissue within the exposed volume. Hemorrhage frequently occurred in insonated parenchymas. Destructed ghost cells just inside the demarcation were full of vacuoles, when introducing microbubbles. In control group, the volumes of ablated tissues varied drastically between animals despite a same treatment template., Conclusion: Microbubbles increased the ablation efficiency of HIFU against kidney tissues. A preoperative regime might poorly predict the therapeutic outcome.

In this prospective study, selected biochemical markers of glomerular and tubular function, proteinuria, and ultrasound findings in 62 pediatric patients who underwent surgery for obstructive uropathy were examined. Patients were younger than 12 months, normocreatininemic at the time of surgery, and examined at a mean age of 6.3+/-0.9 years. Out of the markers tested, serum concentration of cystatin C was significantly higher in patients when compared with the control group (p<0.001), and serum creatinine concentration was within reference interval in all patients. With respect to tubular function, 26% of patients had decreased concentration ability. Proteinuria was detected in 4.8% of patients. On ultrasound, 66.7% of kidneys after surgery had residual dilatation of the renal pelvis. The patients thrive well, and their somatic parameters do not differ from their peers. Half of the patients had one or more urinary tract infections from the date of surgery to the date of examination. Study results support the need for long-term nephrologic follow-up in patients after surgery for obstructive uropathy. The hypothesis that renal function in patients undergoing surgery aged younger than 3 or 6 months is better when compared with those aged 6 to 12 months has not been confirmed.

Renal scarring is known to be associated with hypertension. The primary objective of this study was to investigate the prevalence of renal scarring in children referred to our clinic with hypertension. The secondary objective was to compare renal ultrasound (US) examination with dimercaptosuccinic acid (DMSA) renal scan in diagnosing renal scars in these patients. The study included 159 patients who underwent DMSA renal scan as well as renal US for the evaluation of hypertension of unknown etiology. Thirty-three (21%) patients were found to have renal scars; their demographic details, including mean age and gender distribution, were not significantly different from those without renal scars. In comparison with the DMSA renal scan, sensitivity and specificity of renal US in diagnosing renal scars were 36% and 94%, respectively. In our study, in which the prevalence of scarring was 21%, this gave positive predictive and negative predictive values of 63% and 85%, respectively. In conclusion, our study indicates that renal scarring is present in 21% of otherwise healthy children who are evaluated for newly diagnosed hypertension, and renal US is not a sensitive imaging modality to rule out renal scarring.

Exclusive lower pole pelvi-ureteric junction obstruction (PUJO) in double collecting systems in children is a rare condition requiring reconstructive surgery. We report on the feasibility of laparoscopic transabdominal dismembered pyeloplasty in two cases. Two children with duplicated collecting systems presented with hydronephrosis of lower pole moiety due to exclusive PUJO. Isotope renography revealed impaired drainage of affected lower kidney pole. A four-trocar transabdominal technique was used. No stent was used in one patient with bilateral duplication (male, 6 years) while a 4 Fr. double-J stent was placed laparoscopically in another with unilateral duplication (male, 9 months). Both patients had uneventful laparoscopic transabdominal dismembered pyeloplasty. The operation time was 115 and 155 min, respectively, and was comparable to our previously reported patient series undergoing laparoscopic pyeloplasty for singular collecting systems. After a mean follow-up of 21 months (range 12-42), both patients were asymptomatic and showed improved pelvi-ureteric drainage on isotope renography and improved hydronephrosis on ultrasound scan. Laparoscopic transabdominal dismembered pyeloplasty is safe and effective in children with rare lower pole PUJO in double collecting systems.

Microbubble contrast agents for ultrasound (US) have gained increasing interest in recent years, and contrast-enhanced US (CEUS) is a rapidly evolving field with applications now extending far beyond the initial improvements achieved in Doppler US. This has been achieved as a result of the safe profile and the increased stability of microbubbles persisting in the bloodstream for several minutes, and also by the availability of specialized contrast-specific US techniques, which allow a definite improvement in the contrast resolution and suppression of signal from stationary tissues. CEUS with low transmit power allows real-time scanning with the possibility of prolonged organ insonation. Several reports have described the effectiveness of microbubble contrast agents in many clinical applications and particularly in the liver, spleen, and kidneys. CEUS allows the assessment of the macrovasculature and microvasculature in different parenchymas, the identification and characterization of hepatic and splenic lesions, the depiction of septal enhancement in cystic renal masses, and the quantification of organ perfusion by the quantitative analysis of the echo-signal intensity. Other fields of application include the assessment of abdominal organs after traumas and the assessment of vesico-ureteral reflux in children. Finally, tumor-targeted microbubbles make possible the depiction of specific biologic processes.

A consensus is yet to be reached regarding the best strategy for ensuring maximum ureteric delineation during CT urography (CTU). In this study we have compared various CTU protocols to try to establish the best method for ureteric delineation. Saline infusion in the supine position, saline infusion in the prone position, furosemide administration (10 mg, iv) and buscopan administration (20 mg iv) with saline infusion in the prone position were tried in four groups, each having 15 patients who were undergoing CTU. The pelvicalyceal system and ureter were divided into six segments, to each of which an opacification score was assigned (0, unopacified segment; 1, less than 50% opacified segment; 2, 50-99% of the segment opacified; or 3, completely opacified segment) and the results compared. Furosemide administration resulted in complete opacification of 93% of the ureters (28 of 30). In the distal (below the sciatic notch) ureter, the mean score with furosemide was 2.9, while that with saline, supine and prone positioning was 1.87 and 1.83, respectively, and this difference was highly significant (P = 0.0002 and P = 0.0001). It was also significantly higher than the buscopan group (score 2.3, P = 0.002). Also in the lower (the iliac crest to the sciatic notch) and upper (above the iliac crest) ureter, furosemide had significantly higher scores than saline infusion in either position. Saline infusion in the supine and prone positions had very similar scores in all segments that were less than the buscopan group, but this difference was not statistically significant. During CT urography, furosemide administration in low doses is the most effective and convenient technique for ureteric opacification.

To elucidate the Doppler ultrasonographic cut-off value of nutcracker syndrome causing hematuria in children, we analyzed Doppler spectral findings between 15 children with nutcracker syndrome and 15 age- and sex-matched normal control subjects. A follow-up Doppler ultrasound (US) was also performed in children with nutcracker syndrome when hematuria subsided completely after a median period of 1.7 years (range: 1.0-3.5 years) (relieved nutcracker syndrome). The peak velocity (PV) ratios of the left renal vein (LRV) were significantly higher in children with nutcracker syndrome than in those with relieved nutcracker syndrome (P<0.0001) and normal children (P<0.0001). The PV ratios of the LRV at the follow-up US were significantly higher than those in the control subjects (P=0.019). None of the 15 normal children showed PV ratios of the LRV>3.7, but five of the 15 children with relieved nutcracker syndrome without hematuria had PV ratios of 3.91-5.02. When we set the cut-off values for nutcracker syndrome at the mean+/-2 SD (mean: 2.95+/-0.92, range: 1.60-5.02) of 30 controls (normal children and relieved nutcracker without hematuria), the calculated cut-off value was 4.8, and the sensitivity and specificity were 100% and 93%, respectively. Given its high sensitivity, renal Doppler US can be used as a useful initial non-invasive test in the diagnosis of nutcracker syndrome in children with hematuria.

Contrast-enhanced sonography (CEUS) is a recently introduced, promising technique in the evaluation of the kidney. CEUS allows real-time assessment of normal and abnormal renal perfusions. As a consequence of the macrocirculation analysis allowed by Doppler techniques, it is possible to obtain real-time information about microcirculation. US contrast media are not nephrotoxic and can be employed safely, even in subjects with impaired renal function. There are several clinical scenarios where CEUS may play the role of a low-cost, scarcely invasive tool, including renal tumors (with special reference to small, indeterminate masses, i.e., differentiation between carcinoma and angiomyolipoma), renal atypical cystic masses (i.e., differentiation of malignant from benign cysts and follow-up of cystic lesions managed conservatively), renal infarction, renal infections, and renal injuries. In addition, CEUS can be useful in the assessment of renal pseudotumors (including any case with possible renal mass on conventional US imaging) and has been employed in radiofrequency ablation guidance. This pictorial review illustrates the CEUS findings recognizable in a wide spectrum of renal disorders and discusses the strengths and limitations of renal imaging with CEUS.

The technological development of multidetector CT offers new possibilities for better imaging of organic structures that can be used in diagnosis of the kidney. The thinner slices allow a better spatial resolution, and slice fusion allows improved contrast resolution. The isotropic voxel has been realized in the latest 64-channel scanners. The image quality of arbitrarily reconstructed planes has arrived at the image quality of the scan plane. Faster scanning allows studies in different contrast phases, which is helpful for better discrimination of benign or malignant lesions especially in the highly vascularized kidney. Different phases of contrast uptake can be differentiated (arterial, cortico-medullary, nephrographic, and excretory phase). Multidetector CT brings along the risk of increased dose due to thinner slice collimation and overranging phenomena. Indications for CT investigation of the kidney include urolithiasis, tumor diagnosis and staging, renal trauma, and vascular disease. Even in children, special indications for CT of the kidney remain in polytrauma and tumor staging. Multidetector CT of the kidney has become a very valuable tool in urology, but a careful protocol strategy is mandatory.

Electron-beam computed tomography is an imaging technology with a variety of medical applications, primarily in cardiology due to its sub-second acquisition time enabling visualization of a beating heart. Recently, this technique has also been introduced into other fields because of lower radiation exposure compared to traditional computed tomography, as well as the strengths of post-procedural three-dimensional visualization. This report evaluates electron-beam computed tomography as a diagnostic modality in pediatric nephrology patients. Seven patients reflecting typical clinical scenarios in pediatric nephrology were reviewed with regard to the value of electron-beam computed tomography and its contribution to the diagnostic workup. Electron-beam computed tomography is noninvasive and allows three-dimensional post-processing, enabling highly accurate images while requiring less radiation and acquisition time. It is very useful for clinical questions that require a detailed description of vascular and renal anatomy.

Functional compensation occurs in a kidney when the function of the contralateral kidney is decreased or absent. What is, however, not documented is the level of unilateral renal impairment at which functional compensation occurs. Split function, as obtained from a radionuclide renogram, can only show the asymmetry between both kidneys. The aim of the present work was to evaluate at what level of unilateral impairment a functional compensation can be observed in the contralateral normal kidney. From a large database, 180 children over 2 years of age with unilateral pathology were retrospectively selected. All of them underwent a radionuclide study, combining a technetium-99m mercaptoacetyltriglycine (Tc-99m MAG3) renogram associated with a chromium-51 ethylenediaminetetraacetic acid (Cr-51 EDTA) overall clearance, allowing a precise estimation of single-kidney glomerular filtration rate (SKGFR). Below 30-35 ml/min/1.73 m2, there was a significant inverse correlation between SKGFR on the normal and the abnormal side. Above this level, no such correlation was observed, the mean SKGFR on the normal side remaining around 58 ml/min/1.73 m2, whatever the value of SKGFR on the abnormal side. In pediatric patients, hyperfunction occurs when SKGFR of the diseased kidney is below 30-35 ml/min/1.73 m2.

To evaluate the utility of imaging-guided fine-needle percutaneous biopsy of renal masses, we conducted a prospective analysis of our imaging-guided procedures from January 1999 to February 2003. We performed 54 percutaneous core biopsies in 46 patients. Fluoro-computed tomography and ultrasound guidance were respectively used in 48 and six cases. One to four specimens were obtained by using an 18-gauge automated coaxial biopsy system. We reviewed the patients medical records, pathology results, and imaging studies. Core biopsy results were compared with surgical pathology (n=27) or clinical follow-up (n=19). All biopsies provided sufficient material for analysis. The mean tumor size was 33 mm. Biopsy findings were positive for malignancy in 31 cases; histologic diagnoses included renal cell carcinoma (n=23), transitional cell carcinoma (n=5), and metastasis (n=3). Biopsy revealed 15 benign diagnoses: oncocytoma (n=6), hemorrhagic renal cyst (n=3), chronic nephritis (n=3), angiomyolipoma (n=2), and mycotic renal abscess (n=1). The average follow-up period for patients with benign diagnoses was 16 months. Biopsy results showed normal renal parenchyma in eight of 54 procedures, all of which had recuperated by subsequent biopsies. No immediate complications occurred after the procedures. Imaging-guided percutaneous core biopsy is a safe and accurate method for the evaluation of renal masses.

This paper describes the correlation between US-CT images and pathologic findings in the most common solid and cystic renal tumors, to better differentiate malignant and benign renal masses. Several intratumoral tissue components present correlation with US-CT images. Macroscopic components, corresponding to necrotic, hemorrhagic and cystic changes, are identified by visual analysis of the gross specimen, while microscopic components are identified by histopathologic analysis. Microscopic components are classified as cellular [(1) high cellularity with poor extracellular stroma, +/-high nucleus-cytoplasm ratio+/-high uniformity in tumoral cells dimensions; (2) low cellularity with large extracellular stroma+/-low nucleus-cytoplasm ratio+/-low uniformity in tumoral cells dimensions], stromal [(1) fibrotic; (2) fibrovascular; (3) fibromyxoid], vascular related to neoangiogenesis, necrotic [(1) coagulative; (2) colliquative; (3) hemorrhagic], calcific, and adipose.

Idiopathic renal hypouricemia is a hereditary disease characterized by abnormally high renal uric acid clearance. Most patients are clinically silent, but acute renal failure (ARF), urolithiasis, or hematuria may develop. A defect in the SLC22A12 gene, which encodes the renal uric acid transporter, URAT1, is the known major cause of this disorder. We performed a mutational analysis of the SLC22A12 gene in five Korean patients with idiopathic renal hypouricemia in this study. Two patients presented with microscopic hematuria, one with uric acid urolithiasis, and one with exercise-induced ARF. One patient was asymptomatic. Three different mutations, W258X, R90H and R477H, were detected in four of the patients. However, no mutation was found in the fifth ARF patient. This is the first study of SLC22A12 mutations in a country other than Japan. W258X was found to be the predominant SLC22A12 mutation in Korean renal hypouricemia patients, as has been reported in Japan.

Dent's disease is a hereditary renal tubular disorder caused by mutations of the CLCN5 gene and is clinically characterized by low molecular weight proteinuria, hypercalciuria and nephrocalcinosis. This disease has been reported in several countries. However, there are some phenotypic differences between countries, such as hypophosphatemic rickets, progressive renal failure and hematuria. In this study, phenotypes were analyzed in three Korean boys with Dent's disease, and genetic diagnoses were performed using a new convenient method using peripheral blood RNA. Gene studies revealed two nonsense mutations, R637X in two patients and E609X in one patient. The phenotypes of the two patients with R637X were very similar to those of Japanese patients, i.e., they presented with asymptomatic proteinuria without rickets, renal failure or hematuria. The E609X patient was diagnosed genetically at 3 months of age before the onset of clinical symptoms because of superimposed furosemide-induced nephrolithiasis. This is the first report to characterize mutations in the CLCN5 gene in Korean patients with Dent's disease, and expands the spectrum of CLCN5 mutations by reporting a novel mutation, E609X. In addition, the mutational analysis using peripheral blood RNA can be easily applied in the clinical diagnosis.

The diagnostic role of retrograde pyelography in children with secondary hypertension has never been discussed in the literature. We report a child with severe hypertension, who apparently has a normal renin level and a solitary kidney by renal sonography and renal scan. Retrograde pyelography was able to identify the scarred renal mass. To our knowledge this is the first report to discuss the role of retrograde pyelography in a child with a solitary kidney and severe hypertension.

The development of ultrasound contrast agents and dedicated software for the detection of microbubbles has improved the potential contrast resolution of ultrasound and this, added to the already excellent spatial and temporal resolution, makes contrast-enhanced ultrasound (CEUS) well suited for the study of many organs, not only the liver. The contrast agents in clinical use today are so called blood pool agents meaning that, contrary to X-ray contrast media, they do not leave the blood vessels. This provides us with an excellent tool for delineating tissues with perfusion differences and for following the dynamic phases of contrast enhancement, in both large vessels and the microcirculation in parenchymatous organs. For vascular applications, CEUS improves detection of the renal arteries as well as strengthening Doppler signals. Emboli, posttraumatic rupture and other conditions impairing perfusion are readily detected and it may be possible to estimate blood flow by quantifying the contrast enhancement. The CEUS changes in diffuse renal disease are little explored but regional perfusion differences, such as in pyelonephritis, may be seen and quantified. In focal lesions, CEUS helps in the evaluation of atypical cysts and indeterminate masses detected on CT or MR. Many solid lesions may have a perfusion similar to the renal parenchyma but since many tumours are hypovascular, they tend to become echopoor relative to the enhanced renal parenchyma. The detection of a necrotic centre may further help both detection and characterization.

One of the most serious helminth infections in humans with widespread occurrence is hydatid disease. Although the majority of the cases are referred in adults, many of them have to do with children. The hydatid cysts can occur in any organ of the human body and in rare cases in a combination of different sites. We present the case of a young boy with hydatid cysts in both lungs and in the upper pole of the left kidney. The rarity of this case is the unusual combination of the cyst development in these organs without the involvement of the liver.