Role of MRI in the management of patients with nephroblastoma.

Magnetic resonance imaging (MRI) presents the main diagnostic tool for differentiation and staging of renal tumors in childhood. Nephroblastoma is the most common malignant tumor in children. Radiological findings play an important role in therapy study trials of SIOP (International Society of Pediatric Oncology), especially for indicating preoperative chemotherapy. In the past few years MRI has gained great importance in imaging of nephroblastoma and has replaced computed tomography (CT). The aim of this review is to present the diagnostic possibilities of MRI in relation to the requirements of therapy studies. For nephroblastoma, MRI provides important information about tumor extent and distant metastasis. A special focus of MRI in distant staging is venous extent of the tumor into the inferior vena cava. In addition, MRI has an important role in monitoring chemotherapy and in preoperative planning by volume rendering and three-dimensional postprocessing.

Intracerebellar hemorrhage in premature infants: sonographic detection and outcome.

AIMS: Intracerebellar hemorrhage is a rarely confirmed diagnosis in preterm infants in comparison to peri-/intraventricular hemorrhage. This study evaluates the incidence of intracerebellar hemorrhage and neurological outcome in preterm infants. METHODS: 260 infants with gestational age of 22-32 weeks were studied prospectively by cranial ultrasound. Neurodevelopmental outcome was examined in the first three years of life. RESULTS: 15 infants had intracranial hemorrhage grade II-IV (10 intraventricular, 6 intracerebellar hemorrhage). Neurodevelopmental follow-up showed that one infant with intracerebellar hemorrhage is severely handicapped, two have moderate and two mild impairments and one has no sequelae. CONCLUSION: Cerebellar hemorrhage is not rare if ultrasound examination is specifically focused on cerebellar lesions.

Current radiological management of intussusception in children.

Intussusception is the most common abdominal emergency situation in infants and small children. There has been great progress in diagnostic and therapeutic management of intussusception. Ultrasound (US) has been shown to be the first-choice imaging technique in diagnosing intussusception for reasons of high accuracy, simultaneous exclusion of differential diagnoses, and disclosure of additional pathologies. Controversial opinions exist worldwide concerning the nonoperative treatment of intussusception in infants and children. Pneumatic reduction under fluoroscopic guidance and hydrostatic reduction under US monitoring are the preferred techniques. The aim should be a success rate of at least 90% in idiopathic intussusception. This review summarizes different types of intussusception and outlines diagnostic aspects as well as several treatment concepts.

Visualization of intrarenal vessels by 3.0-T MR angiography in comparison with digital subtraction angiography using renal specimens.

BACKGROUND: MRI at 3.0 T enables high-spatial resolution for renal MR angiography. OBJECTIVE: Evaluation of an arterial tree model in animal kidney specimens with comparison of digital subtraction angiography (DSA) and high-field MRI to find out the maximum spatial resolution of intrarenal vessels. It was considered that objective quantitation of angiogram quality could be achieved. MATERIALS AND METHODS: A total of 27 pig kidney specimens were examined by MR angiography (flash 3D) using a 3.0-T scanner (TRIO; Siemens, Erlangen, Germany) with an eight-channel head coil and a voxel size of 0.9x0.9x1.1 mm in the early arterial phase after implantation of a 4F catheter in the renal artery. DSA (Integris, Philips, Best, The Netherlands) was performed immediately after the MRI. With the help of semiautomated segmentation, all vessels were marked for comparison of the vessel trees. The Wilcoxon rank test was used for statistical evaluation of vessel numbers and branching depths. RESULTS: Objective comparison between DSA and MR angiography was achieved. High-field MR angiography had the ability to depict vessels up to the seventh branching on average. Significant differences in vessel delineation and counts were found from the fifth level of intrarenal branching onwards with DSA showing an advantage. CONCLUSION: High-field MRI has great potential in the detection of intrarenal arteries and is comparable to DSA in visualization of the central intrarenal vessel tree.

Imaging of congenital anomalies and variations of the caudal spine and back in neonates and small infants.

Spinal dysraphisms are categorized in open dysraphisms with prominent abnormal nervous tissue above the skinlevel and closed dysraphisms with a skin covered malformation. Especially the occult dysraphisms are marked by suspect skin masses and other dermal anomalies. The purpose of this review is to demonstrate the indications and spectrum of spinal sonography in neonates and infants. In comparison typical dysraphisms are demonstrated in sonography and MR Imaging. We demonstrate the value of ultrasound in comparison to MRI and describe a usefull handling of the methods in neonates and infants. The differentiation between the potentially dangerous dimples associated with dermal sinus, which can lead to meningitis and the harmless coccygeal dimple in the cranial gluteal cleft is presented. An inconspicious examination does not need a further imaging, but suspicious results of sonography need an MR imaging dependent of clinical conditions. Neurologically conspicious infants need MR imaging completed by sonography. Great advantages of sonography are the real time examination and the potential to show oscillations of the conus, filum and cauda equina in M-mode-imaging.

Normative values for intima-media thickness and distensibility of large arteries in healthy adolescents.

OBJECTIVE: Sonographic evaluation of arterial wall morphology and elasticity is increasingly accepted as a non-invasive tool in cardiovascular assessment. Several studies suggest that intima-media thickness (IMT) and arterial elasticity indices may sensitively reflect different vasculopathic processes in children. However, normative values and the impact of adolescent growth are largely unknown. METHODS: We assessed the IMT of the common carotid (cIMT) and femoral arteries (fIMT), carotid elasticity indices and interacting anthropometric factors in 247 healthy subjects aged 10-20 years. RESULTS: cIMT, fIMT, incremental elastic modulus (Einc) and circumferential wall stress (CWS) were positively, and distensibility coefficient (DC) inversely, correlated with age, height, body mass index (BMI), systolic blood pressure (BP) and brachial pulse pressure (r = 0.56 to -0.45, P < 0.05 to 0.0001). DC (r = -0.29, P < 0.0001) and stiffness index beta (r = 0.25, P < 0.0001), but not Einc, were significantly associated with cIMT independently of age. All vascular parameters showed non-Gaussian distributions. Excessively high IMT was associated with BMI and pulse pressure above the 90th percentile, and elevated Einc with high-normal BMI. Multivariate analysis identified independent positive effects of standardized BMI and brachial pulse pressure on normalized cIMT, negative effects of systolic BP and cIMT on DC, a positive effect of cIMT on stiffness, and positive effects of systolic BP and BMI on Einc and CWS. CONCLUSIONS: Morphological and functional measures of large arteries should be normalized to take account of changes during adolescence and skewed distributions. Relative body mass, systolic blood pressure and/or pulse pressure are determinants of IMT and elasticity.

MR volumetric analysis of the course of nephroblastomatosis under chemotherapy in childhood.

Nephroblastomatosis is a paediatric renal disease that may undergo malignant transformation. When neoadjuvant chemotherapy is indicated for nephroblastomatosis or bilateral Wilms' tumours, exact volumetric analysis using high-speed data processing and visualization may aid in determining tumour response. Using 3D-volume-rendering software, the 0.5-T MRI data of a 2-year-old girl with bilateral nephroblastomatosis was analysed. Exact volume determination of foci of nephroblastomatosis was performed by automatic and manual segmentation, and the relation to normal renal parenchyma was determined over a 12-month period. At the first visit, 80% (460/547 ml) of the extremely enlarged right kidney was due to nephroblastomatosis. Total tumour volume within the right kidney decreased to 74 ml under chemotherapy. Volume analysis of the two emerging right-sided masses after treatment correctly suggested Wilms' tumour. Three-dimensional rendering of the growing masses aided the surgeon in nephron-sparing surgery during tumour resection.

MR to assess renal function in children.

Renal function evaluation in the pediatric patient is generally based on scintigraphic examinations where a baseline gamma-camera renography is used to determine single kidney function, and diuresis renography is obtained to assess urinary drainage from the pelvicalyceal system. Magnetic resonance imaging also permits the evaluation of renal functional processes using fast dynamic sequences. Principally, an agent cleared by renal excretion is intravenously injected and its cortical uptake, parenchymal transport, and eventually its urinary excretion are followed with serial images. Different approaches have been presented most of which are based on T1-weighted gradient-recalled echo sequences with short TR and TE and a low flip angle obtained after intravenous injection of Gd-DTPA or Gd-DOTA. These techniques permit renal functional assessment using different qualitative and quantitative parameters; however, most of these methods are not suitable for the evaluation of urinary tract dilatation in infants and children. For the diagnostic work-up of children with congenital urinary tract obstruction and malformation a technique was developed which permits quantitative determination of single kidney function, in addition to evaluating urinary excretion disturbances analogous to that possible with scintigraphy.

Functional and morphologic evaluation of congenital urinary tract dilatation by using combined static-dynamic MR urography: findings in kidneys with a single collecting system.

PURPOSE: To assess combined static-dynamic magnetic resonance (MR) urography in the evaluation of congenital urinary tract dilatation in infants and children. MATERIALS AND METHODS: Sixty-two patients with urinary tract dilatation underwent prospective examination with combined static-dynamic MR urography. A combination examination involved use of a static T2-weighted three-dimensional inversion-recovery fast spin-echo sequence and a dynamic T1-weighted two-dimensional fast field-echo sequence with gadopentetate dimeglumine-DTPA and furosemide application. Twelve additional patients underwent examination with only static MR urography. Thus, both image quality and morphologic features were assessed in 74 patients with the use of MR urography. The results were compared with those of ultrasonography and, when available, conventional urography or surgery. In 62 patients, the dynamic sequence was used to calculate split renal function from renograms generated from parenchymal regions of interest and to assess urinary excretion from whole-kidney renograms. Results were compared with those of diuretic renal scintigraphy (DRS) for split function (Spearman rank correlation coefficient) and urinary excretion (kappa coefficient). RESULTS: Stenoses at the ureteropelvic (n = 33) and ureterovesical (n = 31) junctions and within the ureter (n = 3) and nonstenotic dilatation (n = 23) were clearly depicted, while the normal urinary tract (n = 51) was depicted in its entirety in 47 of 51 examinations. Image quality was considered good or excellent in 95% of the kidney-ureter units. For split renal function, dynamic MR urography and DRS showed significant correlation (r = 0.92, P <.001). For urinary excretion, MR urography and DRS showed strong agreement (kappa = 0.67), with concordant classification of urinary excretion in 59 (81%) of 73 abnormal kidney-ureter units and in all 47 (100%) normal kidney-ureter units. CONCLUSION: Combined static-dynamic MR urography provides high-quality depiction of the urinary tract in infants and children, while allowing accurate determination of single-kidney function and reliable evaluation of urinary excretion.