Chronic urinary obstruction: evaluation of dynamic contrast-enhanced MR urography for measurement of split renal function.

PURPOSE: To evaluate if measurement of split renal function ( SRF split renal function ) with dynamic contrast material-enhanced ( DCE dynamic contrast enhanced ) magnetic resonance (MR) urography is equivalent to that with renal scintigraphy ( RS renal scintigraphy ) in patients suspected of having chronic urinary obstruction. MATERIALS AND METHODS: The study protocol was approved by the institutional ethics committee of the coordinating center on behalf of all participating centers. Informed consent was obtained from all adult patients or both parents of children. This prospective, comparative study included 369 pediatric and adult patients from 14 university hospitals who were suspected of having chronic or intermittent urinary obstruction, and data from 295 patients with complete data were used for analysis. SRF split renal function was measured by using the area under the curve and the Patlak-Rutland methods, including successive review by a senior and an expert reviewer and measurement of intra- and interobserver agreement for each technique. An equivalence test for mean SRF split renal function was conducted with an α of 5%. RESULTS: Reproducibility was substantial to almost perfect for both methods. Equivalence of DCE dynamic contrast enhanced MR urography and RS renal scintigraphy for measurement of SRF split renal function was shown in patients with moderately dilated kidneys (P < .001 with the Patlak-Rutland method). However, in severely dilated kidneys, the mean SRF split renal function measurement was underestimated by 4% when DCE dynamic contrast enhanced MR urography was used compared with that when RS renal scintigraphy was used. Age and type of MR imaging device had no significant effect. CONCLUSION: For moderately dilated kidneys, equivalence of DCE dynamic contrast enhanced MR urography to RS renal scintigraphy was shown, with a standard deviation of approximately 12% between the techniques, making substitution of DCE dynamic contrast enhanced MR urography for RS renal scintigraphy acceptable. For severely dilated kidneys, a mean underestimation of SRF split renal function of 4% should be expected with DCE dynamic contrast enhanced MR urography, making substitution questionable.

Apparent diffusion coefficient measurements of the fetal brain during the third trimester of pregnancy: how reliable are they in clinical practice?

OBJECTIVE: The objective of this study was to determine the reproducibility, the inter-hemispheric difference and the reference apparent diffusion coefficient (ADC) values of the fetal brain according to gestational age. METHOD: One hundred and one normal fetal brain (29.4-38.4 weeks) were analysed with diffusion-weighted MR imaging. ADC was measured in frontal white matter (FWM), occipital white matter (OWM), centrum semi-ovale (CSO), basal ganglia (BG), cerebellar hemisphere (CBM) and pons. ADC ratios (fronto-occipital, fronto-cerebellar and occipito-cerebellar) were calculated. Inter-observer reproducibility was assessed on 27 studies, using intra-class correlation coefficient and Bland-Altman plot. Inter-hemispheric difference was evaluated with Bland-Altman plot. Gestation-specific reference intervals were estimated for each brain region. RESULTS: Inter-observer bias was near zero. Limits of agreement (LOA) were clinically acceptable (-0.17; 0.20 to -0.38; 0.31 × 10(-3) mm(2) /s) for all brain regions except for CSO and pons. Inter-hemispheric bias was near zero. Smallest LOA were for FWM (±0.09 mm(2) /s) and BG (±0.019 mm(2) /s). ADC values decreased, whereas ADC ratio increased with gestational age, reflecting normal maturation. Fronto-occipital, fronto-cerebellar and occipito-cerebellar ratios were consistently above 0.8, 1 and 1, respectively. CONCLUSION: The fetal brain regions with the highest reproducibility and smallest inter-hemispheric differences are the frontal, occipital, cerebellar white matter and BG. ADC ratio could be useful to assess differential temporo-spatial maturation.

Extracranial carotid arteriopathy in stroke-free children with sickle cell anemia: detection by submandibular Doppler sonography.

BACKGROUND: Cerebral vasculopathy is a serious complication of sickle cell anemia. Overt strokes are largely due to intracranial arteriopathy, detected by routine transcranial Doppler and largely prevented through chronic transfusions. As extracranial internal carotid artery arteriopathy was considered rare, it has not been routinely assessed in sickle cell anemia. Recent cases of overt strokes associated with stenosis/occlusion of the extracranial portion of the internal carotid artery prompted us to include extracranial internal carotid artery assessment to our transcranial Doppler sonography protocol. OBJECTIVE: The aim of the study was to perform a cross-sectional study in children with sickle cell anemia to evaluate Doppler flow patterns of the extracranial internal carotid arteries and to assess potential associated factors. MATERIALS AND METHODS: Between June 2011 and April 2012, 435 consecutive stroke-free children with sickle cell anemia (200/235 M/F, median age: 7.9 years) were assessed for extracranial internal carotid artery using a 2-MHz transcranial Doppler sonography probe via a submandibular window during routine transcranial Doppler sonography visits. The course of both extracranial internal carotid artery was assessed by color Doppler mapping, and the highest flow velocity was recorded after insonation of the entire length of the artery and analyzed. Intra- and extracranial MR angiographies were available in 104/435 subjects for comparison. RESULTS: Mean (SD) extracranial internal carotid artery time-averaged mean of maximum velocity was 96 (40) cm/s. Extracranial internal carotid artery tortuosities were echo-detected in 25% cases and were more frequent in boys (33% vs.18%; P < 0.001). Velocity ≥160 cm/s in at least one extracranial internal carotid artery was found in 45 out of 435 patients with sickle cell anemia (10.3%) and was highly predictive of MR angiography stenosis. Simultaneous abnormal intracranial velocity (≥200 cm/s) was recorded in 5/45 patients, while 40 patients had isolated extracranial internal carotid artery velocity ≥160 cm/s. Low hemoglobin (odds ratio: 1.9/g/dL, 95% confidence interval (CI): 1.3-2.9; P = 0.001) and tortuosities (odds ratio: 19.2, 95% CI: 7.1-52.6; P < 0.001) were significant and independent associated factors for isolated extracranial internal carotid artery velocities ≥160 cm/s. CONCLUSION: Adding extracranial internal carotid artery evaluation via the submandibular window to transcranial Doppler sonograpy allowed us to detect 10.3% patients at risk for extracranial internal carotid arteriopathy. Further studies are needed to evaluate the prognosis of these anomalies.

Is fetal cerebral MRI worthwhile in antenatally diagnosed isolated cleft lip with or without palate?

OBJECTIVE: This study aims to evaluate the use of fetal brain magnetic resonance imaging (MRI) following an antenatal sonographic diagnosis of isolated cleft lip with or without cleft palate (CL/P). METHOD: This was a retrospective study of 92 fetuses antenatally diagnosed with isolated CL/P on screening ultrasound. All patients underwent expert diagnostic antenatal ultrasound, fetal brain MRI, and karyotype analysis. RESULTS: Five cases were excluded from the study as associated abnormalities were detected on expert ultrasound: corpus callosum agenesis (n = 1), retrognathism (n = 3), and ectrodactyly (n = 1). Fetal MRI diagnosed unsuspected midline cerebral abnormalities in four out of the 87 remaining cases (4.6%): vermis agenesis (n = 1), isolated arhinencephaly (n = 2), and suspicion of pituitary abnormality (n = 1). All karyotype analyses were normal. CONCLUSION: In CL/P, the incidence of associated cerebral abnormalities overlooked on ultrasound is 4.6%. Careful evaluation of midline structures by expert ultrasound in CL/P is necessary and may be sufficient. MRI can be useful if the US examination is limited or in case of family history. However, the choice to proceed to fetal MRI may vary from institution to institution.

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system.

PURPOSE: Computed tomography can be used for three-dimensional (3D) evaluation of adolescent idiopathic scoliosis (AIS) patients, but at the expense of high radiation exposure, and with the limitation of being performed in the supine position. These drawbacks can now be avoided with low-dose stereoradiography, even in routine clinical use. The purpose of this study was to determine the 3D postoperative correction of AIS patients treated by posteromedial translation. METHODS: Forty-nine consecutive patients operated for AIS (Lenke 1-4) using posteromedial translation were included. Corrections were evaluated preoperatively, postoperatively and after at least 2 years using the EOS imaging system. 3D angles were measured in the plane of maximum deformity. RESULTS: Mean number of levels fused and operative time were 13.5 ± 1 and 215 ± 25 min, respectively. Main thoracic, proximal thoracic, and lumbar curves corrections averaged 64.4 ± 18, 31 ± 10 and 69 ± 20 %, respectively. Mean T4-T12 kyphosis increased 18.8° ± 9° in the subgroup of hypokyphotic patients. Mean apical vertebral rotation reduction was 48.3 ± 20 %. Trunk height gain averaged 27.8 ± 14 mm. There was no pseudarthrosis or significant loss of correction in any plane during follow-up. Two patients (4 %) developed asymptomatic proximal junctional kyphosis, despite having normal thoracic kyphosis. Their sagittal balance was shifted posteriorly by 36 and 47 mm, respectively, by the operation, but revision surgery was not performed. CONCLUSIONS: Low-dose stereoradiography provided 3D reconstructions of the fused and unfused spine in routine clinical use. Postoperative 3D analysis showed that posteromedial translation enhanced sagittal balance correction, without sacrificing frontal or axial correction of the deformity.

Reliability of cervical lordosis and global sagittal spinal balance measurements in adolescent idiopathic scoliosis.

STUDY DESIGN: Radiological reproducibility study. PURPOSE: To assess intra and interobserver reliability of radiographic measurements for global sagittal balance parameters and sagittal spine curves, including cervical spine. Sagittal spine balance in adolescent idiopathic scoliosis (AIS) is a main issue and many studies have been reported, showing that coronal and sagittal deformities often involve sagittal cervical unbalance. Global sagittal balance aims to obtain a horizontal gaze and gravity line at top of hips when subject is in a static position, involving adjustment of each spine curvature in the sagittal plane. To our knowledge, no study did use a methodologically validated imaging analysis tool able to appreciate sagittal spine contours and distances in AIS and especially in the cervical region. METHODS: Lateral full-spine low-dose EOS radiographs were performed in 75 patients divided in three groups (control subjects, AIS, operated AIS). Three observers digitally analyzed twice each radiograph and 11 sagittal measures were collected for each image. Reliability was assessed calculating intraobserver Pearson's r correlation coefficient, interobserver intra-class correlation coefficient (ICC) completed with a two-by-two Bland-Altman plot analysis. RESULTS: This measurement method has shown excellent intra and interobserver reliability in all parameters, sagittal curvatures, pelvic parameters and global sagittal balance. CONCLUSIONS: This study validated a simple and efficient tool in AIS sagittal contour analysis. It defined new relevant landmarks allowing to characterize cervical segmental curvatures and cervical involvement in global balance.

In vivo assessment of experimental neonatal excitotoxic brain lesion with USPIO-enhanced MR imaging.

PURPOSE: To assess the feasibility of magnetic resonance imaging (MRI) enhanced with ultrasmall superparamagnetic particles of iron oxide (USPIO) for assessing excitotoxic brain lesions in an experimental model of neonatal periventricular white matter (PWM) lesions. MATERIALS AND METHODS: Brain lesions were induced by intracerebral injection of ibotenate in 14 newborn rats. Pre- and post-USPIO T2-weighted MRI was performed in seven of them (group A) and in five control newborns (group C). In seven newborns with induced cerebral lesions, USPIO-enhanced MRI was not performed (group B). We compared the signal intensity of the lesion to the contralateral unaffected brain (lesion-to-brain contrast, LBC) and the lesion signal-to-noise ratio (SNR) before and after USPIO injection. MR imaging was correlated with histology. RESULTS: USPIO injection significantly (P<0.05) decreased LBC and SNR of brain lesion but induced no changes in normal controls. The densities of macrophages and iron-laden cells were higher on the lesion side than on the contralateral side (P<0.05). Neither lesion size nor the surrounding macrophage infiltrate was significantly different between groups A and B. CONCLUSION: Post-USPIO T2-weighted MRI demonstrated negative enhancement of neonatal excitotoxic brain lesion. USPIO injection does not appear to exacerbate brain lesions.

Computed Tomography measurements of the normal and the pathologic cochlea in children.

BACKGROUND: Radiological investigation is frequently undertaken to assess the aetiology of sensorineural hearing loss (SNHL). OBJECTIVE: To establish the CT measurements of the normal cochlea in children and to determine radiological criteria correlated with SNHL. MATERIALS AND METHODS: A retrospective study of temporal bone CT performed in 159 children, age range from 3 days to 16 years between February 1999 and July 2004. A control group (n = 88) comprised children without SNHL; the SNHL group comprised 71 children. The width of the second turn of the cochlea (CW), the cochlear height (CH), and the width of the bony canal for the cochlear nerve (WCN) were measured on a reference plane containing the modiolus, the posterior semicircular canal, the footplate, and the stapes arch. RESULTS: Width of the canal measurements or=2.5 mm supported the diagnosis of SNHL with a specificity of 97% and 91%, respectively. Cochlear width was found to be significantly smaller in the SNHL group (5.61 +/- 0.51 mm) than in the control group (5.75 +/- 0.31 mm, P < 0.02), a size <5.4 mm being highly suggestive of SNHL with a specificity of 90%. No significant variations of all measurements were found with age. CONCLUSION: Appropriate measurements of WCN and CW are highly correlated with SNHL.

Development of molecular imaging in the European radiological community.

The recent and concomitant advances in molecular biology and imaging for diagnosis and therapy will place in vivo imaging techniques at the centre of their clinical transfer. Before that, a wide range of multidisciplinary preclinical research is already taking place. The involvement of radiologists in this new field of imaging sciences is therefore absolutely mandatory during these two phases of development. Achievement of such objectives requires the refinement of strategy within the European radiological community and the European Society of Radiology (ESR) will have to drive a number of actions to stimulate the younger generation of radiologists and to facilitate their access to knowledge. For that purpose, a molecular imaging (MI) subcommittee of the ESR Research Committee based on a group of involved radiologists will be constituted to develop contacts with other constitutive committees and associated societies to provide proposals to our community.

Partial unilateral ureteral obstruction in newborn mice: magnetic resonance imaging and pathology studies.

PURPOSE: The mechanism underlying the evolution of congenital obstructive hydronephrosis in humans is still unclear. Although partial unilateral ureteral obstruction has been extensively explored in rats, studies in neonatal mice may lead to new insights into underlying cellular mechanisms, especially with the availability of mutant mice. We developed a model of partial unilateral ureteral obstruction in newborn mice. MATERIALS AND METHODS: Mice were operated on by the fifth day of life. We created 3 groups, namely partial unilateral ureteral obstruction (embedding the ureter in the psoas muscle), complete unilateral ureteral obstruction (ligating the ureter) and sham (exposing the ureter). We studied pelvis diameter and kidney length on magnetic resonance imaging, and kidney weight, inflammation, apoptosis and fibrosis on histological assessment during the second (early) and fourth weeks (late) postoperatively. RESULTS: Magnetic resonance imaging showed enlarged pelvis diameter in late partial unilateral ureteral obstruction, and in early and late complete unilateral ureteral obstruction. Pathological studies revealed parenchyma atrophy in early and late partial unilateral ureteral obstruction. Apoptosis occurred early in partial unilateral ureteral obstruction and decreased later. Macrophage infiltration was enhanced in early and late partial unilateral ureteral obstruction. Fibrosis increased in late partial unilateral ureteral obstruction. All of these results were significantly intermediate between mice with complete unilateral ureteral obstruction and sham operated mice. CONCLUSIONS: It is possible to create renal lesions in newborn mice specific to partial ureteral obstruction. Magnetic resonance imaging of morphological changes demonstrated specific features of partial unilateral ureteral obstruction. Being noninvasive, this approach opens the way for further studies to investigate prognostic parameters after partial ureteral obstruction. In the future this model could be used in knockout mice to study the pathogenesis of renal lesions secondary to obstruction.

Long-term outcome of prenatally detected posterior urethral valves: single center study of 65 cases managed by primary valve ablation.

PURPOSE: Management of posterior urethral valves is significantly modified by the prenatal diagnosis. Our aim was to assess long-term outcome of children with prenatally detected posterior urethral valves treated at our institution by primary valve ablation without routine urinary drainage or diversion. MATERIALS AND METHODS: A total of 79 cases of posterior urethral valves were detected prenatally at our hospital between 1987 and 2004. Of these cases 65 were managed postnatally, while pregnancy was terminated in 14. We studied the prenatal parameters of gestational age at diagnosis, renal parenchyma on ultrasound and amniotic fluid volume. Fetal urine was analyzed when indicated. Long-term outcome was assessed. RESULTS: Primary valve ablation was done in all cases except 2. Median followup was 6.8 years (range 1 to 14.3). At the end of followup there were 11 cases of renal failure (17%) with 5 detected before 24 weeks of gestation, 6 cases of oligohydramnios and 9 cases of abnormal parenchyma. Gestational age at diagnosis and oligohydramnios were statistically significant predictors of final renal outcome (p = 0.003 and p = 0.02, respectively), while renal parenchymal changes were not (p = 0.23). When fetal urinalysis detected good prognosis (12 cases) renal failure developed in none, compared to 2 of the 3 cases with a bad prognosis. Continence was achieved in 42 of 55 toilet trained children (76%), 3 had nocturnal enuresis and 10 (18%) were incontinent. CONCLUSIONS: Our long-term results of prenatally detected posterior urethral valves confirm that early valve ablation can be considered as the primary treatment in the majority of patients, without the need for preoperative drainage or diversion. Gestational age at diagnosis and volume of amniotic fluid are significant predictors of postnatal renal outcome.

Lower bone mineral content in children with type 1 diabetes mellitus is linked to female sex, low insulin-like growth factor type I levels, and high insulin requirement.

CONTEXT: Studies on bone mineral characteristics in children with type 1 diabetes mellitus (T1DM) have generated conflicting results. OBJECTIVE: Our objective was to investigate bone mineral characteristics in children with T1DM and to analyze their associations with bone metabolism and the IGF-I system. DESIGN: We recruited a cohort of Caucasian patients with T1DM for at least 3 yr and healthy children between January 2003 and June 2004. SETTING: This was a university hospital-based study. PARTICIPANTS: A total of 127 patients and 319 controls aged 6 to 20 yr participated. METHODS: Dual-energy x-ray absorptiometry was performed in patients and controls. Serum bone alkaline phosphatase, CrossLaps, IGF-I, and IGF-binding protein 3 levels were determined in patients with values analyzed using our normative data from 1150 healthy children. RESULTS: After adjustment for age, sex, pubertal stage, and body mass index sd score, total body bone mineral content (BMC)/lean body mass was significantly lower in patients than in controls (P < 0.04). This difference was a result of the differences between the girls of the two groups. Girls with T1DM had significantly lower lumbar spine and total body BMC than control girls (P = 0.002), whereas no such difference was observed in boys. Serum bone alkaline phosphatase level was significantly lower in girls than in boys (P = 0.04). Low serum IGF-I levels and the administration of large amounts of insulin were found to have independent deleterious effects on BMC for children of all ages and both sexes, whereas disease duration and glycosylated hemoglobin levels did not. CONCLUSIONS: A sex-related difference in the impairment of bone mineral characteristics was identified in children with T1DM. Longitudinal studies are required to investigate whether boys may gain slightly less bone mass during skeletal growth.

Is there functional vascular information in anatomical MR sequences? A preliminary in vivo study.

According to the type of sequences used, either morphological or dynamic functional study can be performed using magnetic resonance imaging (MRI). The aim of this study is to find out if vascular information found, in dynamic MR sequences, already exists in anatomical MR sequences in the particular case of Legg-Calvé-Perthes disease (LCPD). LCPD is due to a loss of circulation to the femoral head in a growing child resulting in avascular necrosis and leading to possible distortion of size and shape of the proximal femur. MRI acquisitions consist in performing two anatomical sequences and one dynamic sequence with a gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) injection. Five new parametric images characterizing hyper- and hypo-vascularized areas are computed from the dynamic MR sequence. For each new image, the two corresponding anatomical images are found and registered. Then, four types of regions of interest (ROIs) are extracted: healthy hyper- and hypo-vascularized areas and pathological hyper- and hypo-vascularized areas. First-order statistical parameters and texture parameters (Haralick's method, run length method, fractal parameters, autoregressive factors and Laws' texture energy method) are computed in each ROI. Then, a statistical study based on a T test is performed. Results show that some parameters could discriminate the four ROI types. Hence, dynamic vascular image and intrinsic anatomical image characteristics seem to be correlated. Finally, the disease can be evaluated with objective parameters using only anatomical sequences.

Quantitative Shear-Wave Elastography of the Liver in Preterm Neonates with Intra-Uterine Growth Restriction.

The feasibility and reproducibility of liver stiffness measurements using Supersonic Shear-wave Imaging (SSI) in preterm neonate have not been reported. Our aim was to determine if liver stiffness differs between intra-uterine growth restriction (IUGR) and appropriate for gestational age (AGA) preterm infants with/without cholestasis. We measured liver stiffness (in kPa) in 45 AGA and 18 IUGR preterm infants, and assessed reproducibility in 26 preterms using Intraclass Correlation Coefficients (ICC) and Bland-Altman tests. Liver stiffness values were compared between AGA and IUGR with and without cholestasis and correlated with birth weight. Measurements showed high reproducibility (ICC = 0.94-0.98 for intra-operator, 0.86 for inter-operator) with good agreement (95% limits: -1.24 to 1.24 kPa). During the first postnatal week, liver stiffness was higher in IUGR (7.50 ±1.53 kPa) than in AGA infants (5.11 ±0.80 kPa, p<0.001). After day 8, liver stiffness remained unchanged in AGA but increased progressively in IUGR infants (15.57 ±6.49 kPa after day 21). Liver stiffness was higher in IUGR neonates with cholestasis (19.35 ± 9.80 kPa) than without cholestasis (7.72 ± 1.27 kPa, p<0.001). In conclusion, quantitative liver SSI in preterms is feasible and reproducible. IUGR preterms who will develop cholestasis present high liver stiffness even at birth, before biological cholestasis occurs.

Gestational hypoxia induces white matter damage in neonatal rats: a new model of periventricular leukomalacia.

In the premature infant, periventricular leukomalacia, usually related to hypoxicischemic white matter damage, is the main cause of neurological impairment. We hypothesized that protracted prenatal hypoxia might induce white matter damage during the perinatal period. Pregnant Sprague-Dawley rats were placed in a chamber supplied with hypoxic gas (10% O2-90% N2) from embryonic day 5 (E5) to E20. Neonatal rat brains were investigated by histology, immunocytochemistry, western blotting, in situ hybridization, DNA fragmentation analysis, and in vivo magnetic resonance imaging (MRI). Body weight of pups subjected to prenatal hypoxia was 10 to 30% lower from P0 to P14 than in controls. Specific white matter cysts were detected between P0 and P7 in pups subjected to prenatal hypoxia, in addition to abnormal extra-cellular matrix, increased lipid peroxidation, white matter cell death detected by TUNEL, and increased activated macrophage counts in white matter. Subsequently, gliotic scars and delayed myelination primarily involving immature oligodendrocytes were seen. In vivo MRI with T1, T2, and diffusion sequences disclosed similar findings immediately after birth, showing strong correlations with histological abnormalities. We speculate that protracted prenatal hypoxia in rat induces white matter damage occurring through local inflammatory response and oxidative stress linked to re-oxygenation during the perinatal period.