Mesure pratique de l’irradiation en radiopédiatrie : utilisation du produit dose surface en fluorographie numérique et pour les radiographies pulmonaires néonatales

PURPOSE

Control of radiation dose in pediatric radiology requires knowledge of the reference levels for all examinations. These data are useful for daily quality assessment, but are not perfectly known for some radiographic examinations. The purpose of our study was to evaluate the dose related to voiding cystourethrograms (VCUG), upper GI (UGI) and intravenous urography (IVU). Neonatal chest radiographs in the intensive care unit were also evaluated.

MATERIAL AND METHODS

For examinations with contrast material (478VCUG, 220UGI, 80IVU), the children were divided in groups based on their weight, from 5 to 30 Kg. Measurements were performed using an ionization chamber and expressed with the dose-area product (DAP). For chest radiographs, a direct measurement of the entrance-skin dose was performed, with secondary calculation of the DAP.

RESULTS

For VCUGs, the DAP ranged between 42.89cGy.cm2 and 125.41cGy.cm2. The range was between 76.43 and 150.62cGy.cm2 for UGIs and between 49.06 and 83.33cGy.cm2 for IVUs. For neonate chest radiographs, DAP calculations were between 0.29 and 0.99cGy.cm2.

CONCLUSION

These values represent our reference doses. They allow continuous monitoring of our radiographic technical parameters and radiographic equipment and help to correct and improve them if necessary.

[Imaging of chilhood and adolescent scoliosis]

Scoliosis is frequent, especially during the peripubertal period, which corresponds to the period of greatest activity. About 75% of scoliosis are idiopathic, while the remaining 25% can be divided into neuromuscular, congenital and miscellaneous etiologies. When it is associated with pain, a comprehensive work up should be undertaken to identify the underlying etiology of the scoliosis. Idiopathic scoliosis is typically evaluated using standard radiographs. The number of follow-up radiographs and radiation exposure must be maintained to a minimum. Radiation safety guidelines and protocols must be implemented. Large cassettes can be replaced by digital acquisitions using units with reconstruction software. The technique of evaluation of these scoliosis series radiographs as well as their results will be reviewed. Recent data regarding the evaluation of spinal and pelvic balance parameters in the standing position will be introduced. Atypical idiopathic and other scoliosis require additional evaluation. Computed tomography, with 2D and 3D reformations, is ideal for evaluation of bony anomalies. MRI is ideal for evaluation of the spinal canal and cord, from the skull base down to the sacrum, for all patients with surgical scoliosis or patients with neurological symptoms. The increased availability of MR imaging has resulted in an increased number of so-called idiopathic asymptomatic scoliosis where an underlying anomaly can be identified.

[Familial idiopathic hypertrophic osteoarthropathy and atopic dermatitis (Currarino's disease)]

CASE REPORT

Two brothers with a Currarino's disease are reported. Patients characteristics included a dysmorphic syndrome, cranial suture defects, hypertrophic osteoarthropathy and severe chronic eczema.

COMMENTS

Consanguinity of parents suggests an autosomal recessive inheritance.

CONCLUSION

Currarino's disease is a rare unknown constitutional syndrome. The age of beginning of the disease, the cranial suture defects and the chronic eczema allow to distinguish it from the others primary hypertrophic osteoarthropathies.

Abdominal cystic lymphangiomas in children: presurgical evaluation with imaging

Cystic lymphangiomas are benign vascular tumors which are most often seen in young children. They are considered to be congenital malformations stemming from sequestration of lymphatic tissue. The authors report 15 cases of abdominal location and detail the findings of imaging in the etiologic and topographic diagnosis of these lesions. The initial incidents were essentially the discovery of a palpable abdominal mass, and more rarely, an acute gastrointestinal complication. There was also one case of prenatal diagnosis. Plain films provide only indirect signs related to the displacement of neighboring organs. Ultrasonography permits the etiologic diagnosis by showing an often voluminous, septated cyst. The intra- or retroperitoneal location of the lesion is sometimes difficult to determine by sonography, in which case CT scanning is usually adequate. For abdominal locations, percutaneous sclerosis is not available, and surgical removal is the only treatment for this disorder. The topography of the lesion and the involvement of retroperitoneal structures is important to determine.

[Color Doppler sonography of superficial capillary hemangiomas]

PURPOSE

Retrospective analysis of the morphologic and hemodynamic characteristics of hemangiomas in infants provided by color Doppler sonography.

MATERIALS AND METHODS

94 hemangiomas were studied in 87 children separated into four classes of age (0-3 months, 3-6 months, 6-12 months, > 12 months). Eleven were followed with several examinations. Echogenicity, compared to normal subcutaneous tissues, and degree of vascularization were assessed qualitatively. Resistive index (RI) was measured in 78 cases.

RESULTS

All lesions presented as vascularized solid masses: 63% were hypoechoic, 16% hyperechoic and 21% mixed. All hypoechoic and mixed lesions showed higher vascularity than hyperechoic ones. Hyperechoic hemanigomas were more frequent in the fourth class of age. Mean resistive index was significantly higher in the first (0.61 +/- 0.14) and the fourth (0.6 +/- 0.14) classes of age than in the second (0.51 +/- 0.12) (p = 0.01 and < 0.03, respectively), and higher in the hyperechoic group (0.7 +/- 0.13) than in the hypoechoic group (0.53 +/- 0.11), (p < 0.01). Seven of 11 cases moved from hypoechoic to hyperechoic or mixed. Increase of resistive index with age was noted in 9/11 cases.

CONCLUSIONS

Superficial hemangiomas have typical but variable gray-scale, spectral and color flow sonographic patterns. These fluctuations are probably related to phases of evolution.

Prenatal diagnosis of schizencephaly by fetal magnetic resonance imaging

Schizencephaly is a neuronal migration anomaly characterized by gray matter lined clefts extending from the ventricle to the cortical surface leading to specific lesions, well demonstrated by imaging. The lips of the clefts can be fused or separated. Prognosis is related to the extend of the involved cortex. Both genetic and acquired factors can be responsible for this pathology. Three cases of antenatal diagnosed open schizencephaly are reported. Two cases are unilateral and one is bilateral. A cerebral anomaly has been detected in all cases by routine ultrasonography (US) revealing a ventricular dilatation with cortical associated abnormalities. Prenatal magnetic resonance imaging (MRI) permitted the diagnosis in the 3 cases. All cases had led to abortion because of the importance of the cortical defect. The aim of this report is to point out the importance of fetal MRI in the diagnosis of migration disorder and to discuss the medical implications. Indeed, MRI is better suited than US for the prenatal diagnosis of schizencephaly, being able to detect normal and abnormal brain cellular migration, especially with fast imaging (HASTE sequences). With its multiplanar imaging capability, MRI demonstrates the cleft extending from the pial surface to the ventricular ependyma and thus provides characteristic diagnosis of this disorder. Moreover, ventricular dilatation, a frequent anomaly detected by US should be completed with MRI in order to research a neuronal migration disorder.

[Multiple sclerosis: pathogenesis and manifestations in children]

Multiple sclerosis (MS) is rare in children and occurs exceptionally before ten years. Sex ratio (girl/boy) is around 2.5 to 3, higher than in adults. Brain stem dysfunction and meningeal symptoms are more commonly first manifestations of the disease than in adults. Optic neuritis is also a frequent early manifestation. The etiology of the disease remains unclear and none of the advanced hypotheses (infectious, genetic, environmental) can by themselves explain its occurrence. There is a genetic susceptibility which is probably linked to many genes leading to a low related risk (less than two). A viral trigger mechanism in a person with a genetic predisposition is possible. New therapies result from a better understanding of the closed immune mechanisms of the disease.

Giant cystic Schmorl's nodes: imaging findings in six patients

OBJECTIVE

We describe the imaging findings of an unusual type of Schmorl's node appearing as giant cystlike lesion of the vertebral bodies.

CONCLUSION

Giant cystic Schmorl's nodes are unusual entities; their radiologic appearance differs dramatically from the classic description and is diagnostically challenging. However, the appearance of these nodes on conventional radiographs and especially on MR images is characteristic. Knowledge of this entity would help to eliminate unnecessary invasive diagnostic or therapeutic procedures.

MRI and clinical differences between optic pathway tumours in children with and without neurofibromatosis

The purpose of this study was to evaluate the value of MRI in studying optic pathway tumours associated with neurofibromatosis, and to look for potentially helpful criteria for the management of such lesions. This retrospective study included 14 children with neurofibromatosis type 1 (NF-1) as well as a lesion of the optic pathway. Clinical data and MRI findings were analysed with regard to location, structure and course of the tumours, and were compared with 13 optic pathway tumours in patients without NF-1. The median age of onset was 4.1 years. 11 patients with NF-1 were asymptomatic. In the NF-1 group, the optic nerves were involved in 10 cases without a cystic component at the time of diagnosis. In the non-NF-1 group, the tumour was located in the chiasma in 11 cases; 12 cases had a cystic component. 10 of the NF-1 group had no tumour progression over an average follow-up of 3.2 years without treatment. These findings suggest that optic astrocytomas in association with NF-1 are distinct lesions from isolated optic gliomas. In NF-1, most such tumours show only slight progression, and may correspond to perineural gliomatosis rather than a true pilocytic astrocytoma. Among NF-1 patients, initial MRI provides no prognostic criteria in children who subsequently show tumour progression. Nevertheless, MRI can be useful in establishing the diagnosis of NF-1 and can serve as a baseline study.

Schizencephaly: clinical and imaging features in 30 infantile cases

Schizencephaly is an uncommon structural disorder of cerebral cortical development, characterized by congenital clefts spanning the cerebral hemispheres from the pial surface to the lateral ventricles and lined by cortical gray matter. Either an antenatal environmental incident or a genetic origin could be responsible for this lesion which occurs between the third and fourth month of gestation. We report the clinical and cranial imaging features of 30 children, of whom 15 had unilateral and 15 had bilateral lesions. Their ages at the time of the first presentation ranged from 1 month to 10 years. They were thoroughly studied from clinical, epileptical, imaging and electroencephalographic (EEG) viewpoints. Five patients were investigated by cranial computed tomography (CT), eight by cranial magnetic resonance (MR) imaging, and 17 by both methods. The clinical features consisted of mild hemiparesis in 17 cases (57%), 12/17 were related to a unilateral phenotype (80% of all unilateral forms) and 5/17 to a bilateral phenotype. A tetraparesis was present in nine cases, all of which were due to a bilateral cleft. Bilateral forms were significantly associated with tetraparesis, whereas unilateral forms were associated with hemiparesis. Mental retardation was observed in 17 cases (57%), and was observed significantly more often in bilateral clefts (80%). When both hemispheres are involved, an absence of reorganization of the brain function between the two hemispheres leads to severe mental deficits, in addition to the cerebral anomaly itself. Eleven patients had seizures (seven from unilateral and three from bilateral forms). The degree of malformation was not related to the severity of epilepsy. Migration disorders, such as dysplasia or heterotopia, were observed in 30% of cases and are also important etiopathogenetic factors. The septum pellucidum was absent in 13 cases (43%), with septo-optical dysplasia in two cases. Corpus callosum dysgenesis was noted in 30% of cases. Four cases of mega cisterna magna were noted. Although familial cases and environmental factors have been previously reported, schizencephaly appears to be, in the majority of cases, sporadic.

Capillary haemangioma of the greater omentum in a 5-month-old female infant: a case report

Capillary haemangiomas are frequent benign tumours in infancy. The authors report a case of capillary haemangioma of the greater omentum, discovered in a child of 5 months of age and studied with US, CT and MRI. The localization of such a lesion in the greater omentum is exceptional. Abdominal US revealed a heterogeneous, multinodular intraperitoneal mass. Doppler study demonstrated hypervascularity of the lesion. CT localized the mass to the greater omentum. The mass was hypodense on the unenhanced scan and enhanced massively after injection. The infant suffered a reaction to contrast medium during the CT. MRI demonstrated a mass which was hypointense on T1-weighted images and hyperintense on T2-weighted images. Laparotomy confirmed the location of the mass within the greater omentum and allowed resection of the tumour.

[Contribution of medical imaging to visceral manifestations of sickle cell anemia in the child]

Sickle cell anemia is one of the qualitative hemoglobinopathies which are the most widespread in the world. In a retrospective study on 11 drepanocytary patients (10 SS and 1 SC) observed at the BORDEAUX children's hospital. 3 Processus were identified: Hemolysis: 3 hepatomegaly, 3 splenomegaly, 1 hematochromatosis and 4 pigmentary lithiasis; Thrombosis: 1 infarctus case of spleen, kidney, lung, 1 papillary necrosis and 1 brain vascular ischemic appearance;

INFECTION

1 spleen abscess and 1 pneumopathy. In 15% of instances, visceral appearances are allowed to discoverer sickle cell anemia. Hemolysis type appearances were currently observed (63.6%) like pigmentary lithiasis and hepatomegaly. The authors analyze the major radiological appearances of this hemoglobinopathy and recall the interest in knowing this disease even in low endemicity countries.

[Contribution of medical imaging in osteoarticular manifestations of sickle cell anemia in the child]

Drepanocytosis is one of the qualitative hemoglobinopathies which are the most widespread in the word. In a retrospective study on 16 drepanocytary patients observed at the Bordeaux Children's hospital, 7 patients showed medullar hyperplasia, 10 patients showed vaso-occlusive, and 4 patients showed infections. Medullar hyperplasia: bone demineralisation was the current appearance (47%), cortical thinning down (40.5%). They touch long bone. Thrombosis: bone demineralisation was the current appearance (86.3%) and touch long bone, 1 first appearance right femoral head infarct. Some particular appearances we found. 2 cases of "hand foot syndrome", 1 case ischemic aseptic arthritis and 1 case of vertebra "step staircase". Three salmonella pandiaphysite and 1 tuberculosis spondylodiscite were observed. The authors analyse the major radiological appearances of this hemoglobinopathy and recall the interest in knowing this disease even in low endemicity countries.

Portal vein thrombosis after splenectomy for hereditary stomatocytosis in childhood

Portal vein thrombosis is a rare but potentially lethal complication in children requiring splenectomy. We report on a 15-year-old boy with a dehydrated hereditary stomatocytosis, who underwent splenectomy and presented a postoperative partial portal vein thrombosis. With prompt heparin therapy, neither propagation of the thrombus nor further cavernous transformation in the following occurred 6 years.

CONCLUSION

Recent data suggest that hereditary stomatocytosis carries a high risk of thrombotic complications, especially after splenectomy. This procedure, the benefit of which is limited in this condition, should therefore be strongly avoided.

[Para-articular and intraosseous synovial cysts and articular mucoid cysts]

The authors review the mechanism and imaging findings of intraarticular, juxtaarticular, and intraosseous ganglion cysts. They specially emphasize particular features according to the most frequent locations.

Abdominal lymphatic dysplasia and 22q11 microdeletion

We report the case of a child with 22q11 microdeletion who presented with abdominal lymphatic dysplasia resulting in exsudative enteropathy. This primitive and localized lymphatic malformation is consistent with the vascular theory in the velocardiofacial syndrome.

Localised proton magnetic resonance spectroscopy of the brain after perinatal hypoxia: a preliminary report

OBJECTIVES

Perinatal hypoxic ischaemic injury is a significant cause of neurodevelopmental impairment. The aim of this study was to evaluate localised proton magnetic resonance spectroscopy (1H-MRS) after birth asphyxia.

MATERIALS AND METHODS

Thirty newborn infants suspected of having perinatal asphyxia (Apgar score < 3) were studied. The mean gestational age was 37 weeks, mean age at the MR examination was 18 days and mean weight was 2.9 kg. A 1.5-T unit was used for imaging and spectroscopy. None of the babies had mechanically assisted ventilation. No sedation was used. Axial T1-weighted and T2-weighted images were obtained. 1H-MRS was recorded in a single voxel, localised in white matter, using a STEAM sequence.

RESULTS

Image quality was good in 25 of 30 babies. 1H-MRS was performed in 19 of 30 subjects, with adequate quality in 16. Choline, creatine/phosphocreatine and N-acetylaspartate peaks and peak-area ratios were analysed. Lactate was detected in four infants. The N-acetylaspartate/choline ratio was lower in infants with an impaired neurological outcome, but the difference was not statistically significant.

CONCLUSIONS

This study suggests that 1H-MRS may be useful for assessing cerebral metabolism in the neonate. A raised lactate level and decreased N-acetylaspartate/choline ratio may be predictive of a poor outcome. However, in our experience this method is limited by the difficulty in performing the examination during the first hours after birth in critically ill babies, the problems related to use of a monovoxel sequence, the dispersion of the ratios and the lack of determination of the absolute concentration of the metabolites.