Radiation protection in pediatric radiology.

BACKGROUND: The German Federal Law on Radiation Control contains no special provisions for X-ray studies in children and adolescents, even though exposure to ionizing radiation must be kept especially low in young persons, because their tissues are highly radiosensitive. Children, who have many years left to live, are more likely than adults to develop radiation-induced cancer; also, as future parents, they are at risk for passing on radiation-induced genetic defects to the next generation. Whenever possible, radiological studies on children and adolescents should be of a type that does not involve ionizing radiation, such as ultrasonography or magnetic resonance imaging. Pediatric conventional X-rays and computerized tomography (CT) require special examining techniques and protocols that are adapted to the patient's age and to the indication for the study. METHODS: We selectively review the literature on pediatric dose reduction and discuss our own investigations on the subject as well. RESULTS: The essential technical prerequisites for lowering the dose of ionizing radiation in conventional X-ray studies include the proper setting of tube voltage, the use of tube filters, suitable patient positioning and fixation, variable use of a scattered-radiation grid, and a modern storage-plate system. In CT studies, the use of age- and indication-adapted protocols can lower radiation exposure by as much as 95%. CONCLUSION: There are now many ways to lower the exposure of children and adolescents to ionizing radiation without sacrificing diagnostic reliability. The main factors in lowering exposure are proper attention to clinical indications, the use of special X-ray protocols, the use of alternative imaging studies without ionizing radiation wherever possible, and the expertise of the examiner.

Focal nodular hyperplasia of the liver in longterm survivors of neuroblastoma: how much diagnostic imaging is necessary?

OBJECTIVES: Focal nodular hyperplasia of the liver is a tumor-like lesion, uncommon in children, but it has recently been more frequently observed in children treated for malignant diseases, especially neuroblastoma. The aetiology is unclear, the pathogenesis remains controversial. Focal nodular hyperplasia of the liver is suspected to be a sequela of tumor therapy. METHODS: Besides the clinical data we evaluated the imaging modalities needed to diagnose focal nodular hyperplasia of the liver in children with neuroblastoma who have been followed in our institution for more than 5 years. RESULTS: Out of 60 children six developed focal nodular hyperplasia at a median time of 10.5 years after diagnosis of neuroblastoma and 9.4 years after the end of treatment. The diagnosis of focal nodular hyperplasia was based on imaging criteria which are variable in ultrasonography and specific in MRI. Only one child underwent surgical biopsies to rule out liver metastases. CONCLUSIONS: Longterm survivors of neuroblastoma are at risk of developing focal nodular hyperplasia, especially if they underwent toxic chemotherapy and/or radiotherapy to the liver during initial treatment. The recommended diagnostic imaging tools are ultrasonography for detecting liver lesions and MRI for confirming and characterizing these lesions as focal nodular hyperplasia.

Localized infant neuroblastomas often show spontaneous regression: results of the prospective trials NB95-S and NB97.

PURPOSE: The excellent prognosis of localized neuroblastoma in infants, the overdiagnosis observed in neuroblastoma screening studies, and several case reports of regression of localized neuroblastoma prompted us to initiate a prospective cooperative trial on observation of localized neuroblastoma without cytotoxic treatment. PATIENTS AND METHODS: For infants with localized neuroblastoma without MYCN amplification, chemotherapy was scheduled only in cases with threatening symptoms; otherwise, the tumor was either resected or observed by ultrasound and magnetic resonance imaging (MRI). RESULTS: Of 340 eligible participants, 190 underwent resection, 57 were treated with chemotherapy, and 93 were observed with gross residual tumor. Of those 93 patients with unresected tumors, spontaneous regression was seen in 44, local progression in 28, progression to stage 4S in seven, and progression to stage 4 in four. Time to regression was quite variable, with first signs of regression noted 1 to 18 months after diagnosis and in 15 of 44 patients even after the first year of life. So far, complete regression was observed in 17 of 44 patients 4 to 20 months after diagnosis. Known clinical risk factors were not able to differentiate between patients with regression and regional or metastatic progression. Overall survival (OS; 3-year OS, 0.99 +/- 0.01) and metastases-free survival (rate at 3 years, 0.94 +/- 0.03) for patients with unresected tumors was excellent and was not different from patients treated with surgery or chemotherapy. CONCLUSION: Spontaneous regression is regularly seen in infants with localized neuroblastoma and is not limited to the first year of life. A wait-and-see strategy is justified in those patients.

Review of image defined risk factors in localized neuroblastoma patients: Results of the GPOH NB97 trial.

BACKGROUND: Recently, an international expert group proposed revision of the International Neuroblastoma Staging System (INSS). Localized disease can be classified as L1 without and as L2 with image defined risk factors (IDRF published in JCO 2005; 23:8483-8489). Our aim was to evaluate IDRF for the prediction of resectability, complications, and outcome. PROCEDURE: Records of 520 localized neuroblastoma patients of the NB97 trial were reviewed. Patients were retrospectively classified as having IDRF or not. A total of 366 evaluable patients were then analyzed for extent and complications of surgery and the prognostic value of IDRF. RESULTS: Any IDRF was present in 26/160 of stage 1, 49/113 of stage 2, and 64/93 of stage 3 patients. Complete primary resection was achieved in 156/227 patients without IDRF and 43/139 patients with IDRF (P < 0.001). The frequency of complications was higher if any IDRF was present: 37/139 versus 33/227 (P = 0.006). Lack of IDRF was associated with better event free survival (3-year-EFS 86 +/- 2% vs. 75 +/- 4%, P = 0.010), whereas overall survival was similar (3-year-OS 98 +/- 1% vs. 96 +/- 2%, P = 0.462). EFS clearly depended on INSS stage (3-year-EFS 93 +/- 2% in stage 1, 78 +/- 4% in stage 2, and 69 +/- 5% in stage 3, P < 0.001). OS was not different (3-year-OS 98 +/- 1% vs. 99 +/- 1% vs. 94 +/- 2%, P = 0.056). Multivariate analysis demonstrated an impact of INSS stage on EFS only. IDRF were not shown to be significant for predicting EFS or OS. CONCLUSIONS: IDRF were useful in predicting risk and completeness of operation. IDRF failed as independent risk predictors in localized neuroblastoma. INSS more precisely identified patients with poor prognosis.

True thymic hyperplasia associated with severe thymic cyst bleeding in a newborn: case report and review of the literature.

We report on a 5-week-old male infant with recurrent respiratory distress since birth and congenital thymic hyperplasia. Acute life-threatening thymic bleeding apparently from ruptured thymic cysts into the pleural spaces complicated the clinical situation. Thoracotomy and complete thymectomy were performed. Histologic examination revealed normal thymic architecture with cysts of different sizes and an increased thymic weight of 30 g. The combination of true thymic hyperplasia and cyst bleeding in a newborn has not been previously reported and will be discussed in relation to the available literature on respiratory distress due to thymic pathology in childhood.

Prospective volumetric analysis of gallbladders in critically ill newborns: the impact of nutrition.

BACKGROUND: Neonatal reference values of gallbladder size have been assessed in healthy newborns with enteral feeding regimen. Their applicability to critically ill patients under total parenteral nutrition (TPN) remains to be questioned. OBJECTIVE: Our aim was to evaluate the impact of short-term TPN versus enteral nutrition (EN), gender and birth weight on neonatal gallbladder volume. METHOD: A prospective pilot study was initiated with a single sonographic investigator blinded towards feeding regimen. In total, 61 neonates (33 males, 28 females) were consecutively enrolled on the intensive care unit; 31 newborns were examined both under TPN and bolus EN (breast milk/formula). Patients with malformations of the biliary tract were excluded. Prior to ultrasound examinations, a minimum fasting period of 2 h was maintained. Sonographic measurements of gallbladder length, depth and width were performed to calculate gallbladder volume using the ellipsoid formula. RESULTS: Neonatal gallbladder volume differed significantly between TPN and EN (p < 0.001). Using TPN, range of gallbladder length, width and volume exceeded reference values. Birth weight was weakly correlated with gallbladder volume (correlation index 0.3776, p = 0.01). We found no gender-related differences. CONCLUSIONS: Neonatal gallbladder volume under TPN was significantly larger compared to EN. Using TPN, gallbladder dimensions exceeded reference values without causing clinical complications. The benign course of gallbladder enlargement required no specific medication or surgical treatment.

Prospective sonographic evaluation of fentanyl side effects on the neonatal gallbladder.

OBJECTIVE: In an effort to minimise the stress and pain of mechanically ventilated neonates, the application of opioids has increased markedly. Abdominal adverse effects of opioid analgesics are constipation and increased pressure in the biliary system. Our aim was to evaluate the impact of continuous intravenous infusion of fentanyl on the volume of the neonatal gallbladder and to assess potential gastrointestinal side effects. METHODS: We prospectively matched pairs of 40 mechanically ventilated neonates (28-42 gestational weeks) under total parenteral nutrition and midazolam sedation. One group (20 patients) received continuous fentanyl infusions (dose 0.5-2 microg kg(-1) h(-1)) the other group (20 patients) served as controls. Sonographic measurements of gallbladder length, depth and width were performed to calculate gallbladder volume using the ellipsoid method. Repeated ultrasound images, date of meconium release and serum bilirubin levels were documented. RESULTS: Fentanyl application was not associated with gallbladder sludge/stones, gallbladder hydrops, hyperbilirubinemia or prolonged meconium release. Neonatal gallbladder length, width and volume did not differ significantly (data expressed as mean, standard deviation, median, interquartile range: length (cm) 3.16+/-0.68, 3.3, 0.675 vs 3.06+/-0.62, 3.3, 1.1; P=0.645; width (cm) 1.02+/-0.23, 1.0, 0.28 vs 0.89+/-0.27, 0.9, 0.38, P=0.12; volume (cm(3)) 1.52+/-0.67, 1.7, 0.86 vs 1.22+/-0.77, 1.09, 1.19, P=0.20). CONCLUSION: In our study fentanyl caused no major complications in the biliary system and intestine of ventilated preterm and term neonates. Sonographic investigations of the gallbladder under fentanyl treatment may be dispensable. Further investigations are required to assess adverse gastrointestinal effects.

Isolated femoral hypoplasia: an intrauterine differential diagnosis to campomelia.

The isolated form of femoral bowing is an important differential diagnosis of campomelia. Therefore, knowledge of isolated anomalies is fundamental for prenatal diagnosis, especially for the differential diagnosis from severe syndromes. Four cases are presented to discuss the differential diagnosis of femoral bowing including a review of the literature. We report four newborn babies with unilateral bowing and shortening of the femur. Three had no further anomaly; one child had additional abnormalities due to coumarin embryopathy. The radiological findings were shortened femora with bowing and varus deformity and cortical thickening on the concave side. All other parts showed normal bone structure. The aetiology of femoral bowing is unknown. Early damage of the cartilaginous model followed by remodelling with thickening on the concave side of the bone similar to the healing of malaligned fractures is suspected. The isolated form of femoral bowing without any other anomalies has to be differentiated from complex and more often severe congenital syndromes such as campomelia. Postpartum radiological examination should be reduced to a single exposure of the affected limb and follow-up should be done by clinical examination.

Proton spectroscopic metabolite signal relaxation times in preterm infants: a prerequisite for quantitative spectroscopy in infant brain.

PURPOSE: To determine relaxation times of metabolite signals in proton magnetic resonance (MR) spectra of immature brain, which allow a correction of relaxation that is necessary for a quantitative evaluation of spectra acquired with long TE. Proton MR spectra acquired with long TE allow a better definition of metabolites as N-acetyl aspartate (NAA) and lactate especially in children. MATERIALS AND METHODS: Relaxation times were determined in the basal ganglia of 84 prematurely born infants at a postconceptional age of 37.8 +/- 2.2 (mean +/- SD) weeks. Metabolite resonances were investigated using the double-spin-echo volume selection method (PRESS) at 1.5 T. T1 was determined from intensity ratios of signals obtained with TRs of 1884 and 6000 msec, measured at 3 TEs (25 msec, 136 msec, 272 msec). T2 was determined from signal intensity ratios obtained with TEs of 136 msec and 272 msec, measured at 2 TR. Taking only long TEs reduced baseline distortions by macromolecules and lipids. For myo-inositol (MI), an apparent T2 for short TE was determined from the ratio of signals obtained with TE = 25 msec and 136 msec. Intensities were determined by fitting a Lorentzian to the resonance, and by integration. RESULTS: Relaxation times were as follows: trimethylamine-containing compounds (Cho): T1 = 1217 msec/T2 = 273 msec; total creatine (Cr) at 3.9 ppm: 1010 msec/111 msec; Cr at 3.0 ppm: 1388 msec/224 msec; NAA: 1171 msec/499 msec; Lac: 1820 msec/1022 msec; MI: 1336 msec/173 msec; apparent T2 at short TE: 68 msec. CONCLUSION: T1 and T2 in the basal ganglia of premature infants do not differ much from previously published data from basal ganglia of older children and adults. T2 of Cho was lower than previous values. T2 of Cr at 3.9 ppm and Lac have been measured under different conditions before, and present values differ from these data.

Nephrocalcinosis in preterm infants: a single center experience.

The risk of nephrocalcinosis in preterm infants is considerable, but conflicting numbers are given for the actual incidence (10-65%). Furosemide induced hypercalciuria is said to be the main risk factor. We examined retrospectively the incidence, causes and outcome of nephrocalcinosis in preterm infants born in our hospital from 1988 to 1998 ( n=2190). An abnormal renal echogenicity or nephrocalcinosis was seen in 31 infants (29.7+/-3.3 weeks gestational age; 1307+/-690 g birth weight). Nephrocalcinosis was diagnosed in 16, hyperechoic kidneys (HK) in 10 and Tamm-Horsfall kidneys in 5 infants. Main risk factors were low gestation age and birth weight, length of hospitalization, variations in acid-base status, length of assistant ventilation and hypercalciuria at diagnosis. The incidence of nephrocalcinosis was 0.73% [1.7% for low birth weight infants (VLBW)]. Taking the cases of nephrocalcinosis and HK together, incidence was calculated to be 1.2% overall and 2.5% for VLBW infants, but increased to 7% in 1998. The follow-up showed persisting nephrocalcinosis or hyperechoic kidneys in 8/26 preterm infants. In conclusion, the incidence of nephrocalcinosis was lower in our population than is usually reported. The numbers have, however, increased over the past few years. From the follow-up it was obvious that long-term observation of preterm infants is necessary and that complications might arise in the long run.