Quantitative cerebral perfusion imaging in children and young adults with Moyamoya disease: comparison of arterial spin-labeling-MRI and H(2)[(15)O]-PET.

BACKGROUND AND PURPOSE: Cerebral perfusion assessment is important in the preoperative evaluation and postoperative follow-up of patients with Moyamoya disease. The objective of this study was to evaluate the correlation of quantitative CBF measurements performed with arterial spin-labeling-MR imaging and H2[(15)O]-PET in children and young adults with Moyamoya disease. MATERIALS AND METHODS: Thirteen children and young adults (8 female patients; age, 9.7 ± 7.1 years; range, 1-23 years) with Moyamoya disease underwent cerebral perfusion imaging with H2[(15)O]-PET (Discovery STE PET/CT, 3D Fourier rebinning filtered back-projection, 128 × 128 × 47 matrix, 2.34 × 2.34 × 3.27 mm(3) voxel spacing) and arterial spin-labeling (3T scanner, 3D pulsed continuous arterial spin-labeling sequence, 32 axial sections, TR = 5.5 seconds, TE = 25 ms, FOV = 24 cm, 128 × 128 matrix, 1.875 × 1.875 × 5 mm(3) voxel spacing) within less than 2 weeks of each other. Perfusion of left and right anterior cerebral artery, MCA, and posterior cerebral artery territories was qualitatively assessed for arterial spin-labeling-MR imaging and H2[(15)O]-PET by 2 independent readers by use of a 3-point-Likert scale. Quantitative correlation of relative CBF with cerebellar normalization between arterial spin-labeling-MR imaging and H2[(15)O]-PET was evaluated in a volume-based approach for each vascular territory after 3D image coregistration. RESULTS: Interreader agreement was good (κ = 0.67-0.69), and strong and significant correlations were found between arterial spin-labeling-MR imaging and H2[(15)O]-PET for both qualitative perfusion scoring (ρ = 0.77; P < .001) and quantitative perfusion assessment of relative CBF with cerebellar normalization (r = 0.67, P < .001). CONCLUSIONS: In children and young adults with Moyamoya disease, quantitative evaluation of CBF is possible with the use of arterial spin-labeling-MR imaging without ionizing radiation or contrast injection with a good correlation to H2[(15)O]-PET after cerebellar normalization.

Abnormal interhemispheric connectivity in neonates with D-transposition of the great arteries undergoing cardiopulmonary bypass surgery.

BACKGROUND AND PURPOSE: Neonates with severe CHD require CPB within the first days of life. White matter injury can occur before surgery, and this may impair the long-term neurodevelopmental and psychosocial outcome. The purpose of this study was to assess the microstructural development of the CC in infants with CHD before and after CPB for transposition of the great arteries. MATERIALS AND METHODS: Fifteen patients with CHD and 11 age-matched HC were recruited. We separately quantified the parallel (E1) and perpendicular (E23) diffusions, the ADC, and FA of the genu of the CC and splenium of the CC before and after surgery. RESULTS: In presurgical measures of the genu of the CC, higher E23 (P = .018), higher ADC (P = .026), and lower FA (P = .033) values were measured compared with those in HC. In the postsurgery scans, the genu of the CC had higher E23 (P = .013), higher ADC (P = .012), and lower FA (P = .033) values compared with those in HC. There was no significant difference in any DTI indices between the pre- and postsurgical groups. CONCLUSIONS: We report abnormal microstructural development in the genu of the CC of infants with d-TGA before and after CPB. High E23, high ADC, and low FA values in the genu of the CC may be explained by abnormal axonal pruning, thinner myelin sheaths, smaller axonal diameters, or more oligodendrocytes. It appears that the genu of the CC is more vulnerable than the splenium of the CC in patients with CHD and may serve as a biomarker to identify infants at highest risk for adverse neurodevelopmental outcome.

Joubert syndrome and related disorders: spectrum of neuroimaging findings in 75 patients.

VH and MTS are the neuroimaging hallmarks of JSRD. We aimed to look at the full spectrum of neuroimaging findings in JSRD and reviewed the MR imaging of 75 patients with JSRD, including 13 siblings and 4 patients with OFD VI. All patients had VH and enlargement of the fourth ventricle. The degree of VH and the form of the MTS were variable. In most patients, the cerebellar hemispheres were normal and the PF was enlarged. Brain stem morphology was abnormal in 30% of the patients. Supratentorial findings included hippocampal malrotation, callosal dysgenesis, migration disorders, cephaloceles, and ventriculomegaly. All patients with OFD VI had a similar pattern, including HH in 2 patients. No neuroimaging-genotype correlation could be found. The wide neuroimaging spectrum in our patients supports the heterogeneity of JSRD. Neuroimaging differences in siblings represent intrafamilial heterogeneity. Due to the absence of a correlation with genotype, neuroimaging findings are of limited value in classifying patients with JSRD.

[Subcutaneous annular granuloma: a differential diagnosis not to be forgotten in expansive lower leg (soft-tissue) lesions of young children]. / Subkutanes Granuloma annulare: eine nicht zu vergessende Differenzialdiagnose bei expansiven (Weichteil-) Läsionen an den unteren Extremitäten von jungen Kindern.

PURPOSE: Expansive lower leg lesions in children include numerous, even malignant, entities. Good differential diagnostic knowledge is extremely important in those conditions in order to prevent unnecessary biopsy. Therefore, our own observations of a not particularly rare pseudotumorous soft-tissue disease are presented and the value of ultrasonography is emphasized. MATERIALS AND METHODS: The imaging material (sonograms in all, MRI and radiograms in the first 4 and 3 patients, respectively) and the clinical charts of 7 young children (4 females, 3 males; aged 28 - 65 months) were analyzed retrospectively. RESULTS: All lesions were pretibial, firm, indolent, non-movable, and without inflammatory signs. They had developed spontaneously. Laboratory tests were normal. Ultrasound demonstrated all lesions located subcutaneously, homogeneously echopoor with indistinct borders and only little increased perfusion. On MRI they presented with low signal in T 1, high in T 2 and marked contrast enhancement. No intraosseous changes or calcifications were found. Histological proof in the first 2 patients disclosed subcutaneous annular granuloma. Based on an identical clinical and sonographic initial presentation, biopsy and additional imaging were dispensed in the later patients. Their clinical course with only sonographic controls was as expected. CONCLUSION: When dealing with expansive lower leg soft-tissue lesions in young children, the presented typical clinical and sonographic findings should give rise to consideration of the benign entity of subcutaneous annular granuloma and primary monitoring of those patients with only ultrasound.

What harm does a second delivery to the pelvic floor?

OBJECTIVE: To compare the pelvic floor function of primiparous women to women after a second delivery regarding symptoms of urinary and anal incontinence, anal sphincter ruptures and bladder-neck mobility. METHODS: A questionnaire evaluating symptoms of urinary and anal incontinence was used in nulliparous women before and 27 months after childbirth. Furthermore these symptoms were correlated with functional changes of the pelvic floor based on a careful gynecologic examination as well as perineal and endoanal ultrasound. RESULTS: 112 nulliparous women were included, 49 women returned for follow-up on average 27 months (SD 4.4 months) after the first delivery. 39 women (group A) had just one delivery, 10 women (group B ? 10/49) had had a second delivery. Apart from levator ani muscle strength, no significant difference between pelvic floor function of group A vs group B was demonstrable. Furthermore, we could show no significant difference for symptoms of urinary (11 (28.2%) vs. 5 (50.0%)) and anal incontinence (14 (35.9%) vs. 4 (40.0%)) between both groups. However, we found a lasting increase of stress urinary and anal incontinence as well as overactive bladder symptoms after one or more deliveries. The position of the bladder neck at rest was lower in both groups compared to the position before the first delivery and bladder neck mobility increased after one or more deliveries. DISCUSSION: Our study shows several statistically significant changes of the pelvic floor function even on average 27 months after delivery, but a subsequent delivery did not compromise the pelvic floor any further.

Incontinence, bladder neck mobility, and sphincter ruptures in primiparous women.

OBJECTIVE: To compare the function of the pelvic floor in primiparae before and during pregnancy with the status post partum concerning symptoms of incontinence, sphincter ruptures, bladder-neck mobility and the influence of the different modes of deliveries. METHODS: Questionnaire evaluating symptoms of urinary and anal incontinence in nulliparous women before and after delivery and correlating these symptoms with functional changes of the pelvic floor based on a careful gynaecologic examination as well as perineal and endoanal ultrasound. RESULTS: 112 women were included in our study and came for the first visit, 99 women returned for follow-up 6 months after childbirth. Stress and flatus incontinence significantly increased from before pregnancy (3 and 12%) to after childbirth (21 and 28%) in women with spontaneous delivery or vacuum extraction. No new symptoms occurred after c-section. There was no significant difference between the bladder neck position before and after delivery. The mobility of the bladder neck was significantly higher after vaginal delivery using a vacuum extraction compared to spontaneous delivery or c-section. The bladder neck in women with post partum urinary stress incontinence was significantly more mobile than in continent controls. The endoanal ultrasound detected seven occult sphincter defects without any correlation to symptoms of anal incontinence. CONCLUSION: Several statistically significant changes of the pelvic floor after delivery were demonstrated. Spontaneous vaginal delivery or vacuum extraction increases the risk for stress or anal incontinence, delivery with vacuum extraction leads to higher bladder neck mobility and stress incontinent women have more mobile bladder necks than continent women.

[Chloroquine cardiotoxicity in long-term lupus therapy in two patients]. / Cardiotoxicité après un traitement au long cours par chloroquine chez deux patientes lupiques.

BACKGROUND: The antimalarial compounds chloroquine and hydroxychloroquine are widely used in the treatment of connective tissue diseases and are usually well tolerated. We report two cases of chloroquine cardiotoxicity. PATIENTS AND METHODS: Two women (aged 43 and 48 years) were treated for 5 years for lupus. They developed severe conduction disturbances requiring a pacemaker. Plasma chloroquine concentrations were abnormally high in both cases. In one case, a genetic polymorphism modulating the activity of a cytochrome involved in chloroquine metabolism (CYP2C8) was identified. DISCUSSION: Since 1965, 60 cases of occasionally severe cardiotoxicity have been reported following long-term treatment with chloroquine in most cases, but also with hydroxychloroquine. This toxicity must be detected early and close cardiac assessment is required.

Cerebellar cleft: a form of prenatal cerebellar disruption.

In contrast to malformations, cerebellar disruptions have attracted little interest in the literature. We draw attention for the first time to the hypothesis that cerebellar clefts are residual changes following a prenatal cerebellar insult, and represent disruptions. We reviewed the clinical records and MR findings of six patients with a cerebellar cleft, two of whom also had prenatal MRI at 24 weeks of gestation. The clefts were located in the left cerebellar hemisphere in five cases, in the right in one patient. Other typical findings included disorderly alignment of the cerebellar folia and fissures, irregular gray/white matter junction, and abnormal arborization of the white matter in all patients. The cerebellar cleft extended into the fourth ventricle in three cases, and in two children cystic cortical lesions were seen. Supratentorial schizencephaly was found in two patients. In two patients there was a documented fetal cerebellar hemorrhage at 24 weeks of gestation. We conclude that cerebellar clefts are residual changes resulting from a prenatal cerebellar insult and consequently represent disruptions rather than primary malformations. The supratentorial findings are also in agreement with an acquired lesion. The outcome in these children was variable, mainly depending of the presence of supratentorial lesions.

Prenatal and neonatal MR imaging findings in oral-facial-digital syndrome type VI.

We report prenatal and neonatal neuroimaging findings in a case of oral-facial-digital syndrome type VI (OFDS VI). Prenatal MR imaging at 29 weeks' gestation showed hypoplastic cerebellar vermis and hemispheres, the molar tooth sign, and a hypothalamic hamartoma. Neonatal MR imaging confirmed these findings. The neonate developed breathing abnormalities and exhibited frontal bossing, multiple bucco-alveolar frenula, and postaxial hexadactyly of both hands. If the molar tooth sign and a hypothalamic hamartoma are present, prenatal diagnosis of OFDS VI is possible.

Trials and tribulations of the current national consent form.

The aim of this survey was to evaluate patients' understanding of the current standardised National Health Service consent form. Of the 285 patients, 47% were performed as emergency and 53% as elective procedures. Almost all patients indicated that they understood the consent form. Although the benefits of the procedure were known in 94%, only 69% were aware of the risks associated with the performed operation. Less than 40% claimed to have been informed about the risk of requiring additional surgery. Patients undergoing elective surgery were significantly more likely to be aware of the risks, the likelihood of additional surgery and the fact that the consultant may not be performing the operation. Although the current national consent form introduced by the Department of Health appears to be understood by obstetric and gynaecology patients, there appears to be a need for improved counselling regarding the attendant risks and benefits of surgery, especially for patients undergoing emergency surgery.

Ultrasound in abdominal and soft-tissue childhood PTLD (post-transplant lymphoproliferative disease).

AIM: Post-transplant lymphoproliferative disease (PTLD) is a rare condition, which should be well known to all paediatric medical facilities dealing with bone marrow and solid organ transplantation. The spectrum and the primary detecting modality of the initial imaging findings in paediatric transplant recipients with abdominal and soft-tissue PTLD should be studied retrospectively. METHOD: 7 children/adolescents (female: 4, male: 3; age: 3 - 19 yrs.; study period: 7 yrs.) after heart (5), kidney (1) or liver (1) transplantation were evaluated regarding their initial clinical and imaging findings of PTLD. RESULTS: 6 patients had a latent Epstein-Barr virus (EBV) infection. PTLD presented with clinical symptoms in only 5 patients (ileus: 2, soft-tissue swelling: 2, intussusception: 1) and was detected on routine abdominal ultrasound (US) controls in the remaining patients. US was the primary imaging modality in all children and led to suspecting PTLD in 6 patients. In the seventh case, US had been misinterpreted first. Compared to US, additional magnetic resonance imaging (MRI) and/or computed tomography (CT) better demonstrated the extent of the disease in 3 children, but were even inferior in another 3. There was no completely false-negative US examination during the study period. CONCLUSION: US is reliable for detecting as well as excluding abdominal and soft-tissue PTLD in paediatric patients after solid-organ transplantation and might even be superior to MRI/CT. Therefore, all patients with an increased risk of developing PTLD should be closely monitored by ultrasound. MRI/CT may be reserved for supplementary imaging in cases incomplete or equivocal on US, but are primarily essential in all patients with a localisation of PTLD not accessible by US.

[Infradiaphragmatic extralobar pulmonary sequestration]. / Infradiaphragmale extralobäre pulmonale Sequestration.

PURPOSE: To demonstrate characteristic imaging findings in infradiaphragmatic extralobar pulmonary sequestration (IEPS) with special emphasis on ultrasound (US). MATERIALS AND METHODS: The imaging material (pre- and postnatal US in all cases, magnetic resonance imaging (MRI) in 2 cases) for 4 infants (3 girls, 1 boy) was reviewed. 2 patients underwent surgery (after birth and at 4 months of age, respectively) and the diagnosis of IEPS was confirmed. The other 2 patients were monitored conservatively using US for up to 15 months. RESULTS: All 4 left-side suprarenal masses exhibited the same characteristic sono-morphology, leading to the suspected diagnosis of IEPS. The masses were small (max. 10 ml), hyperechoic with cystic components and without calcifications, well demarcated and separate from the normal kidney and the suprarenal gland, and without any change in prenatal and directly postnatal size. Doppler US showed low-grade perfusion in all cases and an aberrant systemic artery originating from the abdominal aorta in 2 cases. MRI did not add any fundamental information. Despite the suspected imaging diagnosis of IEPS and negative urinalyses for neuroblastoma, 2 patients underwent surgery for histological confirmation. The lesions in the other 2 patients were monitored via US. A complete disappearance after 4 months in one patient and a continuous decrease in size over 15 months in the other patient were documented. CONCLUSION: Based on the characteristic findings of prenatal and postnatal US, IEPS can be diagnosed reliably. With the knowledge of its benign spontaneously regressing behavior, suspected suprarenal lesions should be treated conservatively via US monitoring.

Bilateral agenesis of the superior vena cava associated with congenital hydrothorax.

Agenesis of the superior vena cava is a rare anomaly that is generally asymptomatic in the neonate. We report a male neonate with bilateral (total) agenesis of the superior vena cava with obstructed thoracic duct and subsequent congenital hydrothorax, anomalies that were detected by prenatal ultrasound at 25 weeks' gestation. The cardiac anomaly was confirmed by postnatal magnetic resonance angiography. The chylothorax disappeared with conservative therapy.

[Congenital cystic lung malformations]. / Konnatale zystische Lungenfehlbildungen.

PURPOSE: The aim of the study concerning congenital cystic lung malformations was to evaluate prenatal diagnoses postnatally to determine prognostic factors as well as to define optimized perinatal management. MATERIALS AND METHODS: The study is based on 45 prenatal ultrasound examinations depicting fetal cystic lung lesions. 32 of the mothers had follow-up examinations. 5 pregnancies were terminated due to CCAM and additional malformations. Complete regression of the lesions was seen prenatally in 8 cases and postnatally in 5 children. RESULTS: Surgical intervention due to respiratory insufficiency was necessary in 4 neonates. According to the imaging results, CCAM was present in 4 cases and sequestration in 7 patients. No correlation between the imaging findings and the surgical results was found in 3 children: One child suffered from rhadomyoid dysplasia, and in the case of the second child, a left-sided hernia of the diaphragm and additional sequestration were detected. The third child showed AV malformation. The cystic lesions of the 14 children operated upon were proven histologically. The degree of accuracy in the present study was high. CONCLUSION: Precise perinatal management is warranted in order to determine according to the clinical relevance surgical intervention and to prevent complications after the first year of life. This is performed during the neonatal period for respiratory insufficient neonates and within the first year of life for clinically stable children.

[Currarino syndrome: variability of imaging findings in 22 molecular-genetically identified (HLXB9 mutation) patients from five families]. / Currarino-Syndrom: Variabilität der bildgebenden Befunde bei 22 molekulargenetisch identifizierten (HLXB9-Mutation) Patienten aus fünf Familien.

PURPOSE: The imaging documents, obtained in connection with a primarily molecular genetic study on Currarino syndrome, should be evaluated with special respect to the constancy resp. the variability of findings in patients with proven HLBX9 mutations. METHODS: In five female non-related index patients with clinico-radiologically diagnosed Currarino syndrome and further 53 members of their families, changes of the homeobox gene HLXB9 had been analysed. Variable mutations of this gene were found in a total of 23 individuals including the five index patients. In 22 of them the preexisting radiological documents could be collected as well as further imaging (plain sacrococcygeal radiography and/or lumbosacral MRI at least) initiated. This was followed by a detailed evaluation of pathological findings in the os sacrum/coccyx as well as in the presacral, the intraspinal, the anorectal, and the urogenital region, finally. RESULTS: Imaging investigations revealed concomitant phenotypic abnormalities in all and even nine clinically asymptomatic individuals with proven HLXB9 mutations. A sacrococcygeal defect of varying intensity was depicted in every case. Complete Currarino triad (i. e. sacrococcygeal defect, presacral mass = anterior meningocele and/or tumor, anorectal malformation) was only found in the five index patients and three further relatives. In all other cases, one or more of the following anomalies were detected with variable combination and with decreasing frequency: anterior meningocele (12), presacral tumor (11), tethered cord (10), intraspinal lipoma (8), anorectal stenosis/atresia (8), syringocele (5), rectal fistula (3), urogenital (2). CONCLUSION: Currarino syndrome should be considered as a differential diagnosis in all patients with chronic constipation since early infancy and its imaging index finding, i. e. a sacrococcygeal defect, should be looked for with plain radiography, first. In positive cases or other phenotypic suspicious constellations molecular genetic analysis for HLBX9 mutations should be the next step. If positive again, this should be followed by complete adequate imaging in the patient as well as by plain sacrococcygeal radiography in, at least, symptomatic family members.

[Sonographic detection of a "VIPoma" in a small child with intractable gastroenteritis]. / Sonographische Detektion eines "VIPoms" bei einem Kleinkind mit therapieresistenter Gastroenteritis.

As case report we describe a rare cause of intractable "gastroenteritis" detected by ultrasonography. The 14 months-old boy was admitted to hospital because of intensive dehydration due to massive vomiting and diarrhoea. A salmonella enteritis with intractable hyponatraemia and hypokalaemia was thought to be the cause. After a dramatic relapse during oral treatment measures, further extensive laboratory tests finally disclosed an elevated serum level of vasoactive intestinal polypeptide ("VIP"). The VIP secreting tumor ("VIPoma") was detected ultrasonographically in a retroperitoneal localization mediocaudally of the right kidney. Diffuse distinct calcifications and an increased perfusion could be demonstrated. Intraspinal tumour spread was excluded by magnetic resonance imaging. After complete surgical removal of the tumour the clinical symptomatology normalized promptly and permanently. A VIP-excreting ganglioneuroblastoma with low grade growth fraction ("VIPoma") was diagnosed histologically. Common gastroenteritis in childhood represents no indication for ultrasound. In cases of unclear and therapy-resistant symptomatology, however, diagnostic work-up should include ultrasonography to search for retroperitoneal or pancreatic VIP-excreting tumours.

Patent ductus venosus: diagnosis by MR angiography.

We report a 15-year-old boy with patent ductus venosus in whom the diagnosis was made by MR angiography. A patent ductus venosus Arantii is a rare form of portosystemic shunt. Only a few cases have been reported in adults and children. The diagnosis is usually made by US and digital subtraction angiography. In our patient, the diagnosis was first made by MR angiography. This demonstrates the excellent diagnostic potential of the method in paediatric patients.

Multifocal nodular fatty infiltration of the liver mimicking metastatic disease on CT: imaging findings and diagnosis using MR imaging.

The aim of this study was to describe the MR appearance of multifocal nodular fatty infiltration of the liver (MNFIL) using T1-weighted in-phase (IP) and opposed-phase (OP) gradient-echo as well as T2-weighted turbo-spin-echo sequences with fat suppression (FSTSE) and without (HASTE). Magnetic resonance imaging examinations at 1.5 T using T1-weighted IP and OP-GRE with fast low angle shot (FLASH) technique, and T2-weighted FSTSE, T2-weighted HASTE of 137 patients undergoing evaluation for focal liver lesions were reviewed. Five patients were identified in whom CT indicated metastatic disease; however, no liver malignancy was finally proven. Diagnosis was confirmed by biopsy (n = 3), additional wedge resection (n = 1) or follow-up MRI 6-12 months later (n = 5). Regarding the identified five patients, the number of focal liver lesions was 2 (n = 2) and more than 20 (n = 3). The MR imaging characteristics were as follows: OP-image: markedly hypointense (n = 5); IP image: isointense (n = 2) or slightly hyperintense (n = 3); T2-weighted FSTSE-image: isointense (n = 5); T2-weighted HASTE image isointense (n = 1); slightly hyperintense (n = 4). On OP images all lesions were sharply demarcated and of almost spherical configuration (n = 5). Further evaluation by histology or follow-up MR imaging did not give evidence of malignancy in any case. Histology revealed fatty infiltration of the liver parenchyma in three patients. Magnetic resonance follow-up showed complete resolution in two patients and no change in three patients. Multifocal nodular fatty infiltration can simulate metastatic disease on both CT and MR imaging. The combination of in-phase (IP) and opposed-phase (OP) gradient-echo imaging can reliably differentiate MNFIL from metastatic disease.

Low-dose spiral CT: applicability to paediatric chest imaging.

BACKGROUND: Spiral CT of the chest is an imaging technique with unequivocal indications and proven higher sensitivity and specificity than conventional chest X-rays. However, particularly in children, attempts should be made to reduce radiation exposure to a minimum. OBJECTIVE. To evaluate whether a low-dose technique in spiral CT scanning results in adequate diagnostic information. MATERIALS AND METHODS: In a prospective study, 27 children (range 3 weeks to 14 years, mean 7 years) underwent a low-dose CT examination of the chest for various indications. The tube energy was 12.5 mAs (n = 5), 25 mAs (n = 17), 50 mAs (n = 3), or 75 mAs (n = 2) per slice. Two radiologists evaluated, in consensus, the CT scans with respect to their diagnostic value and comparison was made with 20 standard-dose chest CT examinations of adults (175 mAs per slice, mean age 56 years) with respect to technical image quality (noise and artefacts). In a second part of the study, dose measurements were carried out by means of exposing thermoluminescent dosimeters attached to a water/air phantom simulating a child's chest. RESULTS: All low-dose CT scans were of diagnostic image quality and no additional studies were necessary. The average image noise was significantly higher than in standard-dose CT examinations (SD 39.5 compared with 12.5 for unenhanced soft tissue, P < 0.01), but did not hinder accurate diagnosis. Artefacts were exclusively due to patient motion. Radiation exposure per slice was approx. 4 mGy at 25 mAs and 34 mGy at 250 mAs, regardless of slice thickness. CONCLUSIONS: For all indications in paediatric CT scanning of the chest, low-dose technique provides adequate image quality without loss of diagnostic information. The radiation exposure is approximately 5-20 % of a standard-dose CT.