A rapid, reliable radiation-free method of pediatric body venography may complement ultrasound by evaluating veins in the abdomen and pelvis, as well as providing a global depiction of venous anatomy. We describe a MR venography technique utilizing gadofosveset, a blood pool contrast agent, in pediatric patients. The technique allows high-spatial-resolution imaging of the veins from the diaphragm to the knees in less than 15 minutes of total exam time.

MRI potentially offers an alternative to CT, and thus is central to an ALARA strategy. However, long exam times, limited magnet availability, and motion artifacts are barriers to expanded use of MRI. This article reviews developments in pediatric body MRI that may reduce these barriers: high field systems, acceleration, navigation, and newer contrast agents.

Background

Menkes disease is an X-linked recessive disorder of copper transport caused by mutations in ATP7A, a copper-transporting ATPase. Certain radiologic findings reported in this condition overlap with those caused by child abuse. However, cervical spine defects simulating cervical spine fracture, a known result of nonaccidental pediatric trauma, have not been reported previously in this illness.

Objective

To assess the frequency of cervical spine anomalies in Menkes disease after discovery of an apparent C2 posterior arch defect in a child participating in a clinical trial.

Materials and methods

We examined cervical spine radiographs obtained in 35 children with Menkes disease enrolled in a clinical trial at the National Institutes of Health Clinical Center.

Results

Four of the 35 children with Menkes disease had apparent C2 posterior arch defects consistent with spondylolysis or incomplete/delayed ossification.

Conclusion

Defects in C2 were found in 11% of infants and young children with Menkes disease. Discovery of cervical spine defects expands the spectrum of radiologic findings associated with this condition. As with other skeletal abnormalities, this feature simulates nonaccidental trauma. In the context of Menkes disease, suspicions of child abuse should be considered cautiously and tempered by these findings to avoid unwarranted accusations.

Background

Cerebral MRI performed on preterm infants at term-equivalent 30 weeks' gestational age (GA) is increasingly performed as part of standard clinical care.

Objective

We evaluated safety of these early MRI procedures.

Materials and methods

We retrospectively collected data on patient safety of preterm infants who underwent early MRI scans. Data were collected at fixed times before and after the MRI scan. MRI procedures were carried out according to a comprehensive guideline.

Results

A total of 52 infants underwent an MRI scan at 30 weeks’ GA. Although no serious adverse events occurred and vital parameters remained stable during the procedure, minor adverse events were encountered in 26 infants (50%). The MRI was terminated in three infants (5.8%) because of respiratory instability. Increased respiratory support within 24 h after the MRI was necessary for 12 infants (23.1%) and was significantly associated with GA, birth weight and the mode of respiratory support. Hypothermia (core temperature < 36°C) occurred in nine infants (17.3%). Temperature dropped significantly after the MRI scan.

Conclusion

Minor adverse events after MRI procedures at 30 weeks GA were common and should not be underestimated. A dedicated and comprehensive guideline for MRI procedures in preterm infants is essential.

Electronic supplementary material

The online version of this article (doi:10.1007/s00247-012-2426-y) contains supplementary material, which is available to authorized users.

Background

Little information exists regarding pediatric contrast enhanced ultrasonography.

Objective

To assess the safety and feasibility of contrast enhanced ultrasonography of pediatric abdominal and pelvic tumors.

Materials and Methods

This prospective study included eight boys and five girls (mean age, 10.8 years) with abdominal or pelvic tumors. Cohorts of three subjects underwent ultrasound with perflutren contrast agent at escalating dose levels.Neurological and funduscopic examination, electrocardiography, and continuous pulse oximetry were performed before and after contrast administration. Threeradiologists independently scored six imaging parameters on pre- and post-contrast sonography. Inter-reviewer agreement was measured by the Kappa statistic.

Results

No neurological, retinal, electrocardiographic, or pulse oximetry changes were attributable to the contrast agent. Two subjects reported minor, transient symptoms. Post-contrast ultrasound parameter scores improved slightly in 8 of 12 subjects. Post-contrast ultrasound inter-reviewer agreement improved slightly for detection of tumor margins (pre-contrast = 0.20, post-contrast = 0.26), local tumor invasion (pre-contrast = −0.01, post-contrast = 0.10) and adenopathy (pre-contrast = 0.35, post-contrast = 0.44).

Conclusions

Although our sample size is small, perflutren contrast agents appear to be safe and well tolerated in children. Contrast enhanced sonography of pediatric abdominal and pelvic tumors is feasible but larger studies are needed to define their safety and efficacy in this patient population.

Background

A number of radiogrammetrical metacarpal indices are in use, some of which have been adapted for children.

Objective

The purpose of this study was to compare four known indices—bone mineral density (BMD), relative cortical area, Exton-Smith index, bending breaking resistance index—and the more recently defined pediatric bone index (PBI) according to the two criteria of minimum height dependence and minimum variability in children of equal bone age.

Materials and methods

A total of 3,121 left-hand radiographs from 231 healthy Caucasian children ranging in age from 3 to 19 years old were analysed using BoneXpert®, a programme for automatic analysis of hand radiographs and assessment of bone age.

Results

Dependence on height for chronological age or bone age and the mean relative standard deviation were lowest in the PBI for both genders pooled. The differences in height dependence were statistically significant and are shown to be clinically relevant. Reference data for PBI are presented.

Conclusion

PBI may be a better indicator than BMD for bone health in children; however, verification in a clinical group is needed.

Background

During surgery for spinal deformities, accurate placement of pedicle screws may be guided by intraoperative cone-beam flat-detector CT.

Objective

The purpose of this study was to identify appropriate paediatric imaging protocols aiming to reduce the radiation dose in line with the ALARA principle.

Materials and methods

Using O-arm® (Medtronic, Inc.), three paediatric phantoms were employed to measure CTDIw doses with default and lowered exposure settings. Images from 126 scans were evaluated by two spinal surgeons and scores were compared (Kappa statistics). Effective doses were calculated. The recommended new low-dose 3-D spine protocols were then used in 15 children.

Results

The lowest acceptable exposure as judged by image quality for intraoperative use was 70 kVp/40 mAs, 70 kVp/80 mAs and 80 kVp/40 mAs for the 1-, 5- and 12-year-old-equivalent phantoms respectively (kappa = 0,70). Optimised dose settings reduced CTDIw doses 89–93%. The effective dose was 0.5 mSv (91–94,5% reduction). The optimised protocols were used clinically without problems.

Conclusions

Radiation doses for intraoperative 3-D CT using a cone-beam flat-detector scanner could be reduced at least 89% compared to manufacturer settings and still be used to safely navigate pedicle screws.

Background

A mother’s circulating estrogen increases over the third trimester, producing physiological effects on her newborn that wane postnatally. Estrogenization might be prolonged in newborns exposed to exogenous estrogens, such as isoflavones in soy formula.

Objective

We evaluated ultrasonography for monitoring growth of multiple estrogen-responsive organs in healthy infants and developed organ-growth trajectories.

Materials and methods

We studied 38 boys (61 visits) from birth to age 6 months and 41 girls (96 visits) from birth to age 1 year using a partly cross-sectional, partly longitudinal design. We measured uterus and ovaries in girls, testes and prostate in boys, and kidneys, breasts, thymus, and thyroid in all children. We imaged all organs from the body surface in one session of < 1 h.

Results

Uterine volume decreased from birth (P<0.0001), whereas ovarian volume increased sharply until age 2 months and then decreased (P<0.001). Testicular volume increased with age (P<0.0001), but prostatic volume showed minimal age trend. Breast bud diameter showed no age trend in girls but declined from birth in boys (P=0.03).

Conclusion

US examination of multiple estrogen-responsive organs in infants in a single session is feasible and yields volume estimates useful for assessing potential endocrine disruptor effects on organ growth.

Until now, brain magnetic resonance imaging (MRIs) in asphyxiated neonates receiving therapeutic hypothermia have been performed after treatment is complete. However, there is increasing interest in early brain MRI while hypothermia is still being provided, in order to rapidly understand the degree of brain injury and possibly refine neuroprotective strategies. This study was designed to assess whether therapeutic hypothermia can be maintained while performing a brain MRI. Twenty MRI scans were obtained in twelve asphyxiated neonates while they were treated with hypothermia. Median difference between esophageal temperature on NICU departure and return was 0.1°C (range: −0.8 to 0.8°C). In conclusion, therapeutic hypothermia can be safely and reproducibly maintained during a brain MRI. Hypothermia treatment should not prevent obtaining an early brain MRI if clinically indicated.

Adrenal abscess is an uncommon finding in neonates and young infants. It may have a fatal outcome if inadequately treated. This case report describes the successful diagnosis and treatment of a left-sided adrenal abscess in a 5-week-old girl. Abdominal US and antigranulocyte antibody-scintigraphy showed an encapsulated suprarenal mass with debris suspicious for an adrenal abscess. Treatment is generally surgical. In this case, however, we performed US-guided percutaneous drainage combined with intravenous antibiotic treatment. The child recovered fully.

Background

Children with severe neurological impairment and intellectual disability (ID) are susceptible for developing low bone mineral density (BMD) and fractures. BMD is generally measured with dual-energy X-ray absorptiometry (DXA).

Objective

To describe the occurrence of factors that may influence the feasibility of DXA and the accuracy of DXA outcome in children with severe neurological impairment and ID.

Materials and methods

Based on literature and expert opinion, a list of disrupting factors was developed. Occurrence of these factors was assessed in 27 children who underwent DXA measurement.

Results

Disrupting factors that occurred most frequently were movement during measurement (82%), aberrant body composition (67%), small length for age (56%) and scoliosis (37%). The number of disrupting factors per child was mean 5.3 (range 1–8). No correlation was found between DXA outcomes and the number of disrupting factors.

Conclusion

Factors that may negatively influence the accuracy of DXA outcome are frequently present in children with severe neurological impairment and ID. No systematic deviation of DXA outcome in coherence with the amount of disrupting factors was found, but physicians should be aware of the possible influence of disrupting factors on the accuracy of DXA.

Background

MRI is the most sensitive imaging modality in juvenile idiopathic arthritis (JIA), but has practical limitations. Optimizing the scanning protocol is, therefore, necessary to increase feasibility and patient comfort.

Objective

To determine the feasibility of bilateral non-contrast-enhanced open-bore MRI of knees and to assess the presence of literature-based MRI features in unsedated children with JIA.

Materials and methods

Children were classified into two clinical subgroups: active arthritis (group 1; n = 29) and inactive disease (group 2; n = 18). MRI features were evaluated using a literature-based score, comprising synovial hypertrophy, cartilage lesions, bone erosions, bone marrow changes, infrapatellar fat pad heterogeneity, effusion, tendinopathy and popliteal lymphadenopathy.

Results

The MRI examination was successfully completed in all 47 children. No scan was excluded due to poor image quality. Synovial hypertrophy was more frequent in group 1 (36.2%), but was also seen in 19.4% of the knees in group 2. Infrapatellar fat pad heterogeneity was more prevalent in group 2 (86.1%; P = 0.008). Reproducibility of the score was good (Cohen kappa, 0.49–0.96).

Conclusion

Bilateral non-contrast-enhanced open-bore knee MRI is feasible in the assessment of disease activity in unsedated children with JIA. Signs differing among chidren with active and inactive disease include infrapatellar fat pad heterogeneity and synovial hypertrophy.

Background

Laterality defects are quite common in thoracoileopagus and parapagus dicephalus but rare in other types of conjoined twins.

Objective

To present the presumed laterality defects in cephalothoracoileopagus and prosopothoracoileopagus conjoined twins, based on the unilateral or bilateral absence or duplication of the spleen.

Materials and methods

Three human anatomical specimens of craniothoracoileopagus (CTIP) twins and one of prosopothoracoileopagus (PTIP) twins were investigated. The specimens were part of the Museum Vrolik collection of the Department of Anatomy and Embryology of the Academic Medical Centre, University of Amsterdam, The Netherlands. The specimens were taken out of their jars and scanned with multidetector CT and volumetric T2-weighted MRI at 1.5 T.

Results

The internal anatomy of the specimens was largely in accordance with previous reports. However, there was no recognisable spleen in the right twin in one CTIP specimen, in the left twin in one other CTIP specimen, and in both twins in the third CTIP specimen and in the PTIP specimen.

Conclusion

Asplenia and polysplenia are considered reliable indicators of right and left isomerism, respectively. However, three of our four specimens had laterality patterns that did not correspond with those previously reported. Since no other parameters of laterality defects could be verified in these specimens, we concluded that asplenia was unlikely to be caused by laterality defects.

Respiratory motion degrades MRI exams. Adequate detection of respiratory motion with pneumatic respiratory belts in small children is challenging and time-consuming.

Background

Measurement of liver MRI T2* and R2* is emerging as a reliable alternative to liver biopsy for the quantitation of liver iron content. A systematic investigation of the influence of the region of interest size and placement has not been conducted.

Objective

To compare small and whole liver region of interest (ROI) MRI R2* values to each other and to biopsy liver iron content in patients with iron overload.

Materials and Methods

Forty-one iron-overloaded patients, ages 7 to 35 years, underwent biopsy for liver iron content quantitation and MRI for liver R2* measurement, within 30 days. Three reviewers independently used small and whole liver ROIs to measure R2*. Inter-reviewer agreement was assessed with the intra-class correlation coefficient (ICC). Associations between R2* and liver iron content were investigated using Spearman's rank-order correlation and Monte Carlo estimated exact P-values.

Results

Biopsy liver iron content and small and whole liver ROI R2* measurements were strongly associated for all reviewers (all P < 0.0001). Although inter-reviewer agreement was excellent for both ROI methods (ICC = 0.98 – 0.99), the small ROI technique more frequently led to inter-reviewer differences larger than 75 Hz, slightly higher R2* values, larger standard errors and greater range in values.

Conclusions

Small and whole liver ROI techniques are strongly associated with biopsy liver iron content. We found slightly greater inter-reviewer variability in R2* values using the small ROI technique. Because such variability could adversely impact patient management when R2* values are near a threshold of iron chelation therapy, we recommend using a whole liver ROI.

Retinoblastoma is the most common intraocular tumor in children. The diagnosis is usually established by the ophthalmologist on the basis of fundoscopy and US. Together with US, high-resolution MRI has emerged as an important imaging modality for pretreatment assessment, i.e. for diagnostic confirmation, detection of local tumor extent, detection of associated developmental malformation of the brain and detection of associated intracranial primitive neuroectodermal tumor (trilateral retinoblastoma). Minimum requirements for pretreatment diagnostic evaluation of retinoblastoma or mimicking lesions are presented, based on consensus among members of the European Retinoblastoma Imaging Collaboration (ERIC). The most appropriate techniques for imaging in a child with leukocoria are reviewed. CT is no longer recommended. Implementation of a standardized MRI protocol for retinoblastoma in clinical practice may benefit children worldwide, especially those with hereditary retinoblastoma, since a decreased use of CT reduces the exposure to ionizing radiation.

Background

It is debated whether iso-osmolar and low-osmolar contrast media are associated with different incidences of contrast medium-induced nephropathy (CIN) in patients with renal insufficiency.

Objective

To compare the incidence of CIN in children undergoing contrast-enhanced multidetector computer tomography (MDCT) with intravenous injection of low-osmolar (iobitridol, Xenetix® 300) or an iso-osmolar (iodixanol, Visipaque® 270) iodinated contrast medium.

Materials and methods

One hundred forty-six children with normal renal function were included in this multicenter trial and underwent contrast-enhanced MDCT. The primary endpoint was the relative change in creatinine clearance from 48 h pre- to 72 h postcontrast medium administration using a noninferiority analysis in the intent-to-treat (ITT, n = 128) and per protocol (n = 68) populations. Secondary endpoints were incidence of CIN, global image quality, diagnostic efficacy and clinical safety.

Results

In the ITT population, the noninferiority of iobitridol over iodixanol was demonstrated. CIN incidence was 4.8% (three cases) with iobitridol and 10.6% (seven cases) with iodixanol (not significant). No statistically significant differences were observed for the secondary endpoints.

Conclusion

Comparable satisfactory safety profiles were confirmed for both contrast media, with no significant difference in the incidence of CIN in children with normal renal function.

The exposure index is currently a method by which digital radiography manufacturers provide feedback to the technologist regarding the estimated exposure on the detector, as a surrogate for image signal-to-noise ratio and an indirect indication of digital image quality. Unfortunately, there are as many exposure index values and methods as there are manufacturers, and in an environment with multiple vendors and a need to share data across institutions and dose registry databases, the situation is complicated. Fortunately, a new exposure index of digital X-ray imaging systems has been implemented. Developed concurrently by the International Electrotechnical Commission and the American Association of Physicists in Medicine in cooperation with digital radiography system manufacturers, the index has been implemented as an international standard. As explained, the exposure index does not indicate patient dose but rather a linearly proportional estimate of the incident radiation exposure to the detector. However, the use of the standardized exposure index and its associated target exposure index and deviation index values will likely lead to improved technologist performance in terms of uniformity and use of optimized radiographic techniques, leading to safer care of children needing radiographic examinations. Radiologists will benefit from standardized terminology, and institutions and clinics will be able to compare exposure index values with others through a national dose index registry database now under development. The Alliance for Radiation Safety in Pediatric Imaging, in its role as a benefactor of and advocate for the pediatric patient, is using the Image Gently campaign to disseminate information regarding the exposure index standard for digital radiography so that these benefits can be achieved in a rapid and effective manner.

Background

Ultrasound (US) is used to identify causes of neonatal cholestasis. We describe a potential sonographic pitfall, the “pseudo gallbladder,” in biliary atresia (BA).

Objective

To describe the Pseudo Gallbladder sign (PsGB sign).

Materials and methods

Sonograms/clinical records of 20 confirmed BA infants and 20 non-BA cases were reviewed retrospectively. For the BA group, preoperative sonography and surgical and pathological findings were examined. For the non-BA group, sonographic features and pathological findings were examined. The PsGB sign is defined as a fluid-filled structure, located in the expected region of the gallbladder, measuring ≤ 15 mm in length but without a well-defined or normal-appearing gallbladder wall.

Results

A recognizable gallbladder and normal gallbladder wall were present in all non-BA infants. However, none of the BA infants had a sonographically normal gallbladder. Seventy-three percent of BA patients had a PsGB, and in 27% no gallbladder or gallbladder-like structure was detected.

Conclusion

A gallbladder-like structure in BA is common and can be misinterpreted as a normal gallbladder, delaying diagnosis and therapy. Recognition of this imaging pitfall, described here as the pseudo gallbladder sign, will help avoid this error.

Pectus excavatum, the most common congenital deformity of the anterior chest wall, is both a cosmetic and functional abnormality. The degree of abnormal chest wall deformity determines its functional effect, particularly its cardiac and pulmonary impact. Although CT scanning is the most widely used cross-sectional imaging technique used to measure the Haller index, the radiation exposure is reason to seek other alternatives. At our institution, we have introduced a rapid MRI technique for this purpose, which utilizes a single-axial 2-D FIESTA acquisition.

T1-weighted imaging in the pediatric abdomen suffers from respiratory motion artifacts. Though navigation has been employed commonly for coronary MRA and T2 imaging, navigation for T1-weighted imaging is less developed. Thus, a navigator pulse was incorporated into a fat-suppressed T1-weighted SPGR sequence such that steady-state contrast was not disrupted. 10 pediatric patients were recruited and scanned after gadolinium administration three times in immediate succession: breath-hold with no navigation, free-breathing with navigation, and free-breathing without navigation. Motion artifacts were scored for each sequence by two radiologists, showing less motion artifacts with navigation compared to free-breathing and greater motion artifacts than with breath-holding. This work demonstrates the feasibility and potential utility of navigation for pediatric abdominal T1-weighted imaging.

To obtain information on the occurrence and location of molecular events as well as to track target-specific probes such as antibodies or peptides, drugs or even cells non-invasively over time, optical imaging (OI) technologies are increasingly applied. Although OI strongly contributes to the advances made in preclinical research, it is so far, with the exception of optical coherence tomography (OCT), only very sparingly applied in clinical settings. Nevertheless, as OI technologies evolve and improve continuously and represent relatively inexpensive and harmful methods, their implementation as clinical tools for the assessment of children disease is increasing. This review focuses on the current preclinical and clinical applications as well as on the future potential of OI in the clinical routine. Herein, we summarize the development of different fluorescence and bioluminescence imaging techniques for microscopic and macroscopic visualization of microstructures and biological processes. In addition, we discuss advantages and limitations of optical probes with distinct mechanisms of target-detection as well as of different bioluminescent reporter systems. Particular attention has been given to the use of near-infrared (NIR) fluorescent probes enabling observation of molecular events in deeper tissue.