Normal volumetric and T1 relaxation time values at 1.5 T in segmented pediatric brain MRI using a MP2RAGE acquisition.

OBJECTIVES: This study introduced a tailored MP2RAGE-based brain acquisition for a comprehensive assessment of the normal maturing brain. METHODS: Seventy normal patients (35 girls and 35 boys) from 1 to 16 years of age were recruited within a prospective monocentric study conducted from a single University Hospital. Brain MRI examinations were performed at 1.5 T using a 20-channel head coil and an optimized 3D MP2RAGE sequence with a total acquisition time of 6:36 min. Automated 38 region segmentation was performed using the MorphoBox (template registration, bias field correction, brain extraction, and tissue classification) which underwent a major adaptation of three age-group T1-weighted templates. Volumetry and T1 relaxometry reference ranges were established using a logarithmic model and a modified Gompertz growth respectively. RESULTS: Detailed automated brain segmentation and T1 mapping were successful in all patients. Using these data, an age-dependent model of normal brain maturation with respect to changes in volume and T1 relaxometry was established. After an initial rapid increase until 24 months of life, the total intracranial volume was found to converge towards 1400 mL during adolescence. The expected volumes of white matter (WM) and cortical gray matter (GM) showed a similar trend with age. After an initial major decrease, T1 relaxation times were observed to decrease progressively in all brain structures. The T1 drop in the first year of life was more pronounced in WM (from 1000-1100 to 650-700 ms) than in GM structures. CONCLUSION: The 3D MP2RAGE sequence allowed to establish brain volume and T1 relaxation time normative ranges in pediatrics. KEY POINTS: • The 3D MP2RAGE sequence provided a reliable quantitative assessment of brain volumes and T1 relaxation times during childhood. • An age-dependent model of normal brain maturation was established. • The normative ranges enable an objective comparison to a normal cohort, which can be useful to further understand, describe, and identify neurodevelopmental disorders in children.

Posterior fossa tumors in children: Radiological tips & tricks in the age of genomic tumor classification and advance MR technology.

Imaging plays a major role in the comprehensive assessment of posterior fossa tumor in children (PFTC). The objective is to propose a global method relying on the combined analysis of radiological, clinical and epidemiological criteria, (taking into account the child's age and the topography of the lesion) in order to improve our histological approach in imaging, helping the management and approach for surgeons in providing information to the patients' parents. Infratentorial tumors are the most frequent in children, representing mainly medulloblastoma, pilocytic astrocytoma and brainstem glioma. Pre-surgical identification of the tumor type and its aggressiveness could be improved by the combined analysis of key imaging features with epidemiologic data.

Detection of recurrent brain tumors in children: No significant difference in sensitivity between unenhanced and contrast-enhanced MRI.

BACKGROUND: Magnetic resonance imaging (MRI) with a gadolinium injection is currently used in the follow-up of children in remission of cerebral tumors (CTs). Intracerebral gadolinium deposition has been recently reported with unknown risks. The aim of this study was to evaluate the sensitivity of unenhanced brain MRI (U-MRI) in detection of tumor recurrence. METHODS AND MATERIALS: A set of 58 U-MRIs of children in remission was retrospectively evaluated by three seniors (a neuroradiologist, a pediatric and a general radiologist) and one junior to look for any recurrence. Clinical, tumoral and imaging data were collected. The final diagnosis was anatomopathological when available, or the clinicoradiological evolution. Sensitivity, specificity, predictive values and interobserver agreement were calculated. A Fisher test and Fleiss kappa coefficient were performed. RESULTS: For the seniors, the U-MRI had a sensitivity of 81% (95% confidence interval (CI): 0.56-0.90), and a negative predictive value (NPV) of 82% (95% CI: 0.63-0.94). The U-MRI sensitivity, regardless of the observer, was not significantly different from the contrast-enhanced MRI sensitivity (86%) according to a Fisher test (p > 0.05). No significant difference in sensitivity within the subgroups was found. The interobserver agreement of seniors was good (κ = 0.68). CONCLUSION: U-MRI brain was suboptimal for 80% of patients. Three-dimensional millimetric, fluid-attenuated inversion recovery, and diffusion would constitute helpful sequences in follow-up. Further specific studies depending on each tumor type are still required to determine whether a potential abstention of gadolinium intravenous injection should be discussed for children.

Individual radiation exposure from computed tomography: a survey of paediatric practice in French university hospitals, 2010-2013.

OBJECTIVES: To describe computed tomography (CT) scanning parameters, volume CT dose index (CTDIvol) and dose-length product (DLP) in paediatric practice and compare them to current diagnostic reference levels (DRLs). METHODS: The survey was conducted in radiology departments of six major university hospitals in France in 2010-2013. Data collection was automatised to extract and standardise information on scanning parameters from DICOM-header files. CTDIvol and DLP were estimated based on Monte Carlo transport simulation and computational reference phantoms. RESULTS: CTDIvol and DLP were derived for 4,300 studies, four age groups and 18 protocols. CTDIvol was lower in younger patients for non-head scans, but did not vary with age for routine head scans. Ratios of 95th to 5th percentile CTDIvol values were 2-4 for most body parts, but 5-7 for abdominal examinations and 4-14 for mediastinum CT with contrast, depending on age. The 75th percentile CTDIvol values were below the national DRLs for chest (all ages) and head and abdominal scans (≥10 years). CONCLUSION: The results suggest the need for a better optimisation of scanning parameters for routine head scans and infrequent protocols with patient age, enhanced standardisation of practices across departments and revision of current DRLs for children. KEY POINTS: • CTDIvol varied little with age for routine head scans. • CTDIvol was lowest in youngest children for chest or abdominal scans. • Individual and inter-department variability warrant enhanced standardisation of practices. • Recent surveys support the need for revised diagnostic reference levels. • More attention should be given to specific protocols (sinuses, neck, spine, mediastinum).

Sonography of suspected acute appendicitis in children: Evaluation of the progress in performance of senior residents.

PURPOSE: The objective of this study was to evaluate the progress in performance of senior residents in diagnosing acute appendicitis. MATERIAL AND METHODS: Results were collected and compared of ultrasound examinations performed for suspected acute appendicitis by three senior residents and two faculty members over a six-month period in a university hospital setting. A grid with the sonographic findings was completed separately by the residents and the faculty members immediately after each examination. The duration of each examination was reported. The final ultrasound diagnosis was compared to the surgical and pathological results and to the clinical follow-up. RESULTS: The residents and faculty members performed 171 consecutive ultrasound examinations including 49 children with acute appendicitis and 122 with normal appendices. The accuracy of the diagnosis by the residents was 96%, and was similar to that of the faculty members (kappa=0.90) over the six months. The duration of the resident ultrasound examinations was significantly shorter during the second three-month period (p=0.01). No significant differences in diagnostic accuracy were demonstrated by the residents between the first and second three-month periods (p=0.06). CONCLUSIONS: The residents performed well when using sonography to diagnose acute appendicitis in children, and were faster during the second three-month period. LEVEL OF EVIDENCE: I.

Variability in Imaging Practices and Comparative Cumulative Effective Dose for Neuroblastoma and Nephroblastoma Patients at 6 Pediatric Oncology Centers.

The purpose of this study was to estimate the cumulative effective dose (CED) from diagnosis and posttherapy computed tomographic (CT) scans performed on children treated for neuroblastoma or nephroblastoma (Wilms tumor) and to examine the different imaging practices used in 6 regional pediatric oncology centers between January 2010 and December 2013. We analyzed retrospectively the CT scan acquisition data in children aged 10 years or younger at diagnosis. The use of nonionizing imaging modalities was reported. The CT examinations of 129 children, with a mean age at diagnosis of 36 months, treated for 66 neuroblastomas and 63 nephroblastomas, were analyzed. The mean follow-up period was 28 months (minimum, 8 months, maximum, 41 mo). There were 600 CT scans, with a total of 1039 acquisitions. The mean CED from CT scans was 27 mSv (minimum=18.25, maximum=45). Abdominal CT examinations contributed 85% of the total CED. A median of 4.6 CT scans, 10.3 sonograms, and 0.4 magnetic resonance imaging examinations per child were performed. Our results suggest a reduction in radiation exposure but variability in the imaging modality choice and acquisition protocols. We emphasize the need for consensus and standardization in oncologic pediatric imaging procedures. When feasible, we encourage the substitution of nonionizing examinations for CT.

T1-weighted dynamic contrast-enhanced brain magnetic resonance imaging: A preliminary study with low infusion rate in pediatric patients.

Background The aim of this preliminary study is to evaluate the results of T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in pediatric patients at 1.5T, with a low peripheral intravenous gadoteric acid injection rate of 1 ml/s. Materials and methods Children with neurological symptoms were examined prospectively with conventional MRI and T1-weighted DCE MRI. An magnetic resonance perfusion analysis method was used to obtain time-concentration curves (persistent pattern, type-I; plateau pattern, type-II; washout pattern, type-III) and to calculate pharmacokinetic parameters. A total of two radiologists manually defined regions of interest (ROIs) in the part of the lesion exhibiting the greatest contrast enhancement and in the surrounding normal or contralateral tissue. Lesion/surrounding tissue or contralateral tissue pharmacokinetic parameter ratios were calculated. Tumors were categorized by grade (I-IV) using the World Health Organization (WHO) Grade. Mann-Whitney testing and receiver-operating characteristic (ROC) curves were performed. Results A total of nine boys and nine girls (mean age 10.5 years) were included. Lesions consisted of 10 brain tumors, 3 inflammatory lesions, 3 arteriovenous malformations and 2 strokes. We obtained analyzable concentration-time curves for all patients (6 type-I, 9 type-II, 3 type-III). Ktrans between tumor tissue and surrounding or contralateral tissue was significantly different ( p = 0.034). Ktrans ratios were significantly different between grade I tumors and grade IV tumors ( p = 0.027) and a Ktrans ratio value superior to 0.63 appeared to be discriminant to determine a grade IV of malignancy. Conclusions Our results confirm the feasibility of pediatric T1-weighted DCE MRI at 1.5T with a low injection rate, which could be of great value in differentiating brain tumor grades.

Tracheobronchial Branching Abnormalities: Lobe-based Classification Scheme.

Boyden's nomenclature, which was based on postmortem specimens and published in 1955 prior to the advent of computed tomography (CT), is commonly used to describe the normal segmental bronchial anatomy and various abnormalities. However, several additional anomalies have been recognized since that time, and there is some confusion over the names used to describe these anomalies. Several congenital branching anomalies affecting the trachea, main bronchi, and intermediate bronchus have been reported, all of which can be recognized at chest CT but are often overlooked. These anomalies, which probably occur early in fetal life, can be either supernumerary, with defects occurring at 29-30 days gestation, or displaced, with defects occurring later. Tracheobronchial positional anomalies are often associated with other congenital abnormalities but may be isolated. They often are asymptomatic but can be responsible for pulmonary symptoms such as dyspnea, recurrent pneumonia, and hemoptysis. It is essential that these anomalies are recognized prior to lung resection to avoid complications, especially when video-assisted thoracoscopic surgery is performed. In addition, bronchoscopists should be aware of these anomalies before performing diagnostic or therapeutic bronchoscopic procedures. Awareness of a few key bronchial anatomic principles and use of a lobe-based classification scheme will facilitate recognition of tracheobronchial positional anomalies.

Efficacy and safety of embolization in arteriovenous malformations of the extremities and head and neck: a retrospective study of 32 cases.

BACKGROUND: Definitive treatment of arteriovenous malformations (AVMs) consists of complete surgical excision. When not possible, embolization may be performed. OBJECTIVES: We aimed to evaluate the efficacy and safety of embolization for AVMs of the extremities and head and neck. MATERIALS AND METHODS: This retrospective study included all patients undergoing embolization for AVMs of skin and soft tissues on the limbs, head and neck, in the University Hospital Center of Tours between January 1996 and December 2009. The main outcome was efficacy, assessed by two independent assessors, as the percentage of AVM devascularized at the end of embolization. Secondary outcomes were patient satisfaction, evolution of symptoms and safety of embolization. RESULTS: We included 32 AVMs in 31 patients, for 66 embolizations evaluated. In 18 AVMs (56.3%), devascularization was greater than 75% of the initial vascularization. Efficacy was lower for AVMs of the upper limbs than other body parts (p = 0.003). For 18 patients who could be contacted by telephone, the mean global satisfaction was 6.0 ± 2.7 on a scale of 0 to 10, and 13 (72.2%) reported an improvement of the symptoms linked to the AVM. Severe adverse events were reported after 4 embolizations, all located on the head and neck. CONCLUSION: Embolization can lead to good devascularization and improve symptoms linked to AVMs, especially in lower limbs. Minor complications are frequent, and severe adverse events may occur, especially after procedures on the head and neck.

Sturge-Weber syndrome in patients with facial port-wine stain.

Facial port-wine stain (PWS) may be associated with cerebrovascular abnormalities such as Sturge-Weber syndrome (SWS). In a large series, we aimed to assess which topography of facial PWS can predict SWS. This was a cross-sectional study of consecutive patients with facial PWS seen in pediatric dermatologic or angiodysplasia consultations from 1993 to 2005 at the University Hospital Center of Tours. A standardized form was used to collect data on clinical and imaging findings. Patients with and without SWS were compared in terms of topography of the cutaneous angioma and related ophthalmologic and neurologic features. Two hundred fifty-nine patients were included, 15 with a diagnosis of SWS. All patients with SWS showed involvement of the V1 trigeminal cutaneous area. SWS was significantly associated with bilateral topography of the PWS, its extension to another territory, and involvement of the upper eyelid. Knowledge of the topography of facial PWS with risk of associated neurological or ocular anomalies allows for early diagnosis of SWS and avoids unnecessary and costly radiography for patients with uncomplicated facial PWS.

Proton MR spectroscopic imaging of basal ganglia and thalamus in neurofibromatosis type 1: correlation with T2 hyperintensities.

INTRODUCTION: Neurofibromatosis type 1 (NF1) is frequently associated with hyperintense lesions on T2-weighted images called "unidentified bright objects" (UBO). To better characterize the functional significance of UBO, we investigate the basal ganglia and thalamus using spectroscopic imaging in children with NF1 and compare the results to anomalies observed on T2-weighted images. METHODS: Magnetic resonance (MR) data of 25 children with NF1 were analyzed. On the basis of T2-weighted images analysis, two groups were identified: one with normal MR imaging (UBO- group; n = 10) and one with UBO (UBO+ group; n = 15). Within the UBO+ group, a subpopulation of patients (n = 5) only had lesions of the basal ganglia. We analyzed herein seven regions of interest (ROIs) for each side: caudate nucleus, capsulo-lenticular region, lateral and posterior thalamus, thalamus (lateral and posterior voxels combined), putamen, and striatum. For each ROI, a spectrum of the metabolites and their ratio was obtained. RESULTS: Patients with abnormalities on T2-weighted images had significantly lower NAA/Cr, NAA/Cho, and NAA/mI ratios in the lateral right thalamus compared with patients with normal T2. These abnormal spectroscopic findings were not observed in capsulo-lenticular regions that had UBO but in the thalamus region that was devoid of UBO. CONCLUSION: Multivoxel spectroscopic imaging using short-time echo showed spectroscopic abnormalities in the right thalamus of NF1 patients harboring UBO, which were mainly located in the basal ganglia. This finding could reflect the anatomical and functional interactions of these regions.

Thalamo-striatal T2-weighted hyperintensities (unidentified bright objects) correlate with cognitive impairments in neurofibromatosis type 1 during childhood.

Learning disabilities represent the main childhood complication in neurofibromatosis type 1 (NF1). Patients frequently exhibit T2-weighted hyperintensities called unidentified bright objects (UBOs) on brain magnetic resonance imaging (MRI), with unclear relationship to such cognitive disabilities. This study aimed to determine whether thalamo-striatal UBOs correlate with cognitive disturbances. Thirty-seven NF1 children were studied: 24 with UBOs (18 of which were thalamo-striatal UBOs), and 13 without UBOs. NF1 subjects carrying thalamo-striatal UBOs had significantly lower IQs and visuospatial performances than those without UBOs in this location. These results suggest that UBOs may contribute to NF1 cognitive impairments through thalamo-cortical dysfunction.