Neurofibromatosis bright objects in children with neurofibromatosis type 1: a proliferative potential?

Identifying Lesions of the Corpus Callosum in Patients With Neurofibromatosis Type 1

BACKGROUND

Neurofibromatosis type 1 (NF1) is a multisystemic autosomal dominant disorder that includes intracranial lesions such as unidentified bright objects (UBOs)-areas of increased T2 signal on magnetic resonance imaging (MRI)-and tumors known as gliomas. The presence of these lesions in the corpus callosum (CC) has not been previously studied in a large cohort.

METHODS

We reviewed medical records of 681 patients (aged three months to 86 years) followed at our institution from 2000 to 2023 with NF1 and one or more brain MRI. Patients with lesions in the CC were identified, and RAPNO/RANO criteria were used to determine changes in size over time, where a change of 25% in the product of perpendicular measurements indicates growth or shrinkage.

RESULTS

Forty-seven patients had CC UBOs, most of which were in the splenium (66.0%). Seventeen patients had CC gliomas (10% of those with any glioma), two of whom had two gliomas. Seventeen of 19 gliomas were in the splenium. Over follow-up, eight of 19 remained stable, three shrunk, and eight grew. The mean percentage change in the product of the dimensions was 311.5% (ranging from -46.7% to 2566.6%). Of the eight lesions that grew, one required treatment.

CONCLUSIONS

There is a 6.9% and 2.5% prevalence of CC UBOs and gliomas, respectively, in our cohort of patients with NF1. Most lesions are present in the splenium, and although some gliomas demonstrate significant growth, they rarely require treatment. This work is the largest series of CC lesions in NF1 and adds to the growing data to inform appropriate follow-up.

Evaluating Focal Areas of Signal Intensity (FASI) in Children with Neurofibromatosis Type-1 (NF1) Treated with Selumetinib on Pediatric Brain Tumor Consortium (PBTC)-029B

Background: Understanding the effect of selumetinib on FASI may help elucidate the biology, proliferative potential, and role in neurocognitive changes for these NF1-associated lesions. Methods: Patients with NF1-associated LGG and FASI treated with selumetinib on PBTC-029B were age-matched to untreated patients with NF1-associated FASI at Cincinnati Children’s Hospital Medical Center. Paired bidirectional measurements were compared over time using nonparametric tests. Results: Sixteen age-matched pairs were assessed (age range: 2.8–16.9 years, 60% male). Initial FASI burden was not different between groups (median range 138.7 cm2 [88.4–182.0] for the treated subjects vs. 121.6 cm2 [79.6—181.9] for the untreated subjects; p = 0.98). Over a mean follow-up of 18.9 (±5.9) months, the LGG size consistently decreased with treatment while no consistent change among the treated or untreated FASI size was seen. At the paired time points, the median treated LGG decreased significantly more than the treated FASI (−41.3% (LGG) versus −10.7% (FASI), p = 0.006). However, there was no difference in the median size change in the treated versus untreated FASI (−10.7% (treated FASI) versus −17.9% (untreated FASI), p = 0.08). Among the treated subjects, there was no correlation between the change in LGG and FASI (r = −0.04, p = 0.88). Conclusions: Treatment with selumetinib did not affect the overall FASI size in children with NF1 treated for progressive low-grade glioma.

[Neurofibromatosis type 1 : From diagnosis to follow-up]

BACKGROUND

Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome and is one of the most common genetic diseases. It is therefore a condition encountered by radiologists in clinical routine. Since the variability of the clinical expression is very high and several organ systems are affected, we present a standardized diagnostic approach in this article.

METHODS

Evaluation of the literature on neurofibromatosis type 1 in the context of radiological examination methods.

RESULTS

In addition to the frequently known changes in the central and peripheral nervous system such as optic gliomas and plexiform neurofibromas, lesions from the orthopedic spectrum and vascular changes must also be included in the radiological diagnosis.

CONCLUSIONS

Due to the diversity of the clinical picture of NF1, it is reasonable to define an examination strategy which takes into account the needs of radiological routine and also reliably detects the most frequent and prognostically significant pathologies accompanying this disease. In this article, the current recommendations for diagnosis of neurofibromatosis-associated tumors and skeletal changes are summarized, and examination protocols and time intervals are suggested.

The RASopathies: Biology, genetics and therapeutic options

The RASopathies are a group of genetic diseases in which the Ras/MAPK signaling pathway is inappropriately activated as a result of mutations in genes encoding proteins within this pathway. As their causative mutations have been identified, this group of diseases has expanded to include neurofibromatosis type 1 (NF1), Legius syndrome, Noonan syndrome, CBL syndrome, Noonan syndrome-like disorder with loose anagen hair, Noonan syndrome with multiple lentigines, Costello syndrome, cardiofaciocutaneous syndrome, gingival fibromatosis and capillary malformation-arteriovenous malformation syndrome. Many of these genetic disorders share clinical features in common such as abnormal facies, short stature, varying degrees of cognitive impairment, cardiovascular abnormalities, skeletal abnormalities and a predisposition to develop benign and malignant neoplasms. Others are more dissimilar, even though their mutations are in the same gene that is mutated in a different RASopathy. Here, we describe the clinical features of each RASopathy and contrast them with the other RASopathies. We discuss the genetics of these disorders, including the causative mutations for each RASopathy, the impact that these mutations have on the function of an individual protein and how this dysregulates the Ras/MAPK signaling pathway. As several of these individual disorders are genetically heterogeneous, we also consider the different genes that can be mutated to produce disease with the same phenotype. We also discuss how our growing understanding of dysregulated Ras/MAPK signaling had led to the development of new therapeutic agents and what work will be critically important in the future to improve the lives of patients with RASopathies.

Clinical report of a brain magnetic resonance imaging finding in Noonan syndrome

Noonan syndrome (NS) is an autosomal dominant disease caused by aberrant up-regulated signaling through RAS GTPase. It is characterized by facial dysmorphisms, short stature, congenital heart defects, malformations of rib cage bones, bleeding problems, learning difficulties, or mild intellectual disability. Additional intracranial findings in NS patients include tumors, midline anomalies, and malformations of cortical development. In this report, we present the case of a young female patient, with a known diagnosis of Noonan syndrome that in complete well being developed two brain lesions, in the right nucleus pallidus and in the left cerebellar hemisphere respectively, whose location and signal on MRI looked similar to neurofibromatosis type 1 unidentified bright objects (UBOs), and whose spectroscopic characteristics excluded neoplasms.

Longitudinal Assessment of Enhancing Foci of Abnormal Signal Intensity in Neurofibromatosis Type 1

BACKGROUND AND PURPOSE

Patients with neurofibromatosis 1 are at increased risk of developing brain tumors, and differentiation from contrast-enhancing foci of abnormal signal intensity can be challenging. We aimed to longitudinally characterize rare, enhancing foci of abnormal signal intensity based on location and demographics.

MATERIALS AND METHODS

A total of 109 MR imaging datasets from 19 consecutive patients (7 male; mean age, 8.6 years; range, 2.3-16.8 years) with neurofibromatosis 1 and a total of 23 contrast-enhancing parenchymal lesions initially classified as foci of abnormal signal intensity were included. The mean follow-up period was 6.5 years (range, 1-13.8 years). Enhancing foci of abnormal signal intensity were followed up with respect to presence, location, and volume. Linear regression analysis was performed.

RESULTS

Location, mean peak volume, and decrease in enhancing volume over time of the 23 lesions were as follows: 10 splenium of the corpus callosum (295 mm³, 5 decreasing, 3 completely resolving, 2 surgical intervention for change in imaging appearance later confirmed to be gangliocytoma and astrocytoma WHO II), 1 body of the corpus callosum (44 mm³, decreasing), 2 frontal lobe white matter (32 mm³, 1 completely resolving), 3 globus pallidus (50 mm³, all completely resolving), 6 cerebellum (206 mm³, 3 decreasing, 1 completely resolving), and 1 midbrain (34 mm³). On average, splenium lesions began to decrease in size at 12.2 years, posterior fossa lesions at 17.1 years, and other locations at 9.4 years of age.

CONCLUSIONS

Albeit very rare, contrast-enhancing lesions in patients with neurofibromatosis 1 may regress over time. Follow-up MR imaging aids in ascertaining regression. The development of atypical features should prompt further evaluation for underlying tumors.

Genetic basis of neurofibromatosis type 1 and related conditions, including mosaicism

INTRODUCTION

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant disorder characterised by café-au-lait maculae (CALM), skinfold freckling, iris Lisch nodules and benign peripheral nerve sheath tumours (neurofibromas).

MECHANISM

The NF1 gene is a tumour suppressor gene and NF1 individuals have an increased risk for a long list of tumours, all resulting from a second hit in the normal copy of the NF1 gene. Remarkably, some non-tumour phenotypes such as CALM and pseudarthrosis are also caused by a "second hit". Germline mutations inactivating the NF1 gene show a large variability in genetic mechanisms ranging from single-nucleotide substitutions and somatic mosaicism to large deletions affecting neighbouring genes. Molecular confirmation of the clinical diagnosis is becoming increasingly more important to differentiate NF1 from other syndromes such as Legius syndrome, to investigate genotype-phenotype correlations relevant in 10% of cases and to detect somatic mosaicism.

SURVEILLANCE AND THERAPY

Some degree of learning difficulties, attention deficit and social problems are observed in most children and affect quality of life. There is a large individual variability in complications and the evolution of the disease is difficult to predict. Specialised outpatient clinics for children have been widely established and are important for surveillance and guidance. Regular surveillance is also important for adolescents and adults because many tumour complications can be detected by whole-body MRI and treated even before symptoms develop and irreversible damage occurs. Recent data on nodular plexiform neurofibromas with continued growth in adolescents and young adults show that many of these tumours are premalignant lesions called atypical neurofibromatous neoplasm of uncertain biological potential (ANNUBP). Specific surveillance and timely local resection of these benign peripheral nerve sheath tumours might be important to prevent malignant degeneration. In the last years, targeted therapy with MEK inhibitors has shown promise to treat unresectable and symptomatic plexiform neurofibromas. Many more challenges remain to find the best way to monitor children and adults for potential complications and to find a satisfying cure for many complications in this disorder.

Focal Areas of High Signal Intensity in Children with Neurofibromatosis Type 1: Expected Evolution on MRI

BACKGROUND AND PURPOSE

Focal areas of high signal intensity are T2WI/T2-FLAIR hyperintensities frequently found on MR imaging of children diagnosed with neurofibromatosis type 1, often thought to regress spontaneously during adolescence or puberty. Due to the risk of tumor in this population, some focal areas of high signal intensity may pose diagnostic problems. The objective of this study was to assess the characteristics and temporal evolution of focal areas of high signal intensity in children with neurofibromatosis type 1 using long-term follow-up with MR imaging.

MATERIALS AND METHODS

We retrospectively examined the MRIs of children diagnosed with neurofibromatosis type 1 using the National Institutes of Health Consensus Criteria (1987), with imaging follow-up of at least 4 years. We recorded the number, size, and surface area of focal areas of high signal intensity according to their anatomic distribution on T2WI/T2-FLAIR sequences. A generalized mixed model was used to analyze the evolution of focal areas of high signal intensity according to age, and separate analyses were performed for girls and boys.

RESULTS

Thirty-nine patients (ie, 285 MR images) with a median follow-up of 7 years were analyzed. Focal areas of high signal intensity were found in 100% of patients, preferentially in the infratentorial white matter (35% cerebellum, 30% brain stem) and in the capsular lenticular region (22%). They measured 15 mm in 95% of cases. They appeared from the age of 1 year; increased in number, size, and surface area to a peak at the age of 7; and then spontaneously regressed by 17 years of age, similarly in girls and boys.

CONCLUSIONS

Focal areas of high signal intensity are mostly small (<15 mm) abnormalities in the posterior fossa or capsular lenticular region. Our results suggest that the evolution of focal areas of high signal intensity is not related to puberty with a peak at the age of 7 years. Knowledge of the predictive evolution of focal areas of high signal intensity is essential in the follow-up of children with neurofibromatosis type 1.

Retrospective Multicentric Study on Non-Optic CNS Tumors in Children and Adolescents with Neurofibromatosis Type 1

s: The natural history of non-optic central nervous system (CNS) tumors in neurofibromatosis type 1 (NF1) is largely unknown. Here, we describe prevalence, clinical presentation, treatment, and outcome of 49 non-optic CNS tumors observed in 35 pediatric patients (0-18 years). Patient- and tumor-related data were recorded. Overall survival (OS) and progression-free survival (PFS) were evaluated. Eighteen patients (51%) harbored an optic pathway glioma (OPG) and eight (23%) had multiple non-optic CNS lesions. The majority of lesions (37/49) were managed with a wait-and-see strategy, with one regression and five reductions observed. Twenty-one lesions (42.9%) required surgical treatment. Five-year OS was 85.3%. Twenty-four patients progressed with a 5-year PFS of 41.4%. Patients with multiple low-grade gliomas progressed earlier and had a lower 5-year PFS than those with one lesion only (14.3% vs. 57.9%), irrespective of OPG co-presence. Non-optic CNS tumors are common in young patients with NF1. Neither age and symptoms at diagnosis nor tumor location influenced time to progression in our series. Patients with multiple lesions tended to have a lower age at onset and to progress earlier, but with a good OS.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 1 - clinical and neuroimaging findings

Background

Many children with neurofibromatosis type 1 (NF1) have focal abnormal signal intensities (FASI) on brain MRI, whose full clinical impact and natural history have not been studied systematically. Our aims are to describe the clinical and neuroradiological features in children with NF1 and cerebellar FASI, and report on the natural history of FASI that display atypical features such as enhancement and mass effect.

Method

A retrospective review of the hospital charts and brain MRIs was performed on children from Manitoba diagnosed between 1999 and 2008 with NF1, who also had cerebellar FASI on MRI.

Results

Fifty patients (mean age: 16.1y, minimum-maximum: 6.4 - 30y, 27 M) were identified. Mean duration of follow up was 10.1y. Developmental delay, learning disabilities, tumors, and visual signs occurred commonly. Cerebellar signs were not reported. Mean age of the patients at baseline MRI was 7.8 (SD: 4.5) years. FASI occurred in several brain locations and were rarely confined to the cerebellum. FASI displayed mass effect and enhancement infrequently but were associated with malignancy only once. The number of FASI at baseline MRI was significantly less in patients with attention deficient hyperactivity disorder and more if a first degree relative had NF1 or if they had decreased visual acuity.

Discussion

Patients with NF1 and cerebellar FASI do not have motor or consistent non-motor (e.g. developmental delay or learning disabilities) cerebellar features. The number of FASI may correlate with some clinical features. FASI may display enhancement and mass effect but they rarely become malignant.

Cerebellar radiological abnormalities in children with neurofibromatosis type 1: part 2 - a neuroimaging natural history study with clinical correlations

Background

Focal abnormal signal intensities (FASI) on brain MRI occur commonly in patients with neurofibromatosis type 1 (NF1). The natural history of cerebellar FASI and their correlation with clinical features have not been studied comprehensively. Our aims are to describe the natural history of cerebellar FASI on repeat MRI scans and correlate the findings with the clinical features in children with NF1 and cerebellar FASI.

Method

A retrospective review of 226 brain MRI scans and hospital charts was performed in 50 patients with cerebellar FASI, who were diagnosed with NF1 during their childhood between 1999 and 2008.

Results

Mean age at the end of the study period was 16.1 years. There were 27 males. Mean duration of clinical follow up was 10.1 years. Mean duration between the first and the last MRI was 6.6 years (n = 36, SD: 2.8 years). FASI were rarely confined to the cerebellum. The number of FASI was highest in early childhood and decreased significantly on subsequent MRI scans in most brain regions with the exception of the cerebrum, where a fewer number of patients with a smaller number of FASI were seen. Four patterns of change in FASI size over time were determined, none correlated with the clinical features.

Conclusions

In patients with NF1, the natural history of FASI including their number, age at onset, rate of size changes, and resolution if any, varies by brain region. FASI patterns of change over time showed no clinical correlate.

Recent Advances in the Diagnosis and Pathogenesis of Neurofibromatosis Type 1 (NF1)-associated Peripheral Nervous System Neoplasms

The diagnosis of a neurofibroma or a malignant peripheral nerve sheath tumor (MPNST) often raises the question of whether the patient has the genetic disorder neurofibromatosis type 1 (NF1) as well as how this will impact the patient's outcome, what their risk is for developing additional neoplasms and whether treatment options differ for NF1-associated and sporadic peripheral nerve sheath tumors. Establishing a diagnosis of NF1 is challenging as this disorder has numerous neoplastic and non-neoplastic manifestations which are variably present in individual patients. Further, other genetic diseases affecting the Ras signaling cascade (RASopathies) mimic many of the clinical features of NF1. Here, we review the clinical manifestations of NF1 and compare and contrast them with those of the RASopathies. We also consider current approaches to genetic testing for germline NF1 mutations. We then focus on NF1-associated neurofibromas, considering first the complicated clinical behavior and pathology of these neoplasms and then discussing our current understanding of the genomic abnormalities that drive their pathogenesis, including the mutations encountered in atypical neurofibromas. As several neurofibroma subtypes are capable of undergoing malignant transformation to become MPNSTs, we compare and contrast patient outcomes in sporadic, NF1-associated and radiation-induced MPNSTs, and review the challenging pathology of these lesions. The mutations involved in neurofibroma-MPNST progression, including the recent identification of mutations affecting epigenetic regulators, are then considered. Finally, we explore how our current understanding of neurofibroma and MPNST pathogenesis is informing the design of new therapies for these neoplasms.

Seizures in children with neurofibromatosis type 1: is neurofibromatosis type 1 enough?

BACKGROUND

Neurofibromatosis type 1 (NF1) is related to a generally increased prevalence of seizures. The mechanism underlying the increased predisposition to seizures has not been fully elucidated. The aim of the study was to evaluate the role of NF1 in seizures pathogenesis in a cohort of children with NF1 and seizures.

METHODS

The medical records of 437 children (0-18 years old) with NF1 were reviewed. All children with at least one afebrile seizure were included. Demographic, clinical, neurological, NF1 mutation status, and EEG data were collected along with brain magnetic resonance imaging. Depending on etiology, structural seizures have been identified and were further classified as NF1 related or not.

RESULTS

Nineteen patients (4.3%; 13 males) were included. NF1 was inherited in 7 (37.5%), with 3 maternal forms. Ten children with structural seizures were identified. Seven forms were identified someway related to NF1, two of which were associated to 17q11.2 microdeletion and hypoxic-ischemic encephalopathy. Any brain lesion that could explain seizures was found in nine patients, two third of these patients had a familiar history of epilepsy.

CONCLUSIONS

Our results suggest seizures are more frequent in NF1 children (4.3%) than in general pediatric population (0.3-0.5%) and that are someway related to NF1 in half of patients. Facing seizures in NF1, the clinician should first exclude brain tumors but also other, and rarer NF1-related scenarios, such as hydrocephalous and vasculopathies. Children with non-structural seizures frequently had a family history of epilepsy, raising questions about the pathogenic role of NF1. They should be approached as for the general population.

Imaging genetics in neurodevelopmental psychopathology

Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.

Non-optic glioma in adults and children with neurofibromatosis 1

BACKGROUND

Non-optic gliomas occur in 5% of children with NF1, but little is known about these tumours in adults. We aimed to investigate progression, spontaneous regression and the natural history of non-optic gliomas in adults and compare these findings to the results found in children.

RESULTS

One thousand seven hundred twenty-two brain MRI scans of 562 unselected individuals with NF1 were collected at the NF outpatient department of the University Hospital Hamburg-Eppendorf between 2003 and 2015. The number of scans per patient ranged from one to 12; patients were followed for a median of 3.7 years. We identified 24 patients (4.3%) with non-optic gliomas. Median age at first scan with glioma was 21.2 years, much higher than in previous publications. Only seven of the 24 non-optic glioma patients were symptomatic. Five of 24 patients had multiple non-optic gliomas. Four individuals developed a new tumour, and 4 cases showed progression. The risk of new tumour development was 0.19% (95% confidence interval 0.06% to 0.52%) per patient year of follow-up for patients over 10 years. The rate of progressing non-optic gliomas per patient year of follow-up in the first 5 years after tumour diagnosis was 4.7% (95% confidence interval 1.5% to 12%).

CONCLUSIONS

Non-optic gliomas are twice as common in an unselected cohort of NF1 patients as previously reported. This is likely due to increased frequency of diagnosis of asymptomatic tumours when routine MRIs are performed and a higher prevalence in older individuals.

Characterizing the microstructural basis of "unidentified bright objects" in neurofibromatosis type 1: A combined in vivo multicomponent T2 relaxation and multi-shell diffusion MRI analysis

Introduction

The histopathological basis of “unidentified bright objects” (UBOs) (hyperintense regions seen on T2-weighted magnetic resonance (MR) brain scans in neurofibromatosis-1 (NF1)) remains unclear. New in vivo MRI-based techniques (multi-exponential T2 relaxation (MET2) and diffusion MR imaging (dMRI)) provide measures relating to microstructural change. We combined these methods and present previously unreported data on in vivo UBO microstructure in NF1.

Methods

3-Tesla dMRI data were acquired on 17 NF1 patients, covering 30 white matter UBOs. Diffusion tensor, kurtosis and neurite orientation and dispersion density imaging parameters were calculated within UBO sites and in contralateral normal appearing white matter (cNAWM). Analysis of MET2 parameters was performed on 24 UBO–cNAWM pairs.

Results

No significant alterations in the myelin water fraction and intra- and extracellular (IE) water fraction were found. Mean T2 time of IE water was significantly higher in UBOs. UBOs furthermore showed increased axial, radial and mean diffusivity, and decreased fractional anisotropy, mean kurtosis and neurite density index compared to cNAWM. Neurite orientation dispersion and isotropic fluid fraction were unaltered.

Conclusion

Our results suggest that demyelination and axonal degeneration are unlikely to be present in UBOs, which appear to be mainly caused by a shift towards a higher T2-value of the intra- and extracellular water pool. This may arise from altered microstructural compartmentalization, and an increase in ‘extracellular-like’, intracellular water, possibly due to intramyelinic edema. These findings confirm the added value of combining dMRI and MET2 to characterize the microstructural basis of T2 hyperintensities in vivo.

•

We examine MRI white matter T2-weighted hyperintense lesions, “UBOs” in NF1.

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Myelin water and intra- and extracellular water fractions are unchanged in UBOs.

•

Diffusivity is higher, while mean kurtosis and neurite density are lower in UBOs.

•

The combined measures suggest that UBOs may arise from intramyelinic edema.

•

Combining diffusion MRI and multi-exponential T2 relaxation has added value.

Globus pallidus high-signal lesions: A predominant MRI finding in children with neurofibromatosis type 1

Introduction:

Lesions of the brain, recognized as unidentified bright objects (UBOs), are commonly observed as areas of increased T2-weighted signal intensity on magnetic resonance imaging (MRI) in children with neurofibromatosis type 1 (NF1). Identification of these lesions is not currently encompassed in the National Institute of Health (NIH) diagnostic criteria for NF1.

Objective:

We aimed to determine the prevalence of UBOs in children with NF1 and identify areas of the brain that are commonly affected by these lesions, allowing us to evaluate whether UBOs should be included in the diagnostic criteria for the diagnosis of NF1.

Materials and Methods:

We reviewed the cranial MRI scans of 22 children who had been diagnosed with sporadic or familial NF1 in accordance with the criteria established by NIH. UBOs were present in 81% of the children with NF1.

Results:

These lesions have a predilection for specific areas of the brain, including the globus pallidus (72%), cerebellum (66%), brainstem (27%) and cerebral hemispheres (16%). The prevalence of UBOs identified varied significantly with age and sex; they were infrequent in children less than 4 years of age but were common in those aged between 4 and 12 years of age. UBOs were more commonly seen in males (66.6%) compared with females (33.3%). Repeat MRI scan on a subset of these patients with UBOs did not show any significant changes despite a worsening in clinical symptoms.

Conclusion and Discussion:

We have shown that UBOs are a common finding in children with NF1, and are most prevalent between the ages of 4 and 12 years. Many sites of the brain are affected by these lesions, most notably the globus pallidus and the cerebellum. Further research must be conducted to elucidate the significance of UBOs in patients with NF1 and whether these lesions have any utility in the clinical detection of NF1.

Four-year follow-up study in a NF1 boy with a focal pontine hamartoma

Neurofibromatosis is a collective name for a group of genetic conditions in which benign tumours affect the nervous system. Type 1 is caused by a genetic mutation in the NF1 gene (OMIM 613113) and symptoms can vary dramatically between individuals, even within the same family. Some people have very mild skin changes, whereas others suffer severe medical complications. The condition usually appears in childhood and is diagnosed if two of the following are present: six or more café-au-lait patches larger than 1.5 cm in diameter, axillary or groin freckling, 2 or more Lisch nodules (small pigmented areas in the iris of the eye), 2 or more neurofibromas, optic pathway gliomas, bone dysplasia, and a first-degree family relative with Neurofibromatosis type 1. The pattern of inheritance is autosomal dominant, however, half of all NF1 cases are ‘sporadic’ and there is no family history. Neurofibromatosis type 1 is an extremely variable condition whose morbidity and mortality is largely dictated by the occurrence of the many complications that may involve any of the body systems. We describe a family affected by NF1 in whom genetic molecular analysis identified the same mutation in the son and father. Routine MRI showed pontine focal lesions in the eight-year-old son, though not in the father. We performed a four years follow-up study and at follow-up pontine hamartoma size remained unchanged in the son, and the father showed still no brain lesions, confirming thus an intra-familial phenotype variability.

Clinical sensitivity and specificity of multiple T2-hyperintensities on brain magnetic resonance imaging in diagnosis of neurofibromatosis type 1 in children: diagnostic accuracy study

Aim

To determine the prevalence, number, and location of multiple (≥2) T2-hyperintensities on brain magnetic resonance imaging (MRI) in children with neurofibromatosis type 1 (NF1) and their correlation with age, and to establish their sensitivity, specificity, and accuracy for the diagnosis of NF1 in children, especially in the early age (2-7 years).

Methods

We performed a cross-sectional study of 162 patients with NF1 from Croatian Neurofibromatosis Association Database and 163 control children between the ages of 2 and 18 years who underwent brain MRI between 1989 and 2009.

Results

Multiple T2-hyperintensities were present in 74% of NF1 patients and 1.8% of controls. They were mainly located in the basal ganglia, brainstem, and cerebellum and were significantly decreased in prevalence and number in the older age. T2-hyperintensities had excellent diagnostic accuracy with the area under the receiver operating characteristic (ROC) curve of 0.849 and 95% confidence interval (CI) of 0.805-0.886. The diagnostic sensitivity, specificity, and accuracy rate of T2-hyperintensities for NF1 were highest in the youngest age (2-7 years): 81% (95% CI 71%-89.1%), 99% (95% CI 92.3%-100%), and 85.8 (95% CI 83.3-93.8), respectively.

Conclusion

This study strongly suggests the inclusion of T2-hyperintensities on brain MRI on the list of diagnostic criteria for NF1, especially in children of early age, when the clinical penetration of the NF1 gene has not yet been completely finished.

Epileptic seizures in neurofibromatosis type 1 are related to intracranial tumors but not to neurofibromatosis bright objects

OBJECTIVE

To investigate the relationship between intracranial lesions and epileptic seizures in neurofibromatosis type 1 (NF1) patients.

BACKGROUND

NF1 is one of the most common autosomal dominant neurocutaneous disorders, and epilepsy is more prevalent in NF1 patients than in the general population. Epileptic seizures were found to be related to various types of intracranial lesions in NF1 patients.

METHODS

The clinical characteristics of NF1 (1986-2006 in Chung-Gung Memorial Hospital), diagnosed on the basis of the criteria of the National Institutes of Health Consensus Conference (1988), were reviewed by 2 neurologists. We diagnosed epileptic seizures of NF1 patients on the basis of clinical appearances and a history of antiepileptic drugs. Magnetic resonance images were also evaluated by 2 neuroradiologists to confirm the locations of brain tumors or neurofibromatosis bright objects (NBOs). The locations of NBOs were classified into 4 categories: cortex and hippocampus, subcortical white matter, basal ganglia, and infratentorial area. The association between the location of the lesions and the occurrence of seizure in NF1 patients was analyzed statistically.

RESULTS

The medical records of 630 NF1 patients were reviewed. In this cohort, 37 (5.87%) NF1 patients had epileptic seizures. The patients include 22 males (59.5%) and 15 females (40.5%). The mean seizure onset age was 14.8 years (2 months to 72 years). The most common seizure pattern was partial onset seizures, 3 simple partial seizures, and 14 complex partial seizures. Other seizure types found include 15 primary generalized seizures (2 absence seizures and 13 generalized tonic-clonic seizures), 2 infantile spasms, and 3 unclassified. A total of 172 (23 with epilepsy and 149 without epilepsy) NF1 patients underwent MRI examinations. NBOs were identified in 16 (69.6%) epilepsy patients and in 108 (72.5%) patients without epilepsy. The location or the number of these intracranial lesions does not show significant correlation with the occurrence of epilepsy in our cohort. Among 11 NF1 patients with intracranial tumors, 4 patients had seizures (36.36%), vs. 19 out of 161 NF1 patients (11.80%) without tumors.

CONCLUSION

The occurrence of epileptic seizures in NF1 patients is related to intracranial tumors but not to NBOs.

Hydrocephalus in patients with neurofibromatosis type 1: MR imaging findings and the outcome of endoscopic third ventriculostomy

Although hydrocephalus associated with NF-1 is not rare, up to now the MR imaging findings in these patients and the role of ETV in the treatment of hydrocephalus associated with NF-1 have not been investigated thoroughly. We present the MR imaging findings of hydrocephalus associated with NF-1 in 7 of 54 patients with NF-1. Although the types of obstruction were various, including aqueductal web, superior velum medullary synechia, periaqueductal/tectal hamartomas, cerebellar and pontine tegmentum hamartomas, brain stem glioma, or a combination, the presence of hamartomas was a consistent finding in patients with NF-1 with hydrocephalus. In 5 cases, 8 ETV procedures were performed and followed for up to 53 months. All children treated with ETV were shunt-free at their most recent examinations. ETV may be the primary procedure for the treatment of hydrocephalus associated with NF-1, regardless of the cause and the level of the obstruction.

Corpus callosum morphology and microstructure assessed using structural MR imaging and diffusion tensor imaging: initial findings in adults with neurofibromatosis type 1

BACKGROUND AND PURPOSE

Imaging studies have shown that children with NF-1 have increased brain volumes compared with age-matched controls and the CCs are disproportionately large. The purpose of this study was to determine if the CC in adults with NF-1 differed from that in matched controls by using DTI and volumetric imaging.

MATERIALS AND METHODS

MR imaging with DTI was performed in 10 adults with NF-1 and in 10 age-, sex-, and handedness-matched controls by using a 3T system. Total brain volumes and the areas and central lengths of the CC were calculated, along with the radial width of callosal subdivisions, in the 2 groups.

RESULTS

Our results showed that the total brain volume was not significantly different between adults with NF-1 and matched controls. The length and total cross-sectional area of the CC were statistically larger in adults with NF-1 compared with controls (approximately 10% longer and 20% greater area). On DTI we found a preservation of the primary eigenvalue with increases in the minor eigenvalues at the genu.

CONCLUSIONS

We have shown that the increased size of the CC found in children with NF-1 is also present in adults with the syndrome, whereas no difference in total brain volume was found.

The dentate nucleus in children: normal development and patterns of disease

The dentate nuclei lie deep within the cerebellum and play a vital role in the pathways involved in fine motor control and coordination. They are susceptible to a variety of diseases. Some pathological processes preferentially affect the dentate nuclei, while concomitant basal ganglia or white matter involvement can be a striking finding in others. A familiarity with the normal appearance of the dentate nuclei at different ages in combination with the radiological distribution of pathology in the brain allows the paediatric radiologist to develop a logical approach to the interpretation of MR imaging of these deep cerebellar nuclei. In this article we review the normal appearance and MR features of the dentate nuclei, including changes that are seen with myelination. We describe the specific imaging characteristics of childhood diseases that involve the dentate nuclei, and develop a systematic approach to the differential diagnosis of dentate nucleus abnormalities on MR imaging.

Glioblastoma multiforme in the posterior cranial fossa in a patient with neurofibromatosis type I

Patients with Neurofibromatosis type 1 (NF1) have an increased risk of developing neoplasms. The most common brain tumors, found in 15%–20% of NF1 patients, are hypothalamic-optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. These tumors generally have a benign nature. NF1 patients are predisposed to a 5-fold increased incidence of high-grade astrocytomas, which are usually located in supratentorial regions of the brain. We present an NF1 patient who developed a high-grade astrocytoma in the posterior fossa and discuss possible pathophysiological mechanisms.

Clinical presentation of patients with neurofibromatosis type 1 in infancy and childhood: genetic traits and gender effects

The clinical presentations of 32 patients with neurofibromatosis type 1 were examined based on genetic traits, clinical findings, electroencephalogram, and neuroimaging findings. Twenty-eight sequential magnetic resonance images showed multifocal hyperintense T2-weighted images in 14 patients. Seven (5 boys and 2 girls) of the 8 patients (88%) who inherited neurofibromatosis type 1 from affected mothers, and 7 (2 boys and 5 girls) of the 16 de novo patients (44%) had multifocal hyperintense T2-weighted images. In contrast, the patients who inherited this disease from affected fathers did not have any multifocal hyperintense T2-weighted images. Multiple plexiform neurofibromas were observed in 4 patients, of whom 3 boys inherited through at least 3 generations of women. They all presented severe psychomotor delay and epilepsy. These findings suggest that genetic traits, especially through the passage of several generations of women, may affect the clinical presentation in patients with neurofibromatosis type 1.

Glial clusters and perineuronal glial satellitosis in the basal ganglia of neurofibromatosis type 1

Recent biochemical studies demonstrated that astrocytic differentiation and growth regulation are impaired in neurofibromatosis type 1 (NF1). However, non-neoplastic morphological abnormalities of glial cells in the NF1 brain have been hardly explored. We describe here characteristic glial lesions in the basal ganglia in three NF1 cases (age at death in cases 1-3: 77, 6.5, and 11 years). Clusters of 3-10 dysplastic cells similar to reactive astrocytes were observed in the amygdala, caudate nucleus, putamen, thalamus in cases 1 and 2. Gigantic astrocyte-like glial cells were noted in case 2. Perineuronal glial satellitosis was observed in the amygdala in case 1. Many glial clusters were encountered in case 3 as well, but the round nuclei of the glial cells were more hyperchromatic and showed more remarkable variation in size than those in the other cases. Glial clusters in all cases were glial fibrillary acidic protein- and/or vimentin-positive, but synaptophysin-, myelin basic protein-, and olig2-negative. The glial lesions in cases 1 and 3 were excitatory amino acid transporters 1 (EAAT1)- and EAAT2-negative, and those in case 2 EAAT1- and EAAT2-weakly positive. Proliferation markers Ki-67, proliferation cell nuclear antigen, and cyclin D1 were not expressed in any lesion. Glial clusters in case 3 showed weak to intense immunoreactivity to nestin, a stem cell marker protein. The brains of 19 cases including 14 with various degenerative diseases and five normal brains used as controls lacked the glial lesions observed in NF1 cases. Given these findings, glial clusters and perineuronal glial satellitosis may be histopathological features of the NF1 brain and are probably associated with altered regulation of astrocyte growth in NF1.

Neurofibromatose tipo 1 na infância: revisão dos aspectos clínicos

OBJETIVO: Realizar uma revisão da literatura sobre neurofibromatose tipo 1 (NF1) em crianças e adolescentes, enfatizando as manifestações clínicas. FONTES DE DADOS: Artigos publicados, indexados na base de dados Medline e publicados entre 1998 a 2007, buscados pelos seguintes termos: "neurofibromatosis type 1", "neurofibroma", "von Recklinghausen" e "optic pathway gliomas". SÍNTESE DOS DADOS: A NF1 é uma doença genética autossômica dominante, crônica e progressiva, com incidência de 1/2.000 a 1/7.800 nascidos vivos. Tem sido observada em diferentes partes do mundo, em todas as raças e nos dois sexos. Metade dos casos representa mutações novas. A taxa de mutação para o gene NF1 é de 1/10.000, a qual se deve ao fato do gene ser grande e possuir estrutura interna atípica, que predispõe a deleções e mutações. O diagnóstico presuntivo da NF1 é feito por critérios clínicos. As três principais manifestações - neurofibromas, manchas café-com-leite e nódulos de Lisch - ocorrem em mais de 90% dos pacientes até a puberdade. CONCLUSÕES: Os cuidados com os pacientes com NF1 devem antecipar as principais complicações e oferecer um tratamento precoce. No aconselhamento genético, é importante informar pais e familiares a respeito do panorama geral da doença e suas possíveis complicações, enfatizando que a maioria dos pacientes apresenta vida saudável e produtiva.

Unidentified bright objects on brain MRI in children as a diagnostic criterion for neurofibromatosis type 1

BACKGROUND

Lesions of the brain denominated as unidentified bright objects (UBOs), which are not included in the diagnostic criteria for neurofibromatosis type 1 (NF1) established by the National Institutes of Health (NIH), have been detected by MRI.

OBJECTIVE

The purpose of this study was to investigate the possibility of including the presence of UBOs as a diagnostic criterion for NF1 in children.

MATERIALS AND METHODS

The study included 88 children between the ages of 2 and 18 years. The case group consisted of 40 children diagnosed with sporadic or familial NF1 according to the criteria established by the NIH. A control group consisted of 48 individuals referred for routine MRI of the brain for other complaints not related to NF1.

RESULTS

UBOs were identified in 70% of the NF1 patients and in none of the control group. The sensitivity of the presence of UBOs for the diagnosis of NF1 was 70% (CI 53-83%), with a false-negative rate of 30% (CI 27-47%), a specificity of 100% (CI 86-100%) and a false-positive rate of 0% (CI 0-14%).

CONCLUSION

Faced with the difficulties in diagnosing NF1 in children and the high frequency and specificity of the presence UBOs identified by MRI in our series, we recommend the inclusion of the presence UBOs as a diagnostic criterion for NF1 in children.

Fatal glioblastoma multiforme in a patient with neurofibromatosis type I: the dilemma of systematic medical follow-up

INTRODUCTION

Neurofibromatosis type I (NF1) is one of the most prevalent genetic diseases of the nervous system. Although the majority of NF1 patients are only mildly affected, the risk of developing malignancies is significantly increased in this population.

CASE REPORT

Here, we present a 9-year-old girl with clinical stigmata of NF1 and a rapidly evolving glioblastoma multiforme. Molecular genetic analysis uncovered a novel missense mutation in Exon 32 of the NF1 gene [c.6032C>A(p.Ala2011Glu)].

DISCUSSION

The girl's death 3 days after diagnosis of the brain tumor exemplifies that NF1 still is a life-threatening disease despite its generally benign course in most patients. However, it remains questionable if a fatal course as reported here can be prevented by routine MRI screening.

Clinical and instrumental (magnetic resonance imaging [MRI] and multimodal evoked potentials) follow-up of brain lesions in three young patients with neurofibromatosis 1

Diagnosis of neurofibromatosis 1 is based on clinical criteria. In a large number of children with neurofibromatosis 1, magnetic resonance imaging (MRI) reveals high-signal T(2)-weighted intensities in different brain regions, defined as unidentified bright objects. These lesions are asymptomatic; most of them regress spontaneously with age, but the presence of contrast enhancement or mass effect in them usually strongly suggests an increased risk of proliferative changes. To date, few studies have focused on evoked potentials in patients with neurofibromatosis 1, and the reported abnormalities did not have significant clinical correlations. We describe the clinical and instrumental (MRI and evoked potentials) follow-up of three patients with neurofibromatosis 1. MRI and evoked potentials showed subclinical involvement of the central nervous system. Some MRI T(2)-weighted hyperintensities showed enhancement and mass effect of uncertain significance. During follow-up, the MRI lesions spontaneously decreased in size or enhancement, allowing us to exclude the hypothesis of proliferative lesions; in the same way, some asymptomatic evoked potential abnormalities disappeared. These findings suggest that both MRI and evoked potentials could be useful in the detection and monitoring of cerebral complications of neurofibromatosis 1.

Neuroimaging of phakomatoses

The phakomatoses are congenital disorders manifesting with central nervous system and cutaneous abnormalities. The structures predominantly affected are those of ectodermal origin, including the skin, nervous system, and eyes. The 4 most common phakomatoses are neurofibromatosis (types 1 and 2), tuberous sclerosis, Sturge-Weber disease, and von Hippel-Lindau disease. Imaging of the brain and spine in these disorders plays an important role in diagnosis, as well as determining the extent of involvement and guiding surgical interventions. This article reviews the application of x-ray computed tomography and magnetic resonance imaging to these disorders, as well as that of newer, "functional" imaging techniques such as positron emission tomography, magnetic resonance perfusion imaging, and spectroscopy.

Serial MR imaging and 1H-MR spectroscopy of unidentified bright objects in a case of neurofibromatosis type 1

Serial study using MR imaging and 1H-MR spectroscopy (1H-MRS) of unidentified bright objects (UBO) in a 9-year-old boy with neurofibromatosis type 1 (NF1) is described. UBO was indicated in the left globus pallidum at 3 years old, then appeared in the right globus pallidum at 5 years old along with left hemiconvulsion. These UBO gradually disappeared over several years. On 1H-MRS, the ratios of N-acetylaspartate (NAA)/creatine and that of choline/creatine were each mildly reduced in the UBO. These ratios improved in parallel with disappearance of the UBO. In addition, elevation of the lactate/lipid peak was shown in UBO during the early stage, however, it disappeared in the latter. The longitudinal follow-up using MR image and 1H-MRS was useful for metabolic evaluation of UBO in patients with NF1.

[Imaging features of neurofibromatosis type 1]

Neurofibromatosis type 1 (NF1) is the most common of all the phakomatoses. It is an autosomal dominant disorder, with about 50% of patients being new mutations. NF1 is diagnosed based on the presence of well established diagnostic criteria. Prominent cutaneous manifestations include cafe-au-lait spots, freckling and cutaneous neurofibromas. CNS lesions are frequent and imaging is valuable for diagnosis, treatment and follow-up of patients. Tumors of the central nervous system are frequent. Optic nerve glioma usually affects younger patients with clinical symptoms in one third of cases. MRI shows fusiform enlargement with variable enhancement of the optic nerve. These tumors are usually non-aggressive with good prognosis. Other gliomas and astrocytomas can occur as well, usually midline in location, that also generally have good prognosis. Non-tumoral white matter lesions, referred as unidentified bright objects or UBO's, are frequently observed, typically in the basal ganglia and posterior fossa structures. These lesions are usually seen during childhood and they typically diminish with age. The distinction between UBO's and other tumors may be difficult to achieve at imaging, and a malignant evolution may very rarely be observed. Patients with NF1 may have hydrocephalus and dural sac anomalies leading to meningocele formation. Neurofibromas and plexiform neurofibromas involve peripheral nerves and nerve sheaths. Plexiform neurofibromas may cause radicular symptoms. They more frequently involve the lumbosacral plexus. Neurofibromas are homogeneous oval shaped tumors that may extend into the spinal canal. Neurofibrosarcoma is the main cause of death of NF1 patients less than 40 years of age. It may develop de novo or from sarcomatous degeneration of a pre-existing plexiform neurofibroma. It should be suspected in patients with new onset of symptoms or patients with changing symptoms. At imaging, it is characterized by a large heterogeneous tumor invading adjacent structures. Osseous lesions have been described including progressive thoracic scoliosis, vertebral anomalies (posterior scalloping is very suggestive), long bones anomalies with frequent bowing of the tibia, sometimes resulting in pseudarthrosis, and rib anomalies with ribbon ribs. Vascular lesions may occur resulting in arterial hypertension and aneurysm formation.

Quantification and anatomic distribution of choroidal abnormalities in patients with type I neurofibromatosis

BACKGROUND

Choroidal abnormality manifesting as a bright patchy lesion under infrared monochromatic light has previously been described in neurofibromatosis type I patients in whom the choroid appears normal under conventional ophthalmoscopic examination or on the fluorescein angiogram. We investigated the correlation between patient age and the number of choroidal abnormalities, as well as the anatomic distribution of choroidal abnormalities in the fundus.

METHODS

We examined the fundus of 28 eyes in 14 patients with neurofibromatosis type I. Patients ranged in age from 2 to 38 years and were examined between April 2001 and April 2002 by confocal scanning laser ophthalmoscopy with infrared monochromatic light (780 nm wavelength). We divided the fundus into five regions (one within the retinal vascular arcade and those supero-temporal, infero-temporal, supero-nasal, and infero-nasal to it), and lesions on the border between regions were assigned to the region containing the greater part of the lesion. We studied the total number of choroidal abnormalities and the correlation between the total number and age.

RESULTS

A positive correlation was found between the total number of choroidal abnormalities and age (Spearman rank correlation coefficient, r=0.6209, P=0.0178). There was a significantly greater number of choroidal abnormalities in the arcade region than in the other four regions (ANOVA, P<0.001).

CONCLUSIONS

Choroidal abnormalities tend to increase with age and are most often observed within the vascular arcade.

T2-weighted hyperintensities (unidentified bright objects) in children with neurofibromatosis 1: their impact on cognitive function

The impact of magnetic resonance imaging (MRI)-identified T2-weighted hyperintensities (unidentified bright objects) on the cognitive function of children with neurofibromatosis 1 is controversial. We recruited 32 right-handed children with neurofibromatosis 1 (22 boys, 10 girls) aged between 5 and 16 years (mean age 10.2 years) for magnetic resonance imaging examinations and neuropsychologic evaluation. Statistical analysis was performed to evaluate the significance of the hyperintensities. Twenty-four children had unidentified bright objects, whereas eight children did not. Using the t-test, thalamic lesions were associated with lower intellectual function (P = .031). Left globus pallidus hyperintensities were associated with a lower attention score (P = .04), and right middle cerebellar peduncle hyperintensities were associated with a lower sensorimotor score (P = .05). The size of the thalamic lesions correlated with cognitive function (P < .05). Among the group with unidentified bright objects, there was a significant association between more involved sites on the dominant hemisphere and impaired verbal function (r = -.55; P = .005). Unidentified bright objects in the thalamus, globus pallidus, and middle cerebellar peduncles and the laterality of the lesions had an impact on cognitive function.

Pediatric brain MRI in neurofibromatosis type I

Neurofibromatosis (NF) is the most common of the phakomatoses, with a prevalence of 1 in 3-4,000. Many organ systems can be affected. In addition to multiple peripheral neurofibromas, NF I predisposed to CNS tumors including optic glioma, astrocytoma and plexiform neurofibroma. The purpose of this pictorial review is to illustrate characteristic brain MR imaging lesions in children with NF I and to give some recommendations about diagnostic imaging procedures in children suffering from NF I. Typical findings in brain MRI are hyperintense lesion on T2-weighted images, so-called unknown bright objects, which may be useful as an additional imaging criterion for NF I. Contrast administration is necessary in MR studies to maximize tumor detection and characterization, to add confidence to the diagnosis of benign probable myelin vacuolization, and to document stability of neoplasm on follow-up examinations. We recommend to perform serial MR imaging in children every 12 months. The frequency of follow-up in children with known brain tumors will vary with the tumor grade, biological activity and treatment.

Neuroimaging findings in neurofibromatosis type 1 and 2

Neuroimaging, particularly MR imaging, plays an important role in the diagnosis and management of the patient with neurofibromatosis type 1 and 2. These phakomatoses are complex disorders affecting multiple cell types and multiple systems of the body with a wide range of expression. This article summarizes the neuroradiologic central nervous system findings in these neurocutaneous disorders.

Ultrafast MR imaging in pediatric neuroradiology

PURPOSE

To compare the diagnostic information obtained from ultrafast MR imaging with standard MR imaging techniques in pediatric neuroradiology. The goal was to judge whether ultrafast methods can be used to replace standard methods and reduce the need for sedation or general anesthesia as a result of the considerably shorter scan times.

MATERIAL AND METHODS

Our prospective study involved 125 patients. Routine clinical imaging was performed along with two ultrafast methods. Single shot fast spin echo (SSFSE) was used to give T2-weighted images and an echo planar imaging (EPI) sequence to provide a T1-weighted images. The ultrafast images were presented to an experienced neuroradiologist who was also given the information present on the initial referral card. These reports based on the ultrafast images were then compared with the formal radiologic report made solely on the basis of the standard imaging.

RESULTS

The overall sensitivity and specificity for ultrafast imaging when compared to the reference standard were 78% and 98% with positive and negative predictive values of 98% and 76%. Pathologies characterized by small areas of subtle T2 prolongation were difficult or impossible to see on the ultrafast images but otherwise they provided reliable information.

CONCLUSIONS

This paper demonstrates that ultrafast MR imaging can diagnose many pediatric intracranial abnormalities as well as standard methods. Anatomic resolution limits its capacity to define subtle developmental anomalies and contrast resolution limitations of the ultrafast methods reduce the detection of pathology characterized by subtle T2 prolongation.

Spontaneously T1-hyperintense lesions of the brain on MRI: a pictorial review

In this work, the brain lesions that cause spontaneously hyperintense T1 signal on MRI were studied under seven categories. The first category includes lesions with hemorrhagic components, such as infarct, encephalitis, intraparenchymal hematoma, cortical contusion, diffuse axonal injury, subarachnoid hemorrhage, subdural and epidural hematoma, intraventricular hemorrhage, vascular malformation and aneurysm, and hemorrhagic neoplasm. The second category includes protein-containing lesions, such as colloid cyst, craniopharyngioma, Rathke's cleft cyst, and atypical epidermoid. The third category includes lesions with fatty components, such as lipoma, dermoid, and lipomatous meningioma. Lesions with calcification or ossification, such as endocrine-metabolic disorder, calcified neoplasm, infection, and dural osteoma, constitute the fourth category, whereas the fifth category includes lesions with other mineral accumulation, such as acquired hepatocerebral degeneration and Wilson disease. The sixth category includes melanin-containing lesions, such as metastasis from melanoma and leptomeningeal melanosis. The last category is the miscellaneous group, which includes ectopic neurohypophysis, chronic stages of multiple sclerosis, and neurofibromatosis type I. The above-mentioned lesions are presented with their typical T1-hyperintense images, and the underlying reasons for those appearances in magnetic resonance imaging are discussed.

Unidentified bright objects associated with features of neurofibromatosis 1

Unidentified bright objects are commonly observed on magnetic resonance imaging in young neurofibromatosis 1 patients, but their clinical and pathologic significance is largely unknown. Diagnostic features of neurofibromatosis 1 include café-au-lait spots, intertriginous freckling, Lisch nodules, neurofibromas, bony lesions, and optic glioma. We investigated the relationship between unidentified bright objects and other features of neurofibromatosis 1. Data from the National Neurofibromatosis Foundation International Database included 523 neurofibromatosis 1 patients between 2 and 20 years of age who had cranial magnetic resonance imaging examinations. The presence or absence of unidentified bright objects, diagnostic features of neurofibromatosis 1, and central nervous system neoplasms was known in these patients. Logistic regressive models were used to measure associations between unidentified bright objects and the other features while controlling for age. The occurrence of unidentified bright objects was associated with the number of diagnostic features, but most significantly with central nervous system neoplasms other than optic gliomas [odds ratio (OR) = 9.0, 95% confidence interval (CI) = 1.2-70], optic gliomas (OR = 2.1, 95% CI = 1.2-3.6), subcutaneous neurofibromas (OR = 2.0, 95% CI = 1.3-3.1), and Lisch nodules (OR = 1.6, 95% CI = 1.1-2.3). These findings suggest a common causal mechanism between unidentified bright objects and these cardinal clinical features in children with neurofibromatosis 1.

Proton magnetic resonance spectroscopy of brain lesions in children with neurofibromatosis type 1

Two of the recognized cranial MRI findings in children with neurofibromatosis type 1 (NF1) are neurofibromatosis bright objects (NBO) and brain glioma. Their differential diagnosis can be problematic. This study aimed to determine the features of these abnormalities on short echo-time in-vivo proton magnetic resonance spectroscopy. Twenty children under the age of 16 with NF1 were studied. A single voxel, short echo-time technique (TE = 20 ms; TR = 5000 ms) was used to obtain proton spectra of typical NBO and any regions suggestive of atypical bright objects or tumor. Nine children without neurofibromatosis with no structural brain abnormality acted as aged-matched comparisons. A semi-quantitative analysis indicated significant increase in choline and myo-inisitol in tumors compared to typical NBO (p < 0.05) and compared to controls (p < 0.05); reduction in the levels of N-acetyl moieties in NBO compared to controls (p < 0.05); reduction in N-acetyl in tumors compared to controls (p < 0.001); and reduction in glutamate/glutamine in tumors compared to controls (p < 0.05). This cross-sectional data suggests that proton spectroscopy can aid differentiating between NBO and brain (non-optic/hypothalamic) glioma. Typical NBO have different short echo-time spectroscopic appearances compared to normal brain.

Diagnosis and management of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder whose major feature is the occurrence of multiple neurofibromas, which are benign tumors of the nerve sheath. It affects an estimated one in 3000 to 4000 individuals. In addition to neurofibromas, there are many other clinical manifestations, including malignant tumors such as gliomas or malignant peripheral nerve sheath tumors, and nontumor effects such as skeletal dysplasia and learning disability. Diagnosis is established on the basis of clinical criteria. Molecular genetic testing is feasible, but the large size of the gene and wide range of pathogenic mutations have so far impeded the development of a clinical diagnostic test. Insights into pathogenesis have followed from identification of the NF1 gene and the development of animal models. The major function of the gene product appears to be regulation of the ras protein. Tumors are believed to arise by the loss of function of the NF1 protein, suggesting that NF1 behaves as a tumor suppressor gene. Heterozygous effects on some cell types are also likely, however. The role of ras in the pathogenesis of tumors in NF1 has suggested an approach to treatment using ras inhibitors, some of which are likely to begin in clinical trials in NF1 patients in the near future.

Dermatologic clues to inherited disease

Genetic diseases often have cutaneous manifestations, which can be the first or most prominent signs of the underlying problem. Recognition of these dermatologic clues allows prompt diagnosis and intervention. In this article, the authors have attempted to outline several important examples of genodermatoses.