Synthetic MRI in Neurofibromatosis Type 1.

BACKGROUND AND PURPOSE: Synthetic MRI enables the generation of various contrast-weighted images and quantitative data in a reasonable scanning time. We aimed to use synthetic MRI to assess the detection and underlying tissue characteristics of focal areas of signal intensity and normal-appearing brain parenchyma and morphometric alterations in the brains of patients with neurofibromatosis type 1. MATERIALS AND METHODS: Conventional MR imaging and synthetic MRI were prospectively obtained from 19 patients with neurofibromatosis type 1 and 18 healthy controls. Two neuroradiologists independently evaluated focal areas of signal intensity on both conventional MR imaging and synthetic MRI. Additionally, automatically segmented volume calculations of the brain in both groups and quantitative analysis of myelin, including the focal areas of signal intensity and normal-appearing brain parenchyma, of patients with neurofibromatosis type 1 were performed using synthetic MRI. RESULTS: The comparison of conventional MR imaging and synthetic MRI showed good correlation in the supratentorial region of the brain (κ = 0.82-1). Automatically segmented brain parenchymal volume, intracranial volume, and GM volumes were significantly increased in the patients with neurofibromatosis type 1 (P < .05). The myelin-correlated compound, myelin fraction volume, WM fraction volume, transverse relaxation rate, and longitudinal relaxation rate values were significantly decreased in focal areas of signal intensity on myelin and WM maps (P < .001); however, GM, GM fraction volume, and proton density values were significantly increased on the GM map (P < .001). CONCLUSIONS: Synthetic MRI is a potential tool for the assessment of morphometric and tissue alterations as well as the detection of focal areas of signal intensity in patients with neurofibromatosis type 1 in a reasonable scan time.

Pediatric headache and neuroimaging: experience of two tertiary centers.

INTRODUCTION: Headache is a frequent complaint in children and adolescents. Decision-making for neuroimaging should take into account the cost and the need for sedation in young children. AIM: To evaluate the yield of MRI in pediatric headache patients seen in two large tertiary hospitals. METHODS: Data were retrospectively collected from patient records (n = 613) and neuroimaging reports. Headache was classified according to International Headache Society guidelines. RESULTS: There were 346 children with imaging studies (MRI n = 281, CT n = 65). Of patients who had at least one MRI study, 29% demonstrated an abnormal finding. Findings altering the management were obtained in 21 (7%) patients: the majority (n = 17, 80%) had headache for less than 3 months. On the other hand, four patients with headache longer than 3 months (19%) and 12 patients with normal neurological examination (57%) had significant MRI results affecting management. None of the children in whom the diagnosis of migraine could be made on clinical grounds (n = 40) had a significant MRI finding. CONCLUSION: Neuroimaging should be performed selectively in children with headache seen in pediatric neurology clinics, especially in headache of short duration (< 3 months) and features atypical for migraine. A normal neurological examination should not reassure the clinician.

Brachial Plexus Ultrasound and MRI in Children with Brachial Plexus Birth Injury.

BACKGROUND AND PURPOSE: Brachial plexus birth injury is caused by traction on the neck during delivery and results in flaccid palsy of an upper extremity commonly involving C5-C6 nerve roots. MR imaging and MR myelography help to assess the anatomic location, extent, and severity of brachial plexus injuries which influence the long-term prognosis along with the surgical decision making. Recently, sonography has been increasingly used as the imaging modality of choice for brachial plexus injuries. The aim of this study was to assess the degree of correlation among brachial plexus sonography, MR imaging, and surgical findings in children with brachial plexus birth injury. MATERIALS AND METHODS: This prospective study included 55 consecutive patients (girls/boys = 32:23; mean age, 2.1 ± 0.8 months) with brachial plexus birth injury between May 2014 and April 2017. The patients were classified according to the Narakas classification and were followed up at 4- to 6-week intervals for recovery by the Modified Mallet system and sonography without specific preparation for evaluation. All patients had MR imaging under general anesthesia. Nerve root avulsion-retraction, pseudomeningocele, and periscalene soft tissue were accepted brachial plexus injury findings on imaging. Interobserver agreement for MR imaging and the agreement between imaging and surgical findings were estimated using the κ statistic. The diagnostic accuracy of sonography and MR imaging was calculated on the basis of the standard reference, which was the surgical findings. RESULTS: Forty-three patients had pre- and postganglionic injury, 12 had only postganglionic injury findings, and 47% of patients underwent an operation. On sonography, no patients had preganglionic injury, but all patients had postganglionic injury findings. For postganglionic injury, the concordance rates between imaging and the surgical findings ranged from 84% to 100%, and the diagnostic accuracy of sonography and MR imaging was 89% and 100%, respectively. For preganglionic injury, the diagnostic accuracy of MR imaging was 92%. Interobserver agreement and the agreement between imaging and the surgical findings were almost perfect for postganglionic injury (κ = 0.81-1, P < .001). CONCLUSIONS: High-resolution sonography can identify and locate the postganglionic injury associated with the upper and middle trunks. The ability of sonography to evaluate pre- and the postganglionic injury associated with the lower trunk was quite limited. Sonography can be used as a complement to MR imaging; thus, the duration of the MR imaging examination and the need for sedation can be reduced by sonography.

Morphology of cranial sutures and radiologic evaluation of the variations of intersutural bones.

BACKGROUND: As far as our literature searches showed us, morphological characteristics of cranium such as sutures, sutural bones and fontanelles had been examined in the skulls in the museums and dry specimens until now. As a modern method, three-dimensional virtual reconstruction of cranial bones by using multidetector computed tomography-computed tomography angiography (MDCT-CTA) can display in vivo morphological characteristics. In our study, we aimed to determine the presence and incidence of these morphological characteristics that can be clinically significant in our population, by using radiologic methods. MATERIALS AND METHODS: We examined head and neck regions of 185 patients via MDCT-CTA. We evaluated radiologically detectable variations of the metopic sutures, lambda, bregma, asterion and pterion, which can be very easily confused with fractures. Additionally, the differences between the genders and incidence of coexistence of these variations were evaluated. RESULTS: According to our study, the incidence of persistent metopic suture was 8.1% and the incidence of lambda variations was 5.9%. Variations were most commonly encountered on the left asterion, and least commonly on the bregma and left pterion. In the evaluation of the coexistence of the parameters and combinations, the Wormian bones located at the right and left asterions were detected. There were no statistically significant differences between genders. CONCLUSIONS: Variations of the sutures and sutural bones can be easily misdiagnosed with the fractures of related bony regions in unconscious patients with multiple traumas. During surgical interventions in these patients, surgeons must take this fact into consideration in order to make differential diagnosis of fractures and intersutural bone variations.

Neurochemical evaluation of brain function with 1H magnetic resonance spectroscopy in patients with fragile X syndrome.

Fragile X syndrome (FXS) is the most common hereditary disorder of intellectual disability. Cognitive deficits involve executive function, attention, learning and memory. Advanced neuroimaging techniques are available, and (1)H magnetic resonance spectroscopy (MRS) can be used as a complementary method to MR imaging to understand disease processes in brain, by in vivo demonstration of brain metabolites. MRS was performed in 13 male patients with FXS full mutation, and 13 age- and sex-matched healthy controls. FXS diagnosis was based on clinical evaluation, followed by detection of FMR1 full mutation. Axial T2 TSE, sagittal T1 SE and coronal 3D MPRAGE images were obtained for both morphological imaging and voxel localization. Following evaluation of conventional images, multivoxel MRS (CSI) through supraventricular white matter and single voxel MRS (svs) with an intermediate echo time (TE:135 ms) from the cerebellar vermis were performed. Choline/Creatine (Cho/Cr), N-acetyl aspartate/Creatine (NAA/Cr), and Choline/N-acetyl aspartate (Cho/NAA) ratios were examined at right frontal (RF), left frontal (LF), right parietal (RP), left parietal (LP), and cerebellar vermian (C) white matter. Statistical analyses were done using t-test and Mann-Whitney U tests. A statistically significant difference was observed in RP Cho/NAA ratio (cell membrane marker/neuroaxonal marker), FXS patients having lower levels than controls (P = 0.016). The results should be evaluated cautiously in parallel to consequences in brain metabolism leading to alterations in neurotransmitter levels, osmoregulation, energy metabolism and oxidative stress response described in animal models. MRS may serve to define a metabolic signature and biomarkers associated with FXS.

Assessment of whole-brain white matter by DTI in autosomal recessive spastic ataxia of Charlevoix-Saguenay.

BACKGROUND AND PURPOSE: Extension and characteristics of WM involvement other than the brain stem remain inadequately investigated in ARSACS. The aim of this study was to investigate whole-brain WM alterations in patients with ARSACS. MATERIALS AND METHODS: Nine Turkish unrelated patients with ARSACS and 9 sex- and age-matched healthy control participants underwent neurologic examination, molecular studies, electrophysiologic studies, and DTI of the brain. TBSS was used for whole-brain voxelwise analysis of FA, AD, RD, mean diffusivity of WM. Tractographies for the CST and TPF were also computed. RESULTS: Molecular studies revealed 8 novel mutations (3 nonsense, 4 missense, and 1 frameshift insertion) and a missense variation in the SACS gene. Thick TPF displaced and compressed the CST in the pons. The TPF had increased FA, decreased RD, and increased AD, which may be attributed to hypertrophy and/or hypermyelination. Widespread decreased FA and increased RD, suggesting demyelination, was found in the limbic, commissural, and projection fibers. In addition to demyelination, CST coursing cranial and caudal to the pons also showed a marked decrease in AD, suggesting axonal degeneration. Electrophysiologic studies revealed findings that concur with demyelination and axonal involvement. CONCLUSIONS: In addition to developmental changes of the TPF and their effects on the CST in the brain stem, axonal degeneration mainly along the pyramidal tracts and widespread demyelination in WM also occur in patients with ARSACS. Widespread tissue damage may be associated with extensive loss of sacsin protein in the brain and may explain a wide range of progressive neurologic abnormalities in patients with ARSACS.

Effect of patient sex on white matter alterations in unilateral medial temporal lobe epilepsy with hippocampal sclerosis assessed by diffusion tensor imaging.

BACKGROUND AND PURPOSE: Studies shows ictal behavior and symptoms are affected by patient sex in temporal lobe epilepsy. The purpose of our study was to determine whether alterations in the WM as assessed by DTI display different patterns in male and female patients with unilateral HS. MATERIALS AND METHODS: Patients with unilateral HS were categorized as women with right HS (n=12), men with right HS (n=10), women with left HS (n=12), and men with left HS (n=10). DTI of the brain along 64 noncollinear directions was obtained from 44 patients and 37 sex-matched control participants. We used TBSS to analyze whole-brain WM. Regions with significant changes of FA and MD, and their mean FA, MD, total number of significant voxels, and asymmetry indices were determined for each group. RESULTS: All groups showed bilateral and extensive reductions of FA and elevated MD in the WM, more prominent ipsilateral to the affected hippocampus. The total number of voxels with decreased FA in patients compared with that of control participants was higher in women with right HS (24,727 vs 5,459) and in men with left HS (27,332 vs 14,013) than in their counterparts. Changes in MD associated with right HS were more extensive in both men and women (right vs left HS, women: 16,926 vs 5,458; men: 5,389 vs 4,764) than in those with left HS. In patients with right HS, the ipsilateral cingulum, uncinate fasciculus, internal and external capsules, and right acoustic radiation were involved extensively in women. CONCLUSIONS: Women and men showed different patterns in extent of WM alterations associated with HS.

Hypertrophic olivary degeneration in children: four new cases and a review of the literature with an emphasis on the MRI findings.

Injury to the dentato-rubro-olivary pathway causes hypertrophy and enlargement of the inferior olivary nuclei, which is called hypertrophic olivary degeneration (HOD). To date, adult cases of HOD have usually been reported, and there are only a few individual paediatric cases with limited radiological emphasis in the literature. We present the clinical and MRI findings of four new paediatric cases with HOD. Three of the patients had a posterior fossa surgery, and one did not have an identifiable cause.

Diffusion MR imaging features of skull base osteomyelitis compared with skull base malignancy.

BACKGROUND AND PURPOSE: SBO is a life-threatening infection that may have radiologic features similar to those of the neoplastic processes. The purpose of this study was to evaluate the DWI findings in SBO to facilitate the differential diagnosis. MATERIALS AND METHODS: The MR imaging findings of 9 patients with SBO were retrospectively evaluated and compared with MR imaging studies from 9 patients with NPC, 9 with lymphoma, and 9 with metastatic disease of the skull base. ADC measurements were performed from the ADC(ST) and the ADC(NST) in all 4 groups. RESULTS: The mean ADC(ST) values were 1.26 ± 0.19 × 10(-3) mm(2)/s for SBO, 0.74 ± 0.18 × 10(-3) mm(2)/s for NPC, 0.59 ± 0.11 × 10(-3) mm(2)/s for lymphoma, and 0.99 ± 0.34 × 10(-3) mm(2)/s for metastatic disease, respectively. The mean ADC value of SBO was significantly higher than those of NPC and lymphoma (P < .0001). There was no significant difference for the comparison of SBO and metastatic lesions. When an ADC value equal to or higher than 1.08 × 10(-3) mm(2)/s was used to rule out lymphoma and NPC, the accuracy was 96%. CONCLUSIONS: Although SBO is a relatively rare condition, its differential diagnosis from neoplastic processes of the skull base is essential to start appropriate treatment promptly. ADC values may help to distinguish patients with SBO from those with malignant lesions.

Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature.

BACKGROUND AND PURPOSE: Complete labyrinthine aplasia (CLA), also referred to as Michel aplasia, is a severe congenital anomaly of the inner ear, defined by the complete absence of inner ear structures. The purpose of this study was to document the imaging findings in a series of patients with CLA, with review of the literature, to better understand this anomaly. MATERIALS AND METHODS: The CT and MR imaging findings of 9 patients (14 ears with CLA) were retrospectively evaluated. The audiologic tests and patient charts were also retrospectively reviewed. RESULTS: CLA was bilateral in 5 and unilateral in 4 patients. The petrous bone was hypoplastic in all 14 ears, but the otic capsule was aplastic in only 5. The middle ear and mastoid volumes were decreased in most of the ears. The stapes was aplastic in 1 ear and was dysplastic in 5 ears. The internal acoustic canal was aplastic in 4 ears and markedly narrowed in 10 ears. The facial nerve canal showed a variety of anomalies and aberrant courses in 11/14 ears. The bony covering of the jugular bulb was defective in 9 ears. Tegmen tympani defects were seen in 3 patients, and there were several accompanying skull base and posterior fossa anomalies. CONCLUSIONS: Although CLA is a rare developmental anomaly, its accurate diagnosis and its differential diagnosis from labyrinthine ossificans is crucial. Proper guidance of these patients for brain stem implantation in the critical period of brain development depends on the recognition of the characteristic imaging findings of CLA.

Assessment of citrullinated myelin by 1H-MR spectroscopy in early-onset multiple sclerosis.

BACKGROUND AND PURPOSE: Myelin instability and citrullinated myelin basic protein have been demonstrated in the brains of patients with chronic and fulminating forms of multiple sclerosis (MS). Our aim was to trace citrulline in the brains of patients with early-onset MS by using proton MR spectroscopy ((1)H-MR spectroscopy). MATERIALS AND METHODS: A short-echo single-voxel (1)H-MR spectroscopy by using the point-resolved proton spectroscopy sequence was performed in 27 patients with MS and 23 healthy subjects. Voxels of interest were chronic demyelinating lesions (CDLs, n = 25) and normal-appearing white matter (NAWM, n = 25) on T2-weighted imaging, and when available in patients with MS, enhancing demyelinating lesions (EDLs, n = 8). Frontal white matter (WM) was studied in control subjects. N-acetylaspartate, choline, and myo-inositol (mIns)-creatine (Cr) ratios and the presence of a citrulline peak were noted. RESULTS: Citrulline peaks were more frequently observed in patients with MS than in control subjects (P = .035), located in the NAWM in 8/25 (32%), in CDLs in 7/25 (28%), and in EDLs of 1/8 (12.5%) patients with MS. The presence of citrulline and measured metabolite/Cr ratios was not related to age at imaging, age at disease onset, duration of disease, or number of relapses. There was no significant metabolic difference between the NAWM of patients with MS and the WM of the control subjects. mIns/Cr was significantly greater in CDLs compared with the NAWM of patients with MS and the WM of healthy subjects. CONCLUSIONS: Citrulline was more frequently identified in the brains of patients with early-onset MS than in healthy subjects by (1)H-MR spectroscopy, suggesting an association of increased citrullination of myelin proteins with demyelinating diseases.

Peripheral neuropathy in a patient with D-2-hydroxyglutaric aciduria.

D-2-hydroxyglutaric aciduria (D-2-HGA; OMIM 600721) is a rare autosomal recessive neurometabolic disorder with a wide clinical spectrum. The severe phenotype is homogeneous and is characterized by early infantile-onset epileptic encephalopathy with hypotonia, delayed cerebral visual development, cardiomyopathy and facial dysmorphic features. The mild phenotype has a more variable clinical expression with hypotonia and developmental delay. We present peripheral neuropathy as an additional clinical and electrophysiological feature in a 16-year-old boy with a homozygous missense mutation in exon 3 of the D-2-hydroxyglutarate dehydrogenase gene (D2HGDH) at position c.458T>C. This mutation results in replacement of a methionine residue, which was highly conserved during evolution, by threonine (p.Met153Thr).

L-2-hydroxyglutaric aciduria and brain tumors in children with mutations in the L2HGDH gene: neuroimaging findings.

L-2-Hydroxyglutaric aciduria (L-2-HGA, MIM 236792) is a rare autosomal recessive neurodegenerative disorder characterized by psychomotor delay, cerebellar and extrapyramidal signs and subcortical leukoencephalopathy with basal ganglia and dentate nuclei involvement. Mutations in the gene L2HGDH ( C14ORF160/DURANIN/) have been identified as causative for L-2-HGA. A feature disproportionally associated with L-2-HGA is the development of malignant brain tumors. In our cohort of 40 patients with L-2-HGA, two developed medulloblastoma and glioblastoma multiforme during the course of the disease. Two missense mutations in two patients were identified in the L2HGDH gene in exon 3 (c.292C-->T) and in exon 7 (c.887T-->A). Both mutations were present in the homozygous state. Serial MR imaging findings as well as MR spectroscopy imaging is reported in a patient who developed glioblastoma multiforme.

31 cases with oculoauriculovertebral dysplasia (Goldenhar syndrome): clinical, neuroradiologic, audiologic and cytogenetic findings.

Goldenhar syndrome (GS) or oculoauriculovertebral dysplasia (OAVD) is characterized by pre-auricular skin tags, microtia, facial asymmetry, ocular abnormalities and vertebral anomalies of different size and shape. The phenotypical findings of this syndrome are variable due to heterogenous aetiology. For that reason, the physician sometimes faces difficulty when making a definite diagnosis of OAVD. We reviewed the clinical and laboratory findings of 31 patients (15 boys and 16 girls) aged from 1 day to 16 years with the clinical diagnosis of GS. The characteristic features were pre-auricular skin tags (90%), microtia (52%), hemifacial microsomia (77%) and epibulbar dermoids (39%). Vertebral anomalies were noted in 70% of the patients. Cardiac malformations were found in 39% while a genitourinary anomaly was noted in 23% and various central nervous system malformations in 47%. There were 3 pregnancies following an intracytoplasmic sperm injection (ICSI) technique among the 31 patients. Two patients with GS came from the same family. Their relatives had hydrocephaly, myelomeningocele and neural tube defects. It is known that some chromosomal aberrations are seen in GS. We performed chromosome analysis of 29 patients. Among these cases, only one patient with severe mental and motor retardation had a 47,XX,+der(22)t(11,22)(q23; q11 karyotype due to a maternal balanced translocation t(11;22)(q23;q11). This translocation was demonstrated in her sister, brother and maternal uncle. Additionally CATCH 22 analysis in 13 cases with OAVD with a CATCH 22 phenotype revealed no deletion. OAVD patients present with different morphologic features and systemic manifestations. A multidisciplinary approach should be undertaken by departments such as pediatric cardiology, audiology, ophthalmology and plastic surgery when evaluating patients with OAVD. Chromosome analysis should be performed in every patient with Goldenhar syndrome.

Increased gray matter density in the parietal cortex of mathematicians: a voxel-based morphometry study.

BACKGROUND AND PURPOSE: The training to acquire or practicing to perform a skill, which may lead to structural changes in the brain, is called experience-dependent structural plasticity. The main purpose of this cross-sectional study was to investigate the presence of experience-dependent structural plasticity in mathematicians' brains, which may develop after long-term practice of mathematic thinking. MATERIALS AND METHODS: Twenty-six volunteer mathematicians, who have been working as academicians, were enrolled in the study. We applied an optimized method of voxel-based morphometry in the mathematicians and the age- and sex-matched control subjects. We assessed the gray and white matter density differences in mathematicians and the control subjects. Moreover, the correlation between the cortical density and the time spent as an academician was investigated. RESULTS: We found that cortical gray matter density in the left inferior frontal and bilateral inferior parietal lobules of the mathematicians were significantly increased compared with the control subjects. Furthermore, increase in gray matter density in the right inferior parietal lobule of the mathematicians was strongly correlated with the time spent as an academician (r = 0.84; P < .01). Left-inferior frontal and bilateral parietal regions are involved in arithmetic processing. Inferior parietal regions are also involved in high-level mathematic thinking, which requires visuospatial imagery, such as mental creation and manipulation of 3D objects. CONCLUSION: The voxel-based morphometric analysis of mathematicians' brains revealed increased gray matter density in the cortical regions related to mathematic thinking. The correlation between cortical density increase and the time spent as an academician suggests experience-dependent structural plasticity in mathematicians' brains.

Epidermal nevus syndrome with internal carotid artery occlusion and intracranial and orbital lipomas.

We report a case of epidermal nevus syndrome involving the brain in which there is chronic occlusion of the left distal internal carotid artery resulting in ipsilateral atrophy. Orbital and cerebellopontine angle cistern lipomas and a wide cortical developmental malformation are associated with the condition. We present MR imaging findings of a patient and discuss features in the context of other neurocutaneous diseases.

Cerebral alveolar echinoccosis mimicking primary brain tumor.

We present a case of cerebral infestation by Echinococcosis multilocularis mimicking an infiltrative primary brain tumor. A heavily calcified mass invading the midbrain enhanced in a cauliflower-like fashion with small peripheral nodules present on MR imaging. Perfusion-weighted MR imaging revealed low relative cerebral blood volume within the calcified lesion and peripheral hyperemia. Single-voxel proton MR spectroscopy with an echo time of 135 milliseconds was normal.