Magnetic resonance fingerprinting-based myelin water fraction mapping for the assessment of white matter maturation and integrity in typical development and leukodystrophies.

A quantitative biomarker for myelination, such as myelin water fraction (MWF), would boost the understanding of normative and pathological neurodevelopment, improving patients' diagnosis and follow-up. We quantified the fraction of a rapidly relaxing pool identified as MW using multicomponent three-dimensional (3D) magnetic resonance fingerprinting (MRF) to evaluate white matter (WM) maturation in typically developing (TD) children and alterations in leukodystrophies (LDs). We acquired DTI and 3D MRF-based R1, R2 and MWF data of 15 TD children and 17 LD patients (9 months-12.5 years old) at 1.5 T. We computed normative maturation curves in corpus callosum and corona radiata and performed WM tract profile analysis, comparing MWF with R1, R2 and fractional anisotropy (FA). Normative maturation curves demonstrated a steep increase for all tissue parameters in the first 3 years of age, followed by slower growth for MWF while R1, R2R2 and FA reached a plateau. Unlike FA, MWF values were similar for regions of interest (ROIs) with different degrees of axonal packing, suggesting independence from fiber bundle macro-organization and higher myelin specificity. Tract profile analysis indicated a specific spatial pattern of myelination in the major fiber bundles, consistent across subjects. LD were better distinguished from TD by MWF rather than FA, showing reduced MWF with respect to age-matched controls in both ROI-based and tract analysis. In conclusion, MRF-based MWF provides myelin-specific WM maturation curves and is sensitive to alteration due to LDs, suggesting its potential as a biomarker for WM disorders. As MRF allows fast simultaneous acquisition of relaxometry and MWF, it can represent a valuable diagnostic tool to study and follow up developmental WM disorders in children.

Case report: Exploring chemoradiotherapy-induced leukoencephalopathy with 7T imaging and quantitative susceptibility mapping.

Chemotherapy and radiotherapy are widely used in the treatment of central nervous system tumors and acute lymphocytic leukemia even in the pediatric population. However, such treatments run the risk of a broad spectrum of cognitive and neurological deficits. Even though the correlation with cognitive decline is still not clear, neuroradiological defects linked to white matter injury and vasculopathies may be identified. Thanks to the use of 7T MRI it is possible to better define the vascular pattern of the brain lesions with the added advantage of identifying their characteristics and anatomical localization, which, however, are not evident with a conventional brain scan. Moreover, the use of Quantitative Susceptibility Mapping (QSM) makes it possible to discriminate between calcium deposits on vessels (chemo-radiation-induced) and hemoglobin deposition in radio-induced cavernomas, speculating, as a result, about the pathophysiology of iatrogenic brain damage. We describe the case of a 9 year-old boy with a T-type acute lymphoid leukemia who had previously been treated with polychemotherapy and high-dose RT. To better define the child's neuroradiological pattern, 7T MRI and QSM were performed in addition to conventional imaging examinations. Our case report suggests the potential usefulness of a QSM study to distinguish radio-induced vascular malformations from mineralizing microangiopathy.

Case report: Clinical and neuroradiological longitudinal follow-up in Leukoencephalopathy with Calcifications and Cysts during treatment with bevacizumab.

Leukoencephalopathy with Calcifications and Cysts (LCC) is a rare genetic microangiopathy exclusively affecting the central nervous system caused by biallelic mutations in SNORD118. Brain magnetic resonance imaging (MRI) is often diagnostic due to the highly characteristic triad of leukoencephalopathy, intracranial calcifications, and brain cysts. Age at onset, presentation and disease evolution can all vary, ranging from pauci-symptomatic disease to rapid evolution of signs with loss of motor and cognitive abilities. No specific therapies for LCC are currently licensed. According to the literature, bevacizumab might represent an effective modality to improve the clinical and MRI features of the disease. However, uncertainty remains as to the true efficacy of this approach, when to begin therapy, appropriate dosing, and the consequences of drug withdrawal. According to CARE guidelines, we describe the long-term clinical and neuro-radiological follow-up of a 10-year-old child with LCC. We report disease evolution following repeated cycles of treatment with bevacizumab. Our case report suggests that repeated cycles of bevacizumab might effectively modify disease progression, possibly indicating a time-dependent effect.

3D-Flair sequence at 3T in cochlear otosclerosis.

PURPOSE: To assess the capability of three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) sequences in detecting signal alterations of the endolabyrinthine fluid in patients with otosclerosis. MATERIALS AND METHODS: 3D-FLAIR before and after (-/+) gadolinium (Gd) administration was added to the standard MR protocol and acquired in 13 patients with a clinical/audiological diagnosis of severe/profound hearing loss in otosclerosis who were candidates for cochlear implantation and in 11 control subjects using 3-T magnetic resonance imaging (MRI) equipment. The MRI signal of the fluid-filled cochlea was assessed both visually and calculating the signal intensity ratio (SIR = signal intensity cochlea/brainstem). RESULTS: We revealed no endocochlear signal abnormalities on T1-weighted -/+ Gd images for either group, while on 3D-FLAIR we found bilateral hyperintensity with enhancement after Gd administration in eight patients and bilateral hyperintensity without enhancement in one patient. No endocochlear signal abnormalities were detected in other patients or the control group. CONCLUSION: Using 3-T MRI equipment, the 3D-FLAIR -/+ Gd sequence is able to detect the blood-labyrinth barrier (BLB) breakdown responsible for alterations of the endolabyrinthine fluid in patients with cochlear otosclerosis. We believe that 3D-FLAIR +/- Gd is an excellent imaging modality to assess the intra-cochlear damage in otosclerosis patients. KEY POINTS: • Gd-enhanced T1-weighted MRI has limited application to detect intra-cochlear damage. • 3D-FLAIR is less sensitive to flux artefacts and allows multiplanar reconstruction. • Post-Gd 3D-FLAIR is advantageous as it may highlight the BLB breakdown. • Using 3D-FLAIR -/+ Gd, we were able to identify intra-cochlear signal hyperintensities. • 3D-FLAIR might be applied for monitoring disease progression and treatment response.

Delayed post-traumatic fronto-ethmoidal sinus mucocele evaluated with short and long TE MR spectroscopy.

Mucoceles are slow-growing, benign, expansile, mucoid-filled masses developing after obstruction of the sinus ostium. Late post-traumatic mucoceles are relatively rare entities and the literature is limited to single case reports. We describe an unusual case of post-traumatic fronto-ethmoidal mucocele, evaluated with computed tomography (CT), magnetic resonance imaging (MRI) and proton MR-spectroscopy ((1)H-MRS). As a contribution to the diagnostic work-up of the mucocele, (1)H-MRS demonstrates a dominant peak at 2.0 ppm at long echo time (TE) and an additional component at 3.8 ppm at short TE due to mucus glycoprotein compounds of the mucocele.

Analysis of the 3-dimensional fluid-attenuated inversion-recovery (3D-FLAIR) sequence in idiopathic sudden sensorineural hearing loss.

IMPORTANCE: The unpredictability of idiopathic sudden sensorineural hearing loss (ISSNHL) presents a challenge to preventive care. Our study confirms the potentially important role of the 3-T magnetic resonance imaging (MRI), and in particular of the 3-dimensional fluid-attenuated inversion-recovery (3D-FLAIR) sequence, in the diagnosis and prognosis of ISSNHL to guide medical treatment. OBJECTIVE: To confirm the diagnostic, clinical, and prognostic role of 3D-FLAIR MRI in patients with idiopathic sudden sensorineural hearing loss (ISSNHL). DESIGN, SETTING, AND PATIENTS: Retrospective study in a tertiary referral center with a consecutive sample of 23 patients diagnosed as having unilateral ISSNHL from January 2010 to March 2011. EXPOSURES: Patients underwent 3D-FLAIR MRI at 3 T to evaluate ISSNHL, and the MRI images were compared with those belonging to a random group of 20 age-matched healthy patients. MAIN OUTCOMES AND MEASURES: Precontrast and postcontrast high-intensity 3D-FLAIR MRI findings in patients with ISSNHL and the correlation with clinical findings. RESULTS: Thirteen patients showed high-intensity signals in the affected inner ear on precontrast and postcontrast 3D-FLAIR MRI (57%). From the analysis of different MRI sequences, we posited 3 radiologic patterns likely correlated with mild hemorrhage, acute inflammation, and presence or absence of blood-labyrinth or nerve barrier (BLB) breakdown. Hypersignal on 3D-FLAIR MRI was positively associated with pretreatment hearing loss (P = .04) and presence of vertigo (P = .04). A strict correlation also existed between distribution of the signal (vestibule, semicircular canals) and clinical features (vertigo) (P = .04). CONCLUSIONS AND RELEVANCE: Use of 3D-FLAIR MRI at 3 T may contribute to the elucidation of pathologic conditions in the inner ears of patients with ISSNHL and provide new radiologic indicators (mild hemorrhage, acute inflammation, presence or absence of BLB breakdown) that might assume the role of prognostic factors.

6p25 interstitial deletion in two dizygotic twins with gyral pattern anomaly and speech and language disorder.

Submicroscopic 6p25 deletion is now recognized as a clinically identifiable syndrome, characterized by intellectual disability, language impairment, hearing deficit, craniofacial, ophthalmologic, cardiac, and varying central nervous system anomalies. We report on two dyzogotic twins with a maternal segregating hemizygous interstitial deletion on chromosome 6p25.1, spanning 0.9 kb; the smallest ever reported. Both had dysmorphic features (prominence of the metopic suture, synophrys, hypertelorism, down-slanting palpebral fissures, tented mouth), and a distinct brain MRI, showing a focal significant increase of the right peri-frontal subarachnoid space, with shallow sulci and a mild anomaly of the gyral pattern. Such brain anomaly has never been reported in association with del 6p25. Both propositi had a borderline-mild intellectual disability, speech and language difficulties, and behavior abnormalities. Their mother, formally tested, had a borderline cognitive impairment. Although none of the genes mapping to the deleted region are apparently related to the phenotype, LYRM4 resulted down-regulated in the cerebellar cortex of schizophrenia patients compared with controls, and Lyrm4 was down-regulated in the prefrontal cortex of mice with microdeletions in the locus syntenic to human 22q11.2 patients affected by schizophrenia. These data are in agreement with the emerging concept that similar CNVs are pathogenic in patients affected by distinct neurological diseases, and that these loci are more general risk factors for different disorders. The resemblance of our patients to those with the more extensive 6p25.1p25.3 terminal deletion suggests that the gene/s responsible for the physical phenotype should reside in the 6p25.1 genomic region.

Proton MR spectroscopy of mitochondrial diseases: analysis of brain metabolic abnormalities and their possible diagnostic relevance.

BACKGROUND AND PURPOSE: Proton (hydrogen-1 [(1)H]) MR spectroscopy is a useful diagnostic tool in many metabolic diseases, but only scattered and inconclusive data are available on mitochondrial diseases. We performed MR imaging and (1)H MR spectroscopy of the brain in patients with different types of primary mitochondrial diseases to investigate the role of (1)H MR spectroscopy in the clinical evaluation of these disorders. METHODS: In 15 patients (11 adults, four children) with mitochondrial diseases, localized MR spectra were obtained at short TEs in cerebellar white matter, paratrigonal white matter, and parieto-occipital cortex that appeared normal on MR images. Additional spectra of basal ganglia and cortical gray matter structural lesions were obtained in three patients. RESULTS: A significant choline reduction and N-acetylaspartate reduction were found in areas that appeared normal on MR images. Lactate was never found in areas that appeared normal on MR images, except in two children in whom MR studies were performed during episodes of symptom exacerbation and revealed elevated lactate both in areas that appeared damaged on MR images and in normal-appearing areas. An additional abnormal signal at 0.9 ppm was found in a consistent number of studies. CONCLUSION: (1)H MR spectroscopy proved to be a useful investigational tool for mitochondrial diseases, as it enabled detection of metabolic abnormalities even in areas of brain that appeared normal on MR images, especially when it was performed during episodes of clinical relapses or clinical exacerbation.

Unusual clinical and magnetic resonance imaging findings in a family with proteolipid protein gene mutation.

BACKGROUND: Pelizaeus-Merzbacher disease (PMD) and a complicated form of familial spastic paraparesis (spastic paraplegia 2 [SPG2]) are X-linked development disorders of myelin formation caused by a mutation in the proteolipid protein (PLP) gene. Spastic paraplegia 2 is allelic to PMD. The wide range of PLP mutations results in a corresponding large spectrum of clinical severity in PMD, with a continuum of signs and symptoms to SPG2. OBJECTIVE: To report the results of genetic, neurophysiologic, and neuroimaging investigations performed in a child affected by a mild ataxic and spastic form of PLP-related disorder and in his relatives. RESULTS: A missense mutation in exon 6 of the PLP gene (Q233P) was found in the proband and in the female obligate carriers. In the proband, evoked potentials were altered and remained unchanged during the 7 years of follow-up. Magnetic resonance imaging of the child demonstrated patchy hyperintensities of the paraventricular white matter, with microcystic components. These latter findings, along with pallidal calcium deposition, were also present in 2 females heterozygous for PLP mutation. CONCLUSION: The unusual genetic, magnetic resonance imaging, and clinical findings of this family confirm the wide variability of PLP-related disorders.

De novo complete trisomy 5p: clinical and neuroradiological findings.

Partial or complete duplication of 5p is a rare chromosomal abnormality in which genotype-phenotype correlation studies are hampered by other commonly associated chromosomal abnormalities. We report on a new patient in whom a complete de novo trisomy 5p in all metaphases represented the only chromosomal aberration. The present case further contributes to delineate the typical clinical picture of the trisomy 5p syndrome. Long-term clinical follow-up demonstrated low levels of secretory immunoglobulin A (IgA) on several occasions and likely related to the patient's recurrent respiratory infections (RRIs), a main clinical feature of the trisomy 5p syndrome. An extensive neuroradiological study detected a progressive triventricular hydrocephalus during the fist year of life with subsequent stabilization. Neuronal migration disorders were also present and probably account for the drug-resistant epilepsy presented by the patient.