White matter abnormalities are related to microstructural changes in preterm neonates at term-equivalent age: a diffusion tensor imaging and probabilistic tractography study.

BACKGROUND AND PURPOSE: Preterm infants have a high risk of brain injury and neurodevelopmental impairment, often associated with WMA on conventional MR imaging. DTI can provide insight into white matter microstructure. The aim of this study was to investigate the association between WMA on conventional MR imaging and DTI parameters in specific fibers in preterm neonates at term-equivalent age. MATERIALS AND METHODS: Seventy preterm neonates (39 boys and 31 girls) were included in the study. WMA were classified as no, mild, moderate, or severe. Probabilistic tractography provided tract volumes, FA, MD, λ(//), and λ(⊥) in the CST, SLF, TRs, and corpus callosum. Data were compared by using MANOVA, and adjustment for multiple comparisons was performed. RESULTS: Important associations were found between WMA and microstructural changes. Compared with neonates with no WMA (n = 41), those with mild WMA (n = 27) had significantly increased λ(⊥) and MD in the left ATR, the left sensory STR, the bilateral motor STR, and for λ(⊥) also in the right CST; FA decreased significantly in the left sensory STR. Diminished tract volumes and altered diffusion indices were also observed in the 2 neonates with moderate WMA. CONCLUSIONS: Altered DTI indices in specific tracts, with λ(⊥) as most prominent, are associated with mild WMA in preterm neonates at term-equivalent age.

A novel NDUFV1 gene mutation in complex I deficiency in consanguineous siblings with brainstem lesions and Leigh syndrome.

Although deficiency of complex I of the mitochondrial respiratory chain is a frequent cause of encephalopathy in children, only a few mutations have been reported in each of its subunits. In the absence of families large enough for conclusive segregation analysis and of robust functional testing, it is difficult to unequivocally show the causality of the observed mutations and to delineate genotype-phenotype correlations, making additional observations necessary. We observed two consanguineous siblings with an early-onset encephalopathy, medulla, brainstem and mesencephalon lesions on brain magnetic resonance imaging and death before 8 months of age, caused by a complex I deficiency. We used a homozygosity mapping approach and identified a missense mutation in the NDUFV1 gene. The mutation, p.Arg386His, affects a highly conserved residue, contiguous to a cysteine residue known to coordinate an Fe ion. This observation adds to our understanding of complex I deficiency disease. It validates the important role of Arg386 and therefore supports the current molecular model of iron-sulfur clusters in NDUFV1.

Bilateral Meckel's cave amyloidoma: a case report.

Primary solitary amyloidoma of Meckel's cave is rare, and a bilateral location is even more rare. To the best of our knowledge, only 12 cases in the literature have described such a primary lesion, including one case of bilateral involvement of Meckel's cave. We report here on the case of a 57-year-old woman presenting with pseudotumor masses involving both Meckel's caves and responsible for trigeminal neuropathy. The final diagnosis of amyloidoma was made on the basis of histological examination of surgical biopsy specimens.

Gender differences in language and motor-related fibers in a population of healthy preterm neonates at term-equivalent age: a diffusion tensor and probabilistic tractography study.

BACKGROUND AND PURPOSE: Sex differences in white matter structure are controversial. In this MR imaging study, we aimed to investigate possible sex differences in language and motor-related tracts in healthy preterm neonates by using DTI and probabilistic tractography. MATERIALS AND METHODS: Thirty-eight preterm neonates (19 boys and 19 girls, age-matched), healthy at term-equivalent age and at 12 months were included. TBV was measured individually. Probabilistic tractography provided tract volumes, relative tract volumes (volume normalized to TBV), FA, MD, and λ(⊥) in the SLF, in the TRs, and in the CSTs. Data were compared by using independent t tests, and Bonferroni corrections were performed to adjust for multiple comparisons. RESULTS: We showed that healthy preterm boys had larger TBV than girls. However, girls had statistically significantly larger relative tract volumes than boys bilaterally in the parieto-temporal SLF, and in the left CST. Moreover, in the left parieto-temporal SLF, a trend toward lower MD and λ(⊥) was observed in females. CONCLUSIONS: Structural sex differences were found in preterm neonates at term-equivalent age in both sides of the parieto-temporal SLF and in the left CST. Further studies are necessary to investigate whether these structural differences are related to later sex differences in language skills and handedness or to the effect of prematurity.

[Non-functioning pituitary adenoma: is there an interest to treat a residue after surgery?]. / Adénome hypophysaire non sécrétant: faut-il traiter un résidu après chirurgie?

Diagnosis of non-functioning pituitary adenoma is generally posted when there is a compression of the ophthalmic nerve or when a hypopituitarism occurred. Surgery will be the first treatment but complete removal can be achieved in less than 50% of the patients. In the great majority of the patients, there is a recurrence and a new treatment is proposed. The question is when we must treat a residue after surgery. We performed a retrospective study reviewing a series of 111 patients with a non-functioning pituitary adenoma. All patients had a pre- and post-operative MRI (1.5 T). A statistical analysis was done to determine the influence of the resection, the age of the patient on the recurrence. A complete removal was achieved for 45 patients and 11 of these present a recurrence. 39 patients out of 66 patients who had a partial removal presented also a recurrence. The mean age of the population is 53 years. The statistical analysis demonstrates that patients with a complete removal had less recurrence. Patient with an age below 60 years had more frequently a recurrence compared with older than 60 years old. In conclusion, treatment for non-functioning pituitary adenoma is a transsphenoidal approach surgery. A complete surgery must be the aim of the neurosurgeon. And when a residue is present, a secondary treatment must be given for patient with an age below 60 years old like radiosurgery or radiation therapy.

Endovascular treatment of anterior choroidal artery aneurysms.

INTRODUCTION: Endovascular treatment (EVT) of anterior choroidal artery aneurysms (AChAA) may be challenging because of the close relationship with the parent artery. The aim of this study was to report our experience with EVT of AChAA. METHODS: A retrospective review of our prospectively maintained database identified all AChAA treated by embolization. The clinical charts, procedural data and angiographic results were reviewed. RESULTS: From April 2004-August 2008, 11 patients were identified. Five patients presented with a subarachnoid hemorrhage (SAH) and six patients were asymptomatic. Aneurysms size varied from two to 13 mm (mean size=3.6 mm) and nine had an unfavourable neck/sac ratio (>or=0.7). The anterior choroidal artery was arising from the sac (n=6) or from the neck (n=5). Endovascular treatment consisted of balloon-assisted coiling (n=8), coiling (n=2) and stent-assisted coiling (n=1). No procedural complication occurred and all patients had an excellent outcome except one patient who died because of severe vasospasm 8 days after an uneventful EVT. Immediate angiographic control showed six complete occlusions, one neck remnant and four incomplete occlusions. Follow-up controls (mean=18 months) were obtained in eight patients and showed five stable occlusions and three further thrombosis achieving complete occlusion. CONCLUSION: EVT of AChAA is associated with very good clinical and long-term anatomical results. Because of their small size, unfavourable neck/sac ratio and close relationship with the parent artery, EVT frequently requires the use of adjunctive techniques such as balloon or stent-assisted coiling.

Maturation of thalamic radiations between 34 and 41 weeks' gestation: a combined voxel-based study and probabilistic tractography with diffusion tensor imaging.

BACKGROUND AND PURPOSE: This study aimed to investigate brain maturation along gestational age with diffusion tensor imaging in healthy preterm and term neonates. Therefore, a voxel-based study of fractional anisotropy (FA) and mean diffusivity (D(av)) was performed to reveal the brain regions experiencing microstructural changes with age. With tractography, the authors intended to identify which fiber tracts were included in these significant voxels. MATERIALS AND METHODS: There were 22 healthy preterm and 6 healthy term infants who underwent MR imaging between 34 and 41 weeks of gestation. A statistical parametric approach was used to evidence the effect of age on regional distribution of FA and D(av) values. The fiber tracts suspected to be included in the significant clusters of voxels were identified with neuroanatomy and tractography atlases, reconstructed with probabilistic tractography, and superimposed on the parametric maps. RESULTS: Parametric analysis showed that FA increases with age in the subcortical projections from the frontal (motor and premotor areas) and parietal cortices, the centrum semiovale, the anterior and posterior arms of the internal capsules, the optic radiations, the corpus callosum, and the thalami (P < .05, corrected). Superimposition of the parametric maps on tractography showed that the corticospinal tract (CST); the callosal radiations (CR); and the superior, anterior, and posterior thalamic radiations were included in the significant voxels. No statistically significant results were found for D(av) maps. CONCLUSIONS: These results highlight that, besides the already-evidenced FA increase in the CST and CR, the thalami and the thalamic radiations experience microstructural changes in the early development of the human brain.

Brain (1)H-MR spectroscopy in clinical neuroimaging at 3T.

After more than 10 years of use, clinical neuroimaging spectroscopy has proven to be invaluable in the MRI assessment of several brain diseases. The metabolic characterization of diverse brain lesions and pathological conditions is well established by spectroscopy studies at 1.5 T, but recently, an increase in the number of 3T magnets has noticeably improved routine neuroimaging in general. For brain proton spectroscopy, the use of higher magnetic fields has been promising in terms of increasing the signal/noise ratio across the spectrum and widening the frequency bandwidth to allow clearer separation of peaks that are otherwise too close to each other at 1.5 T, especially glutamate, glutamine and gamma-aminobutyric acid (GABA). The individual detection and quantification of these metabolites will add more details to the characterization of brain diseases, and allow the inclusion of more brain pathologies. Moreover, the ongoing advances in dedicated hardware and integrated software have led to more accurate and automated postprocessing, offering neuroradiologists a more user-friendly interface. This is an up to date review of the main clinical applications of brain proton MR spectroscopy that are potentially improved at 3T, taking into account the peculiarities of higher magnetic fields. It is based on both the literature and our own clinical experience, starting from July 2005 and including more than 250 scans at 3T (unpublished material), and emphasizes, for every indication, a practical approach to brain MRS to achieve the optimal clinical impact.

Diffusion tensor imaging (DTI) and tractography of the cerebellar projections to prefrontal and posterior parietal cortices: a study at 3T.

OBJECTIVES: Previous diffusion tensor imaging (DTI) studies have identified cerebellar pathways and supratentorial connections, but none of them have isolated cerebellar projections to prefrontal and posterior parietal cortices using tractography. The aim of our study was to identify and visualize on 3D projections, as well as on 2D cross-sectional images, the cerebellar projections to prefrontal (PF) and posterior parietal (PP) cortices. MATERIAL AND METHODS: The study included 10 healthy volunteers, four males and six females aged 25 to 45 years (mean age 31 years). A DTI sequence was applied at 3 Tesla using diffusion sensitizing gradients in 32 directions. White matter tracts were reconstructed by applying a multiple ROI (region of interest) tractography technique. RESULTS: PF projections were obtained in all subjects. PP projections were obtained in six over 10 subjects. On 2D cross-sectional images, the tracts showed the same anatomical location in each ROI in all subjects. CONCLUSION: This DTI study at 3T resulted in a selective and full visualization of cerebellar projections to PF and PP cortices for the first time and is introductive for further optimized and quantitative DTI study of these tracts.

Apparent diffusion coefficient and cerebral blood volume in brain gliomas: relation to tumor cell density and tumor microvessel density based on stereotactic biopsies.

BACKGROUND AND PURPOSE: MR imaging-based apparent diffusion coefficient (ADC) and regional cerebral blood volume (rCBV) measurements have been related respectively to both cell and microvessel density in brain tumors. However, because of the high degree of heterogeneity in gliomas, a direct correlation between these MR imaging-based measurements and histopathologic features is required. The purpose of this study was to correlate regionally ADC and rCBV values with both cell and microvessel density in gliomas, by using coregistered MR imaging and stereotactic biopsies. MATERIALS AND METHODS: Eighteen patients (9 men, 9 women; age range, 19-78 years) with gliomas underwent diffusion-weighted and dynamic susceptibility contrast-enhanced MR imaging before biopsy. Eighty-one biopsy samples were obtained and categorized as peritumoral, infiltrated tissue, or bulk tumor, with quantification of cell and microvessel density. ADC and rCBV values were measured at biopsy sites and were normalized to contralateral white matter on corresponding maps coregistered with a 3D MR imaging dataset. ADC and rCBV ratios were compared with quantitative histologic features by using the Spearman correlation test. RESULTS: The highest correlations were found within bulk tumor samples between rCBV and cell density (r=0.57, P < .001) and rCBV and microvessel density (r=0.46, P < .01). An inverse correlation was found between ADC and microvessel density within bulk tumor (r=-0.36, P < .05), whereas no significant correlation was found between ADC and cell density. CONCLUSION: rCBV regionally correlates with both cell and microvessel density within gliomas, whereas no regional correlation was found between ADC and cell density.

Contribution of magnetic source imaging to the presurgical work-up of patients with refractory partial epilepsy.

Magnetoencephalography (MEG) is a functional cerebral imaging technique that non-invasively records extracranial magnetic fields generated by the electrical activity of the brain. Magnetic source imaging (MSI) is a combination of MEG and coregistered magnetic resonance imaging (MRI) that is increasingly being used in the non-invasive presurgical evaluation of patients with refractory partial epilepsy to localize the magnetic correlate of interictal epileptiform discharges. This paper reviews the basics of MEG and MSI, briefly describes the characteristics of the MEG system installed at the ULB-Hôpital Erasme and then summarises the available data on the contribution of MSI to the presurgical work-up of refractory partial epilepsy.

Information on heavy equipments and facilities in Belgium: gamma-knife.

PURPOSE: To explain the principles and indications of gamma knife radiosurgery and to illustrate the correlated neuroimaging features. METHODS AND MATERIAL: Between December 1999 and July 2007, 1620 patients were treated by GK for a large variety of indications (metastasis 26%, vascular malformations 7%, trigeminal neuralgia 14%, pituitary adenoma 3%, primary CNS tumour 8%, other tumours 6%, vestibular schwannoma 19%, meningioma 17%, functional disorders <1%). The patients benefited from MRI follow-ups. RESULTS: MRI is the imaging technique of choice for Gamma knife radiosurgery (GKRS) in almost all indications. Computed Tomography, Digital Subtraction Angiography and Positron Emission Tomography have an additional role in some indications. Significant MRI data is illustrated in most indications. Evaluation of the treatment is mainly performed using MRI follow-up studies. The main features of these MRI follow-ups are described. Stabilisation or shrinking of the lesions volumes was generally observed. T2 relaxation times were also modified in and around the treated target areas, in patients responding to treatment and without any symptomatic complications. Modifications in contrast uptake were also observed in those patients. A few patients presented symptomatic complications associated with T2 signal anomalies. The interpretation of those modifications is discussed. CONCLUSION: MRI is the method of choice for GKRS planning in most indications. Imaging changes after radiosurgery provide the best quality control available to assess the response to radiosurgical treatment and to identify and monitor potential complications.

Sixty-four-row multisection CT angiography for detection and evaluation of ruptured intracranial aneurysms: interobserver and intertechnique reproducibility.

BACKGROUND AND PURPOSE: The purpose of this work was to assess intertechnique and interobserver reproducibility of 64-row multisection CT angiography (CTA) used to detect and evaluate intracranial aneurysms. MATERIALS AND METHODS: From October 2005 to November 2006, 54 consecutive patients with nontraumatic subarachnoid hemorrhage (SAH) underwent both CTA and digital substraction angiography (DSA). Four radiologists independently reviewed CT images, and 2 other radiologists reviewed DSA images. Aneurysm diameter (D), neck width (N), and the presence of a branch arising from the sac were assessed. RESULTS: DSA revealed 67 aneurysms in 48 patients and no aneurysm in 6 patients. Mean sensitivity and specificity of CTA for the detection of intracranial aneurysms were, respectively, 94% and 90.2%. For aneurysms less than 3 mm, CTA had a mean sensitivity of 70.4%. Intertechnique and interobserver agreements were good for the detection of aneurysms (mean kappa = 0.673 and 0.732, respectively) and for the measurement of their necks (mean kappa = 0.753 and 0.779, respectively). Intertechnique and interobserver agreements were excellent for the measurement of aneurysm diameters (mean kappa = 0.847 and 0.876, respectively). In addition, CTA was accurate in determining the N/D ratio of aneurysms and adjacent arterial branches. However, the N/D ratio was overestimated by all of the readers at CTA. CONCLUSION: Sixty-four-row multisection CTA is an imaging method with a good interobserver reproducibility and a high sensitivity and specificity for the detection and the morphologic evaluation of ruptured intracranial aneurysms. It may be used as an alternative to DSA as a first-intention imaging technique in patients with SAH.

Endovascular treatment of intracranial aneurysms as the first thérapeutic option.

BACKGROUND AND PURPOSE: To prospectively evaluate the results of endovascular treatment (EVT) of intracranial aneurysms when it is considered as first-intention treatment. METHODS: From April 2004-October 2006, 167 consecutive patients with 202 aneurysms were treated in our institution. Five patients with a ruptured aneurysm with an associated haematoma were excluded. In 162 patients with 197 aneurysms, EVT was considered as first-intention treatment. RESULTS: Surgical clipping was performed in 25 aneurysms (25/197=12.7%) including 22 aneurysms excluded from EVT and three EVT failures. EVT was thus attempted in 144 patients with 175 aneurysms and successfully performed in 141 patients with 172 aneurysms (172/197=87.3%). EVT failure rate was 1.7%. Clinical outcome according to the modified Glasgow Outcome Scale was: Excellent, 81.5%; Good, 7%; Poor or Fair, 3.5%; Death, 8%. Procedural complications occurred in 17 cases (10%). Balloon- or stent-assisted techniques were used in 60 cases (34.9%) and were not associated with higher complication rate. Overall procedural morbidity and mortality rates were 4.2 and 2.1%. Initially, complete occlusion was obtained in 68%, neck remnant in 23%, and incomplete occlusion in 9% of aneurysms. Follow-up (mean 11 months) was obtained in 119 aneurysms and showed major recanalisation--that required re-treatment--in 13 cases (11%) and minor recanalisation in 17 cases (14.3%). CONCLUSION: Our findings suggest that new endovascular techniques allow proposing EVT as first-intention treatment in 87.3% of patients with intracranial aneurysms. This therapeutic strategy is associated with good clinical results. However, anatomical results are not improved and remain the EVT limiting factor.

Neurocutaneous melanosis in a newborn with giant congenital melanocytic nevus.

Neurocutaneous melanosis (NCM) is known as a rare phakomatose characterised by large or numerous pigmented congenital nevi associated with leptomeninges melanin-containing deposits. We report a case of a newborn presenting at birth with a giant nevus covering about 40% of the total body surface. MRI showed T1 hyperintensities in the right amygdala and predominantly in the cerebellum corresponding to melanocytic cells.

Immediate intracranial aneurysm occlusion after embolization with detachable coils: a comparison between MR angiography and intra-arterial digital subtraction angiography.

BACKGROUND AND PURPOSE: To prospectively compare the effectiveness of time-of-flight (TOF) and contrast-enhanced (CE) MR angiography (MRA) with that of digital subtraction angiography (DSA) to assess immediate intracranial aneurysm occlusion after selective embolization. METHODS: From August 2006 to March 2007, 33 consecutive patients with 40 aneurysms were included. Thirty aneurysms were treated by endosaccular coils (group 1). Ten aneurysms were treated by stent placement and subsequent endosaccular coils (group 2). All patients underwent MRA within 24 h after treatment. One senior and one fellow radiologist independently reviewed the MR images, and another senior radiologist reviewed the DSA images. RESULTS: DSA showed 22 complete occlusions, ten residual necks, and eight residual aneurysms. For residual neck detection, there was no difference between TOF-MRA (sensitivity, 80%-80%; specificity, 93.8%-100%, according to both readers) and CE-MRA (sensitivity, 80%-80%; specificity, 100%). For residual aneurysm detection, there was a significant difference between TOF-MRA (sensitivity, 50%-62.5%; specificity, 100%) and CE-MRA (sensitivity and specificity, 100%, according to both readers). In group 2, a residual aneurysm was missed by both readers with TOF-MRA in the same 3 aneurysms. Moreover, both readers judged CE-MRA better than TOF-MRA to assess parent-artery patency in group 2. Interobserver agreement was excellent for TOF-MRA and CE-MRA (kappa=0.9 and 1, respectively). CONCLUSIONS: In our study, both TOF-MRA and CE-MRA had high and comparable sensitivity and specificity for the assessment of immediate aneurysm occlusion after selective embolization, except when a stent-assisted technique was used. In such cases, CE-MRA was superior to TOF-MRA to evaluate aneurysm occlusion and parent-artery patency.

[Intramedullary cavernomas: personal series of 24 cases]. / Les cavernomes intramédullaires: série personnelle de 24 cas.

Intramedullary cavernomas are rare, but with routinely use of MRI detection has improved, raising the problem of choosing the adequate management approach: conservative or surgical. Cavernomas are vascular malformations, but, as hemangioblastomas they appear as vascular tumors of the spinal cord. They can be durably asymptomatic. The symptoms are a progressive clinical deterioration or acute spinal dysfunction (tetra or paraplegia) in case of hemorrhage. Cavernomas have a typical aspect with MRI in contrast with intramedullary gliomas. The lesion is often superficial, covered by the pia-mater, visible immediately after opening the dura, the approach is direct; but in few cases the cavernoma is deep seated in the spinal cord and not visible, the approach is through the midline. It is recommended to perform a complete "en bloc" resection. A yearly MRI control is necessary to search possible "de novo" cases.

Stereotactic comparison among cerebral blood volume, methionine uptake, and histopathology in brain glioma.

BACKGROUND AND PURPOSE: Vascularity, metabolism, and histologic grade are related in gliomas but the exact determinants of these relationships are not fully defined. We used image coregistration and stereotactic biopsies to regionally compare cerebral blood volume (CBV) and (11)C-methionine (MET) uptake measurements in brain gliomas and to assess their relationship by histopathologic examination. MATERIALS AND METHODS: Fourteen patients with brain gliomas underwent MR imaging, including dynamic susceptibility contrast-enhanced MR and positron-emission tomography (PET) using MET acquired in identical stereotactic conditions before biopsy. MR-based CBV maps were calculated and both CBV maps and PET images were coregistered to anatomic images. Sixty-five biopsy samples were obtained on trajectories targeted toward high MET uptake area. The following histopathologic features were semiquantified in each sample: mitotic activity, endothelial proliferation, cellular pleomorphism, and tumor necrosis. CBV and MET uptake values were measured in the biopsy area and normalized to contralateral white matter. CBV ratios were compared with MET uptake ratios, and both measurements were compared with histologic features of each sample. RESULTS: CBV ratios ranged from 0.08 to 10.24 (median = 1.73), and MET uptake ratios ranged from 0.30 to 4.91 (median = 1.67). There was a positive correlation between CBV ratios and MET uptake ratios (r = 0.65, P < .001). Both CBV and MET uptake ratios were found to be significantly related to endothelial proliferation and mitotic activity (P < .01). CONCLUSION: Within glial tumors, there is a local relationship between CBV and MET uptake measurements. Both provide indices of focal malignant activity.