Author Correction: Postzygotic inactivating mutations of RHOA cause a mosaic neuroectodermal syndrome

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effects of Methylphenidate on Default-Mode Network/Task-Positive Network Synchronization in Children With ADHD

OBJECTIVE

A failure of the anti-phase synchronization between default-mode (DMN) and task-positive networks (TPN) may be involved in a main manifestation of ADHD: moment-to-moment variability. The study investigated whereby methylphenidate may improve TPN/DMN synchronization in ADHD.

METHOD

Eleven drug-naive ADHD children and 11 typically developing (TD) children performed a flanker task during functional magnetic resonance imaging. The ADHD group was scanned without and 1 month later with methylphenidate. The signal was analyzed by independent component analysis.

RESULTS

The TD group showed anti-phase DMN/TPN synchronization. The unmedicated ADHD group showed synchronous activity in the posterior DMN only, which was positively correlated with response time variability for the flanker task. Methylphenidate initiated a partial anti-phase TPN/DMN synchronization, reduced variability, and abolished the variability/DMN correlation.

CONCLUSION

Although results should be interpreted cautiously because the sample size is small, they suggest that a failure of the TPN/DMN synchronization could be involved in the moment-to-moment variability in ADHD. Methylphenidate initiated TPN/DMN synchronization, which in turn appeared to reduce variability.

Perfusion magnetic resonance imaging in pediatric brain tumors

PURPOSE

The use of DSC-MR imaging in pediatric neuroradiology is gradually growing. However, the number of studies listed in the literature remains limited. We propose to assess the perfusion and permeability parameters in pediatric brain tumor grading.

METHODS

Thirty children with a brain tumor having benefited from a DSC-MR perfusion sequence have been retrospectively explored. Relative CBF and CBV were computed on the ROI with the largest lesion coverage. Assessment of the lesion's permeability was also performed through the semi-quantitative PSR parameter and the K2 model-based parameter on the whole-lesion ROI and a reduced ROI drawn on the permeability maps. A statistical comparison of high- and low-grade groups (HG, LG) as well as a ROC analysis was performed on the histogram-based parameters.

RESULTS

Our results showed a statistically significant difference between LG and HG groups for mean rCBV (p < 10^-3), rCBF (p < 10^-3), and for PSR (p = 0.03) but not for the K2 factor (p = 0.5). However, the ratio K2/PSR was shown to be a strong discriminating factor between the two groups of lesions (p < 10^-3). For rCBV and rCBF indicators, high values of ROC AUC were obtained (> 0.9) and mean value thresholds were observed at 1.07 and 1.03, respectively. For K2/PSR in the reduced area, AUC was also superior to 0.9.

CONCLUSIONS

The implementation of a dynamic T2* perfusion sequence provided reliable results using an objective whole-lesion ROI. Perfusion parameters as well as a new permeability indicator could efficiently discriminate high-grade from low-grade lesions in the pediatric population.

Insights into cerebrospinal fluid and cerebral blood flows in infants and young children

This study investigates the craniospinal flows of blood and cerebrospinal fluid using phase-contrast magnetic resonance imaging (MRI) on 23 control neonates and infants (5 d-68 mo old). Mean arterial cerebral blood flow increased with age of infant from 180 mL/min after birth to 1330 mL/min around 6 years of age. This corresponds to 51 mL/min/100 g and 95 mL/min/100 g, respectively. Cervical cerebrospinal fluid stroke volume increased from 38 × 10(-3) mL to 752 × 10(-3) mL per cardiac cycle. After arterial systolic blood inflow, we observed a delay of the venous outflow that was always preceded by cerebrospinal fluid flushing out through the spinal canal. These results highlighted the importance of compliance of the spinal compartment and the interaction of blood and cerebrospinal fluid dynamics. The capacity of the spinal compartment to receive intracranial cerebrospinal fluid in presence of fontanels was demonstrated. We provide reference values to understand the physiology of cerebrospinal fluid and cerebral blood.

An innovative approach to investigate the dynamics of the cerebrospinal fluid in the prepontine cistern: A feasibility study using spatial saturation-prepared cine PC-MRI

•

An innovative sat-pulse based cine PC-MRI to investigate complex CSF dynamic.

•

Compared to conventional sequence and validated in the PPC of hydrocephalus patients.

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No compromise neither on temporal nor on spatial resolution.

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Compared to conventional exam: the PPC has same area but lower flow stroke volume.

•

It contributes to a better follow-up of patients with altered CSF circulation.

Purposes

Accurate measurements of the cerebrospinal fluid that flows through the prepontine cistern (PPC) are challenging due to artefacts originating from basilar artery blood flow. We aim to accurately quantify cerebrospinal fluid (CSF) flow and stroke volume in the PPC, which is essential before endoscopic third ventriculostomy.

Materials and methods

We developed a new PC-MRI sequence prepared with Hadamard saturation bands to accurately quantify CSF flow in the PPC by suppressing the blood signal in the surrounding vessels. In total, 28 adult hydrocephalic patients (age 59 ± 20 years) were scanned using conventional PC-MRI and our developed sequence. CSF was separately extracted from the PPC and the foramen of Magendie, and flow (min and max) and stroke volume were quantified.

Results

Our modifications result in a complete deletion of signal from flowing blood, resulting in significantly reduced CSF stroke volume (Conv = 446 ± 113 mm³, Dev = 390 ± 119 mm³, p = 0.006) and flow, both minimum (Conv = −1630 ± 486 mm³/s, Dev = −1430 ± 406 mm³/s, p = 0.005) and maximum (Conv = 2384 ± 657 mm³/s, Dev = 1971 ± 62 mm³/s, p = 0.002) compared with the conventional sequence, whereas no change in the area of interest was noted (Conv = 236 ± 65 mm², Dev = 249 ± 75 mm², p = 0.21).

Conclusions

Accurate and reproducible CSF flow and stroke volume measurements in the PPC can be achieved with sat-band prepared cine PC-MRI.

Relationship between cerebrospinal fluid flow, ventricles morphology, and DTI properties in internal capsules: differences between Alzheimer's disease and normal-pressure hydrocephalus

BACKGROUND

Normal-pressure hydrocephalus (NPH) and Alzheimer's disease (AD) have some similar clinical features and both involve white matter and cerebrospinal fluid (CSF) disorders.

PURPOSE

To compare putative relationships between ventricular morphology, CSF flow, and white matter diffusion in AD and NPH.

MATERIAL AND METHODS

Thirty patients (18 with AD and 12 with suspected NPH) were included in the study. All patients underwent a 3-Tesla MRI scan, which included phase-contrast MRI of the aqueduct (to assess the aqueductal CSF stroke volume) and a DTI session (to calculate the fractional anisotropy [FA] and apparent diffusion coefficient [ADC]) in the internal capsules).

RESULTS

FA was correlated with ventricular volume in the suspected NPH population (P < 0.001; rs = 0.88), whereas the ADC was highly correlated with the aqueductal CSF stroke volume in AD (P < 0.001; rs = 0.79).

CONCLUSION

Although AD and NPH both involve CSF disorders, the two diseases do not have the same impact on the internal capsules. The magnitude of the ADC is related to the aqueductal CSF stroke volume in AD, whereas FA is related to ventricular volume in NPH.

Temporal resolvability analysis of macroscopic morphological development in neonatal cerebral magnetic resonance images

OBJECTIVES

Reliable gradation of neonatal brain development is important for clinical investigation of neurological disorders. A prerequisite for such quantification of development is knowledge about temporal resolvability.

METHODS

 We hypothesized 2-week interval as the temporal resolvability of age-related templates to study macroscopic morphological brain development in the early weeks after birth. Therefore, we constructed two templates for the gestational age (GA) ranges of 39 to 40 and 41 to 42 weeks using T1-weighted magnetic resonance (MR) images. Then, we compared the spatial variation of anatomical landmarks and the average and the maximal length of spatial deformation in 30 subjects normalized to the two templates along x, y, and z directions.

RESULTS

 Multivariate analysis of variance (MANOVA) revealed significant difference between spatial variations of the above macroscopic features in the two age ranges. Furthermore, quantitative analysis of feature scattering yielded the same result even in features for which the null hypothesis was not rejected by MANOVA. Moreover, the same procedure was reiterated on two sets of subjects with the closer age range of 1 week (40 and 41 week's GA) and no significant difference could be detected.

CONCLUSIONS

 The results strengthen the hypothesis that 2-week is the temporal resolvability of age-related templates for macroscopic morphological studies of the developing brain in the early weeks after birth.

Effect of surgery on periventricular white matter in normal pressure hydrocephalus patients: comparison of two methods of DTI analysis

BACKGROUND

Diffusion tensor imaging (DTI) is a useful tool for assessing changes that occur in microstructures. We have developed a novel method for region of interest (ROI) delineation in the assessment of DTI parameters in patients with normal pressure hydrocephalus (NPH).

PURPOSE

To compare the standard method and our novel method in an evaluation of the impact of surgery on periventricular white matter in patients with NPH.

MATERIAL AND METHODS

Ten patients with NPH underwent 3T magnetic resonance imaging (MRI; including 12-direction DTI sequences) before and after surgery. We recorded diffusion parameters (λi, the fractional anisotropy [FA], the apparent diffusion coefficient, and Dr) in the internal capsule (IC) and the body of the corpus callosum (BCC). Using the standard delineation technique, regions of interest (ROIs) were positioned according to anatomical and functional considerations and then filled with several sub-ROIs. The ROIs delineated with our novel technique (extracted as the six sub-ROIs with the lowest standard deviation for the FA) were arranged in two rows (medial and lateral), from the ventricle to the brain surface.

RESULTS

The within-ROI homogeneity was higher with the novel method than with the conventional method (P<10(-4)). When the conventional delineation method was applied to the IC data, only λ2 was found to be significantly greater after surgery; in contrast, application of our novel method evidenced a significant decrease in FA and λ1 and a significant increase in λ2 (P<0.05). Both before and after surgery, the FA in the medial row of ROIs was greater than the FA in the lateral row (P<0.01). In the BCC, only λ2 and Dr varied significantly (when evaluated with the novel method).

CONCLUSION

Our results show that use of a novel method of DTI data analysis may be more sensitive to local changes induced by surgical procedures. Furthermore, this novel method was able to detect the transmantle pressure gradient related to the regional stress distribution.

Percutaneous, computed tomography-guided drainage of deep pelvic abscesses via a transgluteal approach: a report on 30 cases and a review of the literature

AIM

Percutaneous drainage of abdominal and pelvic abscesses is a first-line alternative to surgery. Anterior and lateral approaches are limited by the presence of obstacles, such as the pelvic bones, bowel, bladder, and iliac vessels. The objective of this study was to assess the feasibility, safety, tolerability, and efficacy of a percutaneous, transgluteal approach by reviewing our clinical experience and the literature.

MATERIALS AND METHODS

We reviewed demographic, clinical and morphological data in the medical records of 30 patients having undergone percutaneous, computed tomography (CT)-guided, transgluteal drainage. In particular, we studied the duration of catheter drainage, the types of microorganisms in biological fluid cultures, complications related to procedures and the patient's short-term treatment outcome.

RESULTS

From January 2005 to October 2011, 345 patients underwent CT-guided percutaneous drainage of pelvis abscesses in our institution. A transgluteal approach was adopted in 30 cases (10 women and 20 men; mean age: 52.6 [range 14-88]). The fluid collections were related to post-operative complications in 26 patients (86.7 %) and inflammatory or infectious intra-abdominal disease in the remaining 4 patients (acute diverticulitis: n = 2; appendicitis: n = 1; Crohn's disease: n = 1) (13.3 %). The mean duration of drainage was 8.7 days (range 3-33). Laboratory cultures were positive in 27 patients (90 %) and Escherichia coli was the most frequently present microorganism (in 77.8 % of the positive samples). A transpiriformis approach (n = 5) was more frequently associated with immediate procedural pain (n = 3). No major complications were observed, either during or after the transgluteal procedure. Drainage was successful in 29 patients (96.7 %). One patient died from massive, acute cerebral stroke 14 days after drainage.

CONCLUSION

When an anterior approach is unfeasible, transgluteal, percutaneous, CT-guided drainage is a safe, well tolerated and effective procedure. Major complications are rare. This type of drainage is an alternative to surgery for the treatment of deep pelvic abscesses (especially for post-surgical collections).

Cerebrospinal fluid and blood flow in mild cognitive impairment and Alzheimer's disease: a differential diagnosis from idiopathic normal pressure hydrocephalus

Background

Phase-contrast magnetic resonance imaging (PC-MRI) enables quantification of cerebrospinal fluid (CSF) flow and total cerebral blood (tCBF) flow and may be of value for the etiological diagnosis of neurodegenerative diseases. This investigation aimed to study CSF flow and intracerebral vascular flow in patients with Alzheimer's disease (AD) and patients with amnesic mild cognitive impairment (a-MCI) and to compare the results with patients with idiopathic normal pressure hydrocephalus (NPH) and with healthy elderly volunteers (HEV).

Methods

Ten a-MCI and 9 mild AD patients were identified in a comprehensive neurological and neuropsychological assessment. They underwent brain MRI; PC-MRI pulse sequence was performed with the following parameters: two views per segment; flip angle: 25° for vascular flow and 20° for CSF flow; field-of-view (FOV): 14 × 14 mm²; matrix: 256 × 128; slice thickness: 5 mm; with one excitation for exams on the 3 T machine, and 2 excitations for the 1.5 T machine exams. Velocity (encoding) sensitization was set to 80 cm/s for the vessels at the cervical level, 10 or 20 cm/s for the aqueduct and 5 cm/s for the cervical subarachnoid space (SAS). Dynamic flow images were analyzed with in-house processing software. The patients' results were compared with those obtained for HEVs (n = 12), and for NPH patients (n = 13), using multivariate analysis.

Results

Arterial tCBF and the calculated pulsatility index were significantly greater in a-MCI patients than in HEVs. In contrast, vascular parameters were lower in NPH patients. Cervical CSF flow analysis yielded similar values for all four populations. Aqueductal CSF stroke volumes (in μl per cardiac cycle) were similar in HEVs (34 ± 17) and AD patients (39 ± 18). In contrast, the aqueductal CSF was hyperdynamic in a-MCI patients (73 ± 33) and even more so in NPH patients (167 ± 89).

Conclusion

Our preliminary data show that a-MCI patients present with high systolic arterial peak flows, which are associated with higher mean total cerebral arterial flows. Aqueductal CSF oscillations are within normal range in AD and higher than normal in NPH. This study provides an original dynamic vision of cerebral neurodegenerative diseases, consistent with the vascular theory for AD, and supporting primary flow disturbances different from those observed in NPH.

Design and construction of a brain phantom to simulate neonatal MR images

This paper presents the design and construction of a 3D digital neonatal neurocranial phantom and its application for the simulation of brain magnetic resonance (MR) images. Commonly used digital brain phantoms (e.g. BrainWeb) are based on the adult brain. With the growing interest in computer-aided methods for neonatal MR image processing, there is a growing demand a digital phantom and brain MR image simulator especially for the neonatal brains. This is due to the pronounced differences between adult and neonatal brains not only in terms of size but also, more importantly, in terms of geometrical proportions and the need to subdivide white matter into two different tissue types in neonates. Therefore the neonatal brain phantom created in the here presented work consists of 9 different tissue types: skin, fat, muscle, skull, dura mater, gray matter, myelinated white matter, nonmyelinated white matter and cerebrospinal fluid. Each voxel has a vector consisting of 9 components, one for each of these nine tissue types. This digital phantom can be used to map simulated magnetic resonance signal intensities resulting in simulated MR images of the newborns head. These images with controlled degradation of the image data present a representative, reproducible data set ideal for development and evaluation of neonatal MRI analysis methods, e.g. segmentation and registration algorithms.

[Contribution of phase-contrast MRI to the management of patients with normal pressure hydrocephalus: Can it predict response to shunting?]

The diagnosis and management of patients with idiopathic normal-pressure hydrocephalus (NPH) remain somewhat controversial and there is no clear guideline for assessing the post-shunt outcome. The objective of this study was to investigate whether cerebrospinal fluid (CSF) flow dynamics is linked to post-shunt improvement. Fourteen NPH patients (nine males and five females; mean age, 68 years) investigated by magnetic resonance imaging (MRI) before surgical diversion of CSF were retrospectively reviewed. Phase-contrast sequences were added to the morphological clinical protocol for quantification of CSF oscillations, which were recorded at the level of the cerebral aqueduct and the C2 and C3 subarachnoid spaces (SAS). The phase-contrast images were analysed with custom-designed dedicated flow segmentation software. The oscillations measured in this hydrocephalus population were compared to a previously studied healthy population. A difference of at least two standard deviations was used to define a hyperdynamic or hypodynamic state of CSF flow. The cervical CSF flow of the hydrocephalus patients was not significantly different from those of the volunteer population. Of the 14 hydrocephalus patients, 12 had a good response to the shunt. Of these, 10 presented an increased ventricular CSF flow, one a low ventricular CSF flow, and the last one had a normal ventricular CSF flow. Phase-contrast MRI can help develop guidelines for surgical management of NPH. The shunt responders appear to be the patients with hyperdynamic ventricular CSF flow and normal cervical CSF flow.

Neonatal probabilistic models for brain, CSF and skull using T1-MRI data: preliminary results

Inappropriate results may be produced if one uses adult or pediatric atlases for evaluation of neonatal cerebral images for morphological studies. This is mainly due to anatomical particularities typical for this early stage of development. In this paper, we describe the construction of a digital neonatal brain atlas from a set of images of neonates aged between 39 and 42 weeks. It consists of probabilistic models for brain, cerebrospinal fluid (CSF) and skull. In the first step, the selected images are segmented automatically followed by manual correction. In the second step, the images are normalized to a stereotaxic space defined by the neonatal brain atlas template GRAMFC_T(39-42) using a popular normalization algorithm implemented in Statistical Parametric Mapping (SPM). The normalization parameters of individual subjects are then used to resample the corresponding brain, CSF and skull. Finally, to construct the probabilistic models, the average is computed for each voxel location. The atlas might be used for different applications such as source localization or neonatal structural image analysis.

Phase-contrast MR imaging support for the diagnosis of aqueductal stenosis

BACKGROUND AND PURPOSE

Patients with aqueductal stenosis (AS) present with various clinical and radiologic features. Conventional MR imaging provides useful information in AS but depends on a subjective evaluation by the neuroradiologist. The purpose of this study was to evaluate the support of the phase-contrast MR imaging (PC-MR imaging) technique (sensitive to CSF flows) for the diagnosis of AS.

MATERIALS AND METHODS

We retrospectively considered 17 patients who underwent PC-MR imaging to explore hydrocephalus, with the absence of CSF flow at the aqueductal level. We analyzed their clinical and morphologic MR imaging data.

RESULTS

None of the usually reported direct or indirect signs of aqueductal obstruction were seen in 7 patients in whom the clinical suggestion of AS was confirmed by PC-MR imaging results. Seven patients in this population had a third ventriculostomy, and 5 of them were among those in whom conventional MR imaging failed to reveal signs of aqueductal obstruction. All of these 7 patients had a positive postsurgical outcomes. The analysis of CSF and vascular dynamic data in this population was compared with an aged-matched population, and these data were found similar except for the fourth ventricular CSF flush flow latency.

CONCLUSIONS

PC-MR imaging supports the diagnosis of CSF flow blockage at the aqueductal level in a reliable, reproducible, and rapid way, which aids in the diagnosis of AS in patients with clinical and/or radiologic suggestion of obstructive hydrocephalus. We, therefore, suggest using this technique in the current evaluation of hydrocephalus.

[Acute CSF changes in the mesencephalon aqueduct after subarachnoid hemorrhage as measured by PC-MRI]

PURPOSE

Determining acute intracranial hydrodynamic changes after subarachnoid hemorrhage through an analysis of the CSF stroke volume (SV) as measured by phase-contrast MRI (PC-MRI) in the mesencephalon aqueduct.

METHOD

A prospective study was performed in 33 patients with subarachnoid hemorrhage. A PC-MRI imaging study was performed n the acute phase (< 48 hours). CSF flow was measured in the aqueduct. The appearance of acute hydrocephalus (HCA) was then compared with data on CSF flow, and the location of the intraventricular and perimesencephalic bleeding.

RESULTS

CSF analysis was performed on 27 patients, 11 of whom presented with an acute HCA. All 11 patients had an abnormal SV in the aqueduct: patients with a communicating HCA had an increased SV (n=8); and patients with a noncommunicating HCA had a nil SV (n=3). Patients with a normal SV in the aqueduct did not develop an acute HCA. Intraventricular bleeding significantly led to HCA (P=0.02), which was of the communicating type in 70% of cases.

CONCLUSION

Subarachnoid hemorrhage leads to intracranial CSF hydrodynamic modifications in the aqueduct in the majority of patients. CSF flow can help us to understand the mechanism of the appearance of acute HCA. Indeed, hydrocephalus occurred - of the communicating type in most cases - even in the presence of intraventricular bleeding.

High-resolution electroencephalography and source localization in neonates

Although Electroencephalography (EEG) source localization is being widely used in adults, this promising technique has not yet been applied to newborns because of technical difficulties, such as lack of data concerning the newborn skull conductivity, thickness, and homogeneity. Using a new type of EEG headcap molded on each baby's head, we aimed to determine whether this technique could be adapted to neonates, and to evaluate the importance of these technical difficulties. We carried out EEG source reconstruction of the recordings of five neonates using dipole fit algorithm. We used four different head models for each neonate, obtained from individual MRI scans: normal skull thickness and conductivity of 0.0042 S/m; normal thickness and conductivity of 0.33 S/m; increased thickness and conductivity of 0.0042 S/m; and normal thickness and conductivity with a modeled bregma fontanel. Dipole locations were consistent with MRI and clinical data. The mean difference between the dipole locations in the 0.0042 and the 0.33 S/m skull layer models was 11.6 +/- 2.5 mm, with an average 29.7% decrease in magnitude for the 0.33 S/m model but no significant changes for the dipoles orientation. Skull layer thickness had a large influence on magnitude, but no significant effect on position and orientation. The mean difference between the dipole locations induced by the modeled fontanel was 2.0 +/- 2.1 mm, with an average 2.1% increase in magnitude. Our results show that EEG source localization is feasible in neonates. With further development, the technique may prove useful for neurological evaluation of neonates.

Aging effects on cerebral blood and cerebrospinal fluid flows

Phase-contrast magnetic resonance imaging (PC-MRI) is a noninvasive reliable technique, which enables quantification of cerebrospinal fluid (CSF) and total cerebral blood flows (tCBF). Although it is used to study hydrodynamic cerebral disorders in the elderly group (hydrocephalus), there is no published evaluation of aging effects on both tCBF and CSF flows, and on their mechanical coupling. Nineteen young (mean age 27+/-4 years) and 12 elderly (71+/-9 years) healthy volunteers underwent cerebral MRI using 1.5 T scanner. Phase-contrast magnetic resonance imaging pulse sequence was performed at the aqueductal and cervical levels. Cerebrospinal fluid and blood flow curves were then calculated over the cardiac cycle, to extract the characteristic parameters: mean and peak flows, their latencies, and stroke volumes for CSF (cervical and aqueductal) and vascular flows. Total cerebral blood flow was (P<0.01) decreased significantly in the elderly group when compared with the young subjects with a linear correlation with age observed only in the elderly group (R(2)=0.7; P=0.05). Arteriovenous delay was preserved with aging. The CSF stroke volumes were significantly reduced in the elderly, at both aqueductal (P<0.01) and cervical (P<0.05) levels, whereas aqueduct/cervical proportion (P=0.9) was preserved. This is the first work to study aging effects on both CSF and vascular cerebral flows. Data showed (1) tCBF decrease, (2) proportional aqueductal and cervical CSF pulsations reduction as a result of arterial loss of pulsatility, and (3) preserved intracerebral compliance with aging. These results should be used as reference values, to help understand the pathophysiology of degenerative dementia and cerebral hydrodynamic disorders as hydrocephalus.

A neonatal atlas template for spatial normalization of whole-brain magnetic resonance images of newborns: Preliminary results

Commonly used brain templates are based on adults' or children's brains. In this study, we create a neonatal brain template. This becomes necessary because of the pronounced differences not only in size but even more importantly in geometrical proportions of the brains of adults and children as compared to the ones of newborns. The template is created based on high resolution T1 magnetic resonance images of 7 individuals with gestational ages between 39 and 42 weeks at the dates of examination. As usual, the created template presents two characteristics in a single image: an average intensity and an average shape. The normalization process to map subjects to the same space is done using SPM2 (Statistical Parametric Mapping) and its deformation toolbox. It consists of two steps: an affine and a nonlinear registration for global and local alignments, respectively. The template was evaluated by (i) study of anatomical local deviations and (ii) amount of local deformations of brain tissues in normalized neonatal images. The extracted results were compared with the ones obtained by normalization using adult and pediatric templates. It was shown that the application of our neonatal brain template for alignment of neonatal images results in a pronounced increase in performance of the normalization procedure as indicated by reduction of deviation of anatomical equivalent structures. The neonatal atlas template is freely downloadable from http://www.u-picardie.fr/labo/GRAMFC.

Value of phase contrast magnetic resonance imaging for investigation of cerebral hydrodynamics

OBJECTIVE

Phase Contrast Magnetic Resonance Imaging (PCMRI) is a noninvasive technique that can be used to quantify variations of flow during the cardiac cycle. PCMRI allows investigations of blood flow dynamics in the main arteries and veins of the brain but also the dynamics of cerebrospinal fluid. These cerebral flow investigations provide a description of the regulation mechanisms of intracranial pressure during the cardiac cycle. The objective of this paper is to describe the contribution of this technique in diseases related to disorders of cerebral hydrodynamics in the light of 5 clinical cases.

METHOD

Flow measurements were performed using PCMRI sequences on a 1.5 Tesla MR imager in 4 patients with symptomatic ventricular dilation and 1 patient with a syringomyelic cavity.

RESULTS

Flow quantification in these 5 patients, representative of the diseases mainly concerned by cerebral hydrodynamics, is useful to guide the indication for ventricular shunting in patients with hydrocephalus, to demonstrate obstruction of the cerebral aqueduct, to demonstrate recirculation of ventricular CSF after ventriculostomy and to characterize the dynamic features of CSF inside a spinal cavity.

CONCLUSION

PCMRI, now available to neurosurgeons, is complementary to morphological MR and provides quantitative information on cerebral hydrodynamics. This information is mainly used to confirm alteration of CSF flow in the cerebral and spinal compartments. PCMRI is also a functional tool to better understand the pathophysiology of hydrocephalus and syringomyelia.

Brain hydrodynamics study by phase-contrast magnetic resonance imaging and transcranial color doppler

PURPOSE

To evaluate the contributions of phase-contrast magnetic resonance (PCMR) and transcranial color Doppler (TCCD) imaging in the investigation of cerebral hydrodynamics.

MATERIALS AND METHODS

A total of 13 healthy subjects were studied. Blood velocity measurements were performed with TCCD and gated PCMR imaging in major intracranial and extracranial arteries stages. Peak systolic velocity and end-diastolic velocity were extracted to establish correlations between TCCD and PCMR imaging. Cerebral blood flow (CBF) and intracranial volume change (IVC) during the cardiac cycle were calculated, taking into account cerebrospinal fluid (CSF) oscillations.

RESULTS

Despite an underestimation of velocities with PCMR imaging, significant correlations were observed for velocity measurements between the two modalities in extracranial vessels, but were poorly correlated in intracranial vessels. PCMR data processing gave a mean CBF of 690+/-90 mL/minute.

CONCLUSION

PCMR imaging provides complementary information to TCCD to assess various intracranial parameters such as instantaneous velocities, blood and CSF flow distributions, volume variation, or pressure regulation mechanisms during cardiac cycles.

[Cerebrospinal fluid flow imaging in the meningeal hemorrhage]

BACKGROUND AND PURPOSES

Cerebrospinal fluid (CSF) flow oscillations are synchronized with cerebral blood flow and are also involved in the control of variations of intracranial pressure during the cardiac cycle. The aim of this study was to investigate the possible alterations of CSF flow dynamics during the acute phase of meningeal hemorrhage (MH).

METHODS

Eleven patients with MH confirmed by computed tomography (CT) scan were examined by MR imaging, which comprised morphological sequences and flow dynamic sequences for quantification of CSF oscillations and cerebral blood flow rates. CSF oscillations were recorded at the cerebral aqueduct and C2-C3 subarachnoid space (SAS), where a vascular sequence was also performed to quantify artery blood flow. These results were compared to oscillations of a population of 44 control subjects and a difference of at least two standard deviation was used to define a hyperdynamic or hypodynamic appearance of CSF flow. Dilatation of the ventricular system was determined on radiographs by two neuroradiologists and a neurosurgeon.

RESULTS

Only four patients presented normal ventricular CSF flow, one patient presented hypodynamic flow and five patients presented hyperdynamic flow. Five patients had normal cervical CSF flow and five patients presented hyperdynamic flow. The two patients with ventricular dilatation both presented hyperdynamic ventricular CSF flow associated with normal cervical CSF flow. One patient was excluded.

CONCLUSION

Abnormal CSF flow dynamics were shown suggesting the hypothesis that bleeding increases intracranial volume and induces a reduction of cerebral compliance and an increase of intracranial pressure. The increased oscillations in the ventricular system would therefore predispose to dilatation.

Brain magnetic resonance imaging in patients with Cowden syndrome

Cowden syndrome (CS) is a rare autosomal dominant genodermatosis, characterized by multiple hamartomas, particularly of the skin, associated with high frequencies of breast, thyroid, and genitourinary malignancies. Although Lhermitte-Duclos disease (LDD) or dysplastic gangliocytoma of the cerebellum, a slowly progressive unilateral tumor, is a major criterion of CS, its frequency in patients with CS is unknown. Other cerebral abnormalities, especially meningioma and vascular malformations, have also been described, albeit rarely, in these patients. The aim of the current study was to use cerebral magnetic resonance imaging (MRI) to evaluate LDD frequency and to investigate other brain abnormalities in CS patients recruited by dermatologists. A multicenter study was conducted in 8 hospital dermatology departments between January 2000 and December 2003. Twenty patients with CS were included; specific cerebral MRI abnormalities were found in 35% (7/20) of them. Cerebral MRI revealed LDD in 3 patients, a meningioma in 1, and numerous vascular malformations in 6 patients. Five patients had venous angiomas (3 associated with LDD) and 2 patients had cavernous angiomas (1 associated with LDD and a venous angioma). The discovery of asymptomatic LDD in 3 patients and a cavernous angioma in another prompted us to perform neurologic examinations regularly and MRI to estimate the size and the extension of the tumor, and to assess the need for surgery. CS similarities with Bannayan-Riley-Ruvalcaba (BRR) are discussed because some patients could also have the BRR phenotype (for example, genital lentigines, macrocephaly, multiple lipomas) and because BRR seems to have more central nervous system vascular anomalies. Because CS signs can involve numerous systems, all physicians who might encounter this disease should be aware of its neurologic manifestations. Our findings confirm the contribution of brain MRI to detecting asymptomatic LDD, vascular malformations, and meningiomas in patients with CS.

MR cholangiopancreatography versus endoscopic sonography in suspected common bile duct lithiasis: a prospective, comparative study

OBJECTIVE

Our purpose was to compare the accuracy of MR cholangiopancreatography and endoscopic sonography for the diagnosis of common bile duct stones in patients with a mild to moderate clinical suspicion of common bile duct stones.

SUBJECTS AND METHODS

Forty-seven patients were prospectively enrolled. Inclusion criteria included acute pancreatitis, subclinical jaundice, and clinical features of common bile duct stone migration. Radial endoscopic sonography and MR cholangiopancreatography with the single-shot fast spin-echo technique were performed a maximum of 48 hr apart. The gold-standard diagnosis was obtained with ERCP (n = 20) or intraoperative cholangiography (n = 14) if the results of endoscopic sonography or MR cholangiopancreatography were abnormal or if a cholecystectomy was performed, or by clinical and biochemical follow-up (n = 11) if the results of endoscopic sonography and MR cholangiopancreatography were normal.

RESULTS

The final diagnosis was common bile duct stones in 16 patients, malignant obstructions in four, and another biliary disease in two (lithiasis migration aspect with papillary edema); 23 patients had no biliary disease. The sensitivity and specificity of MR cholangiopancreatography were, respectively, 90.5% and 87.5% for etiologic diagnosis and 87.5% and 96.6% for the detection of common bile duct stones. The corresponding values for endoscopic sonography were 86.4% and 91.3% for etiologic diagnosis and 93.8% and 96.6% for visualization of choledocholithiasis. Accuracy did not significantly differ between the techniques.

CONCLUSION

In cases of mild to moderate suspicion of choledocholithiasis, the accuracies of endoscopic sonography and MR cholangiopancreatography are similar. Because MR cholangiopancreatography is noninvasive, it may be preferred for this indication.

Relationship Between Cerebrospinal Fluid and Blood Dynamics in Healthy Volunteers and Patients with Communicating Hydrocephalus

RATIONALE AND OBJECTIVES

Using magnetic resonance imaging (MRI), we investigated cerebral blood and cerebrospinal fluid (CSF) flows in patients with communicating hydrocephalus (CH) and in healthy volunteers to determine the contribution of CSF flow to brain pressure regulation in CH patients.

METHODS

Cine phase-contrast MRI data from 16 healthy volunteers and 12 patients with CH characterized by hyperdynamic aqueductal CSF flow were analyzed using in-house image-processing software that automatically measured flow curves. Amplitude and temporal CSF and blood flow parameters were compared in the 2 groups.

RESULTS

Jugular peak flow occurred significantly earlier (P < 0.01) in the CH patients than in the healthy volunteers. Cervical CSF oscillations were not significantly different between the 2 groups.

CONCLUSION

Venous vessel compression and/or changes in intracranial subarachnoid CSF flow produce an increase in ventricular CSF flush that compensates for vascular brain expansion in patients with CH.

Differential MRI diagnosis between brain abscesses and necrotic or cystic brain tumors using the apparent diffusion coefficient and normalized diffusion-weighted images

Magnetic Resonance Diffusion-Weighted Imaging (DWI) has been reported to be helpful for the differential diagnosis between abscesses and cystic/necrotic brain tumors. However the number of patients is still limited, and the sensitivity and specificity of the method remain to be confirmed. The primary purpose of this study was to investigate a larger sample of patients, all investigated under the same experimental conditions, in order to obtain statistically significant data. Moreover, there is no consensus about the appropriate values of b required to use to make an accurate diagnosis from DWI. The secondary purpose of this study was to determine the discriminating threshold b values for raw diffusion-weighted images and for normalized diffusion-weighted images. On the basis of 14 abscesses, 10 high-grade gliomas and 2 metastases, we show that the calculation of accurate Apparent Diffusion Coefficient (ADC) values gives a specificity rate of 100%. Without ADC calculation, we show that image normalization is required to make an accurate differential diagnosis, and we highlight the ability of DWI to discriminate between brain abscesses and cystic/necrotic brain tumors using normalized signal intensity at lower b values (503 s/mm(2)) than usual.

Medullary gnathostomiasis in a white patient: use of immunodiagnosis and magnetic resonance imaging

A 48-year-old French diplomat presented with a sensory-motor paraparesis of rapid onset, leading to paraplegia. Successive magnetic resonance image scans showed lesions of the thoracic spinal cord that were at different levels from one examination to the next. Specific anti-gnathostome antibodies were detected by means of enzyme-linked immunosorbent assay and Western blot test in both plasma and cerebrospinal fluid. Albendazole treatment prevented disease progression, but only partial regression of the neurologic symptoms was obtained.

[MR diffusion and perfusion imaging in clinical practice]

MR functional imaging, due to the improvement in ultra-speed imaging technology such as echo-planar imaging, has become a very powerful technique since the beginning of the nineties. This imaging technique is divided into diffusion imaging, perfusion imaging and cerebral activation. Diffusion imaging probes the mobility of water molecules characterized by a diffusion coefficient called the apparent diffusion coefficient (ADC) for biological tissues. Perfusion imaging gives hemodynamic information due to the regional cerebral blood volume by the use of contrast agents such as chelates of gadolinium carrying strong magnetic susceptibility. Both imaging techniques can provide information in a wide nosological range : cerebral ischemia, in the acute phase and in case of intracranial tumors, contributing to tumoral grading, localizing the site of biopsy, and assessing response to therapy (after radiotherapy for example). Nevertheless, a wide range of domains remains incompletely studied, for example cerebral white matter diseases and neurodegenerative diseases. For clinical applications, a precise knowledge of the potentials of both techniques and their limitations is needed. Limitations result from the large number of often patient-related parameters, imaging technique (perfusion) and data analysis. Powerful software has been developed in the workstation environment. Thus this imaging technique requires up-to-date equipment and close collaboration between clinical and research teams for optimal efficiency.

[Value of imaging in early diagnosis of peripheral vein tumors]

Peripheral venous tumors are uncommon and their delayed clinical expression leads to poor prognosis. We report a series of 7 cases including 6 leiomyosacromas and 1 hemangioendothelioma. Duplex Doppler and MR imaging appeared to be best suited for diagnosis, allowing an evaluation of extension and an analysis of associated endoluminal thrombi. These imaging techniques help guide surgery and improve prognosis.

[Spontaneous contained perforation of a hiatal hernia. A new equivalent of Boerhaave's syndrome]

The authors report the case of an alcoholic 49-year-old man hospitalized because of epigastric pain and hematemesis. Upper endoscopy showed a tear in a hiatus hernia (interpreted as a Mallory-Weiss lesion) and a bleeding duodenal ulcer. Upper barium examination performed 16 days later revealed a mediastinal collection communicating with the hiatus hernia. Retrospective evaluation of chest roentgenograms obtained at admission showed a limited mediastinal gas collection. With medical management, the collection progressively disappeared. From a theoretical point of view, this case illustrates Watts' theory on the effect of hiatus hernia on the site of postemetic injury. From a practical point of view, it confirms that conservative management is indicated in contained spontaneous perforations.