Overestimation of moderate carotid stenosis assessed by both Doppler US and contrast enhanced 3D-MR angiography in the CARMEDAS study.

PURPOSE: To evaluate the agreement and diagnostic accuracy of Contrast enhanced magnetic resonance angiography (CE-MRA), Doppler ultrasound (DUS) and Digital subtraction angiography (DSA) in the assessment of carotid stenosis. METHODS: DUS, CE-MRA and DSA were performed in 56 patients included in the Carotide-angiographie par résonance magnétique-échographie-doppler-angioscanner (CARMEDAS) multicenter study with a carotid stenosis ≥ 50%. Three readers evaluated stenoses on CE-MRA and DSA (NASCET criteria). Velocities criteria were used for stenosis estimation on DUS. RESULTS: CE-MRA had a sensitivity and specificity of 96-98% and 66-83% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 94% and 76-84% respectively for carotid stenoses ≥ 70%. The interobserver agreement of CE-MRA was excellent, except for moderate stenoses (50-69%). DUS had a sensitivity and specificity of 88 and 75% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 83 and 86% respectively for carotid stenoses ≥ 70%. Combined concordant CE-MRA and DUS had a sensitivity and specificity of 100 and 85-90% respectively for carotid stenoses ≥ 50% and a sensitivity and specificity of 96-100% and 80-87% respectively for carotid stenoses ≥ 70%. The positive predictive value of the association CE-MRA and DUS for carotid stenoses ≥ 70% is calculated between 77 and 82% while the negative predictive value is calculated between 97 and 100%. CE-MRA and DUS have concordant findings in 63-72%, and the overestimations cases were recorded only for carotid stenosis ≤ 69%. CONCLUSION: Combined DUS-CE-MRA is excellent for evaluation of severe stenosis but remains debatable in moderate stenosis (50-69%) due to the risk of overestimations.

Lacunar lesions are independently associated with disability and cognitive impairment in CADASIL.

OBJECTIVE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary arteriopathy caused by mutations of the Notch3 gene. The disease is characterized by T2-hyperintense lesions (subcortical white matter lesions), T1-hypointense lesions (lacunar lesions), and T2*-weighted gradient-echo (GE) lesions (cerebral microhemorrhages [CMs]) visualized on clinical MRI sequences and is considered as a model of "pure" subcortical ischemic vascular dementia. Although numerous studies have investigated the impact of white matter lesions in patients with CADASIL, the clinical importance of lacunar lesions remains unknown. Our purpose was to examine the influence of the visible MRI markers in the disease, including the load of lacunar lesions on cognitive impairment and disability in CADASIL. METHODS: We collected clinical data from 147 consecutive patients enrolled in an ongoing two-center prospective cohort study. Degree of disability was assessed by modified Rankin scale and Barthel index. Degree of cognitive impairment was assessed by Mattis Dementia Rating Scale and Mini-Mental Status Examination. T1-weighted, fluid-attenuated inversion recovery, and GE images were obtained on a 1.5-T MRI. Volume and location of lacunar lesions, white matter hyperintensities (WMHs), and CMs were assessed. RESULTS: There was a significant independent association between age, volume of lacunar lesions, and global cognitive function scales when analyzed in a multivariable model. In contrast, WMHs and CMs had no independent influence on cognitive function. Disability in this cohort was associated with volume of lacunar lesions, CMs, systolic blood pressure, and age but not with WMHs. CONCLUSIONS: Among the lesions observed on conventional MRI in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the overall lacunar lesion burden seems to have the most important impact on cognitive function and disability. These findings suggest that preventive strategies to decrease the risk of lacunar lesions as observed on MRI may reduce disease-related impairment in CADASIL. These results suggest that lacunar lesions may also play a key role in disability and cognitive impairment in more common forms of small-vessel disease.

Plaque density on CT, a potential marker of ischemic stroke.

The authors sought to determine in a retrospective analysis whether carotid plaque soft TD on CT is associated with recent ischemic neurologic events. Among 141 patients (99 asymptomatic), 106 plaques with more than 50% stenosis were selected for density measurements. They found an odds ratio for neurologic events associated with a 10-point decrease in density of 1.54 (p = 0.002), showing an association between plaque density and neurologic events.

Marchiafava-Bignami disease: diffusion-weighted MRI in corpus callosum and cortical lesions.

The clinical diagnosis of Marchiafava-Bignami disease (MBD) can be difficult. Acute demyelination of the corpus callosum is characteristic of the disease. The authors report the use of MR diffusion-weighted imaging (DWI) in six cases of acute MBD. They show that apparent diffusion coefficient restriction of the corpus callosum and cortical lesions were associated with a higher mortality rate and more severe cognitive sequelae.

[Correlation between cranial vault size and brain size over time: preliminary MRI evaluation]. / Evolution comparative de la voûte crânienne et du parenchyme cérébral avec l'âge: étude préliminaire en IRM.

OBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures.

Cognitive impairment as marker of diffuse brain abnormalities in early relapsing remitting multiple sclerosis.

OBJECTIVES: To establish the frequency of cognitive impairment in a population based sample of patients with recently diagnosed relapsing-remitting multiple sclerosis (RRMS), and to determine the relation between cognitive abnormalities and the extent of macroscopic and microscopic tissue damage revealed by magnetic resonance imaging (MRI) and magnetisation transfer (MT) imaging. METHODS: 58 patients with RRMS consecutively diagnosed in the previous six months in Aquitaine and 70 healthy controls underwent a battery of neuropsychological tests. Lesion load and atrophy indices (brain parenchymal fraction and ventricular fraction) were measured on brain MRI. MT ratio (MTR) histograms were obtained from lesions, normal appearing white matter (NAWM), and normal appearing grey matter (NAGM). Gadolinium enhanced lesions were counted. RESULTS: 44 RRMS patients could be individually matched with healthy controls for age, sex, and education. Patients performed worse in tests of verbal and spatial memory, attention, information processing speed, inhibition, and conceptualisation. Measures of attention and information processing speed were correlated with lesion load, mean NAWM MTR, and the peak location of the NAGM MTR histogram in the patients. Multivariate regression analysis showed that lesion load and mean NAWM MTR were among the MR indices that were most significantly associated with impairment of attention and information processing speed in these early RRMS cases. CONCLUSIONS: Cognitive impairment appears to be common in the early stages of RRMS, mainly affecting attention, information processing speed, memory, inhibition, and conceptualisation. The severity of these deficits reflects the extent of the lesions and the severity of tissue disorganisation outside lesions.

Automated segmentation of multiple sclerosis lesions in multispectral MR imaging using fuzzy clustering.

A method is presented for fully automated detection of Multiple Sclerosis (MS) lesions in multispectral magnetic resonance (MR) imaging. Based on the Fuzzy C-Means (FCM) algorithm, the method starts with a segmentation of an MR image to extract an external CSF/lesions mask, preceded by a local image contrast enhancement procedure. This binary mask is then superimposed on the corresponding data set yielding an image containing only CSF structures and lesions. The FCM is then reapplied to this masked image to obtain a mask of lesions and some undesired substructures which are removed using anatomical knowledge. Any lesion size found to be less than an input bound is eliminated from consideration. Results are presented for test runs of the method on 10 patients. Finally, the potential of the method as well as its limitations are discussed.

A pyramidal approach for automatic segmentation of multiple sclerosis lesions in brain MRI.

Quantitative assessment of Magnetic Resonance Imaging (MRI) lesion load of patients with multiple sclerosis (MS) is the most objective approach for a better understanding of the history of the pathology, either natural or modified by therapies. To achieve an accurate and reproducible quantification of MS lesions in conventional brain MRI, an automatic segmentation algorithm based on a multiresolution approach using pyramidal data structures is proposed. The systematic pyramidal decomposition in the frequency domain provides a robust and flexible low level tool for MR image analysis. Context-dependent rules regarding MRI findings in MS are used as high level considerations for automatic lesion detection.

[MRI in the study of multiple sclerosis]. / Apport de l'IRM à l'étude de la sclérose en plaques.

Magnetic resonance imaging (MRI) has provided considerable insight into the pathological process and disease activity and progression in multiple sclerosis. MRI has become an important tool for the diagnosis of multiple sclerosis, and increasingly for monitoring treatment trial. The growing use of MRI calls for careful consideration in applications so that the technology is not misused. Here we propose a summary of the literature on MRI in application in clinical neurology.