Event-related potentials and deep grey matter atrophy in multiple sclerosis: Exploring the possible associations with cognition.

BACKGROUND: Event-related potentials (ERPs) have been proposed as a neurophysiological biomarker to capture cognitive dysfunction in multiple sclerosis (MS). Few studies have evaluated the relationships between ERPs and brain atrophy as known marker of structural brain damage related to cognitive impairment (CI). OBJECTIVES: To explore the relationships of brain atrophy, including of the cortex and deep grey matter, with ERP abnormalities and cognitive function, as defined using the Brief Repeatable Battery of Neuropsychological Tests (BRBN). RESULTS: Seventy-eight patients with relapsing-remitting MS were enroled, of which 38 (48.7%) had CI. Independent t-test comparisons of the ERP parameters found a significant difference in P300 wave latency, with a latency of 343.7 ± 32.6 ms in the CI group vs. 320.3 ± 16.5 ms in the cognitively preserved (CP) group (p = 0.001). Significant differences in the MRI measurements, including the cortex (p = 0.02) and deep grey matter structures [thalamus (p = 0.001), amygdala (p = 0.030), and nucleus accumbens (p = 0.004)) were observed, with lower measurements in the CI group. Regression models were also performed to explore the impact of brain volumes on ERP parameters. This showed a relationship between P300 latency and the lower amygdala (p = 0.02) and hippocampus (p = 0.03) volumes, while the amplitude of the P300 was significantly associated with a lower cortex volume (p = 0.01). CONCLUSION: Cortex volume emerged as the most significant predictor of the P300 amplitude. The amygdala and hippocampal volumes were found to influence P300 latency, highlighting the role of deep grey matter atrophy in ERPs for the first time. The combination of structural MRI and neurophysiological techniques, sensitive to diverse aspects of MS pathology, could improve the understanding of CI in MS and its neurodegenerative and inflammatory substrate.

Development and validation of a computer-aided diagnostic tool to screen for age-related macular degeneration by optical coherence tomography.

BACKGROUND: To develop and assess the technical validity of new computer-aided diagnostic software (CAD) for automated analyses of optical coherence tomography (OCT) images for the purpose of screening for neovascular age-related macular degeneration. METHODS: Artificial visual techniques were used to develop the CAD in two steps: normalisation and feature vector extraction from OCT images; and training and classification by means of decision trees. Technical validation was performed by a retrospective study design based on OCT images randomly extracted from clinical charts. Images were classified as normal or abnormal to serve for screening purposes. Sensitivity, specificity, positive predictive values and negative predictive values were obtained. RESULTS: The CAD was able to quantify image information by working in the perceptually uniform hue-saturation-value colour space. Particle swarm optimisation with Haar-like features is suitable to reveal structural features in normal and abnormal OCT images. Decision trees were useful to characterise normal and abnormal images using feature vectors obtained from descriptive statistics of detected structures. The sensitivity of the CAD was 96% and the specificity 92%. CONCLUSIONS: This new CAD for automated analysis of OCT images offers adequate sensitivity and specificity to distinguish normal OCT images from those showing potential neovascular age-related macular degeneration. These results will enable its clinical validation and a subsequent cost-effectiveness assessment to be made before recommendations are made for population-screening purposes.

Role of perfusion-weighted imaging at 3 Tesla in the assessment of malignancy of cerebral gliomas.

PURPOSE: This study was performed to clarify the role of perfusion-weighted imaging (PWI) at 3 Tesla in the characterisation of haemodynamic heterogeneity within gliomas and surrounding tissues and in the differentiation of high-grade from low-grade gliomas. MATERIALS AND METHODS: We examined 36 patients with histologically verified gliomas (25 with high-grade and 11 with low-grade gliomas). PWI was performed by first-pass gadopentetate dimeglumine T2*-weighted echo-planar images, and cerebral blood volume (CBV) maps were computed with a nondiffusible tracer model. Relative CBV (rCBV) was calculated by dividing CBV in pathological areas by that in contralateral white matter. RESULTS: In high-grade gliomas, rCBV were markedly increased in mass [mean+/-standard deviation (SD), 4.3+/-1.2] and margins (4.0+/-1.1) and reduced in necrotic areas (0.3+/-0.3). Oedematous-appearing areas were divided in two groups according to signal intensity on T2-weighted images: tumour with lower (nearly isointense to grey matter) and oedema with higher (scarcely isointense to cerebrospinal fluid) signal intensity. Tumour showed significantly higher rCBV than did oedema (1.8+/-0.5 vs. 0.5+/-0.2; p<0.001) areas. In low-grade gliomas, mass (2.0+/-1.5) and margin (2.2+/-1.2) rCBV were significantly lower than in high-grade gliomas (p<0.001). CONCLUSIONS: Three-Tesla PWI helps to distinguish necrosis from tumour mass, infiltrating tumour from oedema and high-grade from low-grade gliomas. It enhances the magnetic resonance (MR) assessment of cerebral gliomas and provides useful information for planning surgical and radiation treatment.

Contrast-bolus MR angiography of the transplanted kidney with a low-field (0.5-T) scanner: diagnostic accuracy, sensitivity and specificity of images and reconstructions in the evaluation of vascular complications.

PURPOSE: This study was performed to assess the feasibility, interobserver variability, sensitivity, specificity and diagnostic accuracy of raw data and postprocessed images from a low-field (0.5-T) magnetic resonance (MR) unit in evaluating vascular complications of kidney grafts. MATERIALS AND METHODS: We enrolled 49 patients undergoing MR angiography (MRA) for a clinical suspicion of renal artery stenosis. The raw data, maximum intensity projections (MIP) and multiplanar reconstruction (MPR) image sets were evaluated independently. We calculated the number and degree of stenosis, and sensitivity, specificity and accuracy for MIP, MPR and raw data image sets, together with interobserver variability. RESULTS: Interobserver agreement was substantial. There were no differences among the MIP and MPR algorithms and raw data images for the detection of stenosis. Raw data images were more accurate in quantifying the severity of stenosis, with higher sensitivity (75% vs. 62.5%), equal specificity and higher diagnostic accuracy (75% vs. 71.43%). CONCLUSIONS: Contrast-enhanced MRA, even with a low-field (0.5-T) unit, is a feasible, sensitive and accurate technique for the study of the renal arteries of the transplanted kidney.

Transient focal lesion in the splenium of the corpus callosum: MR imaging with an attempt to clinical-physiopathological explanation and review of the literature.

PURPOSE: This article discusses the possible pathophysiological conditions responsible for magnetic resonance imaging (MRI) finding of transient focal lesions in the splenium of the corpus callosum on the basis of our experience and a review of the literature. MATERIALS AND METHODS: In six patients undergoing computed tomography (CT) and MRI examinations, focal nonhemorrhagic lesions of the splenium of the corpus callosum were incidentally discovered. Patients had been referred for suspected encephalitis (n=2), dural sinus thrombosis (n=1) and multiple sclerosis (n=3). MRI examinations were repeated after 4, 8 and 12 weeks and in two cases also after 6 and 9 months. MRI and medical records were retrospectively reviewed with respect to patients' clinical history, medication and laboratory findings to define lesion aetiology. RESULTS: In all patients, the lesions were isolated, reversible and with no contrast enhancement. In four patients, the lesion disappeared after complete remission of the underlying disease, whereas in two patients, they persisted for 6 and 9 months, respectively. CONCLUSIONS: To our knowledge and according to previous reports, the fact that these lesions are detected in a relatively large number of conditions with heterogeneous etiopathogenetic factors leads to the hypothesis that a common underlying pathophysiological mechanism that, considering signal characteristic, reversibility and white matter location, could be represented by vasogenic oedema.

MRI post-vertebroplasty.

PURPOSE: Percutaneous vertebroplasty (PVP), first described by Hervè Deramond in 1984, is an interventional procedure for the treatment of aggressive vertebral angioma. The aim of this study was to evaluate magnetic resonance imaging (MRI) patterns in the affected vertebrae before and after vertebroplasty by determining changes in signal intensity and size and distribution of bone cement within the vertebra at follow-up carried out at 1 week, 6 months and 12 months. MATERIALS AND METHODS: Fourteen patients were examined using MRI, for a total of 41 treated vertebrae; MRI was performed with a 0.5-Tesla (T) superconductive magnet (SIGNA GE). RESULTS: MRI patterns following vertebroplasty are mainly characterised by the signal produced by the areas surrounding the cement and by the cement itself. There is little effect on the size of the treated vertebra. Acrylic cement appears as an intraspongy focal area of T1 and T2 hypointensity that is mostly oval (34%) or rounded (26.8%); this appearance tends to become stable 6 months after treatment. The area surrounding the cement appears hypointense on T1 and hyperintense on T2, a likely expression of bone marrow oedema; this signal alteration tends to disappear gradually. CONCLUSIONS: In pre- and post-vertebroplasty imaging, MRI is regarded as the reference standard for correct evaluation of both container and content. Awareness of cement changes over time and of the reaction of the surrounding bone tissue is crucial for correct assessment of post-vertebroplasty images.