Vascular Function Is Improved After an Environmental Enrichment Program

Environmental enrichment may slow cognitive decay possibly acting through an improvement in vascular function. Aim of the study was to assess the effects of a 7-month cognitive, social, and physical training program on cognitive and vascular function in patients with mild cognitive impairment. In a single-center, randomized, parallel-group study, 113 patients (age, 65–89 years) were randomized to multidomain training (n=55) or usual care (n=58). All participants underwent neuropsychological tests and vascular evaluation, including brachial artery flow-mediated dilation, carotid–femoral pulse wave velocity, carotid distensibility, and assessment of circulating hematopoietic CD34+ and endothelial progenitor cells. At study entry, an age-matched control group (n=45) was also studied. Compared with controls, patients had at study entry a reduced flow-mediated dilation (2.97±2.14% versus 3.73±2.06%; P =0.03) and hyperemic stimulus (shear rate area under the curve, 19.1±15.7 versus 25.7±15.1×10 −3 ; P =0.009); only the latter remained significant after adjustment for confounders ( P =0.03). Training improved Alzheimer disease assessment scale cognitive (training, 14.0±4.8 to 13.1±5.5; nontraining, 12.1±3.9 to 13.2±4.8; P for interaction visit×training=0.02), flow-mediated dilation (2.82±2.19% to 3.40±1.81%, 3.05±2.08% to 2.24±1.59%; P =0.006; P =0.023 after adjustment for diameter and shear rate area under the curve), and circulating hematopoietic CD34 + cells and prevented the decline in carotid distensibility (18.4±5.3 to 20.0±6.6, 23.9±11.0 to 19.5±7.1 Pa −1 ; P =0.005). The only clinical predictor of improvement of cognitive function after training was established hypertension. There was no correlation between changes in measures of cognitive and vascular function. In conclusion, a multidomain training program slows cognitive decline, especially in hypertensive individuals. This effect is accompanied by improved systemic endothelial function, mobilization of progenitor CD34 + cells, and preserved carotid distensibility.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01725178.

Semiautomated Evaluation of the Primary Motor Cortex in Patients with Amyotrophic Lateral Sclerosis at 3T

BACKGROUND AND PURPOSE

Amyotrophic lateral sclerosis is a neurodegenerative disease involving the upper and lower motor neurons. In amyotrophic lateral sclerosis, pathologic changes in the primary motor cortex include Betz cell depletion and the presence of reactive iron-loaded microglia, detectable on 7T MR images as atrophy and T2*-hypointensity. Our purposes were the following: 1) to investigate the signal hypointensity-to-thickness ratio of the primary motor cortex as a radiologic marker of upper motor neuron involvement in amyotrophic lateral sclerosis with a semiautomated method at 3T, 2) to compare 3T and 7T results, and 3) to evaluate whether semiautomated measurement outperforms visual image assessment.

MATERIALS AND METHODS

We investigated 27 patients and 13 healthy subjects at 3T, and 19 patients and 18 healthy subjects at 7T, performing a high-resolution 3D multiecho T2*-weighted sequence targeting the primary motor cortex. The signal hypointensity-to-thickness ratio of the primary motor cortex was calculated with a semiautomated method depicting signal intensity profiles of the cortex. Images were also visually classified as "pathologic" or "nonpathologic" based on the primary motor cortex signal intensity and thickness.

RESULTS

The signal hypointensity-to-thickness ratio of the primary motor cortex was greater in patients than in controls (P < .001), and it correlated with upper motor neuron impairment in patients (ρ = 0.57, P < .001). The diagnostic accuracy of the signal hypointensity-to-thickness ratio was high at 3T (area under the curve = 0.89) and even higher at 7T (area under the curve = 0.94). The sensitivity of the semiautomated method (0.81) outperformed the sensitivity of the visual assessment (0.56-0.63) at 3T.

CONCLUSIONS

The signal hypointensity-to-thickness ratio of the primary motor cortex calculated with a semiautomated method is suggested as a radiologic marker of upper motor neuron burden in patients with amyotrophic lateral sclerosis. This semiautomated method may be useful for improving the subjective radiologic evaluation of upper motor neuron pathology in patients suspected of having amyotrophic lateral sclerosis.

Network over-connectivity differentiates autism spectrum disorder from other developmental disorders in toddlers: A diffusion MRI study

Advanced connectivity studies in toddlers with Autism Spectrum Disorder (ASD) are increasing and consistently reporting a disruption of brain connectivity. However, most of these studies compare ASD and typically developing subjects, thus providing little information on the specificity of the abnormalities detected in comparison with other developmental disorders (other-DD). We recruited subjects aged below 36 months who received a clinical diagnosis of Neurodevelopmental Disorder (32 ASD and 16 other-DD including intellectual disability and language disorder) according to DSM-IV TR. Structural and diffusion MRI were acquired to perform whole brain probabilistic and anatomically constrained tractography. Network connectivity matrices were built encoding the number of streamlines (D_NUM ) and the tract-averaged fractional anisotropy (D_FA ) values connecting each pair of cortical and subcortical regions. Network Based Statistics (NBS) was finally applied on the connectivity matrices to evaluate the network differences between the ASD and other-DD groups. The network differences resulted in an over-connectivity pattern (i.e., higher D_NUM and D_FA values) in the ASD group with a significance of P < 0.05. No contra-comparison results were found. The over-connectivity pattern in ASD occurred in networks primarily involving the fronto-temporal nodes, known to be crucial for social-skill development and basal ganglia, related to restricted and repetitive behaviours in ASD. To our knowledge, this is the first network-based diffusion study comparing toddlers with ASD and those with other-DD. Results indicate the detection of different connectivity patterns in ASD and other-DD at an age when clinical differential diagnosis is often challenging. Hum Brain Mapp 38:2333-2344, 2017. © 2017 Wiley Periodicals, Inc.

Effects of adaptation on numerosity decoding in the human brain

Psychophysical studies have shown that numerosity is a sensory attribute susceptible to adaptation. Neuroimaging studies have reported that, at least for relatively low numbers, numerosity can be accurately discriminated in the intra-parietal sulcus. Here we developed a novel rapid adaptation paradigm where adapting and test stimuli are separated by pauses sufficient to dissociate their BOLD activity. We used multivariate pattern recognition to classify brain activity evoked by non-symbolic numbers over a wide range (20-80), both before and after psychophysical adaptation to the highest numerosity. Adaptation caused underestimation of all lower numerosities, and decreased slightly the average BOLD responses in V1 and IPS. Using support vector machine, we showed that the BOLD response of IPS, but not in V1, classified numerosity well, both when tested before and after adaptation. However, there was no transfer from training pre-adaptation responses to testing post-adaptation, and vice versa, indicating that adaptation changes the neuronal representation of the numerosity. Interestingly, decoding was more accurate after adaptation, and the amount of improvement correlated with the amount of perceptual underestimation of numerosity across subjects. These results suggest that numerosity adaptation acts directly on IPS, rather than indirectly via other low-level stimulus parameters analysis, and that adaptation improves the capacity to discriminate numerosity.

Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1) in patients with upper motor neuron (UMN) impairment is pronouncedly hypointense in Magnetic Resonance (MR) T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM). Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.

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Magnetic susceptibility (χ) was measured in ALS patients' and healthy controls' M1.

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In healthy subjects' cortex, χ correlated with the expected concentration of iron.

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In patients, increased χ co-localized with T2* hypointensity in M1 deeper layers.

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χ correlated with clinical scores of upper motor neuron impairment in patients.

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χ could be a radiological sign of iron deposits and severe UMN burden in ALS.

Diffusion Tractography Biomarkers of Pediatric Cerebellar Hypoplasia/Atrophy: Preliminary Results Using Constrained Spherical Deconvolution

BACKGROUND AND PURPOSE

Advances in MR imaging modeling have improved the feasibility of reconstructing crossing fibers, with increasing benefits in delineating angulated tracts such as cerebellar tracts by using tractography. We hypothesized that constrained spherical deconvolution-based probabilistic tractography could successfully reconstruct cerebellar tracts in children with cerebellar hypoplasia/atrophy and that diffusion scalars of the reconstructed tracts could differentiate pontocerebellar hypoplasia, nonprogressive cerebellar hypoplasia, and progressive cerebellar atrophy.

MATERIALS AND METHODS

Fifteen children with cerebellar ataxia and pontocerebellar hypoplasia, nonprogressive cerebellar hypoplasia or progressive cerebellar atrophy and 7 controls were included in this study. Cerebellar and corticospinal tracts were reconstructed by using constrained spherical deconvolution. Scalar measures (fractional anisotropy and mean, axial and radial diffusivity) were calculated. A general linear model was used to determine differences among groups for diffusion MR imaging scalar measures, and post hoc pair-wise comparisons were performed.

RESULTS

Cerebellar and corticospinal tracts were successfully reconstructed in all subjects. Significant differences in diffusion MR imaging scalars were found among groups, with fractional anisotropy explaining the highest variability. All groups with cerebellar pathologies showed lower fractional anisotropy compared with controls, with the exception of cerebellar hypoplasia.

CONCLUSIONS

This study shows the feasibility of constrained spherical deconvolution to reconstruct cerebellar and corticospinal tracts in children with morphologic cerebellar pathologies. In addition, the preliminary results show the potential utility of quantitative analysis of scalars of the cerebellar white matter tracts in children with cerebellar pathologies such as cerebellar hypoplasia and atrophy. Further studies with larger cohorts of patients are needed to validate the clinical significance of our preliminary results.

High-Resolution 7T MR Imaging of the Motor Cortex in Amyotrophic Lateral Sclerosis

BACKGROUND AND PURPOSE

Amyotrophic lateral sclerosis is a progressive motor neuron disorder that involves degeneration of both upper and lower motor neurons. In patients with amyotrophic lateral sclerosis, pathologic studies and ex vivo high-resolution MR imaging at ultra-high field strength revealed the co-localization of iron and activated microglia distributed in the deep layers of the primary motor cortex. The aims of the study were to measure the cortical thickness and evaluate the distribution of iron-related signal changes in the primary motor cortex of patients with amyotrophic lateral sclerosis as possible in vivo biomarkers of upper motor neuron impairment.

MATERIALS AND METHODS

Twenty-two patients with definite amyotrophic lateral sclerosis and 14 healthy subjects underwent a high-resolution 2D multiecho gradient-recalled sequence targeted on the primary motor cortex by using a 7T scanner. Image analysis consisted of the visual evaluation and quantitative measurement of signal intensity and cortical thickness of the primary motor cortex in patients and controls. Qualitative and quantitative MR imaging parameters were correlated with electrophysiologic and laboratory data and with clinical scores.

RESULTS

Ultra-high field MR imaging revealed atrophy and signal hypointensity in the deep layers of the primary motor cortex of patients with amyotrophic lateral sclerosis with a diagnostic accuracy of 71%. Signal hypointensity of the deep layers of the primary motor cortex correlated with upper motor neuron impairment (r = -0.47; P < .001) and with disease progression rate (r = -0.60; P = .009).

CONCLUSIONS

The combined high spatial resolution and sensitivity to paramagnetic substances of 7T MR imaging demonstrate in vivo signal changes of the cerebral motor cortex that resemble the distribution of activated microglia within the cortex of patients with amyotrophic lateral sclerosis. Cortical thinning and signal hypointensity of the deep layers of the primary motor cortex could constitute a marker of upper motor neuron impairment in patients with amyotrophic lateral sclerosis.

Comparison of 3T and 7T susceptibility-weighted angiography of the substantia nigra in diagnosing Parkinson disease

BACKGROUND AND PURPOSE

Standard neuroimaging fails in defining the anatomy of the substantia nigra and has a marginal role in the diagnosis of Parkinson disease. Recently 7T MR target imaging of the substantia nigra has been useful in diagnosing Parkinson disease. We performed a comparative study to evaluate whether susceptibility-weighted angiography can diagnose Parkinson disease with a 3T scanner.

MATERIALS AND METHODS

Fourteen patients with Parkinson disease and 13 healthy subjects underwent MR imaging examination at 3T and 7T by using susceptibility-weighted angiography. Two expert blinded observers and 1 neuroradiology fellow evaluated the 3T and 7T images of the sample to identify substantia nigra abnormalities indicative of Parkinson disease. Diagnostic accuracy and intra- and interobserver agreement were calculated separately for 3T and 7T acquisitions.

RESULTS

Susceptibility-weighted angiography 7T MR imaging can diagnose Parkinson disease with a mean sensitivity of 93%, specificity of 100%, and diagnostic accuracy of 96%. 3T MR imaging diagnosed Parkinson disease with a mean sensitivity of 79%, specificity of 94%, and diagnostic accuracy of 86%. Intraobserver and interobserver agreement was excellent at 7T. At 3T, intraobserver agreement was excellent for experts, and interobserver agreement ranged between good and excellent. The less expert reader obtained a diagnostic accuracy of 89% at 3T.

CONCLUSIONS

Susceptibility-weighted angiography images obtained at 3T and 7T differentiate controls from patients with Parkinson disease with a higher diagnostic accuracy at 7T. The capability of 3T in diagnosing Parkinson disease might encourage its use in clinical practice. The use of the more accurate 7T should be supported by a dedicated cost-effectiveness study.

Ultra-high-field MR imaging in polymicrogyria and epilepsy

BACKGROUND AND PURPOSE

Polymicrogyria is a malformation of cortical development that is often identified in children with epilepsy or delayed development. We investigated in vivo the potential of 7T imaging in characterizing polymicrogyria to determine whether additional features could be identified.

MATERIALS AND METHODS

Ten adult patients with polymicrogyria previously diagnosed by using 3T MR imaging underwent additional imaging at 7T. We assessed polymicrogyria according to topographic pattern, extent, symmetry, and morphology. Additional imaging sequences at 7T included 3D T2* susceptibility-weighted angiography and 2D tissue border enhancement FSE inversion recovery. Minimum intensity projections were used to assess the potential of the susceptibility-weighted angiography sequence for depiction of cerebral veins.

RESULTS

At 7T, we observed perisylvian polymicrogyria that was bilateral in 6 patients, unilateral in 3, and diffuse in 1. Four of the 6 bilateral abnormalities had been considered unilateral at 3T. While 3T imaging revealed 2 morphologic categories (coarse, delicate), 7T susceptibility-weighted angiography images disclosed a uniform ribbonlike pattern. Susceptibility-weighted angiography revealed numerous dilated superficial veins in all polymicrogyric areas. Tissue border enhancement imaging depicted a hypointense line corresponding to the gray-white interface, providing a high definition of the borders and, thereby, improving detection of the polymicrogyric cortex.

CONCLUSIONS

7T imaging reveals more anatomic details of polymicrogyria compared with 3T conventional sequences, with potential implications for diagnosis, genetic studies, and surgical treatment of associated epilepsy. Abnormalities of cortical veins may suggest a role for vascular dysgenesis in pathogenesis.

BOLD human responses to chromatic spatial features

Animal physiological and human psychophysical studies suggest that an early step in visual processing involves the detection and identification of features such as lines and edges, by neural mechanisms with even- and odd-symmetric receptive fields. Functional imaging studies also demonstrate mechanisms with even- and odd-receptive fields in early visual areas, in response to luminance-modulated stimuli. In this study we measured fMRI BOLD responses to 2-D stimuli composed of only even or only odd symmetric features, and to an amplitude-matched random noise control, modulated in red-green equiluminant colour contrast. All these stimuli had identical power but different phase spectra, either highly congruent (even or odd symmetry stimuli) or random (noise). At equiluminance, V1 BOLD activity showed no preference between congruent- and random-phase stimuli, as well as no preference between even and odd symmetric stimuli. Areas higher in the visual hierarchy, both along the dorsal pathway (caudal part of the intraparietal sulcus, dorsal LO and V3A) and the ventral pathway (V4), responded preferentially to odd symmetry over even symmetry stimuli, and to congruent over random phase stimuli. Interestingly, V1 showed an equal increase in BOLD activity at each alternation between stimuli of different symmetry, suggesting the existence of specialised mechanisms for the detection of edges and lines such as even- and odd-chromatic receptive fields. Overall the results indicate a high selectivity of colour-selective neurons to spatial phase along both the dorsal and the ventral pathways in humans.

Language disorder with mild intellectual disability in a child affected by a novel mutation of SLC6A8 gene

We describe the clinical and molecular features of a child harboring a novel mutation in SLC6A8 gene in association with a milder phenotype than other creatine transporter (CT1) deficient patients (OMIM 300352) [1-7]. The mutation c.757 G>C p.G253R in exon 4 of SLC6A8 was hemizygous in the child, aged 6 years and 6 months, who showed mild intellectual disability with severe speech and language delay. His carrier mother had borderline intellectual functioning. Although the neurochemical and biochemical parameters were fully consistent with those reported in the literature for subjects with CT1 deficit, in our patient within a general cognitive disability, a discrepancy between nonverbal and verbal skills was observed, confirming the peculiar vulnerability of language development under brain Cr depletion.

Muscle MRI in FHL1-linked reducing body myopathy

Reducing body myopathy is a rare progressive myopathy identified by characteristic pathological findings and secondary to dominantly acting mutations in the X-linked FHL1 gene. We report muscle MRI findings in two patients affected by reducing body myopathy and in their carrier mothers. All four showed a distinctive pattern of muscle alteration, with a predominant involvement of postero-medial muscle at thigh level and of soleus at calf level, with a striking sparing of glutei muscles that also appeared to be hypertrophic. These findings may help in the differential diagnosis of these disorders.

Phenylketonuria: white-matter changes assessed by 3.0-T magnetic resonance (MR) imaging, MR spectroscopy and MR diffusion

PURPOSE

This study evaluated the sensitivity of a 3.0-Tesla (T) magnetic resonance imaging (MRI) in measuring cerebral phenylalanine using proton magnetic resonance spectroscopy and in assessing MR-documented white-matter changes by means of diffusion studies (diffusion-weighted imaging, apparent diffusion coefficient map; diffusion tensor imaging) in patients with phenylketonuria.

MATERIALS AND METHODS

Thirty-two patients with the classical clinical and biochemical deficits of phenylketonuria underwent biochemical (blood phenylalanine), genotypic (phenylalanine hydroxylase gene) and radiological investigation by means of MRI, proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging with a 3.0-T scanner.

RESULTS

Periventricular and subcortical white-matter changes were detected on all MR scans. In 29/32 patients, proton magnetic resonance spectroscopy easily documented abnormal signal elevation at 7.36 ppm, corresponding to phenylalanine, despite its low concentration. Phenylalanine signal amplitude relative to the creatine/phosphocreatine signal increased linearly with blood phenylalanine values (r 0.7067; p<0.001). Diffusion MRI demonstrated hyperintensity in the areas exhibiting MRI changes as well as decreased apparent diffusion coefficient values, but fractional anisotropy indices were normal.

CONCLUSIONS

The high signal, together with better spectral, spatial, contrast and temporal resolution, makes the 3.0-T MR the most suitable technique in the study of the phenylketonuria. In particular, the multimodal approach with MRI, proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging can provide more information than previous studies performed with low-field systems.

Acquired focal brain lesions in childhood: effects on development and reorganization of language

In the present paper, we address brain-behaviour relationships in children with acquired aphasia, by reviewing some recent studies on the effects of focal brain lesions on language development. Timing of the lesion, in terms of its occurrence, before or after the onset of speech and language acquisition, may be a major factor determining language outcome. However, it is still unclear which are the effects of aphasia occurring between 2 and 5 years of age, a time window which is crucial for acquiring and automatizing the basic rules of native language. A comprehensive review of the literature on acquired childhood aphasia precedes the description of long-term follow-up (20 years) of two identical twins, one of whom became aphasic at 3 years and 4 months after infarction of the left sylvian artery. Psycholinguistic analysis and fMRI data show a slow and incomplete recovery from non-fluent aphasia associated to an intra-hemispheric organization of language. These data, which support the potential but also the limits of neural plasticity during language development, are discussed in the light of the literature on the time-course and neural bases of acquired childhood aphasia.

Brain representation of phonological processing in Italian: individual variability and behavioural correlates

Neuroimaging literature on phonological processing during reading lacks of studies taking into account orthographic differences across languages and behavioural variability across subjects. The present study aimed at investigating brain representation of phonological processing in reading Italian, a language with regular orthography, with particular regard to inter-individual variability and brain-behavioural correlates. Ten Italian adults performed a rhyme generation and a rhyme judgment task during fMRI acquisition and were tested with behavioural measures of phonological processing. Results for both tasks showed activations of the left Inferior Frontal Gyrus and Dorsolateral Prefrontal Cortex, likely underlying output sublexical strategies, for all or most of the subjects, while a minority of subjects activated the Superior Temporal Sulcus and the Temporo-Parietal-Occipital Junction. These results suggest that phonological processing of written Italian is based on the prevalent use of frontal structures. However, it is of interest that the activation of the Superior Temporal Sulcus, involved in phonological input, was associated to better behavioural performances in tasks of phonological processing. Our findings may contribute to understand neural correlates of phonological processing of languages with regular orthography.

Language organisation in left perinatal stroke

Right-hemispheric organisation of language has been observed following early left-sided brain lesions. The role of the site of damage is still controversial, as other aspects influence the pattern of speech organisation including timing of the lesion and the presence of epilepsy. We studied a group of 10 term-born children homogeneous for timing/type of lesion and clinical picture. All subjects had left perinatal arterial stroke, right hemiplegia, normal cognitive functions and no or easily controlled epileptic seizures. In half the patients, the lesion clearly involved Broca's area, in the other half it was remote from it. Language lateralization was explored by an fMRI covert rhyme generation task. Eight of 10 subjects showed a right lateralisation of language, including all five patients with a damaged left Broca and 3/5 of those without it. Group analysis in patients with right hemispheric organisation showed brain activations homotopic to those found in the left hemisphere of a matched control group. Our findings confirm that, at the end of gestation, the human brain exhibits extraordinary (re-)organisational capabilities. Language organisation in the right hemisphere is favoured by the presence of destructive lesions of the left Broca's area at birth, and occurs in brain regions homotopic to those usually involved in language processing.

Reorganisation of the somatosensory system after early brain damage

OBJECTIVE

To examine the reorganisation of the somatosensory system after early brain lesions.

METHODS

We studied 12 young patients with congenital hemiplegia. Causative lesions were brain malformations, periventricular injuries and cortico-subcortical lesions. We explored the somatosensory system using evoked potentials, fMRI during sensory stimulation and clinical assessment of sensory function. To correlate sensory and motor function, we also performed transcranial magnetic stimulation, fMRI of hand movement and assessment of motor function by means of Melbourne test.

RESULTS

Eleven patients showed a perilesional reorganisation of primary somatosensory function, as expressed by short latency potentials following stimulation of the paretic hand; in a remaining patient, delayed latency responses (N27.1) were only elicited over the ipsilateral undamaged hemisphere. Five of the eleven patients with perilesional somatosensory representation of the affected hand showed contralesional shifting of motor function, thus exhibiting sensory-motor dissociation. Significant correlation was found between sensory deficit and fMRI activation during sensory stimulation.

CONCLUSIONS

In subjects with early brain lesions, somato-sensory function is generally reorganised within the affected hemisphere. A contralesional shifting is uncommon and poorly efficient in function restoration.

SIGNIFICANCE

This study confirms and further explores the difference in reorganisation capabilities of the motor and sensory system following early brain injury of different etiologies and timing.

The pathogenesis of the white matter abnormalities in phenylketonuria. A multimodal 3.0 tesla MRI and magnetic resonance spectroscopy (1H MRS) study

OBJECTIVE

To gain insights into the nature and pathogenesis of white matter (WM) abnormalities in PKU.

METHODS

Thirty-two patients with phenylalanine hydroxylase deficiency (21 with early and 11 with late diagnosis and treatment) and 30 healthy controls underwent an integrated clinical, neuroimaging (3.0 T MRI, diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI)) and neurochemical (1H MRS) investigation.

RESULTS

All patients had white matter abnormalities on T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) scans; parietal white was consistently affected, followed by occipital, frontal and temporal white matter. T1-weighted hypointense alterations were also found in 8 of 32 patients. DWI hyperintense areas overlapped with those detected on T2W/FLAIR. The apparent diffusion coefficient (ADC) was reduced and correlated inversely with severity of white matter involvement. Fractional anisotropy index, eigenvalues lambda(min), lambda(middle), lambda(max) obtained from DTI data, and the principal brain metabolites assessed by 1H MRS (except brain phenylalanine (Phe)) were normal. Brain Phe peak was detected in all but two subjects. Brain and blood Phe were strictly associated. Blood Phe at the diagnosis, patient's age, and concurrent brain Phe independently influence white matter alteration (as expressed by conventional MRI or ADC values).

CONCLUSIONS

(a) MRI abnormalities in phenylketonuria are the result of a distinctive alteration of white matter suggesting the intracellular accumulation of a hydrophilic metabolite, which leaves unaffected white matter architecture and structure. (b) White matter abnormalities do not seem to reflect the mechanisms involved in the derangement of mental development in PKU. (c) Our data do not support the usefulness of conventional brain MRI examination in the clinical monitoring of phenylketonuria patients.

Treatment monitoring of brain creatine deficiency syndromes: a 1H- and 31P-MR spectroscopy study

BACKGROUND AND PURPOSE

Brain creatine (Cr) deficiencies (BCr-d) are rare disorders of creatine biosynthesis and transport. We performed consecutive measures of total Cr (tCr) and of its phosphorylated fraction, phosphocreatine (PCr), in the brains of children affected by Cr synthesis defects during a long period of therapy. The aim was to identify the optimal treatment strategy for these disorders.

MATERIALS AND METHODS

Two patients with guanidinoacetate methyltransferase defect (GAMT-d) were treated with different amounts of Cr and with diet restrictions aimed at reducing endogenous guanidinoacetate (GAA) synthesis. Three patients with arginine:glycine amidinotransferase defect (AGAT-d) were treated with different Cr intakes. The patients' treatments were monitored by means of (1)H- and (31)P-MR spectroscopy.

RESULTS

Cr and PCr replenishment was lower in GAMT-d than in AGAT-d even when GAMT-d therapy was carried out with a very high Cr intake. Cr and especially PCr replenishment became more efficient only when GAA blood values were reduced. Adenosine triphosphate (ATP) was increased in the baseline phosphorous spectrum of GAMT-d, and it returned to a normal value with treatment. Brain pH and brain P(i) showed no significant change in the AGAT-d syndrome and at any Cr intake. However, 1 of the 2 GAMT-d patients manifested a lower brain pH level while consuming the GAA-lowering diet.

CONCLUSIONS

AGAT-d treatment needs lower Cr intake than GAMT-d. Cr supplementation in GAMT-d treatment should include diet restrictions aimed at reducing GAA concentration in body fluids. (1)H- and especially (31)P-MR spectroscopy are the ideal tools for monitoring the therapy response to these disorders.

3.0-T functional brain imaging: a 5-year experience

The aim of this paper is to illustrate the technical, methodological and diagnostic features of functional imaging (comprising spectroscopy, diffusion, perfusion and cortical activation techniques) and its principal neuroradiological applications on the basis of the experience gained by the authors in the 5 years since the installation of a high-field magnetic resonance (MR) magnet. These MR techniques are particularly effective at 3.0 Tesla (T) owing to their high signal, resolution and sensitivity, reduced scanning times and overall improved diagnostic ability. In particular, the high-field strength enhances spectroscopic analysis due to a greater signal-to-noise ratio (SNR) and improved spectral, space and time resolution, resulting in the ability to obtain high-resolution spectroscopic studies not only of the more common metabolites, but also--and especially--of those which, due to their smaller concentrations, are difficult to detect using 1.5-T systems. All of these advantages can be obtained with reduced acquisition times. In diffusion studies, the high-field strength results in greater SNR, because 3.0-T magnets enable increased spatial resolution, which enhances accuracy. They also allow exploration in greater detail of more complex phenomena (such as diffusion tensor and tractography), which are not clearly depicted on 1.5-T systems. The most common perfusion study (with intravenous injection of a contrast agent) benefits from the greater SNR and higher magnetic susceptibility by achieving dramatically improved signal changes, and thus greater reliability, using smaller doses of contrast agent. Functional MR imaging (fMRI) is without doubt the modality in which high-field strength has had the greatest impact. Images acquired with the blood-oxygen-level-dependent (BOLD) technique benefit from the greater SNR afforded by 3.0-T magnets and from their stronger magnetic susceptibility effects, providing higher signal and spatial resolution. This enhances reliability of the localisation of brain functions, making it possible to map additional areas, even in the millimetre and submillimetre scale. The data presented and results obtained to date show that 3.0-T morphofunctional imaging can become the standard for high-resolution investigation of brain disease.

High-field proton MRS of human brain

Proton magnetic resonance spectroscopy (1H-MRS) of the brain reveals specific biochemical information about cerebral metabolites, which may support clinical diagnoses and enhance the understanding of neurological disorders. The advantages of performing 1H-MRS at higher field strengths include better signal to noise ratio (SNR) and increased spectral, spatial and temporal resolution, allowing the acquisition of high quality, easily quantifiable spectra in acceptable imaging times. In addition to improved measurement precision of N-acetylaspartate, choline, creatine and myo-inositol, high-field systems allow the high-resolution measurement of other metabolites, such as glutamate, glutamine, gamma-aminobutyric acid, scyllo-inositol, aspartate, taurine, N-acetylaspartylglutamate, glucose and branched amino acids, thus extending the range of metabolic information. However, these advantages may be hampered by intrinsic field-dependent technical difficulties, such as decreased T2 signal, chemical shift dispersion errors, J-modulation anomalies, increased magnetic susceptibility, eddy current artifacts, limitations in the design of homogeneous and sensitive radiofrequency (RF) coils, magnetic field instability and safety issues. Several studies demonstrated that these limitations could be overcome, suggesting that the appropriate optimization of high-field 1H-MRS would expand the application in the fields of clinical research and diagnostic routine.

Sensory-motor cortex activity modulation by hypnotic susceptibility and hypnosis during finger movement

The aim of the experiment was to study whether the activity of the primary sensory-motor (S1/M1), supplementary motor (SMA) and pre-motor (PMA) areas during fingers movement is modulated by hypnotic susceptibility and hypnosis. Cortical activity was studied through functional Magnetic Resonance Imaging (fMRI) during a finger-to-thumb opposition task in awake (Highs) and hypnotized highly susceptible (H-Highs) as well as in awake non susceptible subjects (Lows). Results did not show any significant difference in sensory-motor areas activation between Highs and Lows (trait effect) and between Highs and H-Highs (state effect). The activation in 3 subjects among Highs and only 1 among Lows (out of 5) of the caudal S1, receiving the most part of the cutaneous input, appears noteworthy and prompts further investigation on possible hypnotizability-related differences in sensory-motor integration.

Brain lactic alkalosis in Aicardi-Goutières syndrome

Aicardi-Goutières syndrome is a rare progressive encephalopathy characterized by acquired microcephaly, basal ganglia calcification, and chronic CSF lymphocytosis, raised levels of interferon alpha in CSF and plasma and chill-blain type lesions. A possible mechanism of injury is cytokine related microangiopathy. We report brain imaging and proton (1H) and phosphorus-31 (31P) magnetic resonance spectroscopy (MRS) findings during the first year after birth in two patients. In patient 1 the evolution of brain metabolite ratios and intracellular pH obtained from serial 1H (long TE) and 31P MRS studies are described; in patient 2 a single 1H (short TE) MRS study is described. Imaging findings included basal ganglia calcifications, cerebral atrophy, and leukodystrophy. The MRS results demonstrated that Aicardi-Goutières syndrome is associated with reduced NAA/Cr, reflecting decreased neuronal/axonal density or viability, increased myo-inositol/Cr, reflecting gliosis or osmotic stress and a persisting brain lactic alkalosis. A brain lactic alkalosis has also been observed in those infants surviving perinatal hypoxia-ischaemia but with a poor neurodevelopmental outcome. A possible mechanism leading to brain alkalosis is up-regulation of the Na+/H+ transporter by focal areas of ischaemia related to the microangiopathy or by pro-inflammatory cytokines. Such brain alkalosis may be detrimental to cell survival and may increase glycolytic rate in astrocytes leading to an increased production of lactate.

Brainstem involvement in Unverricht-Lundborg disease (EPM1): An MRI and (1)H MRS study

MRI of the brain and proton MRS ((1)H MRS) of the pons and dentate were obtained in 10 patients with genetically confirmed Unverricht-Lundborg disease (EPM1) and 20 control subjects. Patients with EPM1 showed (p < or = 0.01) loss of bulk of the basis pontis, medulla, and cerebellar hemispheres. Cerebral atrophy was present in six patients. The N-acetylaspartate/creatine and choline/creatine ratios were reduced in the pons but not in the dentate (p < or = 0.005). Brainstem involvement could play a role in pathophysiology of EPM1.

Reorganisation of the sensorimotor cortex after early focal brain lesion: a functional MRI study in monozygotic twins

Sensorimotor cortical reorganization after early brain lesions was studied by means of fMRI in two pairs of monozygotic twins, in each of which one member had a focal brain injury. This offered a unique opportunity to reduce the wide intersubject variability of the controls often found in similar studies. Activation images were acquired during a motor task (sequential opposition finger movements) and a sensory task (passive brushing of palm and fingers). During the tasks with the recovered hand, constant findings in the lesioned subjects were the activation of the undamaged areas adjacent to lesion site and the activation of the ipsilateral sensorimotor cortex. Bilateral activation of the primary sensorimotor cortex was never observed in the healthy co-twin controls.

Proton magnetic resonance spectroscopy (1H-MRS) of motor cortex and basal ganglia in de novo Parkinson's disease patients

Proton MR spectroscopy (1H-MRS) has been previously performed in Parkinson's disease (PD) and parkinsonian syndromes to evaluate in vivo concentrations of basal ganglia and cerebral cortex metabolites such as N-acetylaspartate (NAA), choline (Cho), and creatine (Cr). However, this technique has never been used to evaluate motor cortex in untreated PD patients. In this study, single-voxel 1H-MRS of basal ganglia and motor cortex was carried out in 10 de novo patients with PD and 10 age-matched healthy controls. A significant reduction in the NAA/Cr ratio was observed in the motor cortex of PD patients compared with controls (p)<(0.01). Basal ganglia spectra did not allow any evaluation due to the presence of artefacts related to inorganic paramagnetic substances. The motor cortex reduction of the NAA/Cr ratio in de novo PD patients may reflect an altered neuronal functioning due to a loss of thalamocortical excitatory inputs and may represent an in vivo marker for the diagnosis of PD.

Adult human heart microvascular endothelial cells are permissive for non-lytic infection by human cytomegalovirus

OBJECTIVE

Human cytomegalovirus (CMV) infection has been linked to chronic heart disease. The mechanism of CMV dissemination to the heart remains unknown. CMV antigens and nucleic acid sequences have been detected in endothelial cells (ECs) in vivo, and ECs are fully permissive hosts to CMV replication in vitro. This report examines the characteristics of CMV replication in primary cultures of human heart microvascular ECs (HHMECs).

METHODS

Capillary ECs were isolated from heart tissue biopsies of six patients at the time of heart surgery. HHMECs were infected with CMV and viral antigens were detected by immunofluorescence assay using monoclonal antibodies as specific reagents. Cytokine and chemokine release in the supernatant of sham- and CMV-infected cells was quantitated by ELISA. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to analyse expression of mRNA for adhesion molecules.

RESULTS

CMV was found to productively infect HHMECs without cytolytic effects. Infected cultures released high levels of pro-inflammatory chemokines and enhanced their adhesion molecule expression.

CONCLUSIONS

Our data provide new insights into the mechanism of CMV dissemination to the heart, signalling the need for further investigation of the pathogenetic role of this virus in cardiac disorders.

Proton magnetic resonance spectroscopy (1H-MRS) of the cerebrum in two young infants with Zellweger syndrome

Cerebral metabolic abnormalities have been previously detected by 1H-MRS in infants with the Zellweger syndrome as young as 3 months. We hypothesized that metabolic abnormalities could also be found shortly after birth. Two fullterm infants with Zellweger syndrome were studied at 12 days and two months of age, respectively, using single voxel 1H-MRS. In the first case 1H-MRS was performed using PRESS with variable TE (31, 136, 272 ms); in the second, STEAM and PRESS sequences were used with different TE (STEAM at 30 and 144 ms; PRESS at 270 ms). In both cases a significant decrease of N-acetylaspartate (NAA) and an abnormal signal at 1.33 and 0.9 ppm, consisting of lactate (Lac) and lipids (Lip) were found. The reported MRS abnormalities, although not specific for peroxisomal dysfunctions, may support the suspicion of Zellweger syndrome and may indicate direct referral to the specific laboratory and molecular studies necessary to establish the diagnosis and prognosis of this syndrome.

A cortical area that responds specifically to optic flow, revealed by fMRI

The continuously changing optic flow on the retina provides information about direction of heading and about the three-dimensional structure of the environment. Here we use functional magnetic resonance imaging (fMRI) to demonstrate that an area in human cortex responds selectively to components of optic flow, such as circular and radial motion. This area is within the region commonly referrred to as V5/MT complex, but is distinct from the part of this region that responds to translation. The functional properties of these two areas of the V5/MT complex are also different; the response to optic flow was obtained only with changing flow stimuli, whereas response to translation occurred during exposure to continuous motion.

Brain creatine depletion: guanidinoacetate methyltransferase deficiency (improving with creatine supplementation)

The authors describe an Italian child with guanidinoacetate methyltransferase deficiency, neurologic regression, movement disorders, and epilepsy during the first year of life. Brain MRI showed pallidal and periaqueductal alterations. In vivo 1H-MRS showed brain creatine depletion. The assessment of guanidinoacetic acid concentration in biologic fluids confirmed the diagnosis. Clinical, biochemical, and neuroradiologic improvement followed creatine supplementation.

Clinical significance of brain phenylalanine concentration assessed by in vivo proton magnetic resonance spectroscopy in phenylketonuria

Recent studies using in vivo proton magnetic resonance spectroscopy (1H MRS) have suggested that plasma phenylalanine (Phe) may not be a reliable indicator of brain Phe level in subjects with phenylketonuria (PKU). Interindividual variation in cerebral Phe can contribute to the phenotypic variability of the disease. We report the results of the direct assessment of brain Phe by 1H MRS in 10 off-diet PKU patients (aged 15.5-30.5 years), 4 detected and treated early, 6 late. In a single patient, brain Phe was evaluated before and 15 days after diet discontinuation. FLAIR MRI and 1H MRS were performed in the same setting by a 1.5 T clinical MR scanner. MR images were scored according to the extent of the lobar white-matter hyperintensity. Brain 1H MRS Phe signal (resonating at 7.36 ppm) was evaluated as a ratio to the creatine+phosphocreatine signal. Brain Phe was correlated with clinical, biochemical and MRI findings. Results were as follows. (1) An abnormal concentration of brain Phe was detected in all 10 PKU subjects (ranging from 0.030 to 0.074), associated with a wide interindividual variability of concurrent plasma Phe (ranging from 724 to 2800 micromol/L). (2) In late-detected subjects, brain Phe concentration correlated with clinical phenotype better than did plasma Phe. The discrepancy between brain and plasma Phe was relevant from a clinical point of view in two cases: in one, a late-detected patient with normal mental development, a high level of plasma Phe was associated with a relatively low concentration of brain Phe; in the other, a late-detected subject with severe neurological impairment, a very high level of brain Phe was associated with plasma Phe compatible with the diagnosis of mild PKU. (3) White-matter alterations were detected in all patients. FLAIR MRI sequences disclosed an involvement of optic chiasma and tracts in 7 subjects. No correlation was found between white-matter alterations and concurrent brain Phe concentrations. (4) In the only case assessed under different intake of Phe, the relevant increase of brain Phe paralleled the concurrent increase of plasma Phe, showing that 1H MRS can be a useful tool in evaluating the individual vulnerability of PKU patients to different values of plasma Phe.

Reversible brain creatine deficiency in two sisters with normal blood creatine level

We describe a new creatine metabolism disorder in 2 young sisters who suffered from mental retardation and severe language delay. Blood examination, investigation of the most common neurometabolic disorders, and brain magnetic resonance imaging were normal. Diagnosis was established only by means of in vivo proton magnetic resonance spectroscopy, which disclosed generalized depletion of creatine in the brain. Creatine monohydrate oral administration led to almost complete brain creatine level restoration along with improvement of the patients' disabilities.

Expanding lacunae causing triventricular hydrocephalus. Report of two cases

Two patients are reported in whom the presence of triventricular hydrocephalus and aqueductal obstruction or stenosis due to multiple expanding lacunae in the mesencephalothalamic region possibly corresponds to abnormally dilated perivascular spaces. Placement of a ventriculoperitoneal cerebrospinal fluid (CSF) shunt in one patient and the performance of a third ventricle cisternotomy in the other reversed the hydrocephalic syndrome, but did not modify the complex neuroophthalmological disturbance and rubral tremor presumably related to the compressive effects of the lacunae on adjacent parenchyma. In one patient the number and size of the lacunae were increased 4 years after CSF shunt placement. A review of the literature revealed two cases in which magnetic resonance imaging demonstrated a similar, poorly understood pathological condition.

Proton magnetic resonance spectroscopy in an Italian family with spinocerebellar ataxia type 1

Linkage and DNA analysis, magnetic resonance (MR) imaging, and single-voxel proton MR spectroscopy were obtained in 10 members of an Italian kindred with spinocerebellar ataxia type 1 (SCA1). The size of the basis pontis, cerebellar hemispheres, middle cerebellar peduncles, and medulla oblongata were decreased in 4 members carrying the SCA1 gene, compared with 6 unaffected subjects. Diffuse signal changes in the pons and cerebellum were observed only in the carrier with the longest disease duration and greatest disability. The N-acetylaspartate/creatine ratio and the choline/creatine ratio in the basis pontis were markedly decreased in 2 symptomatic SCA1 carriers and moderately decreased in 2 asymptomatic SCA1 carriers, compared with the unaffected family members and a control group of 10 healthy volunteers. Minor decreases in the N-acetylaspartate/creatine ratio and the normal choline/creatine ratio were observed in the cerebellar hemisphere of the SCA1 carriers. Reduction of the N-acetylaspartate/creatine ratio, demonstrated by MR spectroscopy in the pons, is likely to reflect a loss of neuronal viability and might represent a biochemical marker of SCA1 more sensitive than brainstem and cerebellum atrophy and signal changes shown by MR imaging.

[Computer-assisted combined management of physical radiation protection and quality control of X-ray diagnostic equipment]

A software for the computer-assisted management of radiation protection and quality control of radiodiagnostic equipment is described. The code was written in DB3-plus language. In addition to some independent archives on X-ray diagnostic systems identification, it includes technical and radiation protection checks, environmental dosimetry in the controlled areas and on workers. The data can be searched through a key field and periodical radiation protection reports and action reports can be printed. The software programs can also perform some "intelligent" operations such as the calculation of controlled areas range and the classification of X-ray diagnostic systems and workers. This is done by retrieving the information from the archives. The software can be updated, revised and modified very easily, due to the non-connection of the archives. It is also very simple to connect DB3-plus archives with many other software packages to process and elaborate data. This software is the core of an integrated system we are developing to store and process data from diagnostic X-ray systems control meters and from our TLD personal dosimetry equipment.