Vittorio Cannatà

Gray matter decrease distribution in the early stages of Anorexia Nervosa restrictive type in adolescents.

Few studies have used Voxel-Based Morphometry (VBM) to examine brain structure in Anorexia Nervosa patients. The purpose of the present study was to investigate a sample of Anorexia Nervosa restrictive type (AN-r) adolescent patients in the early stages of the illness, using VBM in order to characterize morphometric gray matter (GM) changes. Participants were 16 AN-r female patients (with no other psychiatric disorders) whose AN-r had been in progress for less than 12 months and 16 age-matched healthy female subjects. High-resolution T1-weighted magnetic resonance images were preprocessed according to the optimized VBM method, and statistically analyzed. The analyses revealed a significant global GM decrease in the AN-r patients; furthermore, a significant region-specific decrease in GM volume was found bilaterally in the middle cingulate cortex, the precuneus, and the inferior and superior parietal lobules. The significant early GM decrease in the aforementioned regions in AN-r adolescent patients suggests that there might be a region-specific GM vulnerability that could play a role in the pathophysiology of the disease. Given that these regions are also involved in the manipulation of mental images and the mental representation of the self, this might explain the presence of a distorted body image in these patients.

Test-retest reliability of graph metrics of resting state MRI functional brain networks: A review.

The employment of graph theory to analyze spontaneous fluctuations in resting state BOLD fMRI data has become a dominant theme in brain imaging studies and neuroscience. Analysis of resting state functional brain networks based on graph theory has proven to be a powerful tool to quantitatively characterize functional architecture of the brain and it has provided a new platform to explore the overall structure of local and global functional connectivity in the brain. Due to its increased use and possible expansion to clinical use, it is essential that the reliability of such a technique is very strongly assessed. In this review, we explore the outcome of recent studies in network reliability which apply graph theory to analyze connectome resting state networks. Therefore, we investigate which preprocessing steps may affect reproducibility the most. In order to investigate network reliability, we compared the test-retest (TRT) reliability of functional data of published neuroimaging studies with different preprocessing steps. In particular we tested influence of global signal regression, correlation metric choice, binary versus weighted link definition, frequency band selection and length of time-series. Statistical analysis shows that only frequency band selection and length of time-series seem to affect TRT reliability. Our results highlight the importance of the choice of the preprocessing steps to achieve more reproducible measurements.

Accidental Exposure to UV Radiation Produced by Germicidal Lamp: Case Report and Risk Assessment

Ultraviolet radiation is known to cause both benefits and harmful effects on humans. The adverse effects mainly involve two target organs, skin and eye, and can be further divided into short‐ and long‐term effects. The present case report describes an accidental exposure of two health‐care workers to ultraviolet radiation produced by a germicidal lamp in a hospital pharmacy. The germicidal lamp presented a spectrum with an intense UV‐C component as well as a modest UV‐B contribution. Overexposure to UV‐C radiation was over 100 times as large as the ICNIRP exposure limits. A few hours after the exposure, the two subjects reported symptoms of acute UV injury and both of them continued having significant clinical signs for over 2 years. In this study, we describe acute and potentially irreversible effects caused by high UV exposure. In addition, we present the results of risk assessment by occupational exposure to germicidal lamps.

Visual Recognition and Visually Guided Action After Early Bilateral Lesion of Occipital Cortex: A Behavioral Study of a 4.6-year-old Girl

We report the case of a 4.6-year-old girl born pre-term with early bilateral occipital damage. It was revealed that the child had non-severely impaired basic visual abilities and ocular motility, a selective perceptual deficit of figure-ground segregation, impaired visual recognition and abnormal navigating through space. Even if the childs visual functioning was not optimal, this was the expression of adaptive anatomic and functional brain modifications that occurred following the early lesion. Anatomic brain structure was studied with anatomic MRI and Diffusor Tensor Imaging (DTI)-MRI. This behavioral study may provide an important contribution to understanding the impact of an early lesion of the visual system on the development of visual functions and on the immature brains potential for reorganisation related to when the damage occurred.

Brain network involved in visual processing of movement stimuli used in upper limb robotic training: an fMRI study.

BackgroundThe potential of robot-mediated therapy and virtual reality in neurorehabilitation is becoming of increasing importance. However, there is limited information, using neuroimaging, on the neural networks involved in training with these technologies. This study was intended to detect the brain network involved in the visual processing of movement during robotic training. The main aim was to investigate the existence of a common cerebral network able to assimilate biological (human upper limb) and non-biological (abstract object) movements, hence testing the suitability of the visual non-biological feedback provided by the InMotion2 Robot.MethodsA visual functional Magnetic Resonance Imaging (fMRI) task was administered to 22 healthy subjects. The task required observation and retrieval of motor gestures and of the visual feedback used in robotic training. Functional activations of both biological and non-biological movements were examined to identify areas activated in both conditions, along with differential activity in upper limb vs. abstract object trials. Control of response was also tested by administering trials with congruent and incongruent reaching movements.ResultsThe observation of upper limb and abstract object movements elicited similar patterns of activations according to a caudo-rostral pathway for the visual processing of movements (including specific areas of the occipital, temporal, parietal, and frontal lobes). Similarly, overlapping activations were found for the subsequent retrieval of the observed movement. Furthermore, activations of frontal cortical areas were associated with congruent trials more than with the incongruent ones.ConclusionsThis study identified the neural pathway associated with visual processing of movement stimuli used in upper limb robot-mediated training and investigated the brain’s ability to assimilate abstract object movements with human motor gestures. In both conditions, activations were elicited in cerebral areas involved in visual perception, sensory integration, recognition of movement, re-mapping on the somatosensory and motor cortex, storage in memory, and response control. Results from the congruent vs. incongruent trials revealed greater activity for the former condition than the latter in a network including cingulate cortex, right inferior and middle frontal gyrus that are involved in the go-signal and in decision control. Results on healthy subjects would suggest the appropriateness of an abstract visual feedback provided during motor training. The task contributes to highlight the potential of fMRI in improving the understanding of visual motor processes and may also be useful in detecting brain reorganisation during training.

Fractal Dimension Estimation Methods for Biomedical Images

The use of medical images has its main aim in the detection of potential abnormalities. This goal is accurately achieved with the synergy between the ability in recognizing unique image patterns and finding the relationship between them and possible diagnoses. One of the methods used to aid this process is the extrapolation of important features from the images called texture; texture is an important source of visual information and is a key component in image analysis.

Comparison of cryoablation with 3D mapping versus conventional mapping for the treatment of atrioventricular re-entrant tachycardia and right-sided paraseptal accessory pathways.

UNLABELLED Aim Transcatheter cryoablation is a well-established technique for the treatment of atrioventricular nodal re-entry tachycardia and atrioventricular re-entry tachycardia in children. Fluoroscopy or three-dimensional mapping systems can be used to perform the ablation procedure. The aim of this study was to compare the success rate of cryoablation procedures for the treatment of right septal accessory pathways and atrioventricular nodal re-entry circuits in children using conventional or three-dimensional mapping and to evaluate whether three-dimensional mapping was associated with reduced patient radiation dose compared with traditional mapping. METHODS In 2013, 81 children underwent transcatheter cryoablation at our institution, using conventional mapping in 41 children - 32 atrioventricular nodal re-entry tachycardia and nine atrioventricular re-entry tachycardia - and three-dimensional mapping in 40 children - 24 atrioventricular nodal re-entry tachycardia and 16 atrioventricular re-entry tachycardia. RESULTS Using conventional mapping, the overall success rate was 78.1 and 66.7% in patients with atrioventricular nodal re-entry tachycardia or atrioventricular re-entry tachycardia, respectively. Using three-dimensional mapping, the overall success rate was 91.6 and 75%, respectively (p=ns). The use of three-dimensional mapping was associated with a reduction in cumulative air kerma and cumulative air kerma-area product of 76.4 and 67.3%, respectively (p<0.05). CONCLUSIONS The use of three-dimensional mapping compared with the conventional fluoroscopy-guided method for cryoablation of right septal accessory pathways and atrioventricular nodal re-entry circuits in children was associated with a significant reduction in patient radiation dose without an increase in success rate.

Radiation exposure in diagnostic imaging: wisdom and prudence, but still a lot to understand.

Since 2000, a series of scientific articles on CT have been raising increasing concern about the risk of radiation induced cancer in children. The alarming conclusions of some of these articles had international echo through global media, provoking widespread public concern. Actually, many of these alarming scientific publications appeared to be flawed by poor study design, but their conclusions were not openly contradicted. In US and Europe pediatric radiologists had to face a huge challenge, which brought to the Image Gently campaign and the Eurosafe initiative with the aim to rebut misinformation and to support medical radiation protection. The Linear No Threshold model—which is the base of contemporary radioprotection—is increasingly questioned by new recent studies suggesting that low dose radiation would decrease cancer risk thanks to the enhancement of immune system response. Actually, pediatric radiologists have to cope with many important issues and contradictory messages. Good medical practice includes good communication about the benefits and risks of health procedures, thus the communication of radiation risk is a key component for radiologists. When considering benefits and risks, an important risk is too often ignored: the risk that skipping a diagnostic exam may cause a misdiagnosis, and therefore, a poor outcome. We should emphasize that a risk from a radiological investigation is very small, if a risk at all, and we are not sure that there is a risk at very low doses, like those doses in the majority of X-ray procedures including CT.

Currents induced by fast movements inside the MRI room may cause inhibition in an implanted pacemaker

The static magnetic field generated by MRI systems is highly non-homogenous and rapidly decreases when moving away from the bore of the scanner. Consequently, the movement around the MRI scanner is equivalent to an exposure to a time-varying magnetic field at very low frequency (few Hz). If people with an implanted pacemaker (PM) enter the MRI room, fast movements may thus induce voltages on the loop formed by the PM lead, with the potential to modify the correct behavior of the stimulator. In this study, we performed in-vitro measurements on a human-shaped phantom, equipped with an implantable PM and with a current sensor, able to monitor the activity of the PM while moving the phantom in the MRI room. Fast rotational movements in close proximity of the bore of the scanner caused the inappropriate inhibition of the PM, programmed in VVI modality, maximum sensitivity, unipolar sensing and pacing. The inhibition occurred for a variation of the magnetic field of about 3 T/s. These findings demonstrate that great care must be paid when extending PM MRI compatibility from patients to healthcare personnel, since the safety procedures and the MRI-conditional PM programming (e.g. asynchronous stimulation or bipolar sensing) used for patients cannot be applied.

Occupational exposure in MR facilities due to movements in the static magnetic field

Purpose: The exposure of operators moving in the static field of magnetic resonance (MR) facilities was assessed through measurements of the magnetic flux density, which is experienced as variable in time because of the movement. Collected data were processed to allow the comparison with most recent and authoritative safety standards. Methods: Measurements of the experienced magnetic flux density B were performed using a probe worn by volunteers moving in MR environments. A total of 55 datasets were acquired nearby a 1.5 T, 3 T, and 7 T whole body scanners. Three different metrics were applied: the maximum intensity of B, to be compared with 2013/35/EU Directive exposure limit values for static fields; the maximum variation of the vector B on every 3s‐interval, for comparison with the ICNIRP‐2014 basic restriction aimed at preventing vertigo effects; two weighted‐peak indices (for “sensory” and “health” effects: SENS‐WP, HLTH‐WP), assessing compliance with ICNIRP‐2014 and EU Directive recommendations intended to prevent stimulation effects. Results: Peak values of |B| were greater than 2 T in nine of the 55 datasets. All the datasets at 1.5 T and 3 T were compliant with the limit for vertigo effects, whereas six datasets at 7 T turned out to be noncompliant. At 7 T, all 36 datasets were noncompliant for the SENS‐WP index and 26 datasets even for the HLTH‐WP one. Conclusions: Results demonstrate that compliance with EU Directive limits for static fields does not guarantee compliance with ICNIRP‐2014 reference levels and clearly show that movements in the static field could be the key component of the occupational exposure to EMF in MR facilities.