Many technological advances have entered the clinical routine of Computed Tomography (CT) imaging. The new CT scanners have specific solutions in gantry design to bear the mechanical solicitations. ...The X-ray tubes have been improved for faster acquisitions at low radiation exposure, while the innovations in CT detectors provide a better image quality. The optimization of image quality and contrast, and the reduction of radiation dose, cannot be achieved without the implementation of adequate reconstruction software, such as Iterative Reconstructions (IR) and Artificial Intelligence (AI). In recent years, dual-energy (DECT) technology has expanded the indications of CT. In this narrative review, a panoramic overview of the technological novelties in CT imaging will be provided for optimal utilization of CT technology.
Synchronization of body movements to an external beat is a universal human ability, which has also been recently documented in nonhuman species. The neural substrates of this rhythmic motor ...entrainment are still under investigation. Correlational neuroimaging data suggest an involvement of the dorsal premotor cortex (dPMC) and the supplementary motor area (SMA). In 14 healthy volunteers, we more specifically investigated the neural network underlying this phenomenon using a causal approach by an established 1-Hz repetitive transcranial magnetic stimulation (rTMS) protocol, which produces a focal suppression of cortical excitability outlasting the stimulation period. Synchronization accuracy between rhythmic cues and right index finger tapping, as measured by the mean time lag (asynchrony) between motor and auditory events, was significantly affected when the right dPMC function was transiently perturbed by "off-line" focal rTMS, whereas the reproduction of the rhythmic sequence per se (inter-tap-interval) was spared. This approach affected metrical rhythms of different complexity, but not non-metrical or isochronous sequences. Conversely, no change in auditory-motor synchronization was observed with rTMS of the SMA, of the left dPMC or over a control site (midline occipital area). Our data strongly support the view that the right dPMC is crucial for rhythmic auditory-motor synchronization in humans.
Purpose
Dedicated tumor feeding vessel detection software (TFVDS) using cone beam CT has shown a higher sensitivity to detect tumor feeding vessels during hepatic arterial embolization (HAE) of ...hepatocellular carcinoma (HCC) compared to 2D imaging. Our primary hypothesis was that HCC tumors treated with HAE guided by a TFVDS would show more complete response (CR) than when treated with 2D imaging alone. Secondary analysis of the impact on X-ray exposure was performed.
Materials and Methods
Nineteen males and 8 females (median age: 69 year, 46–85) with 44 tumors (median size: 38 mm, 6–100) treated with selective HAE between January 2013 and December 2014 were included. Exclusion criteria were: extra-hepatic supply, >4 tumors, tumor size >10 cm, and adjunctive local therapy. Baseline patient and procedure characteristics were reviewed. Differences in CR per modified Response Evaluation Criteria in Solid Tumors were assessed by univariate and multivariate analyses for tumor size, number, location, particles size, and use of TFVDS.
Results
Median imaging follow-up was 20.1 months (2–33). Use of TFVDS (13 patients, 19 tumors) was the only factor predictive of CR (OR = 3.85 CI95%: 1.09, 13.67,
p
= 0.04) on univariate analysis but not on multivariate analysis (OR = 3.26 0.87, 12.23,
p
= 0.08). A higher rate of CR was observed for HAE using TFVDS guidance versus 2D imaging alone (68.4%, 13–19, vs. 36%, 9–25,
p
= 0.03). Median dose area product was lower when TFVDS was used (149.7 Gy.cm
2
, 38–365, vs. 227.8 Gy.cm
2
, 85.3–468.6,
p
= 0.05).
Conclusions
HCC embolized with TFVDS may result in improved local tumor response without increasing the dose exposure.
Deficient voluntary control of behaviour and impulsivity are key aspects of impulse control disorders. The objective of the present study was to evaluate the relationship between behavioural measures ...of impulsivity and awareness of voluntary action. Seventy-four healthy volunteers completed the Barratt Impulsiveness Scale (BIS), a questionnaire used to measure impulsive personality traits, and a go/no-go task. Moreover, all participants performed a task in which, using the Libet’s clock, they were requested to report the time of a self-initiated movement (M-judgment) or the time they first felt intention to move (W-judgment). A positive relationship between W-judgment and impulsivity measures emerged. Namely, high scores in the attentional and motor impulsivity subscales of BIS and in the number of inhibitory failure responses in the go/no-go task, were related to a low difference between the W-judgment and the actual movement (i.e. the awareness of intention to move was closer to the voluntary movement execution). In contrast no relationship emerged with M-judgment. Findings suggest that impulsivity may be related to a delayed awareness of voluntary action. We hypothesize that in impulse control disorders the interval between conscious intention and actual movement could be insufficient to allow a conscious ‘veto’ of the impending action.
Neurophysiological studies suggest that reading sheet music facilitates sensorimotor cortex in musicians. The aim of the present study was twofold: to evaluate (1) whether in piano players, reading ...notes in the bass clef (usually played with the left hand) and in the treble clef (usually played with the right hand) selectively enhances right and left M1 excitability, respectively (inter-hemispheric effect); and (2) whether reading notes played with the thumb or with the little finger selectively modulate the excitability of the abductor pollicis brevis (APB) and abductor digitorum minimi (ADM) muscles, respectively (intra-hemispheric effect). Seven pianists participated to the study. Single pulse TMS was applied to either M1 while subjects alternatively read the bass or the treble clef of five sheets music without any movements. As a baseline condition TMS was delivered during the observation of a blank pentagram. When subjects read the treble clef, the excitability of the left M1 was significantly higher compared to that recorded in the right M1. No significant differences emerged during reading of the bass clef. Moreover, motor-evoked potentials were higher in the ADM muscle regardless the note. These preliminary data support the view that music reading may induce specific inter-hemispheric modulation of the motor cortex excitability.
The cortical silent period (CSP) following transcranial magnetic stimulation reflects GABAB-mediated inhibition in the primary motor cortex (M1), and could contribute to understand the ...pathophysiological substrates of epilepsies. Increased CSP duration has been reported in idiopathic generalized epilepsy (IGE) and in partial epilepsy (PE) involving the M1, although other studies yielded discordant findings. In this meta-analysis we systematically assessed the consistency of CSP changes in untreated epileptic patients. We searched for controlled studies evaluating the CSP in drug-naïve or drug-free patients with IGE or PE. The mean difference between CSP duration obtained in patients and controls was calculated. Fourteen studies (267 patients and 234 controls) were included. A significant mean difference was found, with longer CSP in patients than in controls. The difference was still greater if IGE patients only were analyzed. CSP modifications did not depend from differences in motor threshold between patients and controls. Meta-analysis confirms CSP modifications in epilepsies, with enhancement of this cortical inhibitory measure in most IGE patients. This provides a rationale for investigations aiming to verify the hypotheses that increased CSP reflects compensatory neural phenomena counteracting transition from the interictal to ictal state, and that CSP variability reflects the pathophysiological heterogeneity of epileptic syndromes.
Practice-induced visual perceptual learning is thought to reflect the plasticity of sensory brain regions. The hypothesis that changes in early visual areas may depend on top-down modulation from ...higher level brain regions by attentional mechanisms is still debated. We used a causal approach by repetitive transcranial magnetic stimulation (rTMS) to evaluate the role of primary visual cortex (V1) and posterior parietal cortex (PPC) in visual perceptual learning. Twelve healthy volunteers performed a forced-choice orientation discrimination task of gabor patches (consisting of 500 trials in five blocks) without any intervention or immediately after a conditioning inhibitory 1-Hz rTMS protocol delivered over the V1, the right PPC, and the vertex (control area), in four different days. Conditioning inhibition by 1-Hz rTMS over the V1 produced an overall worsening of the performance accuracy but no effect in the learning rate, as measured by the slope of the learning curve. The learning rate was lower after right PPC inhibition compared to the other conditions, when evaluated during the first two blocks (200 trials) where occurred most of the learning. These preliminary findings suggest that higher level brain regions may be involved in the mechanisms underlying perceptual learning.
Dysprosody is characterized by alterations of rhythm and speed of speech and represents one of the most frequent alteration of speech in patients with Parkinson’s disease (PD). Our aim was to ...identify the presence of rhythmic alterations in the parameters related to speech rate in PD patients with no or mild hypophonia during a sentence repetition task. Twenty PD patients (6 women) and 19 healthy controls (10 women) were tested. The task consisted in the repetition of a standardized Italian vocalic sentence (“Il bambino ama le aiuole della mamma”) at least 10 times at comfortable loudness. Audio analysis is based on a newly developed automatic voiced-unvoiced segmentation to calculate net speech rate and the percentage of voiced segments with respect to the sentence duration. The analysis showed that in PD patients the speech is characterized by short rushes followed by inappropriate pauses, as revealed by the reduction of the sentence duration and the increase in net speech rate. PD patients tend to repeat the same sentence in a shorter time period than controls, but with a longer recovery time. Current data suggest that rhythmic alterations of speech may be detectable in patients using a sentence repetition task.
•We analyze dysprosody in patients with idiopathic Parkinson's disease using a sentence repetition task.•We perform an automatic analysis of speech signals.•PD patients exhibit longer pauses between ...each sentence repetition.•PD patients show a lower percentage of “speech time” during a whole repetition period.
Parkinson's disease (PD) involves impairments of voice and speech (hypokinetic dysarthria). Dysprosody is one of the most common features of PD speech that includes alterations of rhythm and velocity of articulation. The aim of this study is the evaluation of dysprosody patterns in Parkinsonian patients during a sentence repetition task by means of a fully automated tool.
Twenty PD patients (14 male and 6 female) and 19 healthy controls (9 male and 10 female) were tested. Results show significant differences between the two groups as far as the time interval between each sentence repetition (Tinter), the percent of speech time with respect to sentence duration (D%) and the Net Speech Rate (NSR – defined as the number of syllables of the sentence divided by the effective speech time) are concerned. In particular, Tinter is larger in PD patients while D% is higher in the control group. These results show that PD patients may exhibit longer pauses between each sentence repetition and a lower percentage of “speech time” during a whole repetition period. Thus, the decrease of D% leads to an increase of NSR. Other acoustic parameters (noise and F0 variability) did not show any significant difference. This study confirms that speech in PD patients is characterized by short rushes followed by unorthodox pauses. These results may lead to the development of a system for the automatic acoustic analysis which could significantly reduce the processing time in particular during pre-processing, that to date is a time-consuming and operator-dependent step especially in case of recordings of long duration.
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