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Brighton, United Kingdom

Rosazza C.,Neuroradiology Unit | Rosazza C.,Neuroradiology Units | Minati M.,Neuroradiology Unit | Minati M.,Neuroradiology Units | And 4 more authors.
American Journal of Neuroradiology | Year: 2012

BACKGROUND AND PURPOSE: The connectivity across brain regions can be evaluated through fMRI either by using ICA or by means of correlation analysis of time courses measured in predefined ROIs. The purpose of this study was to investigate quantitatively the correspondence between the connectivity information provided by the 2 techniques. MATERIALS AND METHODS: In this study, resting-state fMRI data from 40 healthy participants were independently analyzed by using spatial ICA and ROI-based analysis. To assess the correspondence between the results provided by the 2 methods, for all combinations of ROIs, we compared the time course correlation coefficient with the corresponding "ICA coactivation index."RESULTS: A strongly significant correspondence of moderate intensity was found for 20 ICA components (r = 0.44, P < .001). Repeating the analysis with 10, 15, 25, 30, 35, and 40 components, we found that the correlation remained but was weaker (r = 0.35-0.41). CONCLUSIONS: There is a significant but not complete correspondence between the results provided by ICA and ROI-based analysis of resting-state data. Source


Yoshie M.,University College London | Yoshie M.,Clinical Imaging science Center | Yoshie M.,Japan Society for the Promotion of Science | Yoshie M.,Osaka University | Haggard P.,University College London
Current Biology | Year: 2013

Sense of agency (SoA) refers to the feeling that one's voluntary actions produce external sensory events [1, 2]. Several psychological theories hypothesized links between SoA and affective evaluation [3-6]. For example, people tend to attribute positive outcomes to their own actions, perhaps reflecting high-level narrative processes that enhance self-esteem [3]. Here we provide the first evidence that such emotional modulations also involve changes in the low-level sensorimotor basis of agency. The intentional binding paradigm [1] was used to quantify the subjective temporal compression between a voluntary action and its sensory consequences, providing an implicit measure of SoA. Emotional valence of action outcomes was manipulated by following participants' key-press actions with negative or positive emotional vocalizations [7], or neutral sounds. We found that intentional binding was reduced for negative compared to positive or neutral outcomes. Discriminant analyses identified a change in time perception of both actions and their negative outcomes, demonstrating that the experience of action itself is subject to affective modulation. A small binding benefit was also found for positive action outcomes. Emotional modulation of SoA may contribute to regulating social behavior. Correctly tracking the valenced effects of one's voluntary actions on other people could underlie successful social interactions. © 2013 The Authors. Source


Ganeshan B.,Clinical Imaging science Center | Skogen K.,Clinical Imaging science Center | Pressney I.,Southampton General Hospital | Coutroubis D.,University of Sussex | Miles K.,Clinical Imaging science Center
Clinical Radiology | Year: 2012

Aim: To undertake a pilot study assessing whether tumour heterogeneity evaluated using computed tomography texture analysis (CTTA) has the potential to provide a marker of tumour aggression and prognosis in oesophageal cancer. Materials and methods: In 21 patients, unenhanced CT images of the primary oesophageal lesion obtained using positron-emission tomography (PET)-CT examinations underwent CTTA. CTTA was carried out using a software algorithm that selectively filters and extracts textures at different anatomical scales between filter values 1.0 (fine detail) and 2.5 (coarse features) with quantification as entropy and uniformity (measures image heterogeneity). Texture parameters were correlated with average tumour 2-[ 18F]-fluoro-2- deoxy-d-glucose (FDG) uptake [standardized uptake values (SUV mean and SUV max)] and clinical staging as determined by endoscopic ultrasound (nodal involvement) and PET-CT (distant metastases). The relationship between tumour stage, FDG uptake, and texture with survival was assessed using Kaplan-Meier analysis. Results: Tumour heterogeneity correlated with SUV max and SUV mean. The closest correlations were found for SUV mean measured as uniformity and entropy with coarse filtration (r = -0.754, p < 0.0001; and r = 0.748, p = 0.0001 respectively). Heterogeneity was also significantly greater in patients with clinical stage III or IV for filter values between 1.0 and 2.0 (maximum difference at filter value 1.5: entropy: p = 0.027; uniformity p = 0.032). The median (range) survival was 21 (4-34) months. Tumour heterogeneity assessed by CTTA (coarse uniformity) was an independent predictor of survival [odds ratio (OR)=4.45 (95% CI: 1.08, 18.37); p = 0.039]. Conclusion: CTTA assessment of tumour heterogeneity has the potential to identify oesophageal cancers with adverse biological features and provide a prognostic indicator of survival. © 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. Source


Ng F.,Paul Strickland Scanner Center | Ganeshan B.,Clinical Imaging science Center | Kozarski R.,University of Hertfordshire | Miles K.A.,Clinical Imaging science Center | And 2 more authors.
Radiology | Year: 2013

Purpose: To determine if computed tomographic (CT) texture features of primary colorectal cancer are related to 5-year overall survival rate. Materials and Methods: Institutional review board waiver was obtained for this retrospective analysis. Texture features of the entire primary tumor were assessed with contrast material-enhanced staging CT studies obtained in 57 patients as part of an ethically approved study and by using proprietary software. Entropy, uniformity, kurtosis, skewness, and standard deviation of the pixel distribution histogram were derived from CT images without filtration and with filter values corresponding to fine (1.0), medium (1.5, 2.0), and coarse (2.5) textures. Patients were followed up until death and were censored at 5 years if they were still alive. Kaplan-Meier analysis was performed to determine the relationship, if any, between CT texture and 5-year overall survival rate. The Cox proportional hazards model was used to assess independence of texture parameters from stage. Results: Follow-up data were available for 55 of 57 patients. There were eight stage I, 19 stage II, 17 stage III, and 11 stage IV cancers. Fine-texture feature Kaplan-Meier survival plots for entropy, uniformity, kurtosis, skewness, and standard deviation of the pixel distribution histogram were significantly different for tumors above and below each respective threshold receiver operating characteristic (ROC) curve optimal cutoff value (P = .001, P = .018, P = .032, P = .008, and P = .001, respectively), with poorer prognosis for ROC optimal values (a) less than 7.89 for entropy, (b) at least 0.01 for uniformity, (c) less than 2.48 for kurtosis, (d) at least -0.38 for skewness, and (e) less than 61.83 for standard deviation. Multivariate Cox proportional hazards regression analysis showed that each parameter was independent from the stage predictor of overall survival rate (P = .001, P = .009, P = .006, P = .02, and P = .001, respectively). Conclusion: Fine-texture features are associated with poorer 5-year overall survival rate in patients with primary colorectal cancer. © RSNA, 2012. Source


Simpson A.R.H.,Sussex Eye Hospital | Simpson A.R.H.,Kings College London | Dowell N.G.,Clinical Imaging science Center | Jackson T.L.,Kings College London | And 2 more authors.
Investigative Ophthalmology and Visual Science | Year: 2013

Purpose. To study the effect of pars plana vitrectomy (PPV) on vitreous oxygenation (pO2) using magnetic resonance imaging (MRI). Methods. Patients due to undergo PPV for either macular hole or epiretinal membrane were recruited. MRI scanning was performed 1 week before and at least 3 months after PPV. MRI T1 mapping was performed using an inversion recovery-true fast imaging with steady-state precession (TrueFISP) sequence at several inversion times, from a single slice positioned through the center of both eyes in the axial oblique plane. Additional phantom data were measured in porcine vitreous, to define the relationships between T1 relaxation times and balanced salt solution (BSS), to simulate human vitreous and aqueous, respectively, for a suitable pO2 range (5-70 mm Hg). Pre-PPV pO2 was also measured intraoperatively using a polarographic oxygen probe. Results. Eleven participants (age range 59-84) were recruited; two declined the post-PPV scan. Corrected T1 times indicated that the mean (±SD) pO2 increased significantly following PPV, from 13.2 ± 5.8 to 34.5 ± 8.0 mm Hg (P < 0.001). In the nonsurgical (control) eye, pO2 did not change significantly from the first to second MRI scan (13.7 ± 7.8 vs. 16.3 ± 8.7 mm Hg, P = 0.239). Mean pO2 measured intraoperatively was 7.2 ± 0.6 mm Hg (n = 10). Conclusions. These results confirm that vitrectomy substantially increases vitreous pO2. MRI is a noninvasive technique that can be used to study vitreous oxygenation in both vitrectomized and nonvitrectomized eyes. © 2013 The Association for Research in Vision and Ophthalmology, Inc. Source

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