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| 2. |
- Axelson, Hans W, et al.
(författare)
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Trigeminal Nerve Stimulation Does Not Acutely Affect Cortical Excitability in Healthy Subjects
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 613-617
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Trigeminal nerve stimulation (TNS) has recently emerged as a new therapeutic option for patients with drug-resistant epilepsy but its potential mechanisms of action are not known. Since other antiepileptic treatments have been shown to alter cortical excitability, thereby reducing the liability to seizures, it has been suggested that cranial nerve stimulation such as TNS may act in the same way.OBJECTIVE: To study whether TNS has the potential to alter cortical excitability in healthy subjects.METHODS: An adaptive paired-pulse transcranial magnetic stimulation protocol stimulating the dominant hand motor area was used to measure resting motor threshold (rMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and long-interval intracortical inhibition (LICI) before, during, and after 40 min of 120 Hz bilateral external continuous trigeminal nerve stimulation. Neuronavigation was used for guidance.RESULTS: TNS was well tolerated by all subjects. No significant changes were seen in the parameters studied.CONCLUSION: Unlike for example anti-epileptic drugs and the ketogenic diet, trigeminal nerve stimulation does not seem to alter cortical excitability in healthy subjects. This is the first study on cortical excitability in relation to continuous trigeminal nerve stimulation. It still remains to be proven that TNS has the prerequisites to effectively counteract epileptic events in humans.
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| 4. |
- Caliandro, Pietro, et al.
(författare)
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Jitter of Corticospinal Neurons During Repetitive Transcranial Magnetic Stimulation : Method and Possible Clinical Implications
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 580-586
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Tidskriftsartikel (refereegranskat)abstract
- Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis.
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| 7. |
- Gupta, Vikas, et al.
(författare)
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Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration
- 2018
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Ingår i: Journal of Cardiovascular Computed Tomography. - : Elsevier. - 1934-5925. ; 12:2, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Background Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images.Methods Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature.Results Comparison with manual tracking showed high accuracy (DSC: 0.99± 0.05; PTC: 0.56mm± 0.47 mm) and resulted in determinant(Jacobian) > 0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature.Conclusions Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.
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| 10. |
- Hansson, Nicolaj C., et al.
(författare)
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The impact of calcium volume and distribution in aortic root injury related to balloon-expandable transcatheter aortic valve replacement
- 2015
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Ingår i: JOURNAL OF CARDIOVASCULAR COMPUTED TOMOGRAPHY. - : ELSEVIER SCIENCE INC. - 1934-5925. ; 9:5, s. 382-392
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Tidskriftsartikel (refereegranskat)abstract
- Background: A detailed assessment of calcium within the aortic root may provide important additional information regarding the risk of aortic root injury during transcatheter heart valve replacement (TAVR). Objective: We sought to delineate the effect of calcium volume and distribution on aortic root injury during TAVR. Methods: Thirty-three patients experiencing aortic root injury during TAVR with a balloon-expandable valve were compared with a control group of 153 consecutive TAVR patients without aortic root injury (as assessed by post-TAVR multidetector CT). Using commercial software to analyze contrast-enhanced pre-TAVR CT scans, caltium volume was determined in 3 regions: (1) the overall left ventricular outflow tract (LVOT), extending 10 mm down from the aortic annulus plane; (2) the upper LVOT, extending 2 mm down from the annulus plane; and (3) the aortic valve region. Results: Calcium volumes in the upper LVOT (median, 29 vs 0 mm(3); P less than .0001) and overall LVOT (median, 74 vs 3 mm(3); P = .0001) were higher in patients who experienced aortic root injury compared with the control group. Calcium in the aortic valve region did not differ between groups. Upper LVOT calcium volume was more predictive of aortic root injury than overall LVOT calcium volume (area under receiver operating curve [AUG]; 0.78; 95% confidence interval, 0.69-0.86 vs AUC, 0.71; 95% confidence interval, 0.62-0.82; P = .010). Upper LVOT calcium below the noncoronary cusp was significantly more predictive of aortic root injury compared to calcium underneath the right coronary cusp or the left coronary cusp (AUC, 0.81 vs 0.68 vs 0.64). Prosthesis oversizing greater than20% (likelihood ratio test, P = .028) and redilatation (likelihood ratio test, P = .015) improved prediction of aortic root injury by upper LVOT calcium volume. Conclusion: Calcification of the LVOT, especially in the upper LVOT, located below the noncoronary cusp and extending from the annular region, is predictive of aortic root injury during TAVR with a balloon-expandable valve. (C) 2015 Society of Cardiovascular Computed Tomography. All rights reserved.
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| 14. |
- Kiss, Zelma H. T., et al.
(författare)
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"New and improved" DBS batteries?
- 2019
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Ingår i: Brain Stimulation. - : Elsevier. - 1935-861X .- 1876-4754. ; 12:4, s. 833-834
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 15. |
- Kothari, Simple Futarmal, et al.
(författare)
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Effect of repetitive transcranial magnetic stimulation on altered perception of One's own face
- 2020
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Ingår i: Brain Stimulation. - : Elsevier. - 1935-861X .- 1876-4754. ; 13:3, s. 554-561
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Chronic orofacial pain (COP) patients often perceive the painful face area as "swollen" without clinical signs; such self-reported illusions of the face are termed perceptual distortion (PD). The pathophysiological mechanisms underlying PD remain elusive.OBJECTIVE: To test the neuromodulatory effect of repetitive transcranial magnetic stimulation (rTMS) on PD in healthy individuals, to gain insight into the cortical mechanisms underlying PD.METHODS: PD was induced experimentally by injections of local anesthetic (LA) around the infraorbital nerve and measured as perceived size changes of the affected area. Participants were randomly allocated to inhibitory rTMS (n = 26) or sham rTMS (n = 26) group. The participants rated PD at baseline, 6 min after LA, immediately, 20 and 40 min after rTMS. The rTMS (inhibitory and sham) was applied to face (lip) representation area of primary somatosensory cortex (SI) as an intervention at 10 min after the LA, when the magnitude of PD is large. As inhibitory rTMS, continuous theta-burst stimulation paradigm (50 Hz) for 40s was employed to inhibit cortical activity.RESULTS: We demonstrated a significant decrease in the magnitude of PD immediately and 20 min after the application of inhibitory rTMS compared with sham rTMS (P < 0.006). In two control experiments, we also showed that peripheral muscle stimulation and stimulation of a cortical region other than the lip representation area had no effect on the magnitude of the PD.CONCLUSIONS: Inhibitory rTMS applied to a somatotopical-relevant cortical region modulates PD of the face in healthy individuals and could potentially have therapeutic implications for COP patients.
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| 16. |
- Laroy, Maarten, et al.
(författare)
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Characterization of gray matter volume changes from one week to 6 months after termination of electroconvulsive therapy in depressed patients
- 2024
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Ingår i: Brain Stimulation. - : ELSEVIER SCIENCE INC. - 1935-861X .- 1876-4754. ; 17:4, s. 876-886
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Tidskriftsartikel (refereegranskat)abstract
- Background: Increased gray matter volume (GMV) following electroconvulsive therapy (ECT) has been welldocumented, with limited studies reporting a subsequent decrease in GMV afterwards. Objective: This study characterized the reversion pattern of GMV after ECT and its association with clinical depression outcome, using multi-site triple time-point data from the Global ECT-MRI Research Collaboration (GEMRIC). Methods: 86 subjects from the GEMRIC database were included, and GMV in 84 regions-of-interest (ROI) was obtained from automatic segmentation of T1 MRI images at three timepoints: pre-ECT (T0), within one-week post-ECT (T1), and one to six months post-ECT (T2). RM-ANOVAs were used to assess longitudinal changes and LMM analyses explored associations between GMV changes and demographical and clinical characteristics. Results: 63 of the 84 ROIs showed a significant increase-and-decrease pattern (RM-ANOVA, Bonferroni corrected p < 0.00059). Post hoc tests indicated a consistent pattern in each of these 63 ROIs: significant increase from T0 to T1in GMV, followed by significant decrease from T1 to T2 and no difference between T0 and T2, except for both amygdalae, right hippocampus and pars triangularis, which showed the same increase and decrease but GMV at T2 remained higher compared to T0. No consistent relationship was found between GMV change pattern and clinical status. Conclusion: The GEMRIC cohort confirmed a rapid increase of GMV after ECT followed by reversion of GMV one to six months thereafter. The lack of association between the GMV change pattern and depression outcome scores implies a transient neurobiological effect of ECT unrelated to clinical improvement.
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| 19. |
- Nordin, Teresa, et al.
(författare)
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Probabilistic maps for deep brain stimulation – Impact of methodological differences
- 2022
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 15:5, s. 1139-1152
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Tidskriftsartikel (refereegranskat)abstract
- Background: Group analysis of patients with deep brain stimulation (DBS) has the potential to help understand and optimize the treatment of patients with movement disorders. Probabilistic stimulation maps (PSM) are commonly used to analyze the correlation between tissue stimulation and symptomatic effect but are applied with different methodological variations.Objective: To compute a group-specific MRI template and PSMs for investigating the impact of PSM model parameters.Methods: Improvement and occurrence of dizziness in 68 essential tremor patients implanted in caudal zona incerta were analyzed. The input data includes the best parameters for each electrode contact (screening), and the clinically used settings. Patient-specific electric field simulations (n = 488) were computed for all DBS settings. The electric fields were transformed to a group-specific MRI template for analysis and visualization. The different comparisons were based on PSMs representing occurrence (N-map), mean improvement (M-map), weighted mean improvement (wM-map), and voxel-wise t-statistics (p-map). These maps were used to investigate the impact from input data (clinical/screening settings), clustering methods, sampling resolution, and weighting function.Results: Screening or clinical settings showed the largest impacts on the PSMs. The average differences of wM-maps were 12.4 and 18.2% points for the left and right sides respectively. Extracting clusters based on wM-map or p-map showed notable variation in volumes, while positioning was similar. The impact on the PSMs was small from weighting functions, except for a clear shift in the positioning of the wM-map clusters.Conclusion: The distribution of the input data and the clustering method are most important to consider when creating PSMs for studying the relationship between anatomy and DBS outcome.
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| 21. |
- Renker, Matthias, et al.
(författare)
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Influence of coronary stenosis location on diagnostic performance of machine learning-based fractional flow reserve from CT angiography
- 2021
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Ingår i: JOURNAL OF CARDIOVASCULAR COMPUTED TOMOGRAPHY. - : ELSEVIER SCIENCE INC. - 1934-5925. ; 15:6, s. 492-498
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Tidskriftsartikel (refereegranskat)abstract
- Background: Compared with invasive fractional flow reserve (FFR), coronary CT angiography (cCTA) is limited in detecting hemodynamically relevant lesions. cCTA-based FFR (CT-FFR) is an approach to overcome this insufficiency by use of computational fluid dynamics. Applying recent innovations in computer science, a machine learning (ML) method for CT-FFR derivation was introduced and showed improved diagnostic performance compared to cCTA alone. We sought to investigate the influence of stenosis location in the coronary artery system on the performance of ML-CT-FFR in a large, multicenter cohort. Methods: Three hundred and thirty patients (75.2% male, median age 63 years) with 502 coronary artery stenoses were included in this substudy of the MACHINE (Machine Learning Based CT Angiography Derived FFR: A MultiCenter Registry) registry. Correlation of ML-CT-FFR with the invasive reference standard FFR was assessed and pooled diagnostic performance of ML-CT-FFR and cCTA was determined separately for the following stenosis locations: RCA, LAD, LCX, proximal, middle, and distal vessel segments. Results: ML-CT-FFR correlated well with invasive FFR across the different stenosis locations. Per-lesion analysis revealed improved diagnostic accuracy of ML-CT-FFR compared with conventional cCTA for stenoses in the RCA (71.8% [95% confidence interval, 63.0%-79.5%] vs. 54.8% [45.7%-63.8%]), LAD (79.3 [73.9-84.0] vs. 59.6 [53.5-65.6]), LCX (84.1 [76.0-90.3] vs. 63.7 [54.1-72.6]), proximal (81.5 [74.6-87.1] vs. 63.8 [55.9-71.2]), middle (81.2 [75.7-85.9] vs. 59.4 [53.0-65.6]) and distal stenosis location (67.4 [57.0-76.6] vs. 51.6 [41.1-62.0]). Conclusion: In a multicenter cohort with high disease prevalence, ML-CT-FFR offered improved diagnostic performance over cCTA for detecting hemodynamically relevant stenoses regardless of their location.
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| 22. |
- Sandfort, Veit, et al.
(författare)
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Spectral photon-counting CT in cardiovascular imaging
- 2021
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Ingår i: Journal of Cardiovascular Computed Tomography. - : Elsevier BV. - 1934-5925. ; 15:3, s. 218-225
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Tidskriftsartikel (refereegranskat)abstract
- Photon-counting computed tomography (PCCT) is an emerging technology promising to substantially improve cardiovascular imaging. Recent engineering and manufacturing advances by several vendors are expected to imminently launch this new technology into clinical reality. Photon-counting detectors (PCDs) have multiple potential advantages over conventional energy integrating detectors (EIDs) such as the absence of electronic noise, multi-energy capability, and increased spatial resolution. These developments will have different timescales for implementation and will affect different clinical scopes. We describe the technical aspects of PCCT, explain the current developments, and finally discuss potential advantages of PCCT in cardiovascular imaging.
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| 23. |
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| 24. |
- Vanhoecke, Jonathan, et al.
(författare)
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Deep brain stimulation for disorders of consciousness : Systematic review of cases and ethics
- 2017
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Ingår i: Brain Stimulation. - : Elsevier. - 1935-861X .- 1876-4754. ; 10:6, s. 1013-1023
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Forskningsöversikt (refereegranskat)abstract
- Background: A treatment for patients suffering from prolonged severely altered consciousness is not available. The success of Deep Brain Stimulation (DBS) in diseases such as Parkinson's, dystonia and essential tremor provided a renewed impetus for its application in Disorders of Consciousness (DoC). Objective: To evaluate the rationale for DBS in patients with DoC, through systematic review of literature containing clinical data and ethical considerations. Methods: Articles from PubMed, Embase, Medline and Web of Science were systematically reviewed. Results: The outcomes of 78 individual patients reported in 19 articles from 1968 onwards were pooled and elements of ethical discussions were compared. There is no clear clinical evidence that DBS is a treatment for DoC that can restore both consciousness and the ability to communicate. In patients who benefitted, the outcome of DBS is often confounded by the time frame of spontaneous recovery from DoC. Difficult ethical considerations remain, such as the risk of increasing self-awareness of own limitations, without improving overall wellbeing, and the issues of proxy consent. Conclusion: DBS is far from being evident as a possible future therapeutic avenue for patients with DoC. Double-blind studies are lacking, and many clinical and ethical issues have to be addressed. In the rare cases when DBS for patients with DoC is considered, this needs to be evaluated meticulously on a case by case basis, with comprehensive overall outcome measures including psychological and quality-of-life assessments, and with the guidance of an ethical and interdisciplinary panel, especially in relation to proxy consent.
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