1
|
Zagorchev L, Brueck M, Flaschner N, Wenzel F, Hyde D, Ewald A, Peters J. Patient-Specific Sensor Registration for Electrical Source Imaging Using a Deformable Head Model. IEEE Trans Biomed Eng 2020; 68:267-275. [PMID: 32746029 DOI: 10.1109/tbme.2020.3003112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Electrical source imaging of brain activity is most accurate when using individualized bioelectric head models. Constructing these models requires identifying electrode positions on the scalp surface. Current methods such as photogrammetry involve significant user interaction that limits integration in clinical workflows. This work introduces and validates a new, fully-automatic method for sensor registration. METHODS Average electrode coordinates are registered to the mean scalp mesh of a shape-constrained deformable head model used for tissue segmentation. Patient-specific electrode positions can be identified on the deformed scalp surface using point-based correspondence after model adaptation. RESULTS The performance of the proposed method for sensor registration is evaluated with simulated and real data. Electrode variability is quantified for a photogrammetry-based solution and compared against the proposed sensor registration. CONCLUSION A fully-automated model-based approach can identify electrode locations with similar accuracy as a current state-of-the-art photogrammetry system. SIGNIFICANCE The new method for sensor registration presented in this work is rapid and fully automatic. It eliminates any user dependent inaccuracy introduced in sensor registration and ensures reproducible results. More importantly, it can more easily be integrated in clinical workflows, enabling broader adoption of electrical source imaging technologies.
Collapse
|
2
|
Hironaga N, Kimura T, Mitsudo T, Gunji A, Iwata M. Proposal for an accurate TMS-MRI co-registration process via 3D laser scanning. Neurosci Res 2018; 144:30-39. [PMID: 30170008 DOI: 10.1016/j.neures.2018.08.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/06/2018] [Accepted: 08/27/2018] [Indexed: 01/20/2023]
Abstract
An important technical issue in transcranial magnetic stimulation (TMS) usage is how accurately the specific brain areas activated by TMS are assessed. However, in practice, electric field induced in TMS is dispersed and therefore actual estimation is still difficult. As a preliminary step, the projection line which is perpendicular to the TMS stimulation coil beneath the center of the coil must be accurately estimated into the brain. Therefore, we have developed a new TMS-MRI co-registration procedure that employs a 3D laser-scanner system that is very useful for general hand-manipulated TMS, and which easily estimates the TMS projection point onto the brain. The proposed system accurately captures the positional relationship between the TMS coil and anatomical images. The results of 3D image processing revealed that the registration error at each stage was kept within the submillimeter level. In addition, a motor evoked potential experiment examining the right finger motor area revealed that understandable responses were obtained when stimulation was targeted to the three different motor areas according to Penfield's map. 3D laser scanning is a technique of substantial recent interest for anatomical co-registration. The proposed method demonstrated submillimeter level accuracy of TMS-MRI co-registration.
Collapse
Affiliation(s)
- Naruhito Hironaga
- Brain Center, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
| | - Takahiro Kimura
- Research Institute, Kochi University of Technology, Tosayamada, Kami, Kochi, 782-8502, Japan; Institute of Liberal Arts and Science, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Takako Mitsudo
- Department of Clinical Neurophysiology, Faculty of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Atsuko Gunji
- College of Education, Yokohama National University, 79-2 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 Japan; National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo 187-8551, Japan
| | - Makoto Iwata
- Research Institute, Kochi University of Technology, Tosayamada, Kami, Kochi, 782-8502, Japan
| |
Collapse
|
3
|
Abstract
For high precision in source reconstruction of magnetoencephalography (MEG) or electroencephalography data, high accuracy of the coregistration of sources and sensors is mandatory. Usually, the source space is derived from magnetic resonance imaging (MRI). In most cases, however, no quality assessment is reported for sensor-to-MRI coregistrations. If any, typically root mean squares (RMS) of point residuals are provided. It has been shown, however, that RMS of residuals do not correlate with coregistration errors. We suggest using target registration error (TRE) as criterion for the quality of sensor-to-MRI coregistrations. TRE measures the effect of uncertainty in coregistrations at all points of interest. In total, 5544 data sets with sensor-to-head and 128 head-to-MRI coregistrations, from a single MEG laboratory, were analyzed. An adaptive Metropolis algorithm was used to estimate the optimal coregistration and to sample the coregistration parameters (rotation and translation). We found an average TRE between 1.3 and 2.3 mm at the head surface. Further, we observed a mean absolute difference in coregistration parameters between the Metropolis and iterative closest point algorithm of [Formula: see text] and [Formula: see text] m. A paired sample t-test indicated a significant improvement in goal function minimization by using the Metropolis algorithm. The sampled parameters allowed computation of TRE on the entire grid of the MRI volume. Hence, we recommend the Metropolis algorithm for head-to-MRI coregistrations.
Collapse
Affiliation(s)
- Hermann Sonntag
- Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. Author to whom any correspondence should be addressed
| | | | | |
Collapse
|
4
|
Hironaga N, Hagiwara K, Ogata K, Hayamizu M, Urakawa T, Tobimatsu S. Proposal for a new MEG–MRI co-registration: A 3D laser scanner system. Clin Neurophysiol 2014; 125:2404-12. [DOI: 10.1016/j.clinph.2014.03.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/05/2014] [Accepted: 03/20/2014] [Indexed: 11/25/2022]
|
5
|
Wu X, Eggebrecht AT, Ferradal SL, Culver JP, Dehghani H. Quantitative evaluation of atlas-based high-density diffuse optical tomography for imaging of the human visual cortex. BIOMEDICAL OPTICS EXPRESS 2014; 5:3882-900. [PMID: 25426318 PMCID: PMC4242025 DOI: 10.1364/boe.5.003882] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 08/21/2014] [Accepted: 09/25/2014] [Indexed: 05/24/2023]
Abstract
Image recovery in diffuse optical tomography (DOT) of the human brain often relies on accurate models of light propagation within the head. In the absence of subject specific models for image reconstruction, the use of atlas based models are showing strong promise. Although there exists some understanding in the use of some limited rigid model registrations in DOT, there has been a lack of a detailed analysis between errors in geometrical accuracy, light propagation in tissue and subsequent errors in dynamic imaging of recovered focal activations in the brain. In this work 11 different rigid registration algorithms, across 24 simulated subjects, are evaluated for DOT studies in the visual cortex. Although there exists a strong correlation (R(2) = 0.97) between geometrical surface error and internal light propagation errors, the overall variation is minimal when analysing recovered focal activations in the visual cortex. While a subject specific mesh gives the best results with a 1.2 mm average location error, no single algorithm provides errors greater than 4.5 mm. This work demonstrates that the use of rigid algorithms for atlas based imaging is a promising route when subject specific models are not available.
Collapse
Affiliation(s)
- Xue Wu
- School of Computer Science, University of Birmingham, Birmingham, B15 2TT,
UK
| | - Adam T. Eggebrecht
- Department of Radiology, Washington University School of Medicine, 4525 Scott Avenue, St Louis, MO, 63110,
USA
| | - Silvina L Ferradal
- Department of Radiology, Washington University School of Medicine, 4525 Scott Avenue, St Louis, MO, 63110,
USA
- Department of Biomedical Engineering, Washington University, One Brookings Drive, St. Louis, MO, 63130,
USA
| | - Joseph P. Culver
- Department of Radiology, Washington University School of Medicine, 4525 Scott Avenue, St Louis, MO, 63110,
USA
- Department of Biomedical Engineering, Washington University, One Brookings Drive, St. Louis, MO, 63130,
USA
| | - Hamid Dehghani
- School of Computer Science, University of Birmingham, Birmingham, B15 2TT,
UK
| |
Collapse
|
6
|
Maratos FA, Senior C, Mogg K, Bradley BP, Rippon G. Early gamma-band activity as a function of threat processing in the extrastriate visual cortex. Cogn Neurosci 2013; 3:62-8. [PMID: 22328903 PMCID: PMC3259620 DOI: 10.1080/17588928.2011.613989] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 07/26/2011] [Indexed: 12/02/2022]
Abstract
Various neuroimaging investigations have revealed that perception of emotional pictures is associated with greater visual cortex activity than their neutral counterparts. It has further been proposed that threat-related information is rapidly processed, suggesting that the modulation of visual cortex activity should occur at an early stage. Additional studies have demonstrated that oscillatory activity in the gamma band range (40–100 Hz) is associated with threat processing. Magnetoencephalography (MEG) was used to investigate such activity during perception of task-irrelevant, threat-related versus neutral facial expressions. Our results demonstrated a bilateral reduction in gamma band activity for expressions of threat, specifically anger, compared with neutral faces in extrastriate visual cortex (BA 18) within 50–250 ms of stimulus onset. These results suggest that gamma activity in visual cortex may play a role in affective modulation of visual processing, in particular with the perception of threat cues.
Collapse
|
7
|
Cooper RJ, Caffini M, Dubb J, Fang Q, Custo A, Tsuzuki D, Fischl B, Wells W, Dan I, Boas DA. Validating atlas-guided DOT: a comparison of diffuse optical tomography informed by atlas and subject-specific anatomies. Neuroimage 2012; 62:1999-2006. [PMID: 22634215 DOI: 10.1016/j.neuroimage.2012.05.031] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 04/24/2012] [Accepted: 05/15/2012] [Indexed: 10/28/2022] Open
Abstract
We describe the validation of an anatomical brain atlas approach to the analysis of diffuse optical tomography (DOT). Using MRI data from 32 subjects, we compare the diffuse optical images of simulated cortical activation reconstructed using a registered atlas with those obtained using a subject's true anatomy. The error in localization of the simulated cortical activations when using a registered atlas is due to a combination of imperfect registration, anatomical differences between atlas and subject anatomies and the localization error associated with diffuse optical image reconstruction. When using a subject-specific MRI, any localization error is due to diffuse optical image reconstruction only. In this study we determine that using a registered anatomical brain atlas results in an average localization error of approximately 18 mm in Euclidean space. The corresponding error when the subject's own MRI is employed is 9.1 mm. In general, the cost of using atlas-guided DOT in place of subject-specific MRI-guided DOT is a doubling of the localization error. Our results show that despite this increase in error, reasonable anatomical localization is achievable even in cases where the subject-specific anatomy is unavailable.
Collapse
Affiliation(s)
- Robert J Cooper
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
A Single Camera Photogrammetry System for Multi-angle Fast Localization of EEG Electrodes. Ann Biomed Eng 2011; 39:2844-56. [DOI: 10.1007/s10439-011-0374-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 07/28/2011] [Indexed: 11/26/2022]
|
9
|
Worthen SF, Hobson AR, Hall SD, Aziz Q, Furlong PL. Primary and secondary somatosensory cortex responses to anticipation and pain: a magnetoencephalography study. Eur J Neurosci 2011; 33:946-59. [DOI: 10.1111/j.1460-9568.2010.07575.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
10
|
EEG–MRI Co-registration and Sensor Labeling Using a 3D Laser Scanner. Ann Biomed Eng 2010; 39:983-95. [DOI: 10.1007/s10439-010-0230-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 11/26/2010] [Indexed: 10/18/2022]
|
11
|
Baysal U, Şengül G. Single Camera Photogrammetry System for EEG Electrode Identification and Localization. Ann Biomed Eng 2010; 38:1539-47. [DOI: 10.1007/s10439-010-9950-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 01/29/2010] [Indexed: 11/28/2022]
|
12
|
Coarse threat images reveal theta oscillations in the amygdala: A magnetoencephalography study. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2009; 9:133-43. [DOI: 10.3758/cabn.9.2.133] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
13
|
Whalen C, Maclin EL, Fabiani M, Gratton G. Validation of a method for coregistering scalp recording locations with 3D structural MR images. Hum Brain Mapp 2008; 29:1288-301. [PMID: 17894391 PMCID: PMC6871211 DOI: 10.1002/hbm.20465] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 05/11/2007] [Accepted: 07/12/2007] [Indexed: 11/09/2022] Open
Abstract
A common problem in brain imaging is how to most appropriately coregister anatomical and functional data sets into a common space. For surface-based recordings such as the event related optical signal (EROS), near-infrared spectroscopy (NIRS), event-related potentials (ERPs), and magnetoencephalography (MEG), alignment is typically done using either (1) a landmark-based method involving placement of surface markers that can be detected in both modalities; or (2) surface-fitting alignment that samples many points on the surface of the head in the functional space and aligns those points to the surface of the anatomical image. Here we compare these two approaches and advocate a combination of the two in order to optimize coregistration of EROS and NIRS data with structural magnetic resonance images (sMRI). Digitized 3D sensor locations obtained with a Polhemus digitizer can be effectively coregistered with sMRI using fiducial alignment as an initial guess followed by a Marquardt-Levenberg least-squares rigid-body transform (df = 6) to match the surfaces. Additional scaling parameters (df = 3) and point-by-point surface constraints can also be employed to further improve fitting. These alignment procedures place the lower-bound residual error at 1.3 +/- 0.1 mm (micro +/- s) and the upper-bound target registration error at 4.4 +/- 0.6 mm (micro +/- s). The dependence of such errors on scalp segmentation, number of registration points, and initial guess is also investigated. By optimizing alignment techniques, anatomical localization of surface recordings can be improved in individual subjects.
Collapse
Affiliation(s)
- Christopher Whalen
- Beckman Institute, University of Illinois at Urbana‐Champaign, Urbana, Illinois
| | - Edward L. Maclin
- Beckman Institute, University of Illinois at Urbana‐Champaign, Urbana, Illinois
| | - Monica Fabiani
- Beckman Institute, University of Illinois at Urbana‐Champaign, Urbana, Illinois
- Psychology Department, University of Illinois at Urbana‐Champaign, Urbana, Illinois
| | - Gabriele Gratton
- Beckman Institute, University of Illinois at Urbana‐Champaign, Urbana, Illinois
- Psychology Department, University of Illinois at Urbana‐Champaign, Urbana, Illinois
| |
Collapse
|
14
|
Spiclin Z, Hans A, Duffy FH, Warfield SK, Likar B, Pernus F. EEG to MRI registration based on global and local similarities of MRI intensity distributions. MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION : MICCAI ... INTERNATIONAL CONFERENCE ON MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION 2008; 11:762-70. [PMID: 18979815 PMCID: PMC2690649 DOI: 10.1007/978-3-540-85988-8_91] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/20/2023]
Abstract
In this paper, a novel method for EEG to MRI registration is proposed. Initial registration is achieved by extracting and matching symmetry planes of MRI and EEG data, followed by iterative registration based on minimizing a cost function. Comparison of the intensity distributions of the whole MR image and MRI voxels around a head surface point yields global similarities, while the comparison of intensity distributions of MRI voxels around corresponding EEG points, which reflects the head's sagittal symmetry, yields local similarities. Therefore, when the EEG points are registered to the MR image, maximal global and local similarities should be obtained. The cost function, incorporating global and local similarities, was the sum of Kullback-Leibler divergences between corresponding intensity distributions. The proposed method was evaluated on clinical MRI data with simulated EEG data, yielding mean registration error of 0.48 +/- 0.33 mm, while with real EEG data an average root-mean-square point-to-surface error of 2.27 +/- 0.02 mm was obtained.
Collapse
Affiliation(s)
- Ziga Spiclin
- Faculty of Electrical Engineering, University of Ljubljana, Slovenia.
| | | | | | | | | | | |
Collapse
|
15
|
Koessler L, Maillard L, Benhadid A, Vignal JP, Braun M, Vespignani H. Spatial localization of EEG electrodes. Neurophysiol Clin 2007; 37:97-102. [PMID: 17540292 DOI: 10.1016/j.neucli.2007.03.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
AIM OF THE STUDY An important goal for EEG-based functional brain studies is to estimate the location of brain sources that produce the scalp-recorded signals. Such source localization requires locating precisely the position of the EEG sensors. This review describes and compares different methods that are used for localizing EEG sensors. RESULTS Five different methods have been described in literature. Manual methods consist in manual measurements to calculate the 3D coordinates of the sensors. Electromagnetic and ultrasound digitization permit localization by using trade devices. The photogrammetry system consists in taking pictures of the patient's head with the sensors. The last method consists in directly localizing the EEG sensors in the MRI volume. DISCUSSION AND CONCLUSIONS The spatial localization of EEG sensors is an important step in performing source localization. This method should be accurate, fast, reproducible, and cheap. Currently, electromagnetic digitization is the most currently used method but MRI localization could be an interesting way because no additional method or device needs to be used to locate the EEG sensors.
Collapse
Affiliation(s)
- L Koessler
- Inserm ERI13, University Henri Poincaré, 54000 Nancy, France
| | | | | | | | | | | |
Collapse
|
16
|
Boor R, Jacobs J, Hinzmann A, Bauermann T, Scherg M, Boor S, Vucurevic G, Pfleiderer C, Kutschke G, Stoeter P. Combined spike-related functional MRI and multiple source analysis in the non-invasive spike localization of benign rolandic epilepsy. Clin Neurophysiol 2007; 118:901-9. [PMID: 17317297 DOI: 10.1016/j.clinph.2006.11.272] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2004] [Revised: 10/30/2006] [Accepted: 11/08/2006] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To localize the irritative zone in children by combined spike-related fMRI and EEG multiple source analysis (MSA) in children with benign rolandic epilepsy. METHODS Interictal spikes were averaged and localized using MSA, and source locations were displayed in the anatomical 3D-MRI in 11 patients (5-12 yrs, median 10). Interictal spikes were additionally recorded during the fMRI acquisition (EEG-fMRI), and the fMRI sequences were correlated off-line with the EEG spikes. RESULTS MSA revealed an initial central dipole in all patients, including the face or hand area. A second dipolar source was mostly consistent with propagated activity. BOLD activations from EEG-fMRI, consistent with the locations of the initial dipoles, were found in four patients. We found additional large areas of BOLD activations in 3 of these subjects extending into the sylvian fissure and the insula. These were identified as propagated activity by MSA using the short time differences in the source waveforms. CONCLUSIONS MSA provided reliable localization of the spike onset zone in all children with benign rolandic epilepsy. Using the combination of EEG-fMRI and MSA we were able to discriminate the spike onset zone from propagated epileptiform source activity, using the spatial resolution of the EEG-fMRI technique and the temporal resolution of the MSA. However, the sensitivity of the EEG-fMRI technique was low and further improvements of the technique are warranted. SIGNIFICANCE This study shows that a combination of EEG-fMRI and MSA may be a powerful tool to describe the irritative zone of patients with idiopathic focal epilepsies. Clinical studies in patients with non-idiopathic focal epilepsies may clarify whether both techniques can be used as complementary clinical tools to localize the onset of interictal epileptic activity in focal epilepsies.
Collapse
Affiliation(s)
- R Boor
- University Children's Hospital, Pediatric Neurology Johannes-Gutenberg University, Mainz, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Koikkalainen J, Lötjönen J. Reconstruction of 3-D Head Geometry From Digitized Point Sets: An Evaluation Study. ACTA ACUST UNITED AC 2004; 8:377-86. [PMID: 15484443 DOI: 10.1109/titb.2004.834401] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In this paper, we evaluate different methods to estimate patient-specific scalp, skull, and brain surfaces from a set of digitized points from the target's scalp surface. The reconstruction problem is treated as a registration problem: An a priori surface model, consisting of the scalp, skull, and brain surfaces, is registered to the digitized surface points. The surface model is generated from segmented magnetic resonance (MR) volume images. We study both affine and free-form deformation (FFD) registration, the use of average models, the averaging of individual registration results, a model selection procedure, and statistical deformation models. The registration algorithms are mainly previously published, and the objective of this paper is to evaluate these methods in this particular application with sparse data. The main interest of this paper is to generate geometric head models for biomedical applications, such as electroencephalography and magnetoencephalographic. However, the methods can also be applied to other anatomical regions and to other application areas. The methods were validated using 15 MR volume images, from which the scalp, skull, and brain were manually segmented. The best results were achieved by averaging the results of the FFD registrations of the database: the mean distance from the manually segmented target surface to a deformed a priori model surface for the studied anatomical objects was 1.68-2.08 mm, depending on the point set used. The results support the use of the evaluated methods for the reconstruction of geometric models in applications with sparse data.
Collapse
Affiliation(s)
- Juha Koikkalainen
- Laboratory of Biomedical Engineering, Helsinki University of Technology, FIN-02015 HUT, Finland.
| | | |
Collapse
|
18
|
Adjamian P, Barnes GR, Hillebrand A, Holliday IE, Singh KD, Furlong PL, Harrington E, Barclay CW, Route PJG. Co-registration of magnetoencephalography with magnetic resonance imaging using bite-bar-based fiducials and surface-matching. Clin Neurophysiol 2004; 115:691-8. [PMID: 15036065 DOI: 10.1016/j.clinph.2003.10.023] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2003] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To introduce a new technique for co-registration of Magnetoencephalography (MEG) with magnetic resonance imaging (MRI). We compare the accuracy of a new bite-bar with fixed fiducials to a previous technique whereby fiducial coils were attached proximal to landmarks on the skull. METHODS A bite-bar with fixed fiducial coils is used to determine the position of the head in the MEG co-ordinate system. Co-registration is performed by a surface-matching technique. The advantage of fixing the coils is that the co-ordinate system is not based upon arbitrary and operator dependent fiducial points that are attached to landmarks (e.g. nasion and the preauricular points), but rather on those that are permanently fixed in relation to the skull. RESULTS As a consequence of minimizing coil movement during digitization, errors in localization of the coils are significantly reduced, as shown by a randomization test. Displacement of the bite-bar caused by removal and repositioning between MEG recordings is minimal ( approximately 0.5 mm), and dipole localization accuracy of a somatosensory mapping paradigm shows a repeatability of approximately 5 mm. The overall accuracy of the new procedure is greatly improved compared to the previous technique. CONCLUSIONS The test-retest reliability and accuracy of target localization with the new design is superior to techniques that incorporate anatomical-based fiducial points or coils placed on the circumference of the head.
Collapse
Affiliation(s)
- P Adjamian
- The Wellcome Trust Laboratory for MEG Studies, Neurosciences Research Institute, Aston University, Birmingham B4 7ET, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Bhakoo KK, Bell JD, Cox IJ, Taylor-Robinson SD. The application of magnetic resonance imaging and spectroscopy to gene therapy. Methods Enzymol 2004; 386:303-13. [PMID: 15120258 DOI: 10.1016/s0076-6879(04)86014-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Kishore K Bhakoo
- MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London, United Kingdom
| | | | | | | |
Collapse
|
20
|
Kober H, Nimsky C, Vieth J, Fahlbusch R, Ganslandt O. Co-registration of function and anatomy in frameless stereotaxy by contour fitting. Stereotact Funct Neurosurg 2003; 79:272-83. [PMID: 12890986 DOI: 10.1159/000072396] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We investigated a co-registration algorithm using a contour-fitting procedure to integrate functional data from magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) for frameless stereotaxy. In fMRI the shape of the head was reconstructed from anatomical images, in MEG it was scanned using an electromagnetic sensor position indicator. Functional information was transferred to the 3D-MR image set used for frameless stereotaxy by fitting the digitized (MEG) and reconstructed head shape (fMRI) to the 3D-MR images. The mean residual error of the contour fit was 2.3 mm for the MEG and 1.3 mm for the fMRI registration. According to computer simulations, the achievable transformation error is 0.75 and 0.5 mm, respectively. This method enables independent recording of functional and anatomical measurements with a co-registration accuracy better than 2 mm.
Collapse
Affiliation(s)
- Helmut Kober
- Department of Neurosurgery, University Erlangen-Nürnberg, Erlangen, Germany
| | | | | | | | | |
Collapse
|
21
|
Huppertz HJ, Hoegg S, Sick C, Lücking CH, Zentner J, Schulze-Bonhage A, Kristeva-Feige R. Cortical current density reconstruction of interictal epileptiform activity in temporal lobe epilepsy. Clin Neurophysiol 2001; 112:1761-72. [PMID: 11514259 DOI: 10.1016/s1388-2457(01)00588-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the value of cortical current density (CCD) reconstruction in localizing intracranial generators of interictal epileptiform activity in mesial and lateral temporal lobe epilepsy (TLE). METHODS Non-linear minimum L(1)-norm CCD reconstruction (with current sources restricted to the individual cortical surface and a realistic boundary element method (BEM) head model) was used to localize and to study the propagation of interictal epileptiform EEG activity in 13 pre-surgical patients with TLE. RESULTS In all but one patient with mesial temporal lesions, an initial activation maximum corresponding to the ascending part of averaged sharp waves was found in the ipsilateral anterior basolateral temporal lobe, mostly extending up to the affected mesial structures whose resection rendered the patients seizure-free. In all 3 patients with lateral temporal lesions, the activation was initially confined to temporal neocortex immediately adjacent to the epileptogenic lesion. Towards the peak of sharp waves, two patients showed a propagation of interictal activity to anterior and posterior and partly contralateral temporal regions. A conventional EEG analysis based on amplitude maxima or phase reversal would have missed the initial onset zone. CONCLUSIONS The findings demonstrate that CCD reconstruction can be a valuable additional non-invasive component in the multimodal pre-surgical evaluation of epilepsy patients.
Collapse
Affiliation(s)
- H J Huppertz
- Epilepsy Center, University of Freiburg, Breisacher Strasse 64, D-79106 Freiburg, Germany.
| | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
OBJECTIVES We developed a new technique of fully automatic alignment of brain data acquired with scalp sensors (e.g. electroencephalography/evoked potential (EP) electrodes, magnetoencephalography sensors) with a magnetic resonance imaging (MRI) volume of the head. METHODS The method uses geometrical features (two sets of head points: digitized from the subject and extracted from MRI) to guide the alignment. It combines matching on 3 dimensional (3D) geometrical moments that perform the initial alignment, and 3D distance-based alignment that provides the final tuning. To reduce errors of the initial guessed computation resulting from digitization of the head surface points we introduced weights to compute geometrical moments, and a procedure to remove outliers to eliminate incorrectly digitized points. RESULTS The method was tested on simulated (Monte Carlo trials) and on real data sets. The simulations demonstrated that for the number of test points within the range of 0.1-1% of the total number of head surface points and for the digitization error in the range of -2-2 mm the average map error was between 0.7 and 2.1 mm. The average distance error was less than 1 mm. Tests on real data gave the average distance error between 2.1 and 2.5 mm. CONCLUSIONS The developed technique is fast, robust and comfortable for the patient and for medical personnel. It registers scalp sensor positions with MRI head volume with accuracy that is satisfactory for localization of biological processes examined with a commonly used number of scalp sensors (32, 64, or 128).
Collapse
Affiliation(s)
- D Kozinska
- Interdisciplinary Center for Mathematical and Computational Modelling, University of Warsaw, ul. Pawinskiego 5a, 02-106, Warsaw, Poland.
| | | | | |
Collapse
|
23
|
Huppertz HJ, Hof E, Klisch J, Wagner M, Lücking CH, Kristeva-Feige R. Localization of interictal delta and epileptiform EEG activity associated with focal epileptogenic brain lesions. Neuroimage 2001; 13:15-28. [PMID: 11133305 DOI: 10.1006/nimg.2000.0680] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study was aimed at investigating the accuracy of electric source reconstruction in the presurgical evaluation of epilepsy patients. Spontaneous EEG activity of 14 patients with focal intracerebral epileptogenic lesions was analyzed by source reconstruction based on high-resolution EEG (64-channel system) and a boundary element method head model accounting for the individual head anatomy. Equivalent dipole modeling was applied to focal delta and interictal epileptiform activity. The localization results were validated quantitatively by comparison with the sites of the structural lesions. In 6 of 9 patients with focal delta activity, the maximum of dipole concentration was closer than 10 mm to the nearest lesion margin and mostly at the border or within pathologically altered cortical tissue. In all 11 patients showing interictal epileptiform activity, the localization results were found in the same lobe as the lesion. In almost half of them, they were closer than 10 mm to the lesion margin. Patients with larger distances (22-36 mm) mostly had hippocampal atrophy or sclerosis. Their dipole locations did not appear in the affected hippocampus, but in the adjacent temporal neocortex. In conclusion, electric source reconstruction applied to both abnormal slow and interictal epileptiform EEG activity seems to be a valuable additional noninvasive component in the multimodal presurgical evaluation of epilepsy patients.
Collapse
Affiliation(s)
- H J Huppertz
- Department of Neurology and Clinical Neurophysiology, University of Freiburg, Germany
| | | | | | | | | | | |
Collapse
|
24
|
Feige B, Aertsen A, Kristeva-Feige R. Dynamic synchronization between multiple cortical motor areas and muscle activity in phasic voluntary movements. J Neurophysiol 2000; 84:2622-9. [PMID: 11068003 DOI: 10.1152/jn.2000.84.5.2622] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To study the functional role of synchronized neuronal activity in the human motor system, we simultaneously recorded cortical activity by high-resolution electroencephalography (EEG) and electromyographic (EMG) activity of the activated muscle during a phasic voluntary movement in seven healthy subjects. Here, we present evidence for dynamic beta-range (16-28 Hz) synchronization between cortical activity and muscle activity, starting after termination of the movement. In the same time range, increased tonic activity in the activated muscle was found. During the movement execution a low-frequency (2-14 Hz) synchronization was found. Using a novel analysis, phase-reference analysis, we were able to extract the EMG-coherent EEG maps for both, low- and high-frequency beta range synchronization. The electrical source reconstruction of the EMG-coherent EEG maps was performed with respect to the individual brain morphology from magnetic resonance imaging (MRI) using a distributed source model (cortical current density analysis) and a realistic head model. The generators of the beta-range synchronization were not only located in the primary motor area, but also in premotor areas. The generators of the low-frequency synchronization were also located in the primary motor and in premotor areas, but with additional participation of the medial premotor area. These findings suggest that the dynamic beta-range synchronization between multiple cortical areas and activated muscles reflects the transition of the collective motor network into a new equilibrium state, possibly related to higher demands on attention, while the low-frequency synchronization is related to the movement execution.
Collapse
|
25
|
Bell JD, Taylor-Robinson SD. Assessing gene expression in vivo: magnetic resonance imaging and spectroscopy. Gene Ther 2000; 7:1259-64. [PMID: 10918496 DOI: 10.1038/sj.gt.3301218] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent developments in magnetic resonance imaging and spectroscopy afford the possibility of detecting and assessing transfer, expression and subsequent therapeutic changes of effector or marker transgenes noninvasively. In the field of MR imaging, 'smart' MR contrast agents are being developed, so called because they change their conformational structure and in so doing induce MR detectable changes in a given tissue. These agents become 'switched on' in response to physiological changes brought about by the enzymatic action of a given gene product (enzymes), and are being developed for use in intact cells, isolated organs and animal models. Ultimately, these agents hold the promise of bridging the gap between the laboratory and the patient with noninvasive detection of transgene expression in vivo in man. Similarly, magnetic resonance spectroscopy is being developed as a noninvasive method to assess transgene expression indirectly by means of MR visible intracellular markers. These markers take the form of intracellular endo/exogenous metabolites associated with exogenous enzyme expression and function. Again, this technique will be applicable to a variety of different situations, from cell suspensions through to clinical imaging of the whole body. In this article the unique opportunities for laboratory-based and clinical studies afforded by MR techniques are discussed.
Collapse
Affiliation(s)
- J D Bell
- Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College School of Medicine, Hammersmith Hospital, London, UK
| | | |
Collapse
|
26
|
Ball T, Schreiber A, Feige B, Wagner M, Lücking CH, Kristeva-Feige R. The role of higher-order motor areas in voluntary movement as revealed by high-resolution EEG and fMRI. Neuroimage 1999; 10:682-94. [PMID: 10600414 DOI: 10.1006/nimg.1999.0507] [Citation(s) in RCA: 260] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the human motor cortex structural and functional differences separate motor areas related to motor output from areas essentially involved in higher-order motor control. Little is known about the function of these higher-order motor areas during simple voluntary movement. We examined a simple finger flexion movement in six healthy subjects using a novel brain-imaging approach, integrating high-resolution EEG with the individual structural and functional MRI. Electrical source reconstruction was performed in respect to the individual brain morphology from MRI. Highly converging results from EEG and fMRI were obtained for both executive and higher-order motor areas. All subjects showed activation of the primary motor area (MI) and of the frontal medial wall motor areas. Two different types of medial wall activation were observed with both methods: Four of the subjects showed an anterior type of activation, and two of the subjects a posterior type of activation. In the former, activity started in the anterior cingulate motor area (CMA) and subsequently shifted its focus to the intermediate supplementary motor area (SMA). Approximately 120 ms before the movement started, the intermediate SMA showed a drop of source strength, and simultaneously MI showed an increase of source strength. In the posterior type, activation was restricted to the posterior SMA. Further, three of the subjects investigated showed activation in the inferior parietal lobe (IPL) starting during early movement preparation. In all subjects showing activation of higher-order motor areas (anterior CMA, intermediate SMA, IPL) these areas became active before the executive motor areas (MI and posterior SMA). We suggest that the early activation of the anterior CMA and the IPL may be related to attentional functions of these areas. Further, we argue that the intermediate part of the SMA triggers the actual motor act via the release of inhibition of the primary motor area. Our results demonstrate that a noninvasive, multimodal brain imaging technique can reveal individual cortical brain activity with high temporal and spatial resolution, independent of a priori physiological assumptions.
Collapse
Affiliation(s)
- T Ball
- Neurologic Clinic, Albert-Ludwigs-University, Freiburg, D-79106, Germany
| | | | | | | | | | | |
Collapse
|