| 1. |
- Vandenberghe, Rik, et al.
(författare)
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F-18-Flutemetamol Amyloid Imaging in Alzheimer Disease and Mild Cognitive Impairment A Phase 2 Trial
- 2010
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Ingår i: Annals of Neurology. - : Wiley. - 1531-8249 .- 0364-5134. ; 68:3, s. 319-329
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The most widely studied positron emission tomography ligand for in vivo P-amyloid imaging is C-11-Pittsburgh compound B (C-11-PIB). Its availability, however, is limited by the need for an on-site cyclotron. Validation of the F-18-labeled PIB derivative F-18-flutemetamol could significantly enhance access to this novel technology. Methods: Twenty-seven patients with early-stage clinically probable Alzheimer disease (AD), 20 with amnestic mild cognitive impairment (MCI), and 15 cognitively intact healthy volunteers (HVs) above and 10 HVs below 55 years of age participated. The primary endpoint was the efficacy of blinded visual assessments of F-18-flutemetamol scans in assigning subjects to a raised versus normal uptake category, with clinical diagnosis as the standard of truth (SOT). As secondary objectives, we determined the correlation between the regional standardized uptake value ratios (SUVRs) for F-18-flutemetamol and its parent molecule C-11-PIB in 20 of the AD subjects and 20 of the MCI patients. We also determined test-retest variability of F-18-flutemetamol SUVRs in 5 of the AD subjects. Results: Blinded visual assessments of F-18-flutemetamol scans assigned 25 of 27 scans from AD subjects and 1 of 15 scans from the elderly HVs to the raised category, corresponding to a sensitivity of 93.1% and a specificity of 93.3% against the SOT. Correlation coefficients between cortical F-18-flutemetamol SUVRs and C-11-PIB SUVRs ranged from 0.89 to 0.92. Test-retest variabilities of regional SUVRs were 1 to 4%. Interpretation: F-18-Flutemetamol performs similarly to the C-11-PIB parent molecule within the same subjects and provides high test-retest replicability and potentially much wider accessibility for clinical and research use. ANN NEUROL 2010;68:319-329
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| 2. |
- Andersson, JLR, et al.
(författare)
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A multivariate approach to registration of dissimilar tomographic images
- 1999
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Ingår i: European Journal of Nuclear Medicine. - : SPRINGER VERLAG. - 0340-6997 .- 1432-105X .- 1619-7070 .- 1619-7089. ; 26:7, s. 718-733
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Tidskriftsartikel (refereegranskat)abstract
- We devised a method to allow for retrospective registration of tomographic images with very different information content, the main emphasis being on sets of positron emission tomography images obtained with different tracers. A multivariate cost-function
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| 3. |
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| 4. |
- Antila, Kari, et al.
(författare)
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The PredictAD project : development of novel biomarkers and analysis software for early diagnosis of the Alzheimer's disease
- 2013
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Ingår i: Interface Focus. - : The Royal Society Publishing. - 2042-8898 .- 2042-8901. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common cause of dementia affecting 36 million people worldwide. As the demographic transition in the developed countries progresses towards older population, the worsening ratio of workers per retirees and the growing number of patients with age-related illnesses such as AD will challenge the current healthcare systems and national economies. For these reasons AD has been identified as a health priority, and various methods for diagnosis and many candidates for therapies are under intense research. Even though there is currently no cure for AD, its effects can be managed. Today the significance of early and precise diagnosis of AD is emphasized in order to minimize its irreversible effects on the nervous system. When new drugs and therapies enter the market it is also vital to effectively identify the right candidates to benefit from these. The main objective of the PredictAD project was to find and integrate efficient biomarkers from heterogeneous patient data to make early diagnosis and to monitor the progress of AD in a more efficient, reliable and objective manner. The project focused on discovering biomarkers from biomolecular data, electrophysiological measurements of the brain and structural, functional and molecular brain images. We also designed and built a statistical model and a framework for exploiting these biomarkers with other available patient history and background data. We were able to discover several potential novel biomarker candidates and implement the framework in software. The results are currently used in several research projects, licensed to commercial use and being tested for clinical use in several trials.
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| 5. |
- Buck, TD, et al.
(författare)
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3-D segmentation of medical structures by integration of raycasting with anatomic knowledge
- 1995
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Ingår i: Computers & graphics. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0097-8493. ; 19:3, s. 441-449
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Tidskriftsartikel (refereegranskat)abstract
- We present a graphically interactive procedure which is used to register a digital anatomic brain atlas with the tomographic patient volume. Patient structures to be segmented are outlined by local elastic deformation of corresponding objects from the ana
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| 6. |
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| 7. |
- Hult, Roger, 1969-
(författare)
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Segmentation and Visualisation of Human Brain Structures
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis the focus is mainly on the development of segmentation techniques for human brain structures and of the visualisation of such structures. The images of the brain are both anatomical images (magnet resonance imaging (MRI) and autoradigraphy) and functional images that show blood flow (functional magnetic imaging (fMRI), positron emission tomography (PET), and single photon emission tomograpy (SPECT)). When working with anatomical images, the structures segmented are visible as different parts of the brain, e.g. the brain cortex, the hippocampus, or the amygdala. In functional images, the activity or the blood flow that be seen.Grey-level morphology methods are used in the segmentations to make tissue types in the images more homogenous and minimise difficulties with connections to outside tissue. A method for automatic histogram thresholding is also used. Furthermore, there are binary operations such as logic operation between masks and binary morphology operations.The visualisation of the segmented structures uses either surface rendering or volume rendering. For the visualisation of thin structures, surface rendering is the better choice since otherwise some voxels might be missed. It is possible to display activation from a functional image on the surface of a segmented cortex. A new method for autoradiographic images has been developed, which integrates registration, background compensation, and automatic thresholding to getfaster and more realible results than the standard techniques give.
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| 8. |
- Hult, Roger, et al.
(författare)
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Segmentation of the Brain in MRI Using Grey Level Morphology and Propagation of Information
- 1999
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Ingår i: Proceedings of SCIA'99. - : Pattern Recognition Society of Denmark, Lyngby. - 8788306429 ; , s. 367-373
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Konferensbidrag (refereegranskat)abstract
- An important step in the analysis of 3D MRI brain images is to segment the cortex from surrounding tissue. In this paper we present an algorithm for fully automatic segmentation of the cortex from T1-weighted MRI data. The automatic segmentation starts wi
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| 9. |
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| 10. |
- Kovalev, Vassili, et al.
(författare)
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Classification of SPECT scans of AD and FLD based on intensity and gradient information
- 1999
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Ingår i: Medical Image Understanding and Analysis 99. ; , s. 4-
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Konferensbidrag (refereegranskat)abstract
- This paper describes a method for classification of SPECT perfusion scans of Alzheimer's disease (AD) and Frontal lobe dementia (FLD) when compared to normal controls. A brain atlas was used to define volumes of interests corresponding to the brain lobes.
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| 11. |
- Lilja, Johan, et al.
(författare)
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Visualization and Quantification of 3-Dimensional Stereotactic Surface Projections for F-18-Flutemetamol PET Using Variable Depth
- 2016
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X .- 1535-5667. ; 57:7, s. 1078-1083
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional stereotactic surface projection (3D-SSP) is a widely used method for the analysis of clinical F-18-FDG brain studies. However, for PET amyloid scans the use of 3D-SSP is challenging because of nonspecific uptake in white matter. Our objective was to implement a method for 3D-SSP quantification and visualization of F-18-flutemetamol images that avoids extraction of white matter signal. METHODS: Triangulated brain surface models were extracted from a T1-weighted MR template image. Using an F-18-flutemetamol-negative template, a maximum depth for each vertex on the surface models was calculated to avoid extraction of white matter. The method was evaluated using F-18-flutemetamol images from 2 cohorts. Cohort 1 consisted of 105 healthy volunteers and was used to create a normal database for each reference region. Cohort 2 consisted of 171 subjects including patients with Alzheimer disease and mild cognitive impairment and healthy volunteers. Images were spatially normalized using an adaptive template registration method, and SUV ratio 3D-SSP values were computed using the pons and cerebellar cortex as reference regions. Images from cohort 2 were then compared with the normal database and classified into negatives and positives, based on a calculated z score threshold. The results were compared with consensus visual interpretation results from 5 trained interpreters blinded to clinical data. RESULTS: With the pons as the reference region, the optimal z score threshold was 1.97, resulting in an overall agreement with visual interpretation results in 170 of 171 images (99.42%). With the cerebellar cortex as the reference region, the optimal z score threshold was 2.41, with an overall agreement with visual interpretation in 168 of 171 images (98.25%). CONCLUSION: Variable-depth 3D-SSP allows computation and visualization of F-18-flutemetamol 3D-SSP maps, with minimized contribution from white matter signal while retaining sensitivity in detecting gray matter signal.
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| 12. |
- Lundqvist, Roger, et al.
(författare)
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Classification of Functional Patterns in SPECT Brain Scans Based on Partial Least Squares Analysis
- 1999
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Ingår i: Proceedings of SCIA'99. - : Pattern Recognition Society of Denmark, Lyngby. - 8788306429 ; , s. 375-381
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Konferensbidrag (refereegranskat)abstract
- The main purpose of this paper is to show the potential of the partial least squares (PLS) method for finding image descriptors which can be used for classification of clinical single photon emission computed tomography SPECT neuroimaging data. In this ar
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| 13. |
- Lundqvist, Roger, et al.
(författare)
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Implementation and validation of an adaptive template registration method for 18F-flutemetamol imaging data.
- 2013
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:8, s. 1472-8
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Tidskriftsartikel (refereegranskat)abstract
- UNLABELLED: The spatial normalization of PET amyloid imaging data is challenging because different white and gray matter patterns of negative (Aβ-) and positive (Aβ+) uptake could lead to systematic bias if a standard method is used. In this study, we propose the use of an adaptive template registration method to overcome this problem.METHODS: Data from a phase II study (n = 72) were used to model amyloid deposition with the investigational PET imaging agent (18)F-flutemetamol. Linear regression of voxel intensities on the standardized uptake value ratio (SUVR) in a neocortical composite region for all scans gave an intercept image and a slope image. We devised a method where an adaptive template image spanning the uptake range (the most Aβ- to the most Aβ+ image) can be generated through a linear combination of these 2 images and where the optimal template is selected as part of the registration process. We applied the method to the (18)F-flutemetamol phase II data using a fixed volume of interest atlas to compute SUVRs. Validation was performed in several steps. The PET-only adaptive template registration method and the MR imaging-based method used in statistical parametric mapping were applied to spatially normalize PET and MR scans, respectively. Resulting transformations were applied to coregistered gray matter probability maps, and the quality of the registrations was assessed visually and quantitatively. For comparison of quantification results with an independent patient-space method, FreeSurfer was used to segment each subject's MR scan and the parcellations were applied to the coregistered PET scans. We then correlated SUVRs for a composite neocortical region obtained with both methods. Furthermore, to investigate whether the (18)F-flutemetamol model could be generalized to (11)C-Pittsburgh compound B ((11)C-PIB), we applied the method to Australian Imaging, Biomarkers and Lifestyle (AIBL) (11)C-PIB scans (n = 285) and compared the PET-only neocortical composite score with the corresponding score obtained with a semimanual method that made use of the subject's MR images for the positioning of regions.RESULTS: Spatial normalization was successful on all scans. Visual and quantitative comparison of the new PET-only method with the MR imaging-based method of statistical parametric mapping indicated that performance was similar in the cortical regions although the new PET-only method showed better registration in the cerebellum and pons reference region area. For the (18)F-flutemetamol quantification, there was a strong correlation between the PET-only and FreeSurfer SUVRs (Pearson r = 0.96). We obtained a similar correlation for the AIBL (11)C-PIB data (Pearson r = 0.94).CONCLUSION: The derived adaptive template registration method allows for robust, accurate, and fully automated quantification of uptake for (18)F-flutemetamol and (11)C-PIB scans without the use of MR imaging data.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Thurfjell, Lennart, et al.
(författare)
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A Boundary Approach for Fast Neighborhood Operations on Three-Dimensional Binary Data
- 1995
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Ingår i: Graphical Models and Image Processing. - : ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS. - 1077-3169 .- 1090-2481. ; 57:1, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents algorithms for fast erosion, dilation, and connected component labeling of three-dimensional binary data, The algorithms are based on a boundary representation of the data where the only voxels stored are those that belong to an object
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| 20. |
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| 21. |
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| 22. |
- Thurfjell, Lennart, et al.
(författare)
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Automated Quantification of F-18-Flutemetamol PET Activity for Categorizing Scans as Negative or Positive for Brain Amyloid: Concordance with Visual Image Reads
- 2014
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 2159-662X .- 1535-5667. ; 55:10, s. 1623-1628
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Tidskriftsartikel (refereegranskat)abstract
- Clinical trials of the PET amyloid imaging agent F-18-flutemetamol have used visual assessment to classify PET scans as negative or positive for brain amyloid. However, quantification provides additional information about regional and global tracer uptake and may have utility for image assessment over time and across different centers. Using postmortem brain neuritic plaque density data as a truth standard to derive a standardized uptake value ratio (SUVR) threshold, we assessed a fully automated quantification method comparing visual and quantitative scan categorizations. We also compared the histopathology-derived SUVR threshold with one derived from healthy controls. Methods: Data from 345 consenting subjects enrolled in 8 prior clinical trials of F-18-flutemetamol injection were used. We grouped subjects into 3 cohorts: an autopsy cohort (n = 68) comprising terminally ill patients with postmortem confirmation of brain amyloid status; a test cohort (n = 172) comprising 33 patients with clinically probable Alzheimer disease, 80 patients with mild cognitive impairment, and 59 healthy volunteers; and a healthy cohort of 105 volunteers, used to define a reference range for SUVR. Visual image categorizations for comparison were from a previous study. A fully automated PET-only quantification method was used to compute regional neocortical SUVRs that were combined into a single composite SUVR. An SUVR threshold for classifying scans as positive or negative was derived by ranking the PET scans from the autopsy cohort based on their composite SUVR and comparing data with the standard of truth based on postmortem brain amyloid status for subjects in the autopsy cohort. The derived threshold was used to categorize the 172 scans in the test cohort as negative or positive, and results were compared with categorization using visual assessment. Different reference and composite region definitions were assessed. Threshold levels were also compared with corresponding thresholds derived from the healthy group. Results: Automated quantification (using pons as the reference region) demonstrated 91% sensitivity and 88% specificity and gave 3 false-positive and 4 false-negative scans. All 3 false-positive cases were either borderline-normal by standard of truth or had moderate to heavy cortical diffuse plaque burden. In the test cohort, the concordance between quantitative and visual read categorization ranged from 97.1% to 99.4% depending on the selection of reference and composite regions. The threshold derived from the healthy group was close to the histopathology-derived threshold. Conclusion: Categorization of F-18-flutemetamol amyloid imaging data using an automated PET-only quantification method showed good agreement with histopathologic classification of neuritic plaque density and a strong concordance with visual read results.
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| 23. |
- Thurfjell, Lennart, et al.
(författare)
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CBA—an atlas-based software tool used to facilitate the interpretation of neuroimaging data
- 1995
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Ingår i: Computer Methods and Programs in Biomedicine. - : ELSEVIER SCI PUBL IRELAND LTD. - 0169-2607 .- 1872-7565. ; 47:1, s. 51-71
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Tidskriftsartikel (refereegranskat)abstract
- CBA, a software tool used to improve quantification and evaluation of neuroimaging data has been developed. It uses a detailed 3-dimensional brain atlas that can be adapted to fit the brain of an individual patient represented by a series of displayed ima
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| 24. |
- Thurfjell, Lennart, et al.
(författare)
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Fusion of Multimodality Brain Images
- 1999
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Ingår i: Proceedings of SCIA'99. - : Pattern Recognition Society of Denmark, Lyngby. - 8788306429 ; , s. 359-366
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Konferensbidrag (refereegranskat)abstract
- Fusion of multimodal medical images refers both to the registration of and to the visualization of the images. The system presented uses registration methods that we have reported previously and the paper is mainly focused on visualization. We present a v
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| 25. |
- Thurfjell, Lennart, et al.
(författare)
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Surface reconstruction from volume data used for creating an adaptable functional brain atlas
- 1995
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Ingår i: IEEE Transactions on Nuclear Science. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9499 .- 1558-1578. ; 42:4, s. 1383-1387
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Tidskriftsartikel (refereegranskat)abstract
- Functions for creating adaptable atlas structures from volume data have now been included in the Karolinska Computerized Brain Atlas (CBA) software system. The main objective is to allow the user to create functional structures based on data from brain ac
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