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235 results on '"Leenders, K.L."'

51. On two methods of statistical image analysis

Author

Missimer, J, Knorr, U, Maguire, RP, Herzog, H, Seitz, RJ, Tellman, L, and Leenders, K.L.

Subjects
COMPUTERIZED BRAIN ATLAS, positron emission tomography, PET, POSITRON-EMISSION-TOMOGRAPHY, evaluation of significance, O-15-BUTANOL, fungi, spatial standardization, LOCALIZATION, ddc:610, activation studies, human brain, VALIDATION
Abstract

The computerized brain atlas (CBA) and statistical parametric mapping (SPM) are two procedures for voxel-based statistical evaluation of PET activation studies. Each includes spatial standardization of image volumes, computation of a statistic, and evaluation of its significance. In addition, smoothing and correcting for differences of global means are commonly performed in SPM before statistical analysis. We report a comparison of methods in an analysis of regional cerebral blood flow (rCBF) in 10 human volunteers and 10 simulated activations. For the human studies, CBA or linear SPM standarization methods were followed by smoothing and computation of a statistic with the paired t-test of CBA or general linear model of SPM. No standardization, linear, and nonlinear SPM standardization were applied to the simulations. Significance of the statistic was evaluated using the cluster-size method common to SPM and CBA. SPM employs the theory of Gaussian random fields to estimate the cluster size distributions; simulations described in the Appendix provided empirical distributions derived from t-maps. The quantities evaluated were number and size of functional regions (FRs), maximum statistic, average resting rCBF, and percentage change. For the simulations, the efficiency of signal detection and rate of false positives could be evaluated as well as the distributions of statistics and cluster size in the absense of signal. The similarity of the results yielded by similar methods of analysis for the human studies and the simulated activations substantiates the robustness of the methods for selecting functional regions. However, the analysis of simulated activations demonstrated that quantitative evaluation of significance of a functional region encounters important obstacles at every stage of the analysis. (C) 1999 Wiley-Liss, inc.

Published
1999

52. Gender differences in Parkinson's disease.

Author

Haaxma, C.A., Bloem, B.R., Borm, G.F., Oyen, W.J.G., Leenders, K.L., Eshuis, S., Booij, J., Dluzen, D.E., Horstink, M.W.I.M., Haaxma, C.A., Bloem, B.R., Borm, G.F., Oyen, W.J.G., Leenders, K.L., Eshuis, S., Booij, J., Dluzen, D.E., and Horstink, M.W.I.M.

Abstract

Contains fulltext : 53439.pdf (publisher's version ) (Closed access), OBJECTIVE: To investigate gender differences in basic disease characteristics, motor deterioration and nigrostriatal degeneration in Parkinson's disease (PD). METHODS: We studied 253 consecutive PD patients who were not receiving levodopa or dopamine agonists (disease duration < or = 10 years). We investigated the influence of gender and oestrogen status on: (1) age at onset, (2) presenting symptom, (3) severity and progression of motor symptoms (Unified Parkinson's Disease Rating Scale III (UPDRS-III) scores) and (4) amount and progression of nigrostriatal degeneration ([123I]FP-CIT single photon emission computed tomography measurements). RESULTS: Age at onset was 2.1 years later in women (53.4 years) than in men (51.3 years). In women, age at onset correlated positively with parity, age at menopause and fertile life span. Women more often presented with tremor (67%) than men (48%). Overall, patients presenting with tremor had a 3.6 year higher age at onset and a 38% slower UPDRS-III deterioration. Mean UPDRS-III scores at disease onset were equal for both genders, as was the rate of deterioration. Women had a 16% higher striatal [123I]FP-CIT binding than men at symptom onset and throughout the course of PD. CONCLUSIONS: Our results suggest that, in women, the development of symptomatic PD may be delayed by higher physiological striatal dopamine levels, possibly due to the activity of oestrogens. This could explain the epidemiological observations of a lower incidence and higher age at onset in women. Women also presented more often with tremor which, in turn, is associated with milder motor deterioration and striatal degeneration. Taken together, these findings suggest a more benign phenotype in women with PD.

Published
2007

72. Parkinson en Lewy-body-dementie (DLB).

Author

Leenders, K.L.

Abstract

Copyright of Handboek Dementie is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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73. Corticobasale degeneratie.

Author

de Vries, J.J. and Leenders, K.L.

Abstract

Copyright of Handboek Dementie is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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79. Familial parkinsonism with synuclein pathology: Clinical and PET studies of A30P mutation carriers

Author

Kruger, R., primary, Kuhn, W., additional, Leenders, K.L., additional, Sprengelmeyer, R., additional, Muller, T., additional, Woitalla, D., additional, Portman, A.T., additional, Maguire, R.P., additional, Veenma, L., additional, Schroder, U., additional, Schols, L., additional, Epplen, J.T., additional, Riess, O., additional, and Przuntek, H., additional

Published
2001
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95. Positron emission tomography in drug evaluation: Influence of three different catechol-O-methyltransferase inhibitors on metabolism of [NCA] 6-[18F]fluoro-l-dopa in rhesus monkey

Author

Günther, I., primary, Psylla, M., additional, Reddy, G.N., additional, Antonini, A., additional, Vontobel, P., additional, Reist, H.W., additional, Zollinger, A., additional, Nickles, R.J., additional, Beer, H.-F., additional, Schubiger, P.A., additional, and Leenders, K.L., additional

Published
1995
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100. PET neuroimaging and mutations in the DJ-1 gene.

Author

Dekker, M.C.J., Eshuis, S.A., Maguire, R.P., Veenma-van der Duijn, L., Pruim, J., Snijders, P.J.L.M., Oostra, B.A., van Duijn, C.M., and Leenders, K.L.

Subjects
PARKINSON'S disease, GENETIC mutation, GENES, DIAGNOSTIC imaging, METABOLISM
Abstract

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson’s disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson’s disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene. [ABSTRACT FROM AUTHOR]

Published
2004
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