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David Vállez García

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4 papers

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YNICL Journal 2025 Journal Article

Amyloid PET predicts atrophy in older adults without dementia: Results from the AMYPAD Prognostic & Natural History study

Leonard Pieperhoff
Luigi Lorenzini
Sophie Mastenbroek
Mario Tranfa
Mahnaz Shekari
Alle Meije Wink
Robin Wolz
Sylke Grootoonk

Highlights • Aβ-PET predicts atrophy in key brain regions in older adults without dementia.• Fusiform volumetric loss is linked to Aβ independent of CSF tau levels.• Temporal atrophy is stronger in women with higher Aβ burden.• APOE-ε4 carriers show larger Aβ-driven frontal & hippocampal atrophy.

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YNICL Journal 2021 Journal Article

Feasibility of pharmacokinetic parametric PET images in scaled subprofile modelling using principal component analysis

Débora E. Peretti
Remco J. Renken
Fransje E. Reesink
Bauke M. de Jong
Peter P. De Deyn
Rudi A.J.O. Dierckx
Janine Doorduin
Ronald Boellaard

Scaled subprofile model using principal component analysis (SSM/PCA) is a multivariate analysis technique used, mainly in [18F]-2-fluoro-2-deoxy-d-glucose (FDG) PET studies, for the generation of disease-specific metabolic patterns (DP) that may aid with the classification of subjects with neurological disorders, like Alzheimer’s disease (AD). The aim of this study was to explore the feasibility of using quantitative parametric images for this type of analysis, with dynamic [11C]-labelled Pittsburgh Compound B (PIB) PET data as an example. Therefore, 15 AD patients and 15 healthy control subjects were included in an SSM/PCA analysis to generate four AD-DPs using relative cerebral blood flow (R 1), binding potential (BP ND) and SUVR images derived from dynamic PIB and static FDG-PET studies. Furthermore, 49 new subjects with a variety of neurodegenerative cognitive disorders were tested against these DPs. The AD-DP was characterized by a reduction in the frontal, parietal, and temporal lobes voxel values for R 1 and SUVR-FDG DPs; and by a general increase of values in cortical areas for BP ND and SUVR-PIB DPs. In conclusion, the results suggest that the combination of parametric images derived from a single dynamic scan might be a good alternative for subject classification instead of using 2 independent PET studies.

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YNIMG Journal 2021 Journal Article

Myelin quantification with MRI: A systematic review of accuracy and reproducibility

Chris W.J. van der Weijden
David Vállez García
Ronald J.H. Borra
Patrick Thurner
Jan F. Meilof
Peter-Jan van Laar
Rudi A.J.O. Dierckx
Ingomar W. Gutmann

OBJECTIVES: Currently, multiple sclerosis is treated with anti-inflammatory therapies, but these treatments lack efficacy in progressive disease. New treatment strategies aim to repair myelin damage and efficacy evaluation of such new therapies would benefit from validated myelin imaging techniques. Several MRI methods for quantification of myelin density are available now. This systematic review aims to analyse the performance of these MRI methods. METHODS: Studies comparing myelin quantification by MRI with histology, the current gold standard, or assessing reproducibility were retrieved from PubMed/MEDLINE and Embase (until December 2019). Included studies assessed both myelin histology and MRI quantitatively. Correlation or variance measurements were extracted from the studies. Non-parametric tests were used to analyse differences in study methodologies. RESULTS: =0.90-0.98, COV=1.3-27%), except for MTR (ICC=0.05-0.51). CONCLUSIONS: Overall, MRI-based myelin imaging methods show a fairly good correlation with histology and a good reproducibility. However, the amount of validation data is too limited and the variability in performance between studies is too large to select the optimal MRI method for myelin quantification yet.

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YNICL Journal 2020 Journal Article

Intrastriatal gradient analyses of 18F-FDOPA PET scans for differentiation of Parkinsonian disorders

Gilles N. Stormezand
Lumi T. Chaves
David Vállez García
Janine Doorduin
Bauke M. de Jong
Klaus L. Leenders
Berry P.H. Kremer
Rudi A.J.O. Dierckx

AIM: L -3,4-dihydroxy-6-18F-fluorophenylalanine (18F-DOPA PET may be used to distinguish subjects with Parkinsonism from those with symptoms not originating from impaired dopaminergic transmission. However, it is not routinely utilized to discriminate Idiopathic Parkinson's disease (IPD) from Atypical Parkinsonian Disorders (APD). We investigated the potential of FDOPA PET to discriminate between IPD and APD, with a focus on the anterior-to-posterior decline in het striatum, considered to be more specific for IPD. MATERIALS AND METHODS: 18F-DOPA PET data from a total of 58 subjects were retrospectively analyzed. 28 subjects had idiopathic Parkinson's disease (14 male, 14 female; age at scan 61 +- 11,5), 13 atypical Parkinsonian disease (7 male, 6 females; age at scan: 69,6 +- 6,4) and 17 were controls (6 male, 11 female; age at scan 65,3 +-8,6). Regional striatal-to-occipital ratio's (RSOR's) were calculated, as well as multiple in-line VOI's from the caudate nucleus to the posterior part of the putamen. The linearity of anteroposterior decline was determined by a linear regression fit and associated R squared values. ROC curves were calculated to assess the diagnostic performance of these measurements. Data contralateral to the clinically most affected side were used for analysis. RESULTS: ROC curve analysis for differentiation between controls and Parkinsonism patients showed the highest AUC for the caudate nucleus-to-posterior putamen ratio (AUC = 0.930; p < 0.00) and for the R squared value for the linear regression fit (AUC = 0.948; p = 0.006). For discrimating IPD from APD, the highest AUC was found for the caudate nucleus-to-anterior putamen ratio (0.824; p < 0.001) CONCLUSIONS: Subregional analysis of the striatum in F-DOPA PET scans may provide additional diagnostic information in patients screened for a presynaptic dopaminergic deficit. A more linear decrease from the head of the caudate nucleus to the posterior putamen was present in patients with IPD, although this feature did not have additional diagnostic value over the RSOR analysis.

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