Ilias Thomas

Dr. Ilias Thomas

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Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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27 November 2017 in IEEE Journal of Biomedical and Health Informatics
Verified
Journal Article
Closed access
ITIlias Thomas
Ilias Thomas
JWJerker Westin
Jerker Westin
MAMoudud Alam
Moudud Alam
FBFilip Bergquist
Filip Bergquist
Dag NyholmDag Nyholm
Dag Nyholm
MMMevludin Memedi
Mevludin Memedi
The goal of this study was to develop an algorithm that automatically quantifies motor states (off, on, dyskinesia) in Parkinson's disease (PD), based on accelerometry during a hand pronation-supination test. Clinician's ratings using the Treatment Response Scale (TRS), ranging from -3 (very Off) to 0 (On) to +3 (very dyskinetic), were used as target. For that purpose, 19 participants with advanced PD and 22 healthy persons were recruited in a single center open label clinical trial in Uppsala, Sweden. The trial consisted of single levodopa dose experiments for the people with PD (PwP), where participants were asked to perform standardized wrist rotation tests, using each hand, before and at prespecified time points after the dose. The participants used wrist sensors containing a three-dimensional accelerometer and gyroscope. Features to quantify the level, variation, and asymmetry of the sensor signals, three-level discrete wavelet transform features, and approximate entropy measures were extracted from the sensors data. At the time of the tests, the PwP were video recorded. Three movement disorder specialists rated the participants' state on the TRS. A Treatment Response Index from Sensors (TRIS) was constructed to quantify the motor states based on the wrist rotation tests. Different machine learning algorithms were evaluated to map the features derived from the sensor data to the ratings provided by the three specialists. Results from cross validation, both in tenfold and a leave-one-individual out setting, showed good predictive power of a support vector machine model and high correlation to the TRS. Values at the end tails of the TRS were under and over predicted due to the lack of observations at those values but the model managed to accurately capture the dose-effect profiles of the patients. In addition, the TRIS had good test-retest reliability on the baseline levels of the PD participants (Intraclass correlation coefficient of 0.83) and reasonable sensitivity to levodopa treatment (0.33 for the TRIS). For a series of test occasions, the proposed algorithms provided dose-effect time profiles for participants with PD, which could be useful during therapy individualization of people suffering from advanced PD.

18 January 2019 in Journal of Neurology
Verified
Journal Article
Open access
PDF file
ITIlias Thomas
Ilias Thomas
MAMoudud Alam
Moudud Alam
FBFilip Bergquist
Filip Bergquist
DJDongni Johansson
Dongni Johansson
MMMevludin Memedi
Mevludin Memedi
JWJerker Westin
Jerker Westin
Objective Dosing schedules for oral levodopa in advanced stages of Parkinson’s disease (PD) require careful tailoring to fit the needs of each patient. This study proposes a dosing algorithm for oral administration of levodopa and evaluates its integration into a sensor-based dosing system (SBDS). Materials and methods In collaboration with two movement disorder experts a knowledge-driven, simulation based algorithm was designed and integrated into a SBDS. The SBDS uses data from wearable sensors to fit individual patient models, which are then used as input to the dosing algorithm. To access the feasibility of using the SBDS in clinical practice its performance was evaluated during a clinical experiment where dosing optimization of oral levodopa was explored. The supervising neurologist made dosing adjustments based on data from the Parkinson’s KinetiGraph™ (PKG) that the patients wore for a week in a free living setting. The dosing suggestions of the SBDS were compared with the PKG-guided adjustments. Results The SBDS maintenance and morning dosing suggestions had a Pearson’s correlation of 0.80 and 0.95 (with mean relative errors of 21% and 12.5%), to the PKG-guided dosing adjustments. Paired t test indicated no statistical differences between the algorithmic suggestions and the clinician’s adjustments. Conclusion This study shows that it is possible to use algorithmic sensor-based dosing adjustments to optimize treatment with oral medication for PD patients.

Verified
Journal Article
Open access
PDF file
ITIlias Thomas
Ilias Thomas
Alex DickensAlex Dickens
Alex Dickens
Jussi PostiJussi Posti
Jussi Posti
MMMehrbod Mohammadian
Mehrbod Mohammadian
CLChristian Ledig
Christian Ledig
Matej OresicMatej Oresic
Matej Oresic
Recent evidence suggests that patients with traumatic brain injuries (TBIs) have a distinct circulating metabolic profile. However, it is unclear if this metabolomic profile corresponds to changes in brain morphology as observed by magnetic resonance imaging (MRI). The aim of this study was to explore how circulating serum metabolites, following TBI, relate to structural MRI (sMRI) findings. Serum samples were collected upon admission to the emergency department from patients suffering from acute TBI and metabolites were measured using mass spectrometry-based metabolomics. Most of these patients sustained a mild TBI. In the same patients, sMRIs were taken and volumetric data were extracted (138 metrics). From a pool of 203 eligible screened patients, 96 met the inclusion criteria for this study. Metabolites were summarized as eight clusters and sMRI data were reduced to 15 independent components (ICs). Partial correlation analysis showed that four metabolite clusters had significant associations with specific ICs, reflecting both the grey and white matter brain injury. Multiple machine learning approaches were then applied in order to investigate if circulating metabolites could distinguish between positive and negative sMRI findings. A logistic regression model was developed, comprised of two metabolic predictors (erythronic acid and myo-inositol), which, together with neurofilament light polypeptide (NF-L), discriminated positive and negative sMRI findings with an area under the curve of the receiver-operating characteristic of 0.85 (specificity = 0.89, sensitivity = 0.65). The results of this study show that metabolomic analysis of blood samples upon admission, either alone or in combination with protein biomarkers, can provide valuable information about the impact of TBI on brain structural changes.

1 June 2020 in Computer Methods and Programs in Biomedicine
Verified
Journal Article
Closed access
SASomayeh Aghanavesi
Somayeh Aghanavesi
JWJerker Westin
Jerker Westin
Filip BergquistFilip Bergquist
Filip Bergquist
Dag NyholmDag Nyholm
Dag Nyholm
HAHåkan Askmark
Håkan Askmark
MMMevludin Memedi
Mevludin Memedi

4 September 2018 in Acta Neurologica Scandinavica
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Journal Article
Closed access
PDF file
ITIlias Thomas
Ilias Thomas
MMMevludin Memedi
Mevludin Memedi
JWJerker Westin
Jerker Westin
Dag NyholmDag Nyholm
Dag Nyholm

1 July 2019 in Parkinsonism & Related Disorders
Verified
Journal Article
Closed access
DJDongni Johansson
Dongni Johansson
ITIlias Thomas
Ilias Thomas
AEAnders Ericsson
Anders Ericsson
AJAnders Johansson
Anders Johansson
AMAlexander Medvedev
Alexander Medvedev
FBFilip Bergquist
Filip Bergquist