Grigorios Kalliatakis

Dr. Grigorios Kalliatakis

WMG | University of Warwick, Coventry, UK
orcid

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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1 June 2023 in Radiology
Verified
Journal Article
Closed access
CDCeleste Damiani
Celeste Damiani
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
MSMuthyala Sreenivas
Muthyala Sreenivas
MAMiaad Al-Attar
Miaad Al-Attar
JRJanice Rose
Janice Rose
ABAdam Brentnall
Adam Brentnall
Background Accurate breast cancer risk assessment after a negative screening result could enable better strategies for early detection. Purpose To evaluate a deep learning algorithm for risk assessment based on digital mammograms. Materials and Methods A retrospective observational matched case-control study was designed using the OPTIMAM Mammography Image Database from the National Health Service Breast Screening Programme in the United Kingdom from February 2010 to September 2019. Patients with breast cancer (cases) were diagnosed following a mammographic screening or between two triannual screening rounds. Controls were matched based on mammography device, screening site, and age. The artificial intelligence (AI) model only used mammograms at screening before diagnosis. The primary objective was to assess model performance, with a secondary objective to assess heterogeneity and calibration slope. The area under the receiver operating characteristic curve (AUC) was estimated for 3-year risk. Heterogeneity according to cancer subtype was assessed using a likelihood ratio interaction test. Statistical significance was set at P < .05. Results Analysis included patients with screen-detected (median age, 60 years [IQR, 55-65 years]; 2044 female, including 1528 with invasive cancer and 503 with ductal carcinoma in situ [DCIS]) or interval (median age, 59 years [IQR, 53-65 years]; 696 female, including 636 with invasive cancer and 54 with DCIS) breast cancer and 1:1 matched controls, each with a complete set of mammograms at the screening preceding diagnosis. The AI model had an overall AUC of 0.68 (95% CI: 0.66, 0.70), with no evidence of a significant difference between interval and screen-detected (AUC, 0.69 vs 0.67; P = .085) cancer. The calibration slope was 1.13 (95% CI: 1.01, 1.26). There was similar performance for the detection of invasive cancer versus DCIS (AUC, 0.68 vs 0.66; P = .057). The model had higher performance for advanced cancer risk (AUC, 0.72 ≥stage II vs 0.66 <stage II; P = .037). The AUC for detecting breast cancer in mammograms at diagnosis was 0.89 (95% CI: 0.88, 0.91). Conclusion The AI model was found to be a strong predictor of breast cancer risk for 3-6 years following a negative mammographic screening. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Mann and Sechopoulos in this issue.

1 January 2017
Verified
Conference Paper
Open access
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
SEShoaib Ehsan
Shoaib Ehsan
MFMaria Fasli
Maria Fasli
ALAles Leonardis
Ales Leonardis
JGJuergen Gall
Juergen Gall
Klaus McDonald-MaierKlaus McDonald-Maier
Klaus McDonald-Maier

1 January 2017
Verified
Conference Paper
Open access
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
GSGeorgios Stamatiadis
Georgios Stamatiadis
SEShoaib Ehsan
Shoaib Ehsan
ALAles Leonardis
Ales Leonardis
JGJuergen Gall
Juergen Gall
Klaus McDonald-MaierKlaus McDonald-Maier
Klaus McDonald-Maier

9 January 2019 in IEEE Access
Verified
Journal Article
Open access
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
SEShoaib Ehsan
Shoaib Ehsan
ALAles Leonardis
Ales Leonardis
MFMaria Fasli
Maria Fasli
Klaus McDonald-MaierKlaus McDonald-Maier
Klaus McDonald-Maier

Verified
Journal Article
Open access
PDF file
ASALEXANDROS STERGIOU
ALEXANDROS STERGIOU
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
Christos ChrysoulasChristos Chrysoulas
Christos Chrysoulas
To deal with the richness in visual appearance variation found in real-world data, we propose to synthesise training data capturing these differences for traffic sign recognition. The use of synthetic training data, created from road traffic sign templates, allows overcoming the problems of existing traffic sing recognition databases, which are only subject to specific sets of road signs found explicitly in countries or regions. This approach is used for generating a database of synthesised images depicting traffic signs under different view-light conditions and rotations, in order to simulate the complexity of real-world scenarios. With our synthesised data and a robust end-to-end Convolutional Neural Network (CNN), we propose a data-driven, traffic sign recognition system that can achieve not only high recognition accuracy, but also high computational efficiency in both training and recognition processes.

23 July 2017 in Computers
Verified
Journal Article
Open access
PDF file
Grigorios KalliatakisGrigorios Kalliatakis
Grigorios Kalliatakis
ASALEXANDROS STERGIOU
ALEXANDROS STERGIOU
Nikolas VidakisNikolas Vidakis
Nikolas Vidakis
Affective computing in general and human activity and intention analysis in particular comprise a rapidly-growing field of research. Head pose and emotion changes present serious challenges when applied to player’s training and ludology experience in serious games, or analysis of customer satisfaction regarding broadcast and web services, or monitoring a driver’s attention. Given the increasing prominence and utility of depth sensors, it is now feasible to perform large-scale collection of three-dimensional (3D) data for subsequent analysis. Discriminative random regression forests were selected in order to rapidly and accurately estimate head pose changes in an unconstrained environment. In order to complete the secondary process of recognising four universal dominant facial expressions (happiness, anger, sadness and surprise), emotion recognition via facial expressions (ERFE) was adopted. After that, a lightweight data exchange format (JavaScript Object Notation (JSON)) is employed, in order to manipulate the data extracted from the two aforementioned settings. Motivated by the need to generate comprehensible visual representations from different sets of data, in this paper, we introduce a system capable of monitoring human activity through head pose and emotion changes, utilising an affordable 3D sensing technology (Microsoft Kinect sensor).