Papers by Katerina Vassiou
Precision Medicine for Investigators, Practitioners and Providers, 2020
Abstract Breast cancer is a highly heterogeneous disease, exhibiting substantial spatiotemporal v... more Abstract Breast cancer is a highly heterogeneous disease, exhibiting substantial spatiotemporal variations in gene expression, biochemistry, histopathology, and macroscopic structure. The complexities in the evaluation of malignant tumor heterogeneity, are pushing current clinical examinations to their limits and accounting for most of the failures of targeted therapies, and uncertainties in the clinical outcome among breast cancer patients. The incorporation of state-of-the-art image analysis methods, and emerging machine learning techniques, is providing the application of detailed data-driven quantitative studies of imaging phenotypes, termed Radiomics. Specifically, an immense number of quantifiable imaging features, are extracted with high-throughput computing from medical images, and correlated with other clinical data, for unraveling the complex underlying pathophysiological mechanisms which are potentially reflected in tissue macroscopic phenotype. Therefore, radiomic analysis is holding a key role in the future of clinical decision support, as it provides powerful tools for assessing the spatiotemporal heterogeneity of breast cancer, aiming at increasing the diagnostic accuracy and predicting patient's outcome toward individualized therapy planning.
Applied Clinical Informatics, 2022
Background and Objective Prostate cancer (PCa) is a severe public health issue and the most commo... more Background and Objective Prostate cancer (PCa) is a severe public health issue and the most common cancer worldwide in men. Early diagnosis can lead to early treatment and long-term survival. The addition of the multiparametric magnetic resonance imaging in combination with ultrasound (mpMRI-U/S fusion) biopsy to the existing diagnostic tools improved prostate cancer detection. Use of both tools gradually increases in every day urological practice. Furthermore, advances in the area of information technology and artificial intelligence have led to the development of software platforms able to support clinical diagnosis and decision-making using patient data from personalized medicine. Methods We investigated the current aspects of implementation, architecture, and design of a health care information system able to handle and store a large number of clinical examination data along with medical images, and produce a risk calculator in a seamless and secure manner complying with data se...
International Journal of Endocrinology, 2018
Acta Radiologica, 2021
Background Apparent diffusion coefficient (ADC) measurements are not incorporated in BI-RADS clas... more Background Apparent diffusion coefficient (ADC) measurements are not incorporated in BI-RADS classification. Purpose To assess the probability of malignancy of breast lesions at magnetic resonance mammography (MRM) at 3 T, by combining ADC measurements with the BI-RADS score, in order to improve the specificity of MRM. Material and Methods A total of 296 biopsy-proven breast lesions were included in this prospective study. MRM was performed at 3 T, using a standard protocol with dynamic sequence (DCE-MRI) and an extra echo-planar diffusion-weighted sequence. A freehand region of interest was drawn inside the lesion, and ADC values were calculated. Each lesion was categorized according to the BI-RADS classification. Logistic regression analysis was employed to predict the probability of malignancy of a lesion. The model combined the BI-RADS classification and the ADC value. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were ca...
Dalton Transactions, 2021
Aqueous dispersions of silica hybrid SCO nanoparticles are promising agents for potential use in ... more Aqueous dispersions of silica hybrid SCO nanoparticles are promising agents for potential use in MRI.
Radiology Case Reports, 2021
Congenital agenesis of major salivary glands is considered a very infrequent condition and typica... more Congenital agenesis of major salivary glands is considered a very infrequent condition and typically appears to be a coincidental finding. It can be present as sporadic case or may be combined with aplasia or hypoplasia of other salivary glands or the lacrimal glands, or as a part of syndromes. Only 23 cases documented in the literature to date, while the youngest patient was 50 days old. Plenty of radiographic useful techniques and treatment is closely related to the clinical manifestations; therefore. We present a case of 52 year old female who was referred to our radiology department for recurrent numbness of the left upper limb, experienced over the previous three months. Complete absence of the left parotid gland was incidentally demonstrated at the brain MRI scan. Based on the patient’s past medical history, physical examination and demonstrated radiographic techniques it was an asymptomatic, no-syndromic and no-familious unilateral aplasia of the parotid gland. In the present report, we aimed to underline that this rare condition may be asymptomatic and co-exist with other medical conditions and syndromes.
International Journal of Gynecological Pathology, 2020
Epitope H contains an O-linked N-acetylglucosamine (O-GlcNAcH) residue in a specific conformation... more Epitope H contains an O-linked N-acetylglucosamine (O-GlcNAcH) residue in a specific conformation and/or environment recognized by the mouse monoclonal antibody H. O-GlcNAcH is present in several types of cells and in several polypeptides, including cytokeratin 8 and vimentin, on the latter in cells under stress. In the present work, we examined the expression of the O-GlcNAcH in 60 cases of endometrial curettings from missed miscarriage cases containing normal and simple hydropic degenerated chorionic villi in each case, using monoclonal antibody H and indirect immunoperoxidase and Western blot immunoblot. In all cases examined the expression of the O-GlcNAcH was cytoplasmic as follows: (1) syncytiotrophoblastic cells showed very low expression in chorionic villi (CV) with nonhydropic degeneration (NHD) and high expression in hydropic degenerated (HD) CV; (2) cytotrophoblastic cells showed low expression in CV with NHD and high expression in HD CV; (3) fibroblastic cells showed high expression in CV with NHD and very low expression in HD CV; (4) histiocytes showed very low expression in both types of CV; (5) endothelial cells showed high expression in both types of CV. An immunoblot of CV from one case of a legal abortion from a normal first-trimester pregnancy showed 5 polypeptides with 118.5, 106.3, 85, 53, and 36.7 kD bearing the epitope H and the 53 kD corresponded to cytokeratin 8. The expression of the O-GlcNAcH is upregulated in the trophoblastic cells and downregulated in the fibroblastic cells in the HD CV in comparison to the NHD CV.
Computational and Mathematical Methods in Medicine, 2018
Over the years, MR systems have evolved from imaging modalities to advanced computational systems... more Over the years, MR systems have evolved from imaging modalities to advanced computational systems producing a variety of numerical parameters that can be used for the noninvasive preoperative assessment of breast pathology. Furthermore, the combination with state-of-the-art image analysis methods provides a plethora of quantifiable imaging features, termed radiomics that increases diagnostic accuracy towards individualized therapy planning. More importantly, radiomics can now be complemented by the emerging deep learning techniques for further process automation and correlation with other clinical data which facilitate the monitoring of treatment response, as well as the prediction of patient’s outcome, by means of unravelling of the complex underlying pathophysiological mechanisms which are reflected in tissue phenotype. The scope of this review is to provide applications and limitations of radiomics towards the development of clinical decision support systems for breast cancer dia...
Surgical and Radiologic Anatomy, 2020
Purpose To present the anatomical variations of vidian canal (VC) and sphenoid sinus (SS), relati... more Purpose To present the anatomical variations of vidian canal (VC) and sphenoid sinus (SS), relative to other anatomical landmarks of skull base area, which may be helpful for safer surgical approach to this area. Materials MDCT scans (128-row MDCT system) of 90 patients (mean age 62 years) and six cadaveric heads were studied, and the following parameters were evaluated: mean length and types of VC, distance between VC and foramen rotundum (FR) and optic canal (OC), position of the VC regarding the lateral pterygoid plate (MPTG) and petrous ICA, pneumatization of SS, position of intrasinus septum regarding ICA and OC, bone dehiscence and protrusion of ICA and OC into SS. Six cadaveric heads underwent MDCT and endoscopic dissection, and the type and length of VC were evaluated. The statistical significance was assessed using Chi-square (χ 2) test. Significance level was set at p < 0.05. Results A statistical analysis was performed between the measurements at both sides, as well as between measurements in MDCT and dissection of the six cadaveric heads. Statistically significant difference was found between right and left sides in the horizontal and vertical distances between FR and VC, as well as between VC and OC. Also, there was a statistically positive correlation between type II of VC and lateral pneumatization on the right side. There was not statistically significant difference concerning VC type and length between MDCT and dissection measurements. Conclusion Surgeons addressing skull base surgery must be familiar with the anatomical and positional variations of VC and SS in the preoperative CT images so as to avoid serious complications during surgery.
Physica Medica, 2019
To investigate the value of advanced multiparametric MR imaging biomarker analysis based on radio... more To investigate the value of advanced multiparametric MR imaging biomarker analysis based on radiomic features and machine learning classification, in the non-invasive evaluation of tumor heterogeneity towards the differentiation of Low Grade vs. High Grade Gliomas. Methods and materials: Forty histologically confirmed glioma patients (20 LGG and 20 HGG) who underwent a standard 3T-MRI tumor protocol with conventional (T1 pre/post-contrast, T2-FSE, T2-FLAIR) and advanced techniques (Diffusion Tensor and Perfusion Imaging, 1H-MR Spectroscopy), were included. A semi-automated segmentation technique, based on T1W-C and DTI, was used for tumor core delineation in all available parametric maps. 3D Texture analysis considered 12 Histogram, 11 Co-Occurrence Matrix (GLCM) and 5 Run Length Matrix (GLRLM) features, derived from p, q, MD, FA, T1W-C, T2W-FSE, T2W-FLAIR and raw DSCE data. Along with 1H-MRS metabolic ratios and mean rCBV values, a total of 581 attributes for each subject were obtained. A Support Vector Machine-Recursive Feature Elimination (SVM-RFE) algorithm and SVM classifier were utilized for feature selection and classification, respectively. Results: Three different SVM classifiers were evaluated with consecutively SVM-RFE feature subsets. Linear SMO classifier demonstrated the highest performance for determining the optimal feature subset. Finally, 21 SVM-RFE top-ranked features were adopted, for training and testing the SMO classifier with leave-one-out cross-validation, achieving 95.5% Accuracy, 95% Sensitivity, 96% Specificity and 95.5% Area Under ROC Curve. Conclusion: Results demonstrate that quantitative analysis of phenotypic characteristics, based on advanced multiparametric MR neuroimaging data and texture features, utilizing state-of-the-art radiomic analysis methods, can significantly contribute to the pre-treatment glioma grade differentiation.
Systems Biology in Reproductive Medicine, 2018
Infertile couples with low oocyte yield in combination with abnormal semen parameters may experie... more Infertile couples with low oocyte yield in combination with abnormal semen parameters may experience intra-cytoplasmic sperm injection (ICSI) failure. An established factor associated with ICSI failure is oocyte activation deficiency (AOD). The latter originates from seminal contributors, such as phospholipase C-zeta (PLCζ) that is not adequate to produce calcium (Ca 2+) oscillations for oocyte activation. Apart from this natural activator, other stimulants, such as A23187, ionomycin, strontium chloride or even electric pulses, have been used in embryological laboratories to overcome AOD and ICSI failure. The aim of the present narrative review is to discuss the role of Ca +2 oscillations in oocyte activation and summarize the evidence concerning the use of oocyte activators as agents for artificial oocyte activation (AOA). Studies in humans and animals have emerged many physiological, pathophysiological and ethical aspects of AOA. In conclusion, in mammalian eggs, the cytosolic Ca +2 oscillations derive from a periodic release of Ca +2 from intracellular pools. PLCζ, as well as artificial stimulants, have been used to produce Ca +2 oscillations for AOA. As the latter may increase the risk of epigenetic induced malformations, further studies are required to clarify whether AOA constitutes an effective and safe method to overcome ICSI failure.
Clinical Imaging, 2019
Background: Conventional breast magnetic resonance imaging (MRI), including dynamic contrast-enha... more Background: Conventional breast magnetic resonance imaging (MRI), including dynamic contrast-enhanced MR mammography, may lead to ambiguous diagnosis and unnecessary biopsies. Purpose: To investigate the contribution of quantitative diffusion tensor imaging (DTI) in the discrimination between benign and malignant breast lesions at 3 T MRI. Material and methods: The study included a total of 86 lesions (44 benign and 42 malignant) in 58 women (34 with malignant lesions, 23 with benign lesions and 1 with both types of lesions). All patients were examined on a 3 T MRI scanner. Fractional Anisotropy (FA), Mean Diffusivity (MD), Apparent Diffusion Coefficient (ADC), as well as eigenvalues (λ 1 , λ 2 , λ 3) were calculated and compared between benign and malignant lesions using two different software packages (GE Functool and ExploreDTI). Results: Malignant lesions exhibited significantly lower ADC values compared to benign ones (ADC mal = 1.06 × 10 −3 mm 2 /s, ADC ben = 1.54 × 10 −3 mm 2 /s, p-value < 0.0001). FA measurements in carcinomas indicated slightly higher values than those in benign lesions (FA mal = 0.20 ± 0.07, FA ben = 0.15 ± 0.05, p-value = 0.0003). Eigenvalues λ 1 , λ 2 , λ 3 , showed significantly lower values in malignant tumors compared to benign lesions and normal breast tissue. ROC curve analysis of ADC and DTI metrics demonstrated that ADC provides high diagnostic performance (AUC = 0.944) while, MD and λ 1 showed best discriminative results (AUC = 0.906) for the differentiation of malignant and benign lesions in contrast to other DTI parameters. Conclusion: The addition of eigenvalue analysis improves DTI's ability to differentiate between benign and malignant breast lesions.
Toxics, 2017
Toxicants, such as herbicides, have been hypothesized to affect sperm parameters. The most common... more Toxicants, such as herbicides, have been hypothesized to affect sperm parameters. The most common method of exposure to herbicides is through spraying or diet. The aim of the present study was to investigate the effect of direct exposure of sperm to 1 mg/L of the herbicide Roundup on sperm motility and mitochondrial integrity. Sperm samples from 66 healthy men who were seeking semen analysis were investigated after written informed consent was taken. Semen analysis was performed according to the World Health Organization guidelines (WHO, 2010). Mitochondrial integrity was assessed through mitochondrial staining using a mitochondria-specific dye, which is exclusively incorporated into functionally active mitochondria. A quantity of 1 mg/L of Roundup was found to exert a deleterious effect on sperm's progressive motility, after 1 h of incubation (mean difference between treated and control samples = 11.2%) in comparison with the effect after three hours of incubation (mean difference = 6.33%, p < 0.05), while the relative incorporation of the mitochondrial dye in mitochondria of the mid-piece region of Roundup-treated spermatozoa was significantly reduced compared to relative controls at the first hour of incubation, indicating mitochondrial dysfunction by Roundup. Our results indicate that the direct exposure of semen samples to the active constituent of the herbicide Roundup at the relatively low concentration of 1 mg/L has adverse effects on sperm motility, and this may be related to the observed reduction in mitochondrial staining.
International Journal of Endocrinology, 2016
Objective. To assess body composition in adult male and female patients with thalassemia major by... more Objective. To assess body composition in adult male and female patients with thalassemia major by dual-energy X-ray absorptiometry (DXA) and to compare the findings with a group of healthy age-matched controls. Methods. Our study group included sixty-two patients (27 males, mean age 36 years, and 35 females, mean age 36.4 years) and fifteen age-matched healthy controls. All patients had an established diagnosis of thalassemia major and followed a regular blood transfusion scheme since childhood and chelation treatment. Fat, lean, and bone mineral density (BMD) were assessed with dual-energy X-ray absorptiometry. Ferritin levels and body mass index of all patients and controls were also recorded. Student t-test and Wilcoxon test were performed and statistical significance was set at p<0.05. Results. BMD and whole body lean mass are lower in both male and female adult patients compared with controls (p<0.01 in both groups), whereas whole body fat mass was found to have no statis...
ACS applied materials & interfaces, Jan 28, 2016
Adequately designed multiresponsive water-soluble graft copolymers were used to serve as a multif... more Adequately designed multiresponsive water-soluble graft copolymers were used to serve as a multifunctional polymeric platform for the encapsulation and transfer in aqueous media of hydrophobic magnetic nanoparticles (MNPs). The backbone of the graft copolymers was composed of hydrophilic sodium methacrylate units, hydrophobic dodecyl methacrylate units, and luminescent quinoline-based units, while either the homopolymer poly(N-isopropylacrylamide) or a poly(N,N-dimethylacrylamide-co-N-isopropylacrylamide) copolymer was used as thermosensitive pendent side chains. The polymeric platform forms micellar-type assemblies in aqueous solution, and exhibits pH-responsive luminescent properties and a lower critical solution temperature behavior in water. Depending on the design of the side chains, the cloud point temperatures were determined at 38 and 42 °C, close or slightly above body temperature (37 °C). Above the critical micelle concentration (CMC), both graft copolymers can effectively...
Magnetic Resonance Imaging, 2017
Dynamic contrast enhanced Magnetic Resonance Imaging (DCE-MRI) with gadolinium constitutes one of... more Dynamic contrast enhanced Magnetic Resonance Imaging (DCE-MRI) with gadolinium constitutes one of the most promising protocols for boosting up the sensitivity in breast cancer detection. The aim of this study was twofold: first to design an image processing methodology to estimate the vascularity of the breast region in DCE-MRI images and second to investigate whether the differences in the composition/texture and vascularity of normal, benign and malignant breasts may serve as potential indicators regarding the presence of the disease. Clinical material comprised thirty nine cases examined on a 3.0-T MRI system (SIGNA HDx; GE Healthcare). Vessel segmentation was performed using a custom made modification of the Seeded Region Growing algorithm that was designed in order to identify pixels belonging to the breast vascular network. Two families of features were extracted: first, morphological and textural features from segmented images in order to quantify the extent and the properties of the vascular network; second, textural features from the whole breast region in order to investigate whether the nature of the disease causes statistically important changes in the texture of affected breasts. Results have indicated that: a/ the texture of vessels presents statistically significant differences (p<0.001) between normal, benign and malignant cases. b/ the texture of the whole breast region for malignant and non-malignant breasts, produced statistically significant differences (p<0.001), c/ the relative ratios of the texture between the two breasts may be used for the discrimination of non-malignant from malignant patients, d/ an area under the receiver operating characteristic curve of 0.908 (AUC) was found when features were combined in a logistic regression prediction rule according to ROC analysis.
International Journal of Endocrinology, 2016
The purpose of this study is to identify the prevalence of osteoporosis in male patients with chr... more The purpose of this study is to identify the prevalence of osteoporosis in male patients with chronic obstructive pulmonary disease (COPD) by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) and to compare the diagnostic abilities of the above methods. Thirty-seven male patients with established COPD were examined with DXA and standard QCT in lumbar spine, including L1, L2, and L3 vertebrae.T-scores and bone mineral density values were calculated by DXA and QCT method, respectively. Comparative assessment of the findings was performed and statistical analysis was applied. QCT measurements found more COPD patients with impaired bone mineral density compared to DXA, namely, 13 (35.1%) versus 12 (32.4%) patients with osteopenia and 16 (43.2%) versus 9 (16.2%) patients with osteoporosis (p=0.04). More vertebrae were found with osteoporosis by QCT compared to DXA (p=0.03). The prevalence of osteoporosis among male patients with COPD is increased and DXA m...
Journal of thoracic disease, 2012
The aim of the present study is to investigate means for the reduction or even elimination of enh... more The aim of the present study is to investigate means for the reduction or even elimination of enhancement kinetic curve errors due to breast motion in order to avoid pitfalls and to increase the sensitivity and specificity of the method. 115 women underwent breast Magnetic Resonance Imaging (MRI). All patients were properly immobilized in a dedicated bilateral phased array coil. A magnetic resonance unit 3-Tesla (Signa, GE Healthcare) was used. The following sequences were applied: (I) axial Τ2-TSE, (II) axial STIR and (III) Vibrant axial T1-weighted fat saturation (six phases). Kinetic curves were derived semi-automatically using the software of the system and manually by positioning the regions of interest (ROI) from stable reference points in all the phases. 376 abnormalities in 115 patients were investigated. In 81 (21.5%) cases, a change of the enhancement kinetic curve type was found when the two different methods were used. In cases of large fatty breasts, a change of the enh...
Neurologia i Neurochirurgia Polska, 2012
Dysembryoplastic neuroepithelial tumours (DNTs) are benign lesions affecting young people and are... more Dysembryoplastic neuroepithelial tumours (DNTs) are benign lesions affecting young people and are associated with epilepsy. There have been described more than 300 cases in the literature and the clinical, pathological and radiological findings are well known. Recent advances in neuroimaging allow the acquisition of cerebral microcirculation parameters by perfusion weighted imaging, giving additional diagnostic information improving the diagnostic accuracy. The aim of this study is to show the perfusion sensitive contrast-enhanced magnetic resonance imaging findings of a case of DNT as an additional neuroradiological finding. Further investigation of microcirculation parameters may be helpful to establish the correct diagnosis of such tumours.
Acta Radiologica, 2014
1. Lesional size is one of the main issues in the performance of in-vivo H-MRS, as magnetic reson... more 1. Lesional size is one of the main issues in the performance of in-vivo H-MRS, as magnetic resonance imaging (MRI) machines in routine clinical use (1.5 Tesla) may limit the sensitivity in detecting composite Cho compounds. In our study, the MRS acquisition parameters at a 3.0 Tesla unit were adjusted on a scan-by-scan basis in order to obtain optimum spectral resolution and signal-to-noise ratio (SNR), with an acceptable scan time (<10min for each MRS). This resulted in a compromise between partial volume effects with large voxels and restricted SNR with small voxels. We stated that the voxel size was chosen not less than 1 cm and not greater than 8 cm, aiming to point out the absolute minimum and maximum values that may be used. It is important to keep in mind that reducing the voxel size by a factor of 2 it is required to acquire four times longer to regain SNR. Therefore, reducing the size from a 2 2 2 to a 1 1 1 cm voxel, one has to acquire 64 times longer to get equivalent SNR. It is widely acceptable that for in-vivo studies a voxel size of 3–8 cm generally is used (3–5) and, indeed, this can be considered a limitation for in-vivo breast spectroscopy. However, theoretically with current higher-field-strength MR units, smaller voxels may be selected, although it has become apparent that this magnetic field increase does not seem to translate into the anticipated improvement in spectral resolution (6). Nevertheless, the smaller the voxel the bigger the need to improve the SNR by increasing substantially the examination time and hence the risk of motion artifacts. Therefore, during the actual process we concluded that the optimum minimum voxel size that should be used was approx. 1.5 1.5 1.5 cm. In conclusion, we believe that it will always be a trade-off between the size of the voxel and the acquisition time in relation to the available clinical time and the patient compliance.
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Papers by Katerina Vassiou