Papers by Ioannis Theotokas
Poster: "ECR 2019 / C-0175 / Shear Wave Sound Touch Elastography (STE) for Chronic Liver Dis... more Poster: "ECR 2019 / C-0175 / Shear Wave Sound Touch Elastography (STE) for Chronic Liver Disease (CLD): Guidelines and Case Studies " by: " P. Zoumpoulis 1, E. Panteleakou1, K. Ng2, A. Soultatos1, I. Theotokas1, A. Dell'Era2; 1Athens/GR, 2Shenzhen/CN"
Physics in Medicine & Biology, 2020
Chronic Liver Disease (CLD) is currently one of the major causes of death worldwide. If not treat... more Chronic Liver Disease (CLD) is currently one of the major causes of death worldwide. If not treated, it may lead to cirrhosis, hepatic carcinoma, and death. Ultrasound (US) Shear Wave Elastography (SWE) is a relatively new, popular, non-invasive technique among radiologists. Although many studies have been published validating the SWE technique either in a clinical setting, or by applying machine learning on SWE elastograms, minimal work has been made on comparing the performance of popular pre-trained deep learning networks on CLD assessment. Currently available literature reports suggest technical advancements on specific deep learning structures, with specific inputs and usually on a limited CLD fibrosis stage class group, with limited comparison on competitive deep learning schemes fed with different input types. The aim of the present study is to compare some popular deep learning pre-trained networks using temporally stable and full elastograms, with or without augmentation as well as propose suitable deep learning schemes for CLD diagnosis and progress assessment. 200 liver biopsy validated patients with CLD, underwent US SWE examination. Four images from the same liver area were saved to extract elastograms and processed to exclude areas that were temporally unstable. Then, full and temporally stable masked elastograms for each patient were separately fed into GoogLeNet, AlexNet, VGG16, ResNet50 and DenseNet201 with and without augmentation. The networks were tested for differentiation of CLD stages in seven classification schemes over 30 repetitions using liver biopsy as reference. All Networks achieved maximum mean accuracies ranging from 87.2%-97.4% and AUCs ranging from 0.979-0.990 while the radiologists had AUCs ranging from 0.800-0.870. ResNet50 and DenseNet201 had better average performance than the other networks. The use of the temporal stability mask led to improved performance on about 50% of inputs and networks combinations while augmentation led to lower performance for all networks. These findings can provide potential networks with higher accuracy and better setting in the CLD diagnosis and progress assessment. A larger dataset would help identify the best network and settings for CLD assessment in clinical practice.
Journal of Hepatology, 2020
Medical Physics, 2019
PurposeTo automatically detect and isolate areas of low and high stiffness temporal stability in ... more PurposeTo automatically detect and isolate areas of low and high stiffness temporal stability in shear wave elastography (SWE) image sequences and define their impact in chronic liver disease (CLD) diagnosis improvement by means of clinical examination study and deep learning algorithm employing convolutional neural networks (CNNs).Materials and MethodsTwo hundred SWE image sequences from 88 healthy individuals (F0 fibrosis stage) and 112 CLD patients (46 with mild fibrosis (F1), 16 with significant fibrosis (F2), 22 with severe fibrosis (F3), and 28 with cirrhosis (F4)) were analyzed to detect temporal stiffness stability between frames. An inverse Red, Green, Blue (RGB) colormap‐to‐stiffness process was performed for each image sequence, followed by a wavelet transform and fuzzy c‐means clustering algorithm. This resulted in a binary mask depicting areas of high and low stiffness temporal stability. The mask was then applied to the first image of the SWE sequence, and the derived,...
Medical Physics, 2015
Purpose:The purpose of this study was to quantify liver elastic heterogeneity in Shear Wave Elast... more Purpose:The purpose of this study was to quantify liver elastic heterogeneity in Shear Wave Elastography (SWE) by using textural features and evaluating their diagnostic performance on differentiating healthy from chronic liver disease patients, taking biopsy results as the gold standard.Methods:Clinical material includes 16 healthy (F0) and 15 with Chronic Liver Disease (F1,F2,F3,F4) patients according to the Metavir staging system. All exams were performed using the Aixplorer ultrasound system with a SuperCurved SC6‐1 transducer. From the SWE‐QBox the RGB displayed elasticity data of Young's modulus were transformed from RGB color space into an elasticity matrix of gray tones, whose values varied from zero to the maximum elasticity measurement. Every pixel with no RGB‐values was set to ‘−1’ due to non‐valid elasticity value for that pixel. From the elastogram map 185 textural features were computed (5 from the gray‐tone histogram, 26 second order statistic features, extracted ...
Studies in health technology and informatics, 1997
Differential diagnosis of liver parenchyma disease and grading of the hepatic disease on ultrasou... more Differential diagnosis of liver parenchyma disease and grading of the hepatic disease on ultrasound is a common radiological problem that influences patient management. The aim of this study was to apply image analysis methods on ultrasound images for discriminating liver cirrhosis from fatty liver infiltration and for grading hepatic disease, which is important in the management of the patients. Ultrasound images of histologically confirmed 18 livers with cirrhosis, 37 livers with fatty infiltration, and 24 normal livers of healthy volunteers were selected and were digitized for further computer processing. Twenty two textural features were calculated from small matrix samples selected from the ultrasound image matrix of the liver parenchyma. These features were used in the design a three level hierarchical decision tree classification scheme, employing the multilayer perceptron neural network classifier at each hierarchical tree level. At the first tree level, classification accur...
Ultrasound in Medicine & Biology, 2013
Ultrasound in Medicine & Biology, 2011
ARFI values were not correlated with liver fibrosis in case of aminotransferases level .3x normal... more ARFI values were not correlated with liver fibrosis in case of aminotransferases level .3x normal value. ARFI measurements were correlated with fibrosis in patients with no or mild steatosis (Hepburn I, II, III on LB) (r 5 0.568; p , 0.0001), while in patients with moderate and severe steatosis (Hepburn IV, V) there was no correlation (r 5 0.055; p 5 0.86). Conclusion: Quality technical parameters (IQR and SR) must be introduced to improve the accuracy of ARFI assessment of liver fibrosis. High levels of aminotransferases and severe steatosis can influence the accuracy of ARFI measurements.
Ultraschall in der Medizin - European Journal of Ultrasound, 2013
Ultrasound in Medicine & Biology, 2011
Ultrasound in Medicine & Biology, 2011
They were examined 1 day before liver biopsy. Median value of 10 valid measurements of shear wave... more They were examined 1 day before liver biopsy. Median value of 10 valid measurements of shear wave velocity (SWV) was considered. The diagnostic performance of ARFI was assessed using sensitivity (Se), specificity (Sp), positive (PPV) and negative predictive value (NPV), false positive rate (FPR), false negative rate (FNR), receiver operating characteristic curves (AUROC) and diagnosis accuracy (DA). Results: Although there was a medium correlation with activity (r 5 0.324, p 5 0.001), SWV was significantly and strongly correlated with fibrosis (r 5 0.764, p, 0.0005). There was no correlation with steatosis (r 5-0.020, p 5 0.843). The mean value of SWV (m/s) was:
Ultrasound in Medicine and Biology, 1997
Ultrasound Quarterly
OBJECTIVES Nonalcoholic fatty liver disease (NAFLD) is the most widespread chronic liver disease ... more OBJECTIVES Nonalcoholic fatty liver disease (NAFLD) is the most widespread chronic liver disease type in the Western countries. Ultrasound (US) is used for NAFLD and hepatic steatosis (HS) grading. The most popular US method for NAFLD assessment is the hepatorenal index (HRI), but because of its limitations, other noninvasive methods have been developed. The Resona 7 US system has recently incorporated an US attenuation-related quantitative feature, liver ultrasound attenuation (LiSA), for HS estimation. The purpose of this study is to compare LiSA's and HRI's performance on NAFLD assessment. METHODS A total of 159 NAFLD patients having a magnetic resonance imaging-proton density fat fraction (MRI-PDFF) examination were examined by 2 radiologists, who performed LiSA and HRI measurements in the liver. Correlation of LiSA's and HRI's measurements with MRI-PDFF values was calculated through Pearson correlation coefficient (PCC). To further investigate the performance of LiSA and HRI, optimum cutoffs, provided by the literature, were used to correspond HS grades to MRI-PDFF results. Moreover, a receiver operating characteristic (ROC) analysis on LiSA measurements and steatosis grades was performed. RESULTS Magnetic resonance imaging-PDFF was better correlated with LiSA (PCC = 0.80) than HRI (PCC = 0.67). Receiver operating characteristic analysis showed better performance range for LiSA (77.8%-91.8%) than for HRI (72.8%-85.4%) on all HS grades for all studies used for corresponding MRI-PDFF values to HS grades. CONCLUSIONS The results indicate that LiSA is more accurate than HRI in HS differentiation and can lead to more accurate grading of HS on NAFLD patients.
Clinical Diabetes
Nonalcoholic fatty liver disease (NAFLD) is dramatically increasing in parallel with the pandemic... more Nonalcoholic fatty liver disease (NAFLD) is dramatically increasing in parallel with the pandemic of type 2 diabetes. Here, the authors aimed to assess the performance of the most commonly used noninvasive, blood-based biomarkers for liver fibrosis (FibroTest, NAFLD fibrosis score, BARD score, and FIB-4 Index) in subjects with type 2 diabetes. Liver stiffness measurement was estimated by two-dimensional shear wave elastography. Finally, the authors assessed the diagnostic role of ActiTest and NashTest 2 in liver fibrosis in the examined population.
Objectives: To evaluate the effectiveness of two prostate biopsy schemes, by correlating the canc... more Objectives: To evaluate the effectiveness of two prostate biopsy schemes, by correlating the cancer detection and the biopsy scheme used. Methods: From 2000 to 2005, we studied 700 patients who underwent transrectal ultrasound and prostate biopsy at Sao Paulo Hospital. The patients were divided in two groups. Group A was composed by 408 patients who underwent prostate biopsy where six fragments were taken; and group B was composed by 292 patients who underwent prostate biopsy where 12 fragments were taken. Results: From the total amount of patients, 254 had cancer (36,3%) and 446 did not (63,7%). Among the 408 biopsies with six fragments (Group A), 143 (35%) had cancer and 265 (65%) did not. Out of the 292 biopsies with 12 fragments (Group B), 111 (38%) presented positive results for cancer and 181 (62%) did not. The difference between these two schemes was 3%. This result was not statistically significant (p ϭ 0,421). The patients with prostate cancer had averages of: 69,6-y for age, 41,4 cm3 for prostate volume, 13,11 ng/ml for PSA and 0,4 ng/ml by gram for PSA density. Conclusions: There was no relation between the cancer diagnosis and the two biopsy schemes studied.
Ultrasound in Medicine & Biology, 2011
ARFI values were not correlated with liver fibrosis in case of aminotransferases level .3x normal... more ARFI values were not correlated with liver fibrosis in case of aminotransferases level .3x normal value. ARFI measurements were correlated with fibrosis in patients with no or mild steatosis (Hepburn I, II, III on LB) (r 5 0.568; p , 0.0001), while in patients with moderate and severe steatosis (Hepburn IV, V) there was no correlation (r 5 0.055; p 5 0.86). Conclusion: Quality technical parameters (IQR and SR) must be introduced to improve the accuracy of ARFI assessment of liver fibrosis. High levels of aminotransferases and severe steatosis can influence the accuracy of ARFI measurements.
Physica Medica, 2014
EI of the animals had echogenicity throughout the tumor, which characterized the increase in bloo... more EI of the animals had echogenicity throughout the tumor, which characterized the increase in blood perfusion. Сolor Doppler ultrasound (US) image of Guerin's carcinoma showed that the largest decrease of vessel area occurred after injection of MNC in the tumor after the application of local EI. The elastography performed on diagnostic ultrasound system showed that the injection MNC in tumor increased Young's modulus for Guerin's carcinoma as compared to the group of animal without nanoparticles. These results here suggest that US elastography may provide a useful method to monitor the effectiveness of treatment of cancer patients during magnetic nanotherapy.
Ultrasound in Medicine & Biology
Chronic liver disease (CLD) is currently a major cause of death. Ultrasound elastography (USE) is... more Chronic liver disease (CLD) is currently a major cause of death. Ultrasound elastography (USE) is an imaging method that has been developed for CLD assessment. Our aim in the study described here was to evaluate and compare a new commercial variant of USE, sound touch elastography (STE), with already established USE methods, shear wave elastography (SWE) and vibration-controlled transient elastography (VCTE), using liver biopsy as the "reference standard." For our study, 139 consecutive patients underwent standard liver STE, SWE and VCTE examinations with the corresponding ultrasound devices. A receiver operator characteristic (ROC) curve analysis was performed on the stiffness values measured with each method. ROC analysis revealed, for SWE, STE and VCTE, areas under the ROC curve of 0.9397, 0.9224 and 0.9348 for fibrosis stage (F), F F1; 0.9481, 0.9346 and 0.9415 for F F2; 0.9623, 0.9591 and 0.9631 for F F3; and 0.9581, 0.9541 and 0.9632 for F = F4, respectively. In conclusion, STE performs similarly to SWE and VCTE in CLD stage differentiation.
Ultrasound in medicine & biology, Sep 1, 2017
The purpose of the present study was to employ a computer-aided diagnosis system that classifies ... more The purpose of the present study was to employ a computer-aided diagnosis system that classifies chronic liver disease (CLD) using ultrasound shear wave elastography (SWE) imaging, with a stiffness value-clustering and machine-learning algorithm. A clinical data set of 126 patients (56 healthy controls, 70 with CLD) was analyzed. First, an RGB-to-stiffness inverse mapping technique was employed. A five-cluster segmentation was then performed associating corresponding different-color regions with certain stiffness value ranges acquired from the SWE manufacturer-provided color bar. Subsequently, 35 features (7 for each cluster), indicative of physical characteristics existing within the SWE image, were extracted. A stepwise regression analysis toward feature reduction was used to derive a reduced feature subset that was fed into the support vector machine classification algorithm to classify CLD from healthy cases. The highest accuracy in classification of healthy to CLD subject discr...
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Papers by Ioannis Theotokas