| 1. |
- Polymeri, Erini, et al.
(författare)
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Deep learning-based quantification of PET/CT prostate gland uptake : association with overall survival
- 2020
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Ingår i: Clinical Physiology and Functional Imaging. - Chichester : Blackwell Publishing. - 1475-0961 .- 1475-097X. ; 40:2, s. 106-113
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To validate a deep-learning (DL) algorithm for automated quantification of prostate cancer on positron emission tomography/computed tomography (PET/CT) and explore the potential of PET/CT measurements as prognostic biomarkers. Material and methods: Training of the DL-algorithm regarding prostate volume was performed on manually segmented CT images in 100 patients. Validation of the DL-algorithm was carried out in 45 patients with biopsy-proven hormone-naïve prostate cancer. The automated measurements of prostate volume were compared with manual measurements made independently by two observers. PET/CT measurements of tumour burden based on volume and SUV of abnormal voxels were calculated automatically. Voxels in the co-registered 18F-choline PET images above a standardized uptake value (SUV) of 2·65, and corresponding to the prostate as defined by the automated segmentation in the CT images, were defined as abnormal. Validation of abnormal voxels was performed by manual segmentation of radiotracer uptake. Agreement between algorithm and observers regarding prostate volume was analysed by Sørensen-Dice index (SDI). Associations between automatically based PET/CT biomarkers and age, prostate-specific antigen (PSA), Gleason score as well as overall survival were evaluated by a univariate Cox regression model. Results: The SDI between the automated and the manual volume segmentations was 0·78 and 0·79, respectively. Automated PET/CT measures reflecting total lesion uptake and the relation between volume of abnormal voxels and total prostate volume were significantly associated with overall survival (P = 0·02), whereas age, PSA, and Gleason score were not. Conclusion: Automated PET/CT biomarkers showed good agreement to manual measurements and were significantly associated with overall survival. © 2019 The Authors. Clinical Physiology and Functional Imaging published by John Wiley & Sons Ltd on behalf of Scandinavian Society of Clinical Physiology and Nuclear Medicine
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| 2. |
- Blomgren, Bo, et al.
(författare)
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A computerised, unbiased method for epithelial measurement
- 2004
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Ingår i: Micron. - Amsterdam : Elsevier. - 0968-4328 .- 1878-4291. ; 35, s. 319-329
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo develop and evaluate a standardised method for unbiased measurements of epithelial thickness taking the variability of the dermal papillae in consideration.MethodsA computer-assisted measurement program suitable for haematoxylin and eosin routine stained specimens has been developed.ResultsThe developed program was designed to measure four different distance parameters, taking the number, height and width of dermal papillae into account. The measurement program gave very accurate results compared with manual measurements. The measurement results can be presented as tables or star graphs, and the results can be further processed by multivariate analysis.ConclusionThe computer-assisted measurement program is considered to be a valuable and reliable tool for measurements of epithelial thickness, irrespectively of the variability of the epithelial morphology. Since length, size and number of the papillae may change with certain pathological conditions, age and also under hormonal influence, this method can be a helpful diagnostic tool.
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| 3. |
- Flys, Olena, 1971-, et al.
(författare)
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Using confocal fusion for measurement of metal AM surface texture
- 2020
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Ingår i: Surface Topography: Metrology and Properties. - Bristol : IOP Publishing Ltd. - 2051-672X. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- The highly complex nature of as printed metal AM surfaces pose other challenges for making measurements compared to surfaces made with many conventional processing methods. The high complexity is caused by high aspect ratios, a mix of high and low reflexivity, steep angles etc. It is not clear which method is the most suitable for measuring these surfaces. The objective of this study was to compare four different measurement modes available in one instrument to evaluate the advantages and drawbacks of the respective techniques regarding measurements of metal AM surfaces. The evaluated measurement modes are Confocal Microscopy, Coherence Scanning Interferometry, Focus Variation and Confocal Fusion. The effect of advantages and drawbacks of studied techniques was tested on typical surfaces produced by L-PBF process. Surfaces printed at 0° and 90° inclinations were compared regarding the measurement results achieved from the different methods. The Power Spectral Density analysis and visual comparison were used for the examination of studied measurements methods. Besides the comparison of areal measurements acquired by different modes available in the instrument also extracted profile measurements were compared with profile images acquired using an Optical Microscope. This study reveals that confocal fusion is a promising technique for AM surface characterisation, due to the highest amount of valid data points in the typical measurement. The new approach developed in the study showed that PSD analysis can be used for evaluation of fill in algorithms incorporated in different software. Results of the profile comparisons help to illustrate features that can be depicted by surface measurements, applying different measurement principles, as well as enables comparison of raw profile data between different types of measurements. Further investigation of measurements on AM surfaces in the frequency domain will bring more understanding about the limitations of measurement techniques.
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| 4. |
- Rosén, Stefan, et al.
(författare)
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The Stedman diagram revisited
- 2014
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Ingår i: Surface Topography : Metrology and Properties. - Bristol : Institute of Physics (IOP). - 2051-672X. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- The Stedman diagram has been used for some years to display aspects of the performance of instruments measuring surface roughness. Such diagrams are herein employed to compare the features of a range of proprietary measuring instruments, including contact and non-contact devices. An extension of the basic diagram is proposed, which would allow it to include a further aspect: the speed of data collection. Figures of merit based on the revised diagram are computed, which enable instruments to be ranked on these particular aspects of their performance. Contact instruments emerge as comparable to non-contact, as their slower rate of data acquisition can be offset by the greater area they can access in amplitude–wavelength space. © 2014 IOP Publishing Ltd.
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| 5. |
- Rosén, Stefan, et al.
(författare)
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The Stedman diagram revisited
- 2013
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Ingår i: Metrology and Properties of Engineering Surfaces, 2013. ; , s. 201-206
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Konferensbidrag (refereegranskat)abstract
- The Stedman diagram has been used for some years to display aspects of the performance of surface roughness measuring instruments. Such diagrams are herein employed to compare the features of a range of proprietary measuring instruments, including contact and non-contact devices. An extension of the basic diagram is proposed which would allow it to include a further aspect, speed of data collection. Figures of merit based on the revised diagram are computed which enable instruments to be ranked on these particular aspects of their performance. Contact instruments emerge as comparable to non-contact, as their slower rate of data acquisition can be offset by the greater area they can access in amplitude-wavelength space.
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| 6. |
- Sant'Anna, Anita, 1983-, et al.
(författare)
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Assessment of Gait Symmetry and Gait Normality Using Inertial Sensors : In-Lab and In-Situ Evaluation
- 2013
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Ingår i: Biomedical Engineering Systems and Technologies. - Heidelberg : Springer Berlin/Heidelberg. - 9783642382550 - 9783642382567 ; 357, s. 239-254
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Bokkapitel (refereegranskat)abstract
- Quantitative gait analysis is a powerful tool for the assessment of a number of physical and cognitive conditions. Unfortunately, the costs involved in providing in-lab 3D kinematic analysis to all patients is prohibitive. Inertial sensors such as accelerometers and gyroscopes may complement in-lab analysis by providing cheaper gait analysis systems that can be deployed anywhere. The present study investigates the use of inertial sensors to quantify gait symmetry and gait normality. The system was evaluated in-lab, against 3D kinematic measurements; and also in-situ, against clinical assessments of hip-replacement patients. Results show that the system not only correlates well with kinematic measurements but it also corroborates various quantitative and qualitative measures of recovery and health status of hip-replacement patients
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