| 1. |
- Axelsson, Johan, et al.
(författare)
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Prior information in fluorescence molecular tomography based on multispectral fluorescence emission
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1042-4687 .- 1605-7422. - 9780819465474 ; 6434, s. 4340-4340
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Konferensbidrag (refereegranskat)abstract
- Fluorescence molecular tomography (FMT) suffers from inherent ill-posedness due to the vast number of possible solutions to the reconstruction problem. To increase the robustness of such a problem one need prior information. We present here a method for rendering a priori information of the position of a fluorescent inclusion inside turbid media. The method utilizes solely two spectral bands within the fluorescence spectrum emitted from the fluorophore. The method is presented and verified using experimental data from a tissue phantom. The confinement is also used to impose weights onto the voxels before the inversion of the linear set of equations describing the FMT problem.
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| 2. |
- Johansson, Ann, et al.
(författare)
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Interstitial photodynamic therapy for primary prostate cancer incorporating realtime treatment dosimetry
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1042-4687 .- 1605-7422. ; 6427, s. 4270-4270
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Konferensbidrag (refereegranskat)abstract
- Photodynamic therapy (PDT) for the treatment of prostate cancer has been demonstrated to be a safe treatment option capable of inducing tissue necrosis and decrease in prostate specific antigen (PSA). Research groups report on large variations in treatment response, possibly due to biological variations in tissue composition and shortterm response to the therapeutic irradiation. Within our group, an instrument for interstitial PDT on prostate tissue that incorporates realtime treatment feedback is being developed. The treatment protocol consists of two parts. The first part incorporates the pre-treatment plan with ultrasound investigations, providing the geometry for the prostate gland and surrounding risk organs, an iterative random-search algorithm to determine near-optimal fiber positions within the reconstructed geometry and a Block-Cimmino optimization algorithm for predicting individual fiber irradiation times. During the second part, the therapeutic light delivery is combined with measurements of the light transmission signals between the optical fibers, thus monitoring the tissue effective attenuation coefficient by means of spatially resolved spectroscopy. These data are then used as input for repeated runs of the Block-Cimmino optimization algorithm. Thus, the irradiation times for individual fibers are updated throughout the treatment in order to compensate for the influence of changes in tissue composition on the light distribution at the therapeutic wavelength.
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| 3. |
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| 4. |
- Ruschin, Mark, et al.
(författare)
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Improved in-plane visibility of tumors using breast tomosynthesis
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6510
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this work was to evaluate and compare the visibility of simulated tumors in 2D digital mammography (DM) and breast tomosynthesis (BT) images of patients. Images of the same women were acquired on both a DM system (Mammomat Novation, Siemens) and a BT prototype system adapted from the same type of DM system. Using the geometrical properties of the two systems, simulated, ellipsoid-shaped tumors (average dimension: 8.4 mm × 6.6 mm × 5 mm) with irregular margins were projected and added to each DM image as well as each BT projection image prior to 3D reconstruction. The same beam quality and approximately the same total absorbed dose were used for each breast image acquisition on both systems. Two simulated tumors were added to each of thirty patient scans, yielding sixty cases. A series of 4-alternative forced choice (4-AFC) human observer experiments were conducted in order to determine what projected signal intensity (contrast) of the tumors in the DM images would be needed to achieve the same detectability as in the reconstructed BT images. Nine observers participated. For the BT 4-AFC experiment, when the signal intensity of the tumor on the central projection was 0.010 (natural logarithmic units) the mean percent of correct responses (PC) was measured to be 81.5%, which converted to a detectability index value (d') of 1.96. For the DM system, the same detectability was achieved at a signal intensity determined to be 0.038. Equivalent levels of tumor detection in BT images were thus achieved at around four times less projected signal intensity than in DM images, indicating that the use of BT may lead to earlier detection of breast cancer.
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| 5. |
- Shen, Li, et al.
(författare)
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An interactive 3D visualization and manipulation tool foreffective assessment of angiogenesis and arteriogenesis usingcomputed tomographic angiography
- 2005
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Ingår i: Progress in Biomedical Optics and Imaging. - : SPIE. - 1605-7422 .- 1042-4687. ; 5744:II, s. 848-858
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents IVM, an Interactive Vessel Manipulation tool that can help make effective and efficient assessmentof angiogenesis and arteriogenesis in computed tomographic angiography (CTA) studies. IVM consistsof three fundamental components: (1) a visualization component, (2) a tracing component, and (3) a measurementcomponent. Given a user-specified threshold, IVM can create a 3D surface visualization based on it. Sincevessels are thin and tubular structures, using standard isosurface extraction techniques usually cannot yieldsatisfactory reconstructions. Instead, IVM directly renders the surface of a derived binary 3D image. The imagevolumes collected in CTA studies often have a relatively high resolution. Thus, compared with more complicatedvessel extraction and visualization techniques, rendering the binary image surface has the advantages of beingeffective, simple and fast. IVM employs a semi-automatic approach to determine the threshold: a user can adjustthe threshold by checking the corresponding 3D surface reconstruction and make the choice. Typical tracingsoftware often defines ROIs on 3D image volumes using three orthogonal views. The tracing component in IVMtakes one step further: it can perform tracing not only on image slices but also in a 3D view. We observe thatdirectly operating on a 3D view can help a tracer identify ROIs more easily. After setting a threshold and tracingan ROI, a user can use IVM’s measurement component to estimate the volume and other parameters of vesselsin the ROI. The effectiveness of the IVM tool is demonstrated on rat vessel/bone images collected in a previousCTA study.
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| 6. |
- Svahn, Tony, et al.
(författare)
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In-plane artifacts in breast tomosynthesis quantified with a novel contrast-detail phantom
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6510:PART 3, s. 1853-1864
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Konferensbidrag (refereegranskat)abstract
- The purpose of this work was to develop a contrast-detail phantom that can be used to evaluate image quality in breast tomosynthesis (BT) and as a first step use it to evaluate in-plane artifacts with respect to object size and contrast. The phantom was constructed using a Polylite [registered trademark] resin as bulk material, as it has x-ray mass attenuation properties similar to polymethyl methacrylate (PMMA), a common phantom material in mammography. Six different materials polyoxymethylene (POM), bakelite [registered trademark] , nylon, polycarbonate (PC), acrylonitrilebutadienestyrene (ABS) and polyethene (PE) - were selected to form the phantom details. For each of the six materials, five spherical objects were manufactured (diameters of 4, 8, 12, 16, and 20 mm) resulting in 30 objects that were embedded with their centres approximately aligned at the central plane of a 26 mm thick Polylite [registered trademark] block (210 mm × 300 mm). A 20 mm thick PMMA block was added to yield a phantom with attenuation properties similar to 45 mm PMMA that could simulate a so-called standard breast (50 mm thick, 50% glandular tissue). Images of the phantom were acquired using a BT prototype system that employs filtered backprojection for image reconstruction. The magnitude of the in-plane artifacts was evaluated and was found to increase linearly with increasing contrast (signal) level and size of the embedded objects. The contrast-detail phantom was found to be a useful tool for evaluating BT in-plane artifacts and might also be used to study out-of-plane artifacts and the effect of different acquisition and reconstruction parameters on image quality in BT.
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| 7. |
- Svensson, Jenny, et al.
(författare)
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Pharmacokinetic study of a systemically administered novel liposomal Temoporfin formulation in an animal tumor model
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 6427, s. 4270-4270
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Konferensbidrag (refereegranskat)abstract
- Meso-tetra(hydroxyphenyl)chlorin (mTHPC) (international generic name Temoporfin) is a potent photosensitizer used for photodynamic therapy (PDT). In this study the pharmacokinetics of a systemically administered novel lipid formulation of Temoporfin in a murine tumor model has been investigated. Fluorescence spectroscopy measurements were performed at several time intervals following drug administration, yielding information on the Temoporfin concentration within excised internal organs as a function of time after injection. Both point-monitoring and imaging setups were used. The acquired fluorescence data were correlated to the concentration of Temoporfin obtained with High Performance Liquid Chromatography (HPLC). There was a significant correlation between the fluorescence methods and HPLC for most organs investigated. The pharmacokinetics of this new liposomal formulation of Temoporfin exhibited a rather flat temporal profile in the time interval 2-8 hours in this study.
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| 8. |
- Timberg, Pontus, et al.
(författare)
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Optimization of image quality in breast tomosynthesis using lumpectomy and mastectomy specimens
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1042-4687 .- 1605-7422. ; 6510:PART 2, s. 1379-1386
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to determine how image quality in breast tomosynthesis (BT) is affected when acquisition modes are varied, using human breast specimens containing malignant tumors and/or microcalcifications. Images of thirty-one breast lumpectomy and mastectomy specimens were acquired on a BT prototype based on a Mammomat Novation (Siemens) full-field digital mammography system. BT image acquisitions of the same specimens were performed varying the number of projections, angular range, and detector signal collection mode (binned and non-binned in the scan direction). An enhanced filtered back projection reconstruction method was applied with constant settings of spectral and slice thickness filters. The quality of these images was evaluated via relative visual grading analysis (VGA) human observer performance experiments using image quality criteria. Results from the relative VGA study indicate that image quality increases with number of projections and angular range. A binned detector collecting mode results in less noise, but reduced resolution of structures. Human breast specimens seem to be suitable for comparing image sets in BT with image quality criteria.
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| 9. |
- Yavari, Nazila, et al.
(författare)
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Measurements of optical properties of pig brain tissue in vitro using a novel compact device
- 2005
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422 .- 1042-4687. ; 5864, s. 1-11
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Konferensbidrag (refereegranskat)abstract
- In numerous medical and scientific fields, knowledge of the optical properties of tissues can be applied. Among many different ways of determining the optical properties of turbid media; integrating sphere measurements are widely used. However, this technique is associated with bulky equipment, complicated measuring techniques, interference compensation techniques, and inconvenient sample handling. This paper describes measurements of the optical properties of porcine brain tissue using novel instrumentation for simultaneous absorption and scattering characterization of small turbid samples. The system used measures both angularly and spatially resolved transmission and reflection and is called Combined Angular and Spatially-resolved Head (CASH) sensor. The results compare very well with data obtained with an integrating sphere for well-defined samples. The instrument was shown to be accurate to within 12 % for μa. and 1 % for μs' in measurements of intralipid-ink samples. The corresponding variations of data were 17 %, and 2 %, respectively. The reduced scattering coefficient for porcine white matter was measured to be 100 cm-1, while the value for coagulated brain tissue was 65 cm-1. The corresponding absorption coefficients were 2 and 3 cm-1, respectively. © 2005 SPIE and OSA.
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| 10. |
- Arvidsson, Ida, et al.
(författare)
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Detection of left bundle branch block and obstructive coronary artery disease from myocardial perfusion scintigraphy using deep neural networks
- 2021
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Ingår i: Medical Imaging 2021 : Computer-Aided Diagnosis - Computer-Aided Diagnosis. - : SPIE. - 1605-7422. - 9781510640238 ; 11597
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Konferensbidrag (refereegranskat)abstract
- Myocardial perfusion scintigraphy, which is a non-invasive imaging technique, is one of the most common cardiological examinations performed today, and is used for diagnosis of coronary artery disease. Currently the analysis is performed visually by physicians, but this is both a very time consuming and a subjective approach. These are two of the motivations for why an automatic tool to support the decisions would be useful. We have developed a deep neural network which predicts the occurrence of obstructive coronary artery disease in each of the three major arteries as well as left bundle branch block. Since multiple, or none, of these could have a defect, this is treated as a multi-label classification problem. Due to the highly imbalanced labels, the training loss is weighted accordingly. The prediction is based on two polar maps, captured during stress in upright and supine position, together with additional information such as BMI and angina symptoms. The polar maps are constructed from myocardial perfusion scintigraphy examinations conducted in a dedicated Cadmium-Zinc-Telluride cardio camera (D-SPECT Spectrum Dynamics). The study includes data from 759 patients. Using 5-fold cross-validation we achieve an area under the receiver operating characteristics curve of 0.89 as average on per-vessel level for the three major arteries, 0.94 on per-patient level and 0.82 for left bundle branch block.
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| 11. |
- Arvidsson, Ida, et al.
(författare)
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Domain-adversarial neural network for improved generalization performance of gleason grade classification
- 2020
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Ingår i: Medical Imaging 2020 : Digital Pathology - Digital Pathology. - : SPIE. - 1605-7422. - 9781510634077 ; 11320
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Konferensbidrag (refereegranskat)abstract
- When training a deep learning model, the dataset used is of great importance to make sure that the model learns relevant features of the data and that it will be able to generalize to new data. However, it is typically difficult to produce a dataset without some bias toward any specific feature. Deep learning models used in histopathology have a tendency to overfit to the stain appearance of the training data - if the model is trained on data from one lab only, it will usually not be able to generalize to data from other labs. The standard technique to overcome this problem is to use color augmentation of the training data which, artificially, generates more variations for the network to learn. In this work we instead test the use of a so called domain-adversarial neural network, which is designed to prevent the model from being biased towards features that in reality are irrelevant such as the origin of an image. To test the technique, four datasets from different hospitals for Gleason grading of prostate cancer are used. We achieve state of the art results for these particular datasets, and furthermore for two of our three test datasets the approach outperforms the use of color augmentation.
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| 12. |
- Asplund, Sara, 1976, et al.
(författare)
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Extended analysis of the effect of learning with feedback on the detectability of pulmonary nodules in chest tomosynthesis
- 2011
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 7966
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In chest tomosynthesis, low-dose projections collected over a limited angular range are used for reconstruction of section images of the chest, resulting in a reduction of disturbing anatomy at a moderate increase in radiation dose compared to chest radiography. In a previous study, we investigated the effects of learning with feedback on the detection of pulmonary nodules in chest tomosynthesis. Six observers with varying degrees of experience of chest tomosynthesis analyzed tomosynthesis cases for presence of pulmonary nodules. The cases were analyzed before and after learning with feedback. Multidetector computed tomography (MDCT) was used as reference. The differences in performance between the two readings were calculated using the jackknife alternative free-response receiver operating characteristics (JAFROC-2) as primary measure of detectability. Significant differences between the readings were found only for observers inexperienced in chest tomosynthesis. The purpose of the present study was to extend the statistical analysis of the results of the previous study, including JAFROC-1 analysis and FROC curves in the analysis. The results are consistent with the results of the previous study and, furthermore, JAFROC-1 gave lower p-values than JAFROC-2 for the observers who improved their performance after learning with feedback. © 2011 SPIE.
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| 13. |
- Axelsson, Rebecca, et al.
(författare)
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Computer model of mechanical imaging acquisition for virtual clinical trials
- 2021
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Ingår i: Medical Imaging 2021 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 1605-7422. - 9781510640191 ; 11595, s. 1-115950
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Konferensbidrag (refereegranskat)abstract
- Malignant breast tumours can be distinguished from benign lesions and normal tissue based on their mechanical properties. Our pilot studies have demonstrated the potential of using Mechanical Imaging (MI) combined with mammography to reduce recalls and false positives in breast cancer screening by more accurately identifying benign lesions. To enable further optimization of MI we propose a computer simulation of the MI acquisition, for use in a Virtual Clinical Trial (VCT) framework. VCTs are computer simulated clinical trials used to efficiently evaluate clinical imaging systems. A linear elastic finite element (FE) model of the breast under dynamic compression was implemented using an open-source FE solver. A spherical tumour (15 mm in diameter) was inserted into the simulated predominantly adipose breast. The location and stiffness of the tumour was varied. The average stress on the compressed breast surface was calculated and compared with the local average stress at the tumour location and the Relative Mean Pressure over lesion Area (RMPA) was calculated. Preliminary results were within a realistic range with an average stress on the breast (tumour) of 5.9-16.6 kPa which is in agreement with published values between 1.0 - 22.5 kPa. This corresponds to RMPA values of 0.96-2.15 depending on stiffness and location of the tumour. This can lead to more detailed validation of various MI acquisition schemes through VCTs before their use in clinical studies.
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| 14. |
- Bakic, Predrag R., et al.
(författare)
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Pre-processing for image quality improvement in simultaneous DBT and mechanical imaging
- 2020
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Ingår i: Medical Imaging 2020 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 1605-7422. - 9781510633919 ; 11312
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Konferensbidrag (refereegranskat)abstract
- Simultaneous digital breast tomosynthesis (DBT) and mechanical imaging (MI) offer the potential to combine anatomic information from DBT with functional information from MI. This makes it possible to associate tissue stiffness with specific anatomic structures in the breast, a combination that can reduce false-positive findings by using the MI data to discriminate between ambiguous lesions in DBT. This, in turn, will reduce the frequency of negative biopsies. Simultaneous imaging requires that the MI sensor array be present during DBT acquisition. This introduces artifacts, since the sensor is attenuating. Previously, we demonstrated that the DBT reconstruction could be modified to reduce sensor conspicuity in DBT images. In this paper, we characterize the relative attenuation of the breast and the sensor, to calculate the artifact reduction in DBT reconstruction. We concentrate on pre-processing DBT projections prior to reconstruction. Using commercially available a DBT system, we have confirmed that the sensor array does not completely attenuate the x-rays. This suggests that a pre-processing method based upon flat fielding can be used to reduce artifacts. In a proof-of-concept study, we performed flat fielding by combining DBT projections of the MI sensor with and without an anthropomorphic breast phantom. Visual evaluation confirmed substantially improved image quality. The artifacts were reduced throughout the image for all sensor elements. Few residual artifacts are noticeable where the phantom thickness decreases. The investigation of additional pre-processing, including beam hardening correction is ongoing. Future work includes quantitative validation, noise stabilization, and method optimization in virtual clinical trials and subsequent patient studies.
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| 15. |
- Balbekin, N.S., et al.
(författare)
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Nondestructive monitoring of aircraft composites using terahertz radiation
- 2014
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9781628415643 ; 9448, s. 94482D-
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider using the terahertz (THz) time domain spectroscopy (TDS) for non destructive testing and determining the chemical composition of the vanes and rotor-blade spars. A versatile terahertz spectrometer for reflection and transmission has been used for experiments. We consider the features of measured terahertz signal in temporal and spectral domains during propagation through and reflecting from various defects in investigated objects, such as voids and foliation. We discuss requirements are applicable to the setup and are necessary to produce an image of these defects, such as signal-to-noise ratio and a method for registration THz radiation. Obtained results indicated the prospects of the THz TDS method for the inspection of defects and determination of the particularities of chemical composition of aircraft parts.
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| 16. |
- Bauer, Brigitte, 1978, et al.
(författare)
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Metal nanoparticles amplify photodynamic effect on skin cells in vitro
- 2011
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Optical Interactions with Tissue and Cells XXII; San Francisco, CA; 24-26 January 2011. - : SPIE. - 1605-7422. - 9780819484345 ; 7897
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report on an investigation aimed to increase the efficiency of photodynamic therapy (PDT) through the influence of localized surface plasmon resonances (LSPR's) in metal nanoparticles. PDT is based on photosensitizers that generate singlet oxygen at the tumour site upon exposure to visible light. Although PDT is a well-established treatment for skin cancer, a major drawback is the low quantum yield for singlet-oxygen production. This motivates the development of novel methods that enhance singlet oxygen generation during treatment. In this context, we study the photodynamic effect on cultured human skin cells in the presence or absence of gold nanoparticles with well established LSPR and field-enhancement properties. The cultured skin cells were exposed to protoporphyrin IX and gold nanoparticles and subsequently illuminated with red light. We investigated the differences in cell viability by tuning different parameters, such as incubation time and light dose. In order to find optimal parameters for specific targeting of tumour cells, we compared normal human epidermal keratinocytes with a human squamous skin cancer cell line. The study indicates significantly enhanced cell death in the presence of nanoparticles and important differences in treatment efficiency between normal and tumour cells. These results are thus promising and clearly motivate further development of nanoparticle enhanced clinical PDT treatment.
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| 17. |
- Borglin, Johan, 1986, et al.
(författare)
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Improving multiphoton microscopy using annular beam shaping, focusing on imaging of human skin
- 2014
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Ingår i: Multiphoton Microscopy in the Biomedical Sciences XIV: 2-4 February 2014, San Francisco, California, United States. Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 8948
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Konferensbidrag (refereegranskat)abstract
- Multiphoton fluorescence microscopy (MPM) is a method for high resolution, non-invasive investigations of biological tissue. The aim of introducing an annular shaped laser beam is to reduce the ouf-of-focus generated background signal improving imaging of light scattering tissue such as human skin. Simulations show that 50% of the beam radius can be blocked, while preserving the shape of the point spread function. Initial experiments performed on a phantom consisting of fluorescein and fluorescent beads embedded in agar by using a custom built MPM-set up show that by introducing a simple beam blocker to create an annular beam, the background signal is reduced with approximately 5%. Future work will include optimizing the set up, and creating phantoms with more light scattering properties. © 2014 SPIE.
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| 18. |
- Båth, Magnus, 1974, et al.
(författare)
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Investigation of image components affecting the detection of lung nodules in digital chest radiography
- 2005
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 5749, s. 231-242
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this work was to investigate and quantify the effects of system noise, nodule location, anatomical noise and anatomical background on the detection of lung nodules in different regions of the chest x-ray. Simulated lung nodules of diameter 10 mm but with varying detail contrast were randomly positioned in four different kinds of images: 1) clinical images collected with a 200 speed CR system, 2) images containing only system noise (including quantum noise) at the same level as the clinical images, 3) clinical images with removed anatomical noise, 4) artificial images with similar power spectrum as the clinical images but random phase spectrum. An ROC study was conducted with 5 observers. The detail contrast needed to obtain an Az of 0.80, C0.8, was used as measure of detectability. Five different regions of the chest x-ray were investigated separately. The C0.8 of the system noise images ranged from only 2% (the hilar regions) to 20% (the lateral pulmonary regions) of those of the clinical images. Compared with the original clinical images, the C0.8 was 16% lower for the de-noised clinical images and 71% higher for the random phase images, respectively, averaged over all five regions. In conclusion, regarding the detection of lung nodules with a diameter of 10 mm, the system noise is of minor importance at clinically relevant dose levels. The removal of anatomical noise and other noise sources uncorrelated from image to image leads to somewhat better detection, but the major component disturbing the detection is the overlapping of recognizable structures, which are, however, the main aspect of an x-ray image.
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| 19. |
- Båth, Magnus, 1974, et al.
(författare)
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VGC analysis: Application of the ROC methodology to visual grading tasks
- 2008
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6917
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- To determine clinical image quality in radiography, visual grading of the reproduction of important anatomical landmarks is often used. The rating data from the observers in a visual grading study with multiple scale steps is ordinal, meaning that non-parametric rank-invariant statistical methods are required. However, many visual grading methods incorrectly use parametric statistical methods. This work describes how the methodology developed in receiver operating characteristics (ROC) analysis for characterising the difference in the observer's response to the signal and no-signal distributions can be applied to visual grading data for characterising the difference in perceived image quality between two systems. The method is termed visual grading characteristics (VGC) analysis. In a VGC study, the task of the observer is to rate her confidence about the fulfilment of image quality criteria. Using ROC software, the given ratings for the two systems are then used to determine the VGC curve, which describes the relationship between the proportions of fulfilled image criteria for the two compared systems for all possible decision thresholds. As a single measure of the difference in image quality between the two compared systems, the area under the VGC curve can be used.
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| 20. |
- Chodorowski, Artur, 1959, et al.
(författare)
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An attempt to estimate out-of-plane lung nodule elongation in tomosynthesis images
- 2015
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Ingår i: Medical Imaging 2015: Physics of Medical Imaging (SPIE Proceedings). Conference on Medical Imaging - Physics of Medical Imaging. February 22-25, 2015, Orlando, Florida, USA.. - : SPIE. - 0277-786X .- 1605-7422. - 9781628415025
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Konferensbidrag (refereegranskat)abstract
- In chest tomosynthesis (TS) the most commonly used reconstruction methods are based on Filtered Back Projection (FBP) algorithms. Due to the limited angular range of x-ray projections, FBP reconstructed data is typically associated with a low spatial resolution in the out-of-plane dimension. Lung nodule measures that depend on depth information such as 3D shape and volume are therefore difficult to estimate. In this paper the relation between features from FBP reconstructed lung nodules and the true out-of-plane nodule elongation is investigated and a method for estimating the out-of-plane nodule elongation is proposed. In order to study these relations a number of steps that include simulation of spheroidal-shaped nodules, insertion into synthetic data volumes, construction of TS-projections and FBP-reconstruction were performed. In addition, the same procedure was used to simulate nodules and insert them into clinical chest TS projection data. The reconstructed nodule data was then investigated with respect to in-plane diameter, out-of-plane elongation, and attenuation coefficient. It was found that the voxel value in each nodule increased linearly with nodule elongation, for nodules with a constant attenuation coefficient. Similarly, the voxel value increased linearly with in-plane diameter. These observations indicate the possibility to predict the nodule elongation from the reconstructed voxel intensity values. Such a method would represent a quantitative approach to chest tomosynthesis that may be useful in future work on volume and growth rate estimation of lung nodules.
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| 21. |
- Costa, Arthur C., et al.
(författare)
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Assessment of projection interpolation to compensate for the increased radiation dose in DBTMI
- 2023
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Ingår i: Medical Imaging 2023 : Physics of Medical Imaging - Physics of Medical Imaging. - 1605-7422. - 9781510660311 ; 12463
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Konferensbidrag (refereegranskat)abstract
- The combination of digital breast tomosynthesis (DBT) with other imaging modalities has been investigated in order to improve the detection and diagnosis of breast cancer. Mechanical Imaging (MI) measures the stress over the surface of the compressed breast, using a pressure sensor, during radiographic examination and its response has shown a correlation with the presence of malignant lesions. Thus, the combination of DBT and MI (DBTMI) has shown potential to reduce false positive results in breast cancer screening. However, compared to the conventional DBT exam, the presence of the MI sensor during mammographic image acquisition may cause a slight increase in the radiation dose. This work presents a proposal to reduce the radiation dose in DBTMI exams by removing some projections from the original set and replacing them with synthetic projections generated by a video frame interpolation (VFI) neural network. We compared several DBTMI acquisition arrangements, considering the removal of 16% of the original projections, using a deformable physical breast phantom, and evaluated the quality of the reconstructed images based on the Normalized Root Mean Squared Error (NRMSE). The results showed that, for some arrangements, the slices reconstructed with the addition of synthetic DBTMI projections presented better quality than when they were reconstructed with the reduced set of projections. Further studies must be carried out to optimize the interpolation approach.
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| 22. |
- Daeichin, Verya, 1984, et al.
(författare)
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Self-demodulation effect on subharmonic response of ultrasound contrast agent
- 2012
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819489692 ; 8320, s. Art. no. 83200W-
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Konferensbidrag (refereegranskat)abstract
- In this work the use of the self-demodulation (S-D) signal as a mean of microbubble excitation at the subharmonic (SH) frequency to enhance the SH emission of ultrasound contrast agent (UCA) is studied. SH emission from the UCA is of interest since it is produced only by the UCA and is free of the artifacts produced in harmonic imaging modes. The S-D wave is a low-frequency signal produced by nonlinear propagation of an ultrasound wave in the medium. Single element transducer experiments and numerical simulations were conducted at 10 MHz to study the effect of the S-D signal on the SH response of the UCA by modifying the envelope of the excitation bursts. For 6 and 20 transmitted cycles, the SH response is increased up to 25 dB and 22 dB because of the S-D stimulation for a burst with a rectangular envelope compared with a Gaussian envelope burst. Such optimized excitations were used in an array-based micro-ultrasound system (Vevo 2100, VisualSonics Inc., Toronto, ON, Canada) at 18 MHz for in vitro validation of SH imaging. This study suggests that a suitable design of the envelope of the transmit excitation to generate a S-D signal at the SH frequency can enhance the SH emission of UCA and real-time SH imaging is feasible with shorter transmit burst (6- cycle) and low acoustic pressure (-150 KPa) at high frequencies (>15 MHz).
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| 23. |
- Durán Bosch, Vicente Andrés, 1977, et al.
(författare)
-
Transillumination imaging through biological tissue by single-pixel detection
- 2015
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9781628417067 ; 9541, s. Artno 95410B-
-
Konferensbidrag (refereegranskat)abstract
- One challenge that has long held the attention of scientists is that of clearly seeing objects hidden by turbid media, as smoke, fog or biological tissue, which has major implications in fields such as remote sensing or early diagnosis of diseases. Here, we combine structured incoherent illumination and bucket detection for imaging an absorbing object completely embedded in a scattering medium. A sequence of low-intensity microstructured light patterns is launched onto the object, whose image is accurately reconstructed through the light fluctuations measured by a single-pixel detector. Our technique is noninvasive, does not require coherent sources, raster scanning nor time-gated detection and benefits from the compressive sensing strategy. As a proof of concept, we experimentally retrieve the image of a transilluminated target both sandwiched between two holographic diffusers and embedded in a 6mm-thick sample of chicken breast.
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| 24. |
- Dustler, Magnus, et al.
(författare)
-
Realism of mammography tissue patches simulated using perlin noise : A forced choice reading study
- 2021
-
Ingår i: Medical Imaging 2021 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 1605-7422. - 9781510640191 ; 11595
-
Konferensbidrag (refereegranskat)abstract
- Software breast phantoms are central to the optimization of breast imaging, where in many cases the use of real images would be inefficient - or impossible. Establishing the realism of such phantoms is critical. For this study, patches of simulated breast tissue with different composition - fatty, scattered, heterogenous and dense tissue - were generated using a method based on Perlin noise. The composition of the patches is controlled by numerical parameters derived from input by radiologists and medical physicists with experience of breast imaging. Separate Perlin noise-based methods were used to simulate skin pores, high-frequency noise (representing quantum and electronic noise) and ligaments and vascular structures. In a forced choice reading study, the realism of the simulated tissue patches compared to patches from real mammograms was determined. Patches of 200-500 pixels were extracted from radiolucent, linear, nodular or homogenous (10 per category) mammograms randomly selected from a previously acquired dataset. Eighteen simulated patches in the same size range were added. Four readers, two radiologists and two medical physicists were shown the images in random order and asked to rate them as real or simulated. All readers accepted a substantial fraction of simulated images as real, ranging from 22% to 72%. Only two readers showed a significant difference in the number of images rated real in the real and simulated groups, 22% vs 73% (P=.0003) and 33% vs 63% (P=.04), respectively. These results suggest that the method employed can create images that are almost indistinguishable from patches of real mammograms.
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| 25. |
- Ehteshami Bejnordi, B., et al.
(författare)
-
Novel chromatin texture features for the classification of Pap smears
- 2013
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819494504 ; 8676, s. Art. no. 867608-
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a set of novel structural texture features for quantifying nuclear chromatin patterns in cells on a conventional Pap smear. The features are derived from an initial segmentation of the chromatin into bloblike texture primitives. The results of a comprehensive feature selection experiment, including the set of proposed structural texture features and a range of different cytology features drawn from the literature, show that two of the four top ranking features are structural texture features. They also show that a combination of structural and conventional features yields a classification performance of 0.954±0.019 (AUC±SE) for the discrimination of normal (NILM) and abnormal (LSIL and HSIL) slides. The results of a second classification experiment, using only normal-appearing cells from both normal and abnormal slides, demonstrates that a single structural texture feature measuring chromatin margination yields a classification performance of 0.815±0.019. Overall the results demonstrate the efficacy of the proposed structural approach and that it is possible to detect malignancy associated changes (MACs) in Papanicoloau stain.
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| 26. |
- Enejder, Annika, 1969, et al.
(författare)
-
CARS and SHG microscopy for the characterization of bacterial cellulose
- 2009
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819474292 ; 7183
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have developed a protocol employing dual-mode non-linear microscopy for the monitoring of the biosynthesis of bacterial cellulose at a single-fiber level, with the fundamental aim to achieve a product with material properties similar to those of human blood vessels. Grown in a tubular geometry it could then be used as a natural and biocompatible source of replacement tissue in conjunction with cardiovascular surgery. The bacteria (Acetobacter xylinum) were selectively visualized based on the CH2 vibration of its organic macromolecular contents by the Coherent Anti-Stokes Raman Scattering (CARS) process and, simultaneously, the non-centrosymmetrically ordered, birefringent cellulose fibers were depicted by the Second Harmonic Generation (SHG) process. This dual-channel detection approach allows the monitoring of cellulose-fiber formation in vivo and to determine the influence of e. g. different growth conditions on fiber thickness and orientation, their assembling into higher-order structures and overall network density. The bacterial and fiber distributions were monitored in a simple microscope cultivation chamber, as well as in samples harvested during the actual fermentation process of tubular cellulose grafts. The CARS and SHG co-localization images reveal that highest bacterial population densities can be observed in the surface regions of the cellulose tissue, where the primary growth presumably takes place. The cellulose network morphology was also compared with that of human arteries and veins, from which we conclude that the cellulose matrix is comparatively homogeneous in contrast to the wavy band-like supra-formations of collagen in the native tissue. This prompts for sophisticated fermentation methods by which tunnels and pores of appropriate sizes and shapes can be introduced in the cellulose network in a controllable way. With this protocol we hope to contribute to the fundamental knowledge required for optimal production of bioengineered cellulose tissues, eventually being available for clinical use.
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| 27. |
- Enejder, Annika, 1969, et al.
(författare)
-
CARS and SHG microscopy of artificial bioengineered tissues
- 2010
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819479655 ; 7569
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Major efforts are presently made to develop artificial replacement tissues with optimal architectural and material characteristics, mimicking those of their natural correspondents. Encouraged by the readiness with which cellulose fibers woven by the bacteria Acetobacter xylinum can be formed into organ-like macroscopic shapes and with different microscopic textures, it emerges as an interesting material within tissue engineering. We have developed a protocol employing simultaneous CARS and SHG microscopy for monitoring the cellulose network characteristics and its impact on the integration of smooth muscle cells (SMCs) for functionalized artificial tissues. CARS and SHG overlay images of the cells and the cellulose fibers reveal an immediate interaction irrespective of scaffold morphology and that the SMCs attach to the cellulose fibers already during the first cultivation day without cell-adhesive coatings. During the subsequent 28 days, SMCs were found to readily proliferate and differentiate on the cellulose scaffold without the need for exogenous growth factors. However, the efficiency with which this occurred depended on the topography of the cellulose constructs, benefited by porous and less compact matrices. This brings forward the need for in-depth studies on how the microstructure of tissue scaffolds influences and can be optimized for native cell integration and proliferation, studies where the benefits of multi-modal non-linear microscopy can be fully exploited. © 2010 Copyright SPIE - The International Society for Optical Engineering.
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| 28. |
- Enejder, Annika, 1969, et al.
(författare)
-
CARS microscopy of Alzheimer's diseased brain tissue
- 2014
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 8948
-
Konferensbidrag (refereegranskat)abstract
- Alzheimera's disease (AD) is a progressive neurodegenerative disorder currently without cure, characterized by the presence of extracellular plaques surrounded by dystrophic neurites. In an effort to understand the underlying mechanisms, biochemical analysis (protein immunoblot) of plaque extracts reveals that they consist of amyloid-beta (Aβ) peptides assembled as oligomers, protofibrils and aggregates. Their spatial distribution has been confirmed by Thioflavin-S or immuno-staining with fluorescence microscopy. However, it is increasingly understood that the protein aggregation is only one of several mechanism that causes neuronal dysfunction and death. This raises the need for a more complete biochemical analysis. In this study, we have complemented 2-photon fluorescence microscopy of Thioflavin-S and Aβ immuno-stained human AD plaques with CARS microscopy. We show that the chemical build-up of AD plaques is more complex and that Aβ staining does not provide the complete picture of the spatial distribution or the molecular composition of AD plaques. CARS images provide important complementary information to that obtained by fluorescence microscopy, motivating a broader introduction of CARS microscopy in the AD research field.
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| 29. |
- Enejder, Annika, 1969, et al.
(författare)
-
Chemical release from single PMMA microparticles monitored by CARS microscopy
- 2011
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. Multiphoton Microscopy in the Biomedical Sciences XI; San Francisco, CA; 23-25 January 2011. - : SPIE. - 1605-7422. - 9780819484406 ; 7903
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Microparticles loaded with antigens, proteins, DNA, fungicides, and other functional agents emerge as ideal vehicles for vaccine, drug delivery, genetic therapy, surface- and crop protection. The microscopic size of the particles and their collective large specific surface area enables highly active and localized release of the functional substance. In order to develop designs with release profiles optimized for the specific application, it is desirable to map the distribution of the active substance within the particle and how parameters such as size, material and morphology affect release rates at single particle level. Current imaging techniques are limited in resolution, sensitivity, image acquisition time, or sample treatment, excluding dynamic studies of active agents in microparticles. Here, we demonstrate that the combination of CARS and THG microscopy can successfully be used, by mapping the spatial distribution and release rates of the fungicide and food preservative IPBC from different designs of PMMA microparticles at single-particle level. By fitting a radial diffusion model to the experimental data, single particle diffusion coefficients can be determined. We show that release rates are highly dependent on the size and morphology of the particles. Hence, CARS and THG microscopy provides adequate sensitivity and spatial resolution for quantitative studies on how single-particle properties affect the diffusion of active agents at microscopic level. This will aid the design of innovative microencapsulating systems for controlled release.
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| 30. |
- Enejder, Annika, 1969, et al.
(författare)
-
Neuronal cell growth on polymeric scaffolds studied by CARS microscopy
- 2012
-
Ingår i: Proceedings of SPIE - Multiphoton Microscopy in the Biomedical Sciences XII, San Francisco, CA, 22-24 January 2012. - : SPIE. - 1605-7422. - 9780819488695 ; 8226
-
Konferensbidrag (refereegranskat)abstract
- For studies of neuronal cell integration and neurite outgrowth in polymeric scaffold materials as a future alternative for the treatment of damages in the neuronal system, we have developed a protocol employing CARS microscopy for imaging of neuronal networks. The benefits of CARS microscopy come here to their best use; (i) the overall three-dimensional (3D) arrangement of multiple cells and their neurites can be visualized without the need for chemical preparations or physical sectioning, potentially affecting the architecture of the soft, fragile scaffolds and (ii) details on the interaction between single cells and scaffold fibrils can be investigated by close-up images at sub-micron resolution. The establishment of biologically more relevant 3D neuronal networks in a soft hydrogel composed of native Extra Cellular Matrix (ECM) components was compared with conventional two-dimensional networks grown on a stiff substrate. Images of cells in the hydrogel scaffold reveal significantly different networking characteristics compared to the 2D networks, raising the question whether the functionality of neurons grown as layers in conventional cultivation dishes represents that of neurons in the central and peripheral nervous systems.
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| 31. |
- Enejder, Annika, 1969, et al.
(författare)
-
Nonlinear nearfield microscopy
- 2013
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819493576 ; 8588
-
Konferensbidrag (refereegranskat)abstract
- Higher-order nonlinearity of light-matter interactions, such as second and third harmonic generation (SHG & THG) and Coherent anti-Stokes Raman Scattering (CARS) can be used for improving spatial resolution in microscopy as a consequence of the confinement of the nonlinear polarization to the high-intensity region of the focal volume. However, the resolution is limited to similar to 300 nm, not sufficient to resolve macromolecules or nanostructures of interest in the bio-, life- and nano-sciences. In the strive to push the resolution beyond the diffraction limit, allowing for nanoscale imaging, we have equipped a nonlinear optical microscope with a scanning-probe setup operated in tapping-mode feedback. A tapered, gold-coated, open-aperture tip with an aperture diameter of similar to 150 nm is scanned over the sample, probing the nonlinear nearfield generated by free-beam excitation. First nonlinear coherent Raman nearfield images of biological macromolecules and metallic nanostructures are shown. Limitations and future challenges with nonlinear nearfield microscopy are discussed.
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| 32. |
- Ericson, Marica B, 1974, et al.
(författare)
-
Exploring plasmonic coupling as a stimuli responsive contrast mechanism in multiphoton microscopy
- 2018
-
Ingår i: Proceedings Volume 10509, Plasmonics in Biology and Medicine XV. - : SPIE. - 1605-7422. - 9781510615045 - 9781510615038
-
Konferensbidrag (refereegranskat)abstract
- A novel approach for optical biosensing can be obtained based multiphoton induced luminescence (MIL) and its dependence on plasmonic coupling. It has been shown that the proximity of spherical AuNPs determines the generation of MIL in far-field multiphoton laser scanning microscopy (MPM). A stimuli responsive contrast mediator with high sensitivity can be created by controlling the aggregated state of AuNP. In this study we explore a system based on spherical AuNPs functionalized with beta-cyclodextrin and multiple beta-D-lactose units (lacto-CD-AuNP). The aim of the beta-D- lactose units is to target cancer cells, based on overexpression of galectin3 (Gal-3) receptors. The results demonstrate that clustering of particles, and thereby MIL signal, was only acquired from tumor cell lines, i.e., SK-MEL-28 and A431, while not from normal keratinocytes (HEKn). Thus further studies should be undertaken to translate the concept to a preclinical setting.
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| 33. |
- Fransson, V., et al.
(författare)
-
Deep learning volumetric brain segmentation based on spectral CT
- 2023
-
Ingår i: Medical Imaging 2023 : Physics of Medical Imaging - Physics of Medical Imaging. - 1605-7422. - 9781510660311 ; 12463
-
Konferensbidrag (refereegranskat)abstract
- The purpose of this pilot study was to evaluate if a deep learning network can be used for brain segmentation of grey and white matter using spectral computed tomography (CT) images. Spectral CT has the advantage of a lower noise level and an increased soft tissue contrast, compared to conventional CT, which should make it better suited for segmentation tasks. Being able to do volumetric assessments on CT, not only magnetic resonance imaging (MRI) would be of great clinical benefit. The training set consisted of two patients and the validation data set of one patient. Included patients had a brain CT from a spectral CT as well as a T1-weighted MRI. MRI was used for an MR-based segmentation using FreeSurfer. A convolutional neural network was trained to identify grey and white matter in virtual monoenergetic images (70 keV) from spectral CT, using the MR-based segmentation as reference, and tested to assess its' performance. The network was able to identify both grey and white matter in roughly the correct areas. In general, there was an overestimation of grey matter. These results motivate further studies, as we predict that the network will be more accurate when trained on a larger data set.
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| 34. |
- Fransson, Veronica, et al.
(författare)
-
Dose-length-product determination on cone beam computed tomography through experimental measurements and dose-area-product conversion
- 2021
-
Ingår i: Medical Imaging 2021 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 1605-7422. - 9781510640207 ; 11595
-
Konferensbidrag (refereegranskat)abstract
- The dosimetry of cone beam computed tomography (CBCT) is not fully elaborated yet, and some of these systems presents dose-area-product (DAP) values after an examination rather than, as in the case of traditional CT, the doselength- product (DLP). The purpose of this study was to provide a reproducible and straight-forward method for DLP measurements on CBCT, as well as to validate a tool for estimating DLP for a CBCT system in terms of accuracy. A prototype conversion tool for estimating DLP, using the DAP value, was provided by the vendor of a CBCT system which currently display only DAP. The DAP to DLP conversion tool was validated using five protocols for extremity imaging. DLP was measured using a 30 cm ionization chamber and 30 cm long cylindrical PMMA-phantom. DLP, the integrated absorbed dose within the ionization chamber, was measured through central and peripheral measurements in the phantom in order to calculate the weighted DLP, DLPW,CBCT. Comparisons between DLPW,CBCT and estimated DLP, showed that the conversion tool was accurate within 10%, with a mean average error of 6.1% for all measured protocols. The variation between repeated measurements was small, making the method highly reproducible. In conclusion, in this study a simple method for determining DLP on CBCT was presented, and it was validated that the conversion tool can present the delivered dose in terms of DLP with high accuracy. The measured DLP, as well as the DLP estimated by the conversion tool, is suitable for quality control and relative dose comparisons between protocols, but its’ relation to the DLP of CT systems should be investigated further in order to relate to patient dose.
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| 35. |
- Hellgren, Gustav, et al.
(författare)
-
Evaluation of digital breast tomosynthesis systems
- 2020
-
Ingår i: Medical Imaging 2020 : Physics of Medical Imaging - Physics of Medical Imaging. - : SPIE. - 1605-7422. - 9781510633919 ; 11312
-
Konferensbidrag (refereegranskat)abstract
- In this study, two digital breast tomosynthesis (DBT) systems were evaluated: Siemens Mammomat Inspiration TOMO (Siemens Healthineers, Erlangen, Germany) and GE Senographe Pristina (GE, Buc, France). Along with differences such as angular range and detectors type, the systems use different reconstruction algorithms. One was available for the GE system, based on iterative reconstruction (IR). Two algorithms were available for the Siemens system: TOMO_STANDARD, using filtered back projection (FBP) and EMPIRE, FBP with statistically based artifact reduction. Two commercially available DBT phantoms (CIRS model 020 & 021), with heterogeneous and homogenous background respectively, were used to calculate signal-difference-to-noise-ratio (SDNR) in key structures for varying phantom thickness (30, 45 & 70 mm) and average glandular dose (AGD). Key phantom structures include calcifications and lesion masses of different sizes. Results show a positive correlation between SDNR and AGD except for the EMPIRE algorithm where there was a negative SDNR/AGD trend for one of the microcalcification specks in the heterogeneous phantom. The highest overall SDNR was acquired using the EMPIRE algorithm. Both systems are well within the recommended dose limits but could increase their dose levels in order to achieve higher SDNR. This indicates that there may be room for dose optimization in DBT systems used in screening programs, confirming the importance of continuous evaluation and optimization.
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| 36. |
- Håkansson, Markus, et al.
(författare)
-
ViewDEX 2.0: A Java-based DICOM-compatible software for observer performance studies
- 2009
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 7263
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- ViewDEX (Viewer for Digital Evaluation of X-ray images) is a Java-based DICOM-compatible software tool for observer performance studies that can be used to display medical images with simultaneous registration of the observer's response. The current release, ViewDEX 2.0, is a development of ViewDEX 1.0, which was released in 2007. Both versions are designed to run in a Java environment and do not require any special installation. For example, the program can be located on a memory stick or stand alone hard drive and be run from there. ViewDEX is managed and configured by editing property files, which are plain text files where users, tasks (questions, definitions, etc.) and functionality (WW/WL, PAN, ZOOM, etc.) are defined. ViewDEX reads most common DICOM image formats and the images can be stored in any location connected to the computer. ViewDEX 2.0 is designed so that the user in a simple way can alter if the questions presented to the observers are related to localization or not, enabling e.g. free-response ROC, standard ROC and visual grading studies, as well as combinations of these, to be conducted in a fast and efficient way. The software can also be used for bench marking and for educational purposes. The results from each observer are saved in a log file, which can be exported for further analysis. The software is freely available for non-commercial purposes.
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| 37. |
- Håkansson, Markus, et al.
(författare)
-
ViewDEX - A Java-based software for presentation and evaluation of medical images in observer performance studies
- 2007
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6509
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Observer performance studies are time-consuming tasks, both for the participating observers and for the scientists collecting and analyzing the data. A possible way to optimize such studies is to perform the study in a completely digital environment. A software tool - ViewDEX (Viewer for Digital Evaluation of X-ray images) - has been developed in Java, enabling it to function on almost any computer. ViewDEX is a DICOM-compatible software tool that can be used to display medical images with simultaneous registration of the observer's response. ViewDEX is designed so that the user in a simple way can alter the types of questions and images presented to the observers, enabling ROC, MAFC and visual grading studies to be conducted in a fast and efficient way. The software can also be used for bench marking and for educational purposes. The results from each observer are saved in a log file, which can be exported for further analysis. The software is freely available for non-commercial purposes.
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| 38. |
- James, Jeemol, et al.
(författare)
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Optimizing Ti:Sapphire laser for quantitative biomedical imaging
- 2018
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. 1049824. - : SPIE. - 1605-7422 .- 1996-756X. - 9781510614826
-
Konferensbidrag (refereegranskat)abstract
- Ti:Sapphire lasers are powerful tools in the field of scientific research and industry for a wide range of applications such as spectroscopic studies and microscopic imaging where tunable near-infrared light is required. To push the limits of the applicability of Ti:Sapphire lasers, fundamental understanding of the construction and operation is required. This paper presents two projects, (i) dealing with the building and characterization of custom built tunable narrow linewidth Ti:Sapphire laser for fundamental spectroscopy studies; and the second project (ii) the implementation of a fs-pulsed commercial Ti:Sapphire laser in an experimental multiphoton microscopy platform. For the narrow linewidth laser, a gold-plated diffraction grating with a Littrow geometry was implemented for highresolution wavelength selection. We demonstrate that the laser is tunable between 700 to 950 nm, operating in a pulsed mode with a repetition rate of 1 kHz and maximum average output power around 350 mW. The output linewidth was reduced from 6 GHz to 1.5 GHz by inserting an additional 6 mm thick etalon. The bandwidth was measured by means of a scanning Fabry Perot interferometer. Future work will focus on using a fs-pulsed commercial Ti:Sapphire laser (Tsunami, Spectra physics), operating at 80 MHz and maximum average output power around 1 W, for implementation in an experimental multiphoton microscopy set up dedicated for biomedical applications. Special focus will be on controlling pulse duration and dispersion in the optical components and biological tissue using pulse compression. Furthermore, time correlated analysis of the biological samples will be performed with the help of time correlated single photon counting module (SPCM, Becker & Hickl) which will give a novel dimension in quantitative biomedical imaging.
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| 39. |
- Jansson, Samuel, et al.
(författare)
-
Correlation of mosquito wing-beat harmonics to aid in species classification and flight heading assessment
- 2019
-
Ingår i: Novel Biophotonics Techniques and Applications V. - : SPIE. - 1605-7422 .- 2410-9045. - 9781510628434 ; 20:60
-
Konferensbidrag (refereegranskat)abstract
- Surveying disease vectors is currently excessively laborious for continuous and widespread monitoring. Wing beat modulation spectroscopy gives opportunity for species and sex recognition in electronic traps or mosquito target classification in lidar. We used a polarimetric dual-wavelength-band laboratory system to record kHz modulated backscattered light from insects. The system operates in the near and short-wave infrared at 808 nm and 1550 nm and retrieves both co- and depolarized light. Here we give clues on the harmonic content and covariance of four mosquito species and fruit flies. Further, we interpret the interdependence of harmonic strengths when insects transit the probe volume with random heading direction and provide correlation matrices for coherent and incoherent light. Using the obtained parameters, we demonstrate that species that are difficult to distinguish with microscope can be classified with high accuracy. The results are valuable for understanding wingbeat harmonics in relation to heading and valuable for optimal sensor design for disease vector surveillance.
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| 40. |
- Kanziz, Mustafa, et al.
(författare)
-
Review of life science applications using submicron O-PTIR and simultaneous Raman microscopy: a new paradigm in vibrational spectroscopy
- 2021
-
Ingår i: Advanced Chemical Microscopy for Life Science and Translational Medicine 2021. - : SPIE. - 2410-9045 .- 1605-7422. - 9781510641471 ; 11656
-
Konferensbidrag (refereegranskat)abstract
- The recent advent of Optical Photothermal IR (O-PTIR), has enabled for the first time, submicron infrared microscopy in far-field reflection mode with the combination of Raman for simultaneous, correlative IR+Raman microscopy. These unique and exciting synergistic capabilities are now spawning interest in life science application. A broad range of life science applications, otherwise impossible with traditional FTIR/QCL microscopy, will be presented, ranging from live cell imaging in water, to ultra-high resolution images of breast tissue calcifications, amyloid aggregates in neurons (neurites and dendritic spines), individual collagen fibrils with polarized IR and individual isotopically labelled bacterial cells and more.
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| 41. |
- Karlsson, Jennie, et al.
(författare)
-
Classification of point-of-care ultrasound in breast imaging using deep learning
- 2023
-
Ingår i: Medical Imaging 2023 : Computer-Aided Diagnosis - Computer-Aided Diagnosis. - 1605-7422 .- 2410-9045. - 9781510660359 ; 12465
-
Konferensbidrag (refereegranskat)abstract
- Early detection of breast cancer is important to reduce morbidity and mortality. Access to breast imaging is limited in low- and middle-income countries compared to high-income countries. This contributes to advance-stage breast cancer presentation with poor survival. Pocket-sized portable ultrasound device, also known as point-of-care ultrasound (POCUS), aided by decision support using deep learning-based algorithms for lesion classification could be a cost-effective way to enable access to breast imaging in low-resource settings. A previous study, where using convolutional neural networks (CNN) to classify breast cancer in conventional ultrasound (US) images, showed promising results. The aim of the present study is to classify POCUS breast images. A POCUS data set containing 1100 breast images was collected. To increase the size of the data set, a Cycle-Consistent Adversarial Network (CycleGAN) was trained on US images to generate synthetic POCUS images. A CNN was implemented, trained, validated and tested on POCUS images. To improve performance, the CNN was trained with different combinations of data consisting of POCUS images, US images, CycleGAN-generated POCUS images and spatial augmentation. The best result was achieved by a CNN trained on a combination of POCUS images and CycleGAN-generated POCUS images and augmentation. This combination achieved a 95% confidence interval for AUC between 93.5% - 96.6%.
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| 42. |
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| 43. |
- Molin, Jesper, 1987, et al.
(författare)
-
Feature-enhancing zoom to facilitate Ki-67 hot spot detection
- 2014
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819498342 ; 9041
-
Konferensbidrag (refereegranskat)abstract
- Image processing algorithms in pathology commonly include automated decision points such as classifications. While this enables efficient automation, there is also a risk that errors are induced. A different paradigm is to use image processing for enhancements without introducing explicit classifications. Such enhancements can help pathologists to increase efficiency without sacrificing accuracy. In our work, this paradigm has been applied to Ki-67 hot spot detection. Ki-67 scoring is a routine analysis to quantify the proliferation rate of tumor cells. Cell counting in the hot spot, the region of highest concentration of positive tumor cells, is a method increasingly used in clinical routine. An obstacle for this method is that while hot spot selection is a task suitable for low magnification, high magnification is needed to discern positive nuclei, thus the pathologist must perform many zooming operations. We propose to address this issue by an image processing method that increases the visibility of the positive nuclei at low magnification levels. This tool displays the modified version at low magnification, while gradually blending into the original image at high magnification. The tool was evaluated in a feasibility study with four pathologists targeting routine clinical use. In a task to compare hot spot concentrations, the average accuracy was 75±4.1% using the tool and 69±4.6% without it (n=4). Feedback on the system, gathered from an observer study, indicate that the pathologists found the tool useful and fitting in their existing diagnostic process. The pathologists judged the tool to be feasible for implementation in clinical routine.
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| 44. |
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| 45. |
- Qaiser, Mahmood, 1981, et al.
(författare)
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A fully automatic unsupervised segmentation framework for the brain tissues in MR images
- 2014
-
Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819498311 ; 9038
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Konferensbidrag (refereegranskat)abstract
- This paper presents a novel fully automatic unsupervised framework for the segmentation of brain tissues in magnetic resonance (MR) images. The framework is a combination of our proposed Bayesian-based adaptive mean shift (BAMS), a priori spatial tissue probability maps and fuzzy c-means. BAMS is applied to cluster the tissues in the joint spatialintensity feature space and then a fuzzy c-means algorithm is employed with initialization by a priori spatial tissue probability maps to assign the clusters into three tissue types; white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF). The proposed framework is validated on multimodal synthetic as well as on real T1-weighted MR data with varying noise characteristics and spatial intensity inhomogeneity. The performance of the proposed framework is evaluated relative to our previous method BAMS and other existing adaptive mean shift framework. Both of these are based on the mode pruning and voxel weighted k-means algorithm for classifying the clusters into WM, GM and CSF tissue. The experimental results demonstrate the robustness of the proposed framework to noise and spatial intensity inhomogeneity, and that it exhibits a higher degree of segmentation accuracy in segmenting both synthetic and real MR data compared to competing methods.
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| 46. |
- Roh, Hyung S., et al.
(författare)
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Integrating Color Deconvolution Thresholding and Weakly Supervised Learning for Automated Segmentation of Neurofibrillary Tangle and Neuropil Threads
- 2023
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Ingår i: Medical Imaging 2023 : Digital and Computational Pathology - Digital and Computational Pathology. - 1605-7422. - 9781510660472 ; 12471
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Konferensbidrag (refereegranskat)abstract
- Abnormally phosphorylated tau proteins are known to be a major indicator of Alzheimer's Disease (AD) with strong association with memory loss and cognitive decline. Automated generation of pixel-wise accurate neurofibrillary tangles (NFTs) and neuropil threads (NTs) segmentation is a challenging task, due to lack of ground truth segmentation data of these abnormal tau pathology. This problem is most prominent in the case of segmenting NTs, where the small threadlike morphology makes pixel-wise labeling a laborious task and unrealistic for large-scale studies. Lack of ground truth data poses a significant limitation for many learning-based methods to generate accurate segmentations of NFTs and NTs. This work presents an automated pipeline for pixel level segmentation of NFTs and NTs that does not rely on ground truth segmentation data. The pipeline is composed of four main steps: (1) color deconvolution is used to separate histopathology images into staining channels (DAB, Hematoxylin, and Eosin), (2) Otsu's thresholding is used on the DAB stain channel to generate pixel level segmentation of abnormal tau proteins staining, (3) a weakly-supervised learning paradigm (WildCat), using only global descriptors of images, is used to generate density maps of potential regions of NFTs and NTs, and (4) density maps and segmentations are then integrated using connected component analysis to localize NFTs and NTs in the detected tau segmentations. Our results show high global classification accuracy for NFTs (Acc:0.96) and NTs (Acc:0.91), and statistically significant distinctions when evaluating the percent area occupied of the detected NTs relative to expert ratings of NTs severity. Qualitative assessment of the NFTs and NTs results showed accurate pixel-level segmentations of the NFTs, while modest performance for NTs.
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| 47. |
- Ruschin, Mark, et al.
(författare)
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Shape determination of microcalcifications in simulated digital mammography images with varying pixel size
- 2005
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5749, s. 288-299
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Konferensbidrag (refereegranskat)abstract
- The purpose of this work was to study how the pixel size of digital detectors can affect shape determination of microcalcifications in mammography. Screen-film mammograms containing microcalcifications clinically proven to be indicative of malignancy were digitised at 100 lines/mm using a high-resolution Tango drum scanner. Forty microcalcifications were selected to cover an appropriate range of sizes, shapes and contrasts typically found of malignant cases. Based on the measured MTF and NPS of the combined screen-film and scanner system, these digitised images were filtered to simulate images acquired with a square sampling pixel size of 10 μm × 10 μm and a fill factor of one. To simulate images acquired with larger pixel sizes, these finely sampled images were re-binned to yield a range of effective pixel sizes from 20 μm up to 140 μm. An alternative forced-choice (AFC) observer experiment was conducted with eleven observers for this set of digitised microcalcifications to determine how pixel size affects the ability to discriminate shape. It was found that observer score increased with decreasing pixel size down to 60 μm (p<0.01), at which point no significant advantage was obtained by using smaller pixel sizes due to the excessive relative noise-per-pixel. The relative gain in shape discrimination ability at smaller pixel sizes was larger for microcalcifications that were smaller than 500 μm and circular
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| 48. |
- Shirvany, Yazdan, 1980, et al.
(författare)
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Influence of Different Sources of Noise on Epileptic Spike EEG Source Localization
- 2013
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9780819494467 ; 8672
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Konferensbidrag (refereegranskat)abstract
- Spike EEG source localization results are influenced by different errors and approximations, e.g., head-model complexity, EEG signal noise, electrode misplacements, tissue anisotropy, tissue conductivity noise as well as numerical errors. For accurate source localization, understanding the affects of these errors on the source localization is very crucial. Six finite element head models are selected for a head-model complexity study. A reference head model is used to create the synthetic EEG signals by placing a dipole inside the model to mimic the epileptic spike activity. To understand the influence of EEG signal noise, tissue conductivity noise and electrode misplacements on the EEG source localization, different level of noises are added to EEG signals, tissue conductivities and electrode positions, independently. To investigate the influence of white matter anisotropy, a realistic head model generated from T1-weighted MRI is used and the conductivity anisotropy for the white matter is calculated from diffusion tensor imaging (DTI). Major findings of the study include (1) the CSF layer plays an important role to achieve an accurate source localization result, (2) the source localization is very sensitive to the tissue conductivity noises, (3) one centimeter electrode misplacement cause approximately 8 mm localization error, (4) the source localization is robust with respect to the EEG signal noise and (5) the model with white matter anisotropy has small source localization error but large amplitude and orientation errors compared to the isotropic head model.
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| 49. |
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| 50. |
- Sund, Patrik, et al.
(författare)
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A comparison between 8-bit and 10-bit luminance resolution when generating low-contrast sinusoidal test pattern on an LCD
- 2007
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. ; 6515
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Radiological images are today mostly displayed on monitors, but much is still unknown regarding the interaction between monitor and viewer. Issues like monitor luminance range, calibration, contrast resolution and luminance distribution need to be addressed further. To perform vision research of high validity to the radiologists, test images should be presented on medical displays. One of the problems has been how to display low contrast patterns in a strictly controlled way. This paper demonstrates how to generate test patterns close to the detection limit on a medical grade display using subpixel modulation. Patterns are generated with both 8-bit and 10-bit monitor input. With this technique, up to 7162 luminance levels can be displayed and the average separation is approximately 0.08 of a JND (Just Noticeable Difference) on a display with a luminance range between 1 and 400 cd/m2. These patterns were used in a 2AFC detection task and the detection threshold was found to be 0.75 ± 0.02 of a JND when the adaptation level was the same as the target luminance (20 cd/m2). This is a reasonable result considering that the magnitude of a JND is based on the method of adjustment rather than on a detection task. When test patterns with a different luminance than the adaptation level (20 cd/m2) were displayed, the detection thresholds were 1.11 and 1.06 of a JND for target luminance values 1.8 and 350 cd/m2, respectively.
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