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  • 1.
    Ahlander, Britt-Marie
    Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
    Magnetic Resonance Imaging of the Heart: Image quality, measurement accuracy and patient experience2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Background: Non-invasive diagnostic imaging of atherosclerotic coronary artery disease (CAD) is frequently carried out with cardiovascular magnetic resonance imaging (CMR) or myocardial perfusion single photon emission computed tomography (MPS). CMR is the gold standard for the evaluation of scar after myocardial infarction and MPS the clinical gold standard for ischemia. Magnetic Resonance Imaging (MRI) is at times difficult for patients and may induce anxiety while patient experience of MPS is largely unknown.

    Aims: To evaluate image quality in CMR with respect to the sequences employed, the influence of atrial fibrillation, myocardial perfusion and the impact of patient information. Further, to study patient experience in relation to MRI with the goal of improving the care of these patients.

    Method: Four study designs have been used. In paper I, experimental cross-over, paper (II) experimental controlled clinical trial, paper (III) psychometric crosssectional study and paper (IV) prospective intervention study. A total of 475 patients ≥ 18 years with primarily cardiac problems (I-IV) except for those referred for MRI of the spine (III) were included in the four studies.

    Result: In patients (n=20) with atrial fibrillation, a single shot steady state free precession (SS-SSFP) sequence showed significantly better image quality than the standard segmented inversion recovery fast gradient echo (IR-FGRE) sequence (I). In first-pass perfusion imaging the gradient echo-echo planar imaging sequence (GREEPI) (n=30) had lower signal-to-noise and contrast–to-noise ratios than the steady state free precession sequence (SSFP) (n=30) but displayed a higher correlation with the MPS results, evaluated both qualitatively and quantitatively (II). The MRIAnxiety Questionnaire (MRI-AQ) was validated on patients, referred for MRI of either the spine (n=193) or the heart (n=54). The final instrument had 15 items divided in two factors regarding Anxiety and Relaxation. The instrument was found to have satisfactory psychometric properties (III). Patients who prior CMR viewed an information video scored significantly (lower) better in the factor Relaxation, than those who received standard information. Patients who underwent MPS scored lower on both factors, Anxiety and Relaxation. The extra video information had no effect on CMR image quality (IV).

    Conclusion: Single shot imaging in atrial fibrillation produced images with less artefact than a segmented sequence. In first-pass perfusion imaging, the sequence GRE-EPI was superior to SSFP. A questionnaire depicting anxiety during MRI showed that video information prior to imaging helped patients relax but did not result in an improvement in image quality.

  • 2.
    Feng, X. M.
    et al.
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Olsson, J.
    Centre for Human Studies of Foodstuffs, Uppsala University, Uppsala, Sweden.
    Swanberg, M.
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Schnürer, Johan
    Department of Microbiology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Rönnow, D.
    Department of Electronics, University of Gävle, Gävle, Sweden.
    Image analysis for monitoring the barley tempeh fermentation process2007Ingår i: Journal of Applied Microbiology, ISSN 1364-5072, E-ISSN 1365-2672, Vol. 103, nr 4, s. 1113-1121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims: To develop a fast, accurate, objective and nondestructive method for monitoring barley tempeh fermentation.

    Methods and Results: Barley tempeh is a food made from pearled barley grains fermented with Rhizopus oligosporus. Rhizopus oligosporus growth is important for tempeh quality, but quantifying its growth is difficult and laborious. A system was developed for analysing digital images of fermentation stages using two image processing methods. The first employed statistical measures sensitive to image colour and surface structure, and these statistical measures were highly correlated (r = 0.92, n = 75, P < 0.001) with ergosterol content of tempeh fermented with R. oligosporus and lactic acid bacteria (LAB). In the second method, an image-processing algorithm optimized to changes in images of final tempeh products was developed to measure number of visible barley grains. A threshold of 5 visible grains per Petri dish indicated complete tempeh fermentation. When images of tempeh cakes fermented with different inoculation levels of R. oligosporus were analysed the results from the two image processing methods were in good agreement.

    Conclusion: Image processing proved suitable for monitoring barley tempeh fermentation. The method avoids sampling, is nonintrusive, and only requires a digital camera with good resolution and image analysis software.

    Significance and Impact of the Study: The system provides a rapid visualization of tempeh product maturation and qualities during fermentation. Automated online monitoring of tempeh fermentation by coupling automated image acquisition with image processing software could be further developed for process control.

  • 3.
    Khodadad, Davood
    et al.
    Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
    Ahmadian, Alireza
    Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
    Ay, Mohammadreza
    Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
    Esfahani, Armaghan Fard
    Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
    Banaem, Hossein Yousefi
    Tehran University of Medical Science, Tehran, Islamic Republic of Iran.
    Zaidi, Habib
    Geneva University Hospital, Geneva, Switzerland.
    B-spline based free form deformation thoracic non-rigid registration of CT and PET images2011Ingår i: International Conference on Graphic and Image Processing (ICGIP 2011) / [ed] Yi Xie & Yanjun Zheng, SPIE - International Society for Optical Engineering, 2011, Vol. 8285, artikel-id 82851KKonferensbidrag (Refereegranskat)
    Abstract [en]

    Accurate attenuation correction of emission data is mandatory for quantitative analysis of PET images. One of the main concerns in CT-based attenuation correction(CTAC) of PET data in multimodality PET/CT imaging is misalignment between PET and CT images. The aim of this study, is to proposed a hybrid method which is simple, fast and accurate, for registration of PET and CT data which affected from respiratory motion in order to improve the quality of CTAC. The algorithm is composed of three methods: First, using B-spline Free Form Deformation to describe both images and deformation field. Then applying a pre-filtering on both PET and CT images before segmentation of structures in order to reduce the respiratory related attenuation correction artifacts of PET emission data. In this approach, B-spline using FFD provide more accurate adaptive transformation to align the images, and structure constraints obtained from prefiltering applied to guide the algorithm to be more fast and accurate. Also it helps to reduce the radiation dose in PET/CT by avoiding repetition of CT imaging. These advances increase the potential of the method for routine clinical application.

  • 4.
    Khodadad, Davood
    et al.
    Experimental Mechanics, Luleå University of Technology, Luleå, Sweden.
    Ahmadian, Alireza
    Institute for Advanced Medical Technologies (IAMT), Tehran University of Medical Science, Tehran, Iran.
    Banaem, Hossein Yousefi
    Department of Medical Physics and Medical Engineering, Isfahan University of Medical Sciences, Isfahan, Iran.
    Ay, Mohammad Reza
    Research Institute for Nuclear Medicine, Tehran University of Medical Science, Tehran, Iran .
    Fard-Esfahani, Armaghan
    Research Institute for Nuclear Medicine, Tehran University of Medical Science, Tehran, Iran .
    CT and PET Image Registration: Application to Thorax Area2013Ingår i: Journal of Image and Graphics, ISSN 2301-3699, Vol. 1, nr 4, s. 171-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accurate attenuation correction of emission data is mandatory for quantitative analysis of PET images. One of the main concerns in CT-based attenuation correction (CTAC) of PET data in multimodality PET/CT imaging is misalignment occurred due to respiratory artifact between PET and CT images. In this paper a combined method which is simple and fast is proposed for registration of PET and CT data to correct the effect of this artifact. The algorithm is composed of two step: First step is meant to reduce the noise by applying an adaptive gradient anistropic diffusion filter then using Iterative closest point (ICP) registration method in order to obtain initial estimation to ensure fast and accurate convergence of the algorithm. At the second step, the respiratory related artifact of PET images is greatly reduced by employing Free Form Deformation algorithm based on B-spline which provides more accurate adaptive transformation to align the images.

  • 5.
    Khodadad, Davood
    et al.
    Department of Physics and Electrical Engineering, Linnaeus University, Växjö, Sweden.
    Nordebo, Sven
    Department of Physics and Electrical Engineering, Linnaeus University, Växjö, Sweden.
    Seifnaraghi, Nima
    Faculty of science and technology, Middlesex University, Hendon campus, The Burroughs, London, United Kingdom.
    Waldmann, Andreas D.
    Swisstom AG, Landquart, Switzerland.
    Müller, Beat
    Swisstom AG, Landquart, Switzerland.
    Bayford, Richard
    Faculty of science and technology, Middlesex University, Hendon campus, The Burroughs, London, United Kingdom.
    Breath detection using short-time Fourier transform analysis in electrical impedance tomography2017Ingår i: 2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), IEEE, 2017, s. 1-3Konferensbidrag (Refereegranskat)
    Abstract [en]

    Spectral analysis based on short-time Fourier transform (STFT) using Kaiser window is proposed to examine the frequency components of neonates EIT data. In this way, a simultaneous spatial-time-frequency analysis is achieved.

  • 6.
    Lidén, Mats
    Region Örebro län. Örebro universitet, Institutionen för medicinska vetenskaper. Department of Radiology, Örebro University Hospital, Örebro, Sweden.
    A new method for predicting uric acid composition in urinary stones using routine single-energy CT2018Ingår i: Urolithiasis, ISSN 2194-7228, Vol. 46, nr 4, s. 325-332Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Urinary stones composed of uric acid can be treated medically. Prediction of uric acid stone type is, therefore, desirable when a urinary stone is diagnosed with unenhanced CT. The purpose of the present study was to describe single-energy thin slice quantitative CT parameters of urinary stones correlated to chemical stone type and to develop a method to distinguish pure uric acid stones (UA) from other stones (non-UA/Mix). Unenhanced thin slice single-energy CT images of 126 urinary stones (117 patients) with known chemical stone type were retrospectively included in the study. Among the included stones, 22 were UA and 104 were non-UA/Mix. The included CT images and Laplacian filtered images of the stones were quantitatively analyzed using operator-independent methods. A post hoc classification method for pure UA stones was created using a combination of cutoff values for the peak attenuation and peak point Laplacian. The stone types differed in most quantitative image characteristics including mean attenuation (p < 0.001), peak attenuation (p < 0.001), and peak point Laplacian (p < 0.001). The sensitivity for the post hoc-developed peak attenuation-peak point Laplacian method for classifying pure UA stones was 95% [21/22, 95% CI (77-100%)] and the specificity was 99% [103/104, 95% CI (95-100%)]. In conclusion, quantitative image analysis of thin slice routine single-energy CT images is promising for predicting pure UA content in urinary stones, with results comparable to double energy methods.

  • 7.
    Yousefi-Banaem, Hossein
    et al.
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science, Isfahan Iran.
    Kermani, Saeed
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science, Isfahan Iran.
    Sarrafzadeh, Omid
    Department of Biomedical Engineering, Faculty of Advance Medical Technology, Isfahan University of Medical Science, Isfahan Iran.
    Khodadad, Davood
    Experimental Mechanics, Luleå University of Technology, Luleå, Sweden.
    An improved spatial FCM algorithm for cardiac image segmentation2013Ingår i: 2013 13th Iranian Conference on Fuzzy Systems (IFSC), IEEE, 2013, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    Image segmentation is one of challenging field in medical image processing. Segmentation of cardiac wall is one of challenging work and it is very important step in evaluation of heart functionality by existing methods. For cardiac image analysis, Fuzzy C- Means (FCM) algorithm proved to be superior over the other clustering approaches in segmentation field. However, the nave FCM algorithm is sensitive to noise because of not considering the spatial information in the image. In this paper an improved FCM algorithm is formulated by incorporating the spatial domain neighborhood information into the membership function for clustering (ISFCM). In this paper we applied improved Fuzzy c-Means with spatial information for left ventricular wall segmentation. Obtained results showed that the proposed method can segment cardiac wall automatically with acceptable accuracy. The comparison of proposed method with nave FCM proved that ISFCM can segment with more accuracy than nave FCM.

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