| 1. |
- Bergström, Göran, 1964, et al.
(författare)
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Body weight at age 20 and in midlife is more important than weight gain for coronary atherosclerosis: Results from SCAPIS.
- 2023
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 373, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Elevated body weight in adolescence is associated with early cardiovascular disease, but whether this association is traceable to weight in early adulthood, weight in midlife or to weight gain is not known. The aim of this study is to assess the risk of midlife coronary atherosclerosis being associated with body weight at age 20, body weight in midlife and body weight change.We used data from 25,181 participants with no previous myocardial infarction or cardiac procedure in the Swedish CArdioPulmonary bioImage Study (SCAPIS, mean age 57 years, 51% women). Data on coronary atherosclerosis, self-reported body weight at age 20 and measured midlife weight were recorded together with potential confounders and mediators. Coronary atherosclerosis was assessed using coronary computed tomography angiography (CCTA) and expressed as segment involvement score (SIS).The probability of having coronary atherosclerosis was markedly higher with increasing weight at age 20 and with mid-life weight (p<0.001 for both sexes). However, weight increase from age 20 until mid-life was only modestly associated with coronary atherosclerosis. The association between weight gain and coronary atherosclerosis was mainly seen in men. However, no significant sex difference could be detected when adjusting for the 10-year delay in disease development in women.Similar in men and women, weight at age 20 and weight in midlife are strongly related to coronary atherosclerosis while weight increase from age 20 until midlife is only modestly related to coronary atherosclerosis.
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| 2. |
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| 3. |
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| 4. |
- Engellau, Lena, et al.
(författare)
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Measurements before endovascular repair of abdominal aortic aneurysms : MR imaging with MRA vs. angiography and CT
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 44:2, s. 177-184
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: 1) To compare measurements obtained with MR imaging (MRI)/contrast-enhanced MR angiography (CE MRA) with measurements obtained with angiography (DSA) and CT, for stent-graft sizing of abdominal aortic aneurysms (AAA). 2) To compare MRA measurements obtained with the two post processing techniques MIP (maximum intensity projection) and VRT (3D volume rendering technique).Material and Methods: The prospective study included 20 consecutive patients with AAA identified by DSA and CT as suitable for endovascular repair. For the study, MRI/CE MRA was performed. Five measurement variables for stent-graft sizing were chosen. Comparisons were made between MRI/CE MRA, DSA and CT, and between observers. Comparisons were also made between MIP and VRT.Results: Significantly shorter lengths were obtained with MRA-MIP than with DSA. Three out of six diameter measurements were significantly smaller on MRI/CE MRA than on DSA and CT. No significant differences were found between the observers. One diameter measurement was significantly smaller on MIP than on VRT, while the other measurements showed no significant differences.Conclusion: The length measurements obtained with MRA-MIP were probably more correct than those with DSA. For more reliable diameter measurements with CE MRA, improvements of the technique, including VRT reconstructions and a standardized determination of the vessel boundaries, are needed.
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| 5. |
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| 6. |
- Gimm, Oliver, et al.
(författare)
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Dual-Energy Computed Tomography Localizes Ectopic Parathyroid Adenoma
- 2010
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Ingår i: The Journal of Clinical Endocrinology & Metabolism. - Chevy Chase, MD, United States : The Endocrine Society. - 0021-972X .- 1945-7197. ; 95:7, s. 3092-3093
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Tidskriftsartikel (refereegranskat)abstract
- Dual-energy computed tomography (DECT) can acquire two datasets showing different attenuation levels allowing collectionof additional information about the elementary chemical compositionof the scanned material. Color can then be assigned accordingto the 80- and 140-kV computed tomography (CT) values to obtaina color-mapped, dual-energy image. DECT has been used extensivelyin our department in postmortem CT with excellent results (1).One of the advantages of DECT is that iodine contrast uptakein soft tissue can be quantified. We were wondering about itsability to localize parathyroid adenomas (PAs).
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| 7. |
- Gupta, Vikas, et al.
(författare)
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Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration
- 2018
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Ingår i: Journal of Cardiovascular Computed Tomography. - : Elsevier. - 1934-5925. ; 12:2, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Background Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images.Methods Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature.Results Comparison with manual tracking showed high accuracy (DSC: 0.99± 0.05; PTC: 0.56mm± 0.47 mm) and resulted in determinant(Jacobian) > 0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature.Conclusions Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.
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| 8. |
- Henriksson, Lilian, et al.
(författare)
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The transluminal attenuation gradient does not add diagnostic accuracy to coronary computed tomography
- 2021
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; , s. 867-874
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Tidskriftsartikel (refereegranskat)abstract
- Background A method for improving the accuracy of coronary computed tomography angiography (CCTA) is highly sought after as it would help to avoid unnecessary invasive coronary angiographies. Measurement of the transluminal attenuation gradient (TAG) has been proposed as an alternative to other existing methods, i.e. CT perfusion and CT fractional flow reserve (FFR). Purpose To evaluate the incremental value of three types of TAG in high-pitch spiral CCTA with invasive FFR measurements as reference. Material and Methods TAG was measured using two semi-automatic methods and one manual method. A receiver operating characteristic (ROC) analysis was made to determine the usefulness of TAG alone as well as TAG combined with CCTA for detection of significant coronary artery stenoses defined by an invasive FFR value <= 0.80. Results A total of 51 coronary vessels in 37 patients were included in this retrospective study. Hemodynamically significant stenoses were found in 13 vessels according to FFR. The ROC analysis TAG alone resulted in areas under the curve (AUCs) of 0.530 and 0.520 for the semi-automatic TAG and 0.557 for the manual TAG. TAG and CCTA combined resulted in AUCs of 0.567, 0.562 for semi-automatic TAG, and 0.569 for the manual TAG. Conclusion The results from our study showed no incremental value of TAG measured in single heartbeat CCTA in determining the severity of coronary artery stenosis degrees.
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| 9. |
- Höök, Fredrik, et al.
(författare)
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Nanopartiklar kan förbättra avbildningsteknik och diagnostik
- 2017
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 114
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Forskningsöversikt (refereegranskat)abstract
- Nanotechnology can improve diagnostics The unique properties of nanoparticles make them tailorable into diagnostic agents on a molecular level, which allow more sensitive and precise in vitro diagnostics and in vivo imaging. While in vitro applications already have impact on diagnostics, in vivo use remains challenging due to difficulties in preparing nanoparticles with acceptable properties regarding toxicity, specific target accumulation and degradation. This article describes the innovative work of developing such platforms, and concludes that while nanotechnology-based diagnostics and imaging are still scarce at the clinical level, the rapid development of many new concepts, devices and processes that are now in the laboratory pipeline promises significant impact in the near future.
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| 10. |
- Jackowski, Christian, 1975-, et al.
(författare)
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Magnetic resonance imaging goes postmortem: noninvasive detection and assessment of myocardial infarction by postmortem MRI
- 2011
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Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; Jan;21:1, s. 70-78
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the performance of postmortem magnetic resonance imaging (pmMRI) in identification and characterization of lethal myocardial infarction in a non-invasive manner on human corpses.MATERIALS AND METHODS: Before forensic autopsy, 20 human forensic corpses were examined on a 1.5-T system for the presence of myocardial infarction. Short axis, transversal and longitudinal long axis images (T1-weighted; T2-weighted; PD-weighted) were acquired in situ. In subsequent autopsy, the section technique was adapted to short axis images. Histological investigations were conducted to confirm autopsy and/or radiological diagnoses.RESULTS: Nineteen myocardial lesions were detected and age staged with pmMRI, of which 13 were histologically confirmed (chronic, subacute and acute). Six lesions interpreted as peracute by pmMRI showed no macroscopic or histological finding. Five of the six peracute lesions correlated well to coronary pathology, and one case displayed a severe hypertrophic alteration.CONCLUSION: pmMRI reliably demonstrates chronic, subacute and acute myocardial infarction in situ. In peracute cases pmMRI may display ischemic lesions undetectable at autopsy and routine histology. pmMRI has the potential to substantiate autopsy and to counteract the loss of reliable information on causes of death due to the recent disappearance of the clinical autopsy.
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| 11. |
- Jackowski, Christian, 1975-, et al.
(författare)
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Quantitative MRI in Isotropic Spatial Resolution for Forensic Soft Tissue Documentation. Why and How?
- 2011
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Ingår i: Journal of Forensic Sciences. - : Blackwell. - 0022-1198 .- 1556-4029. ; 56:1, s. 208-215
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Tidskriftsartikel (refereegranskat)abstract
- A quantification of T1, T2, and PD in high isotropic resolution was performed on corpses. Isotropic and quantified postmortem magnetic resonance (IQpmMR) enables sophisticated 3D postprocessing, such as reformatting and volume rendering. The body tissues can be characterized by the combination of these three values. The values of T1, T2, and PD were given as coordinates in a T1-T2-PD space where similar tissue voxels formed clusters. Implementing in a volume rendering software enabled color encoding of specific tissues and pathologies in 3D models of the corpse similar to computed tomography, but with distinctively more powerful soft tissue discrimination. From IQpmMR data, any image plane at any contrast weighting may be calculated or 3D color-encoded volume rendering may be carried out. The introduced approach will enable future computer-aided diagnosis that, e.g., checks corpses for a hemorrhage distribution based on the knowledge of its T1-T2-PD vector behavior in a high spatial resolution.
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| 12. |
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| 13. |
- Kalra, Mannudeep, et al.
(författare)
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Iterative Reconstruction Techniques: The Be-All and End-All for CT Dose Reduction? Pictorial Synopsis of Different Vendor Techniques
- 2010
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Ingår i: In Proceedings of RSNA 2010, LL-PHE 4076.
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Konferensbidrag (refereegranskat)abstract
- Recently introduced IRT for clinical use allow dose reduction for adult and pediatric CT while maintaining or even enhancing image quality compared to filtered back projection based reconstruction. Specific adjustments of scanning protocols and fine-tuning of iterative settings are necessary to ensure optimum usage with understanding of its potential and disadvantages. This educational exhibit focuses on clinical illustrations to simplify application of IRT for reducing CT radiation dose
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| 14. |
- Kalra, Mannudeep K., et al.
(författare)
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Radiation Dose Reduction with Sinogram Affirmed Iterative Reconstruction Technique for abdominal Computer Tomography
- 2012
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Ingår i: Journal of Computer Assisted Tomography. - USA : Lippincott Williams & Wilkins. - 0363-8715. ; 36:3, s. 339-346
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The objective of this study was to assess the effect of Sinogram Affirmed Iterative Reconstruction (SAFIRE) and filtered back-projection (FBP) techniques on abdominal computed tomography (CT) performed with 50% and 75% radiation dose reductions.Methods: Twenty-four patients (mean age, 64 ± 14 years; male-female ratio, 10:14) gave informed consent for an institutional review board–approved prospective study involving acquisition of additional research images through the abdomen on 128-slice multi–detector-row CT (SOMATOM Definition Flash) at quality reference mAs of 100 (50% lower dose) and 50 (75% lower dose) over a scan length of 10 cm using combined modulation (CARE Dose 4D). Standard-of-care abdominal CT was performed at 200 quality reference mAs, with remaining parameters held constant. The 50- and 100-mAs data sets were reconstructed with FBP and at 4 SAFIRE settings (S1, S2, S3, S4). Higher number of SAFIRE settings denotes increased strength of the algorithm resulting in lower image noise. Two abdominal radiologists independently compared the FBP and SAFIRE images for lesion number, location, size and conspicuity, and visibility of small structures, image noise, and diagnostic confidence. Objective noise and Hounsfield units (HU) were measured in the liver and the descending aorta.Results: All 43 lesions were detected on both FBP and SAFIRE images. Minor blocky, pixelated appearance of 50% and 75% reduced dose images was noted at S3 and S4 SAFIRE but not at S1 and S2 settings. Subjective noise was suboptimal in both 50% and 75% lower-dose FBP images but was deemed acceptable on all SAFIRE settings. Sinogram Affirmed Iterative Reconstruction images were deemed acceptable in all patients at 50% lower dose and in 22 of 24 patients at 75% lower dose. As compared with 75% reduced dose FBP, objective noise was lower by 22.8% (22.9/29.7), 35% (19.3/29.7), 44.3% (16.7/29.3), and 54.8% (13.4/29.7) on S1 to S4 settings, respectively (P < 0.001).Conclusions: Sinogram Affirmed Iterative Reconstruction–enabled reconstruction provides abdominal CT images without loss in diagnostic value at 50% reduced dose and in some patients also at 75% reduced dose.
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| 15. |
- Kalra, Mannudeep K., et al.
(författare)
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Sinogram-Affirmed Iterative Reconstruction of Low-Dose Chest CT: Effect on Image Quality and Radiation Dose
- 2013
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Ingår i: American Journal of Roentgenology. - : American Roentgen Ray Society (ARRS). - 0361-803X .- 1546-3141. ; 201:2, s. W235-W244
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE. The purpose of this study is to compare sinogram-affirmed iterative reconstruction (SAFIRE) and filtered back projection (FBP) reconstruction of chest CT acquired with 65% radiation dose reduction.SUBJECTS AND METHODS. In this prospective study involving 24 patients (11 women and 13 men; mean [+/- SD] age, 66 +/- 10 years), two scan series were acquired using 100 and 40 Quality Reference mAs over a 10-cm scan length in the chest with a 128-MDCT scanner. The 40 Quality Reference mAs CT projection data were reconstructed with FBP and four settings of Safire (S1, S2, S3, and S4). Six image datasets (FBP with 100 and 40 Quality Reference mAs, and S1, S2, S3, S4 with 40 Quality Reference mAs) were displayed on a DICOM-compliant 55-inch 2-megapixel monitor for blinded evaluation by two thoracic radiologists for number and location of lesions, lesion size, lesion margins, visibility of small structures and fissures, and diagnostic confidence. Objective noise and CT values were measured in thoracic aorta for each image series, and the noise power spectrum was assessed. Data were analyzed with analysis of variance and Wilcoxon signed rank tests.RESULTS. All 186 lesions were seen on 40 Quality Reference mAs SAFIRE images. Diagnostic confidence on SAFIRE images was higher than that for FBP images. Except for the minor blotchy appearance on SAFIRE settings S3 and S4, no significant artifacts were noted. Objective noise with 40 Quality Reference mAs S1 images (21.1 +/- 6.1 SD of HU) was significantly lower than that for 40 Quality Reference mAs FBP images (28.5 +/- 8.1 SD of HU) (p andlt; 0.001). Noise power spectra were identical for SAFIRE and FBP with progressive noise reduction with higher iteration SAFIRE settings.CONCLUSION. Iterative reconstruction (SAFIRE) allows reducing the radiation exposure by approximately 65% without losing diagnostic information in chest CT.
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| 16. |
- Kataria, Bharti, 1955-, et al.
(författare)
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Assessment of image quality in abdominal computed tomography : Effect of model-based iterative reconstruction, multi-planar reconstruction and slice thickness on potential dose reduction
- 2020
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Ingår i: European Journal of Radiology. - : Elsevier Ireland Ltd. - 0720-048X .- 1872-7727. ; 122
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To determine the effect of tube load, model-based iterative reconstruction (MBIR) strength and slice thickness in abdominal CT using visual comparison of multi-planar reconstruction images. Method: Five image criteria were assessed independently by four radiologists on two data sets at 42- and 98-mAs tube loads for 25 patients examined on a 192-slice dual-source CT scanner. Effect of tube load, MBIR strength, slice thickness and potential dose reduction was estimated with Visual Grading Regression (VGR). Objective image quality was determined by measuring noise (SD), contrast-to-noise (CNR) ratio and noise-power spectra (NPS). Results: Comparing 42- and 98-mAs tube loads, improved image quality was observed as a strong effect of log tube load regardless of MBIR strength (p < 0.001). Comparing strength 5 to 3, better image quality was obtained for two criteria (p < 0.01), but inferior for liver parenchyma and overall image quality. Image quality was significantly better for slice thicknesses of 2mm and 3mm compared to 1mm, with potential dose reductions between 24%-41%. As expected, with decrease in slice thickness and algorithm strength, the noise power and SD (HU-values) increased, while the CNR decreased. Conclusion: Increasing slice thickness from 1 mm to 2 mm or 3 mm allows for a possible dose reduction. MBIR strength 5 shows improved image quality for three out of five criteria for 1 mm slice thickness. Increasing MBIR strength from 3 to 5 has diverse effects on image quality. Our findings do not support a general recommendation to replace strength 3 by strength 5 in clinical abdominal CT protocols. However, strength 5 may be used in task-based protocols.
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| 17. |
- Kataria, Bharti, 1955-, et al.
(författare)
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Assessment of image quality in abdominal CT : potential dose reduction with model-based iterative reconstruction
- 2018
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Ingår i: European Radiology. - Heidelberg : SPRINGER. - 0938-7994 .- 1432-1084. ; 28:6, s. 2464-2473
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Tidskriftsartikel (refereegranskat)abstract
- To estimate potential dose reduction in abdominal CT by visually comparing images reconstructed with filtered back projection (FBP) and strengths of 3 and 5 of a specific MBIR. A dual-source scanner was used to obtain three data sets each for 50 recruited patients with 30, 70 and 100% tube loads (mean CTDIvol 1.9, 3.4 and 6.2 mGy). Six image criteria were assessed independently by five radiologists. Potential dose reduction was estimated with Visual Grading Regression (VGR). Comparing 30 and 70% tube load, improved image quality was observed as a significant strong effect of log tube load and reconstruction method with potential dose reduction relative to FBP of 22-47% for MBIR strength 3 (p < 0.001). For MBIR strength 5 no dose reduction was possible for image criteria 1 (liver parenchyma), but dose reduction between 34 and 74% was achieved for other criteria. Interobserver reliability showed agreement of 71-76% (kappa (w) 0.201-0.286) and intra-observer reliability of 82-96% (kappa (w) 0.525-0.783). MBIR showed improved image quality compared to FBP with positive correlation between MBIR strength and increasing potential dose reduction for all but one image criterion. aEuro cent MBIR's main advantage is its de-noising properties, which facilitates dose reduction. aEuro cent MBIR allows for potential dose reduction in relation to FBP. aEuro cent Visual Grading Regression (VGR) produces direct numerical estimates of potential dose reduction. aEuro cent MBIR strengths 3 and 5 dose reductions were 22-34 and 34-74%. aEuro cent MBIR strength 5 demonstrates inferior performance for liver parenchyma.
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| 18. |
- Kataria, Bharti, 1955-, et al.
(författare)
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Image Quality and Potential Dose Reduction Using Advanced Modeled Iterative Reconstruction (Admire) in Abdominal Ct : A Review
- 2021
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 195:3-4, s. 177-187
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Forskningsöversikt (refereegranskat)abstract
- Traditional filtered back projection (FBP) reconstruction methods have served the computed tomography (CT) community wellfor over 40 years. With the increased use of CT during the last decades, efforts to minimise patient exposure, while maintainingsufficient or improved image quality, have led to the development of model-based iterative reconstruction (MBIR) algorithms fromseveral vendors. The usefulness of the advanced modeled iterative reconstruction (ADMIRE) (Siemens Healthineers) MBIR inabdominal CT is reviewed and its noise suppression and/or dose reduction possibilities explored. Quantitative and qualitativemethods with phantom and human subjects were used. Assessment of the quality of phantom images will not always correlatepositively with those of patient images, particularly at the higher strength of the ADMIRE algorithm. With few exceptions,ADMIRE Strength 3 typically allows for substantial noise reduction compared to FBP and hence to significant (≈30%) patientdose reductions. The size of the dose reductions depends on the diagnostic task.
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| 19. |
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| 20. |
- Lantz, Jonas, 1982-, et al.
(författare)
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Impact of Pulmonary Venous Inflow on Cardiac Flow Simulations : Comparison with In Vivo 4D Flow MRI
- 2019
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Ingår i: Annals of Biomedical Engineering. - : Springer-Verlag New York. - 0090-6964 .- 1573-9686. ; 47:2, s. 413-424
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Tidskriftsartikel (refereegranskat)abstract
- Blood flow simulations are making their way into the clinic, and much attention is given to estimation of fractional flow reserve in coronary arteries. Intracardiac blood flow simulations also show promising results, and here the flow field is expected to depend on the pulmonary venous (PV) flow rates. In the absence of in vivo measurements, the distribution of the flow from the individual PVs is often unknown and typically assumed. Here, we performed intracardiac blood flow simulations based on time-resolved computed tomography on three patients, and investigated the effect of the distribution of PV flow rate on the flow field in the left atrium and ventricle. A design-of-experiment approach was used, where PV flow rates were varied in a systematic manner. In total 20 different simulations were performed per patient, and compared to in vivo 4D flow MRI measurements. Results were quantified by kinetic energy, mitral valve velocity profiles and root-mean-square errors of velocity. While large differences in atrial flow were found for varying PV inflow distributions, the effect on ventricular flow was negligible, due to a regularizing effect by mitral valve. Equal flow rate through all PVs most closely resembled in vivo measurements and is recommended in the absence of a priori knowledge.
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| 21. |
- Lantz, Jonas, 1982-, et al.
(författare)
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Intracardiac Flow at 4D CT : Comparison with 4D Flow MRI
- 2018
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Ingår i: Radiology. - Oak Brook, IL United States : Radiological Society of North America, Inc.. - 0033-8419 .- 1527-1315. ; 289:1, s. 51-58
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo investigate four-dimensional (4D) flow CT for the assessment of intracardiac blood flow patterns as compared with 4D flow MRI.Materials and MethodsThis prospective study acquired coronary CT angiography and 4D flow MRI data between February and December 2016 in a cohort of 12 participants (age range, 36–74 years; mean age, 57 years; seven men [age range, 36–74 years; mean age, 57 years] and five women [age range, 52–73 years; mean age, 64 years]). Flow simulations based solely on CT-derived cardiac anatomy were assessed together with 4D flow MRI measurements. Flow patterns, flow rates, stroke volume, kinetic energy, and flow components were quantified for both techniques and were compared by using linear regression.ResultsCardiac flow patterns obtained by using 4D flow CT were qualitatively similar to 4D flow MRI measurements, as graded by three independent observers. The Cohen κ score was used to assess intraobserver variability (0.83, 0.79, and 0.70) and a paired Wilcoxon rank-sum test showed no significant change (P > .05) between gradings. Peak flow rate and stroke volumes between 4D flow MRI measurements and 4D flow CT measurements had high correlation (r = 0.98 and r = 0.81, respectively; P < .05 for both). Integrated kinetic energy quantified at peak systole correlated well (r = 0.95, P < .05), while kinetic energy levels at early and late filling showed no correlation. Flow component analysis showed high correlation for the direct and residual components, respectively (r = 0.93, P < .05 and r = 0.87, P < .05), while the retained and delayed components showed no correlation.ConclusionFour-dimensional flow CT produced qualitatively and quantitatively similar intracardiac blood flow patterns compared with the current reference standard, four-dimensional flow MRI.
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| 22. |
- Lindholm, Stefan, et al.
(författare)
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Spatial Conditioning of Transfer Functions Using Local Material Distributions
- 2010
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Ingår i: IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS. - : IEEE. - 1077-2626. ; 16:6, s. 1301-1310
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Tidskriftsartikel (refereegranskat)abstract
- In many applications of Direct Volume Rendering (DVR) the importance of a certain material or feature is highly dependent on its relative spatial location. For instance, in the medical diagnostic procedure, the patients symptoms often lead to specification of features, tissues and organs of particular interest. One such example is pockets of gas which, if found inside the body at abnormal locations, are a crucial part of a diagnostic visualization. This paper presents an approach that enhances DVR transfer function design with spatial localization based on user specified material dependencies. Semantic expressions are used to define conditions based on relations between different materials, such as only render iodine uptake when close to liver. The underlying methods rely on estimations of material distributions which are acquired by weighing local neighborhoods of the data against approximations of material likelihood functions. This information is encoded and used to influence rendering according to the users specifications. The result is improved focus on important features by allowing the user to suppress spatially less-important data. In line with requirements from actual clinical DVR practice, the methods do not require explicit material segmentation that would be impossible or prohibitively time-consuming to achieve in most real cases. The scheme scales well to higher dimensions which accounts for multi-dimensional transfer functions and multivariate data. Dual-Energy Computed Tomography, an important new modality in radiology, is used to demonstrate this scalability. In several examples we show significantly improved focus on clinically important aspects in the rendered images.
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| 23. |
- Lundin (Palmerius), Karljohan, 1977-, et al.
(författare)
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Enabling design and interactive selection of haptic modes
- 2007
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Ingår i: Virtual Reality. - : Springer Science and Business Media LLC. - 1359-4338 .- 1434-9957.
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Tidskriftsartikel (refereegranskat)abstract
- The ever increasing size and complexity of volumetric data in a wide range of disciplines makes it useful to augment volume visualization tools with alternative modalities. Studies have shown that introducing haptics can significantly increase both exploration speed and precision. It is also capable of conveying material properties of data and thus has great potential to improve user performance in volume data exploration. In this paper we describe how recent advances in volume haptics can be used to build haptic modes-building blocks for haptic schemes. These modes have been used as base components of a toolkit allowing for more efficient development of haptic prototypes and applications. This toolkit allows interactive construction, configuration and fine-tuning of both visual and haptic representations of the data. The technology is also used in a pilot study to determine the most important issues and aspects in haptic volume data interaction and exploration, and how the use of haptic modes can facilitate the implementation of effective haptic schemes.
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| 24. |
- Löfving, Adam, et al.
(författare)
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Angiographic visualization of the coronary arteries in computed tomography with virtual contrast injection
- 2006
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Ingår i: The Internet Journal of Radiology. - : Internet Scientific Publications, Llc.. - 1528-8404. ; 4:2
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Tidskriftsartikel (refereegranskat)abstract
- Computed Tomography Angiography (CTA) is a non-invasive alternative to catheter angiography but has had limited use in the coronary arteries due to resolution and visualization problems. Maximum intensity projection (MIP) is difficult to apply in the heart with numerous overlying contrast-filled structures. The study proposes virtual contrast injection, originally introduced for MR angiography, for visualizing the coronaries in CTA. Examination after i.v. contrast injection was made in a 16-slice CT. After virtual contrast injection (concurrent grayscale connectedness) separating the vessels, rendering of the right and left coronary separately was made with MIP and volume rendering (VRT). Images similar to invasive angiography were obtained in all 7 projections used in the clinical routine. The observer also has the possibility to freely select an optimal projection. After validation in larger materials, this may become a clinically useful non-invasive alternative for examining coronary arteries.
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| 25. |
- Palm, Fredrik, et al.
(författare)
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Renomedullary Blood Flow And Blood Volume Are Increased During Vasopressin Escape
- 2010
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Konferensbidrag (refereegranskat)abstract
- Hyponatremia is a common electrolyte disorder usually caused by inappropriate vasopressin (AVP) levels relative to serum osmolality. The degree of the hyponatremia is limited by "escape" from AVP-induced antidiuresis, characterized by increased urine volume and decreased urine osmolality independently of circulating AVP. The mechanisms mediating escape are not fully understood, but we have hypothesized that increased renomedullary blood flow (BF) contributes to this process. We therefore investigated intrarenal BF and blood volume distribution in rats with and without escape.Adult male Sprague-Dawley rats (n=10) were infused with DDAVP (5 ng/h) to produce maximal antidiuresis. Half were fed a liquid diet (AIN-76) to produce escape; half were fed a solid diet to prevent escape. After 5 days, all rats were anesthetized with Inactin and high resolution images (voxel size 97x97x600 µm) of renal BF were acquired using a Siemens Definition Dual Source CT. Iopromide (0.15 ml/rat) was rapidly injected iv and the contrast over the kidney area was collected during 30 s. Data were evaluated by analyzing local renal contrast density utilizing the Siemens Syngo body perfusion tool and correlated to the aorta. Cortical and medullary BF were 709±41 and 251±50 ml/100ml/min respectively in non-escaped rats. Cortical BF in escaped rats was similar (588±81 ml/100ml/min), but medullary BF was increased compared to non-escaped rats (666±105 ml/100ml/min). Blood volumes were similar in the two groups in cortex (42±1 vs. 49±6 ml/100ml), but elevated in the medulla of escaped rats (70±3 vs 18±3 ml/100ml).Our results demonstrate that escape is accompanied by markedly elevated renomedullary BF and volume. Elevated BF to the renal medulla results in reduced interstitial osmolality, and may also contribute to the down-regulation of aquarporin-2 water channels known to accompany escape. These results therefore provide a potential mechanistic explanation for the reduced ability to concentrate urine during AVP escape.
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| 26. |
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| 27. |
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| 28. |
- Persson, Anders, 1953-, et al.
(författare)
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A state-of-the-art pipeline for postmortem CT and MRI visualization: from data acquisition to interactive image interpretation at autopsy
- 2011
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Ingår i: Acta Radiologica. - London, United Kingdom : Sage Publications. - 0284-1851 .- 1600-0455. ; 52:5, s. 522-536
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Forskningsöversikt (refereegranskat)abstract
- The importance of autopsy procedures leading to the establishment of the cause of death is well-known. A recent addition to the autopsy work flow is the possibility of conducting postmortem imaging, in its 3D version also called virtual autopsy (VA), using multidetector computed tomography (MDCT) or magnetic resonance imagining (MRI) data from scans of cadavers displayed with direct volume rendering (DVR) 3D techniques. The use of the data and their workflow are presented. Data acquisition was performed and high quality data-sets with submillimeter precision were acquired. New data acquisition techniques such as dualenergy CT (DECT) and quantitative MRI, then were implemented and provided additional information. Particular findings hardly visualized in conventional autopsy can rather easy be seen at the full body CT, such as air distribution, e.g. pneumothorax, pneumopericardium, air embolism, and wound channels. MRI shows natural deaths such as myocardial infarctions. Interactive visualization of these 3D data-sets can provide valuable insight into the corpses and enables non-invasive diagnostic procedures. In postmortem CT imaging, not being limited by a patient depending radiation dose limit the data-sets can, however, be generated with such a high resolution that they become difficult to handle in today’s archive retrieval and interactive visualization systems, specifically in the case of full body scans. To take full advantage of these new technologies the postmortem workflow needs to be tailored to the demands and opportunities that the new technologies allow.
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| 29. |
- Persson, Anders, 1953-, et al.
(författare)
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Advances of dual source, dual-energy imaging in postmortem CT
- 2008
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Ingår i: European Journal of Radiology. - : Elsevier BV. - 0720-048X .- 1872-7727. ; 68:3, s. 446-455
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on the use of multi-detector row dual-energy computed tomography (DECT) in the evaluation of postmortal examinations. The use of dual energy moves postmortem CT to an entirely new dimension of diagnostic sensitivity where contrast in the image is not merely limited to X-ray attenuation differences, but may include elements of functional and tissue characterization. This additional information may be used to improve the benefit postmortem imaging can provide to supplement and simplify the conventional autopsy. © 2008 Elsevier Ireland Ltd. All rights reserved.
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| 30. |
- Persson, Anders, 1953-
(författare)
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CT Colonography
- 2002
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Ingår i: Regionmöte i Radiologi, Västervik, maj 2002,2002.
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Konferensbidrag (refereegranskat)
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| 31. |
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| 33. |
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| 34. |
- Persson, Anders, 1953-
(författare)
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Image Technology of the Future
- 2006
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Ingår i: British Journal of Surgery. - : John Wiley & Sons. - 0007-1323 .- 1365-2168. ; 93:10, s. 1182-1184
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Tidskriftsartikel (refereegranskat)abstract
- Expectation of imaging-based treatments
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Persson, Anders, 1953-
(författare)
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Postmortem Radiology
- 2010
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Ingår i: First World Congress of Forensic Science.
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Konferensbidrag (refereegranskat)
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| 40. |
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| 41. |
- Persson, Anders, 1953-
(författare)
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Rymden i bilden
- 2002
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Ingår i: Odontologisk riksstämma, Göteborg 2002,2002. ; , s. 42-42
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Konferensbidrag (refereegranskat)
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| 42. |
- Persson, Anders, 1953-
(författare)
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Skiktröntgen undersöker hjärtat på några sekunder : The heart examined with tomography in few seconds
- 2008
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 105:43, s. 3043-3046
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Tidskriftsartikel (refereegranskat)abstract
- Selektiv kranskärlsröntgen är i dag den enda kliniska metod som kan avbilda och kvantifiera kranskärlsstenoser in vivo med tillräckligt hög säkerhet. Nackdelarna är att undersökningen är invasiv och relativt resurskrävande. Datortomografi är en teknik under konstant, snabb utveckling, och efter introduktionen av 64-kanalsdatortomografi har kranskärlsdatortomografi fått mycket snabb spridning i världen. Klinisk nytta har påvisats i ett flertal studier, dock saknas ännu stora randomiserade, prospektiva studier. Metoden medger anatomisk kartläggning av kranskärlslumen och kärlvägg med begränsad möjlighet till bedömning av blodflöde. Högt negativt prediktivt värde för kranskärlssjukdom och risk för överskattning av kärlstenoser har påvisats. Kalk i kärlvägg och oregelbunden hjärtfrekvens försvårar bedömningen kraftigt. Stråldosbelastningen är apparatgenerationsberoende och varierar kraftigt från låg till hög dos. Metoden utvecklas snabbt och har stor potential för framtiden, men i dagsläget är den inte lämpad för daglig sjukvård och bör begränsas till att användas inom ramen för kontrollerade studier.
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| 43. |
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| 44. |
- Persson, Anders, 1953-
(författare)
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Staying on course The EU and the Palestinian-Israeli conflict
- 2019
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Ingår i: Osteuropa. - : BWV-BERLINER WISSENSCHAFTS-VERLAG GMBH. - 0030-6428. ; 69:9-11, s. 429-
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Tidskriftsartikel (refereegranskat)abstract
- Despite very rapid changes in the Palestinian-Israeli conflict and throughout the Middle East, the EU continues to support a two-state solution. During the 1970s, the member states of the European Community jointly developed this approach as a pioneering concept for a just peace in the Middle East. Today, the EUs Middle East policy is on the verge of becoming irrelevant. Furthermore, the member states are finding it increasingly difficult to agree on a common position. However, those that criticise the continued adherence to the two-state solution offer no alternative concepts for peace in the Middle East. The EU would therefore be wise, with its new concept of resilience, not throw what is regarded as being the right approach overboard.
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| 45. |
- Persson, Anders, 1953-, et al.
(författare)
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Three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease : a retrospective analysis of feasibility and adverse reaction to contrast material
- 2006
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Ingår i: BMC Medical Imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundComputed Tomography Cholangiography (CTC) is a fast and widely available alternative technique to visualise hepatobiliary disease in patients with an inconclusive ultrasound when MRI cannot be performed. The method has previously been relatively unknown and sparsely used, due to concerns about adverse reactions and about image quality in patients with impaired hepatic function and thus reduced contrast excretion. In this retrospective study, the feasibility and the frequency of adverse reactions of CTC when using a drip infusion scheme based on bilirubin levels were evaluated.MethodsThe medical records of patients who had undergone upper abdominal spiral CT with subsequent three-dimensional rendering of the biliary tract by means of CTC during seven years were retrospectively reviewed regarding serum bilirubin concentration, adverse reaction and presence of visible contrast media in the bile ducts at CT examination. In total, 153 consecutive examinations in 142 patients were reviewed.ResultsContrast media was observed in the bile ducts at 144 examinations. In 110 examinations, the infusion time had been recorded in the medical records. Among these, 42 examinations had an elevated bilirubin value (>19 umol/L). There were nine patients without contrast excretion; 3 of which had a normal bilirubin value and 6 had an elevated value (25–133 umol/L). Two of the 153 examinations were inconclusive. One subject (0.7%) experienced a minor adverse reaction – a pricking sensation in the face. No other adverse effects were noted.ConclusionWe conclude that drip infusion CTC with an infusion rate of the biliary contrast agent iotroxate governed by the serum bilirubin value is a feasible and safe alternative to MRC in patients with and without impaired biliary excretion.In this retrospective study the feasibility and the frequency of adverse reactions when using a drip infusion scheme based on bilirubin levels has been evaluated.
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| 46. |
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| 47. |
- Persson, Anders, 1953-, et al.
(författare)
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Volume rendering compared with maximum intensity projection for magnetic resonance angiography measurements of the abdominal aorta
- 2004
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 45:4, s. 453-459
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To compare the volume rendering technique (VRT) with maximum intensity projection (MIP) for aortic diameter measurements in MR angiography (MRA) data sets.Material and Methods: Existing contrast-enhanced 3-dimensional MRA and digital subtraction angiography (DSA) data sets from 20 patients were analyzed. In each MRA data set, two aortic diameters were measured using MIP and VRT. Agreement with DSA measurements, dependence on rendering parameters, and interobserver agreement were assessed.Results: Diameters measured on MIP with fixed parameters showed no significant difference compared with DSA and with freely selected parameters a slight overestimation relative to DSA. Diameters measured on VRT were larger than on DSA. For both MIP and VRT, the measurements depended on the chosen parameters. The error relative to DSA was larger for VRT than for MIP with fixed parameters but not with freely chosen parameters. Interobserver agreement did not differ significantly.Conclusions: VRT is not suitable for diameter measurements of the abdominal aorta with fixed parameter settings but may be useful with user-selected settings.
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| 48. |
- Persson, Anders, 1953-, et al.
(författare)
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Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease : a retrospective study
- 2005
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Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 78:936, s. 1078-1085
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate the diagnostic potential of prolonged drip infusion CT cholangiography (DIC-CT) using meglumine iotroxate (Biliscopin®) and 3D volume rendering in patients with suspected obstructive biliary disease. From a material of 142 patients who had undergone a drip infusion CT, all cases with a verified surgical or endoscopic retrograde cholangiography (ERC) diagnosis (n=33) were selected. Age-matched controls were selected from the remaining examinations. Three radiologists reviewed all 66 examinations in retrospect, independently as well as in consensus. The image quality and the estimated diagnostic quality were rated as good or moderate in 91% of the 198 reviews. The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively (with sensitivities ranging from 88% to 94% for individual observers, and specificities from 86% to 96%). Two out of three strictures were observed. No false positive strictures were described. The use of volume rendering technique (VRT) improved diagnostic certainty in 28/198 (14%) of the evaluations. The visualization of ductal stones was improved in 18/48 (38%). No differences in diagnostic quality between single and multislice CT were observed. We conclude that a detailed image of the biliary tree with good sensitivity and specificity can be obtained by means of bilirubin-governed infusion time DIC-CT with volume rendering reconstruction.
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| 49. |
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| 50. |
- Persson, Anders, 1953-
(författare)
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Will medical visualisation tools meet medical user requirements in the future?
- 2010
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press. - 0144-8420 .- 1742-3406. ; 139:1-3, s. 12-19
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes state-of-the-art medical visualisation and discusses the need for a research agenda that focuses on the development of the next generation of medical acquisition and visualisation tools, emphasising the fact that these tools must be based on medical user requirement and workflow studies as well as on new technical developments.
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