| 1. |
- Persson, Jan, 1962, et al.
(författare)
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Fully covered stents are similar to semi-covered stents with regard to migration in palliative treatment of malignant strictures of the esophagus and gastric cardia : results of a randomized controlled trial.
- 2017
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Ingår i: Surgical Endoscopy. - : Springer Science and Business Media LLC. - 0930-2794 .- 1432-2218. ; 31:10, s. 4025-4033
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Stent migration is a significant clinical problem in palliation of malignant strictures in the esophagus and gastro-esophageal junction (GEJ). We have compared a newer design of a fully-covered stent to a widely used semi-covered stent using migration >20 mm as the primary outcome variable. Effects on dysphagia, quality of life (QoL) and re-intervention frequency were also investigated.METHODS: Patients with dysphagia due to non-curable esophagus/GEJ cancer were randomized to receive either a more recent design of a fully-covered stent (n = 48) or a conventional semi-covered stent (n = 47). Chest x-ray, dysphagia and QoL were studied at baseline, one week, four weeks and three months thereafter.RESULTS: There were no significant differences either in stent migration distance or in the migration frequency. Stent migration during the total study period occurred in 37.2 % in the semi-covered group compared to 20.0 % for the fully-covered group. Dysphagia was measured with Watson and Ogilvie scores and with the dysphagia module in the QoL scale (QLQ-OG25). On average, there was a tendency to better dysphagia relief for the fully-covered design as scored with the two latter dysphagia instruments (p= 0.081 and p= 0.067) at three months and towards more re-interventions in the semi-covered group (p= 0.083).CONCLUSION: In spite of its somewhat lower intrinsic radial force, the fully-covered stent was comparable to the conventional semi-covered stent with regard to stent migration. The data further suggest a potential benefit of the fully-covered stent in improving dysphagia in patients with longer life expectancy.
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| 2. |
- Engström, Gunnar, et al.
(författare)
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The Swedish CArdioPulmonary BioImage Study : objectives and design
- 2015
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 278:6, s. 645-659
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Tidskriftsartikel (refereegranskat)abstract
- Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started.
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| 3. |
- Arvidsson, Jonathan, et al.
(författare)
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Image Fusion of Reconstructed Digital Tomosynthesis Volumes From a Frontal and a Lateral Acquisition
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 169:1-4, s. 410-415
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Tidskriftsartikel (refereegranskat)abstract
- Digital tomosynthesis (DTS) has been used in chest imaging as a low radiation dose alternative to computed tomography (CT). Traditional DTS shows limitations in the spatial resolution in the out-of-plane dimension. As a first indication of whether a dual-plane dual-view (DPDV) DTS data acquisition can yield a fair resolution in all three spatial dimensions, a manual registration between a frontal and a lateral image volume was performed. An anthropomorphic chest phantom was scanned frontally and laterally using a linear DTS acquisition, at 120 kVp. The reconstructed image volumes were resampled and manually co-registered. Expert radiologist delineations of the mediastinal soft tissues enabled calculation of similarity metrics in regard to delineations in a reference CT volume. The fused volume produced the highest total overlap, implying that the fused volume was a more isotropic 3D representation of the examined object than the traditional chest DTS volumes.
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| 4. |
- Bech-Hanssen, Odd, 1956, et al.
(författare)
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Pulsed-Wave Doppler Recordings in the Proximal Descending Aorta in Patients with Chronic Aortic Regurgitation: Insights from Cardiovascular Magnetic Resonance
- 2018
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Ingår i: Journal of the American Society of Echocardiography. - : Elsevier BV. - 0894-7317. ; 31:3
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Tidskriftsartikel (refereegranskat)abstract
- The pulsed-wave Doppler recording in the descending aorta (PWD DAO ) is one of the parameters used in grading aortic regurgitation (AR) severity. The aim of the present study was to investigate the assessment of chronic AR by PWD DAO with insights from cardiovascular magnetic resonance (CMR). Methods: This prospective study comprised 40 patients investigated with echocardiography and CMR within 4 hours either prior to valve surgery (n = 23) or as part of their follow-up (n = 17) due to moderate or severe AR. End-diastolic flow velocity (EDFV) and the diastolic velocity time integral (dVTI) were measured. The appearance of diastolic forward flow (DFF) was noted. Phase-contrast flow rate curves were obtained in the DAO. Results: Twenty-five patients had severe and eight had moderate AR by echocardiography (seven were indeterminate). The EDFV was below the recommended threshold ( > 20 cm/sec) in 13 patients (52%) with severe AR. Lowering the EDFV threshold ( > 13 cm/sec) and with a dVTI threshold > 13 cm showed negative likelihood ratios of 0.27 and 0.09, respectively. Detection of DFF with PWD DAO identified a nonuniform velocity profile by CMR with positive and negative likelihood ratios of 7.0 and 0.19, respectively. The relation between EDFV and DAO regurgitant volume (DAO-RVol CMR ) was strong in patients without (R = 0.88) and weak in patients with DFF (R = 0.49). The DAO-RVol CMR as a percent of the total RVol CMR decreased with increasing ascending aorta (AAO) size and increased with increasing AR severity. Conclusions: Our findings suggest that PWD DAO provides semiquantitative parameters useful to assess chronic AR severity. The limitations are related to nonuniform velocity contour and variable degree of lower body contribution, which depends on AR severity but also on the AAO size.
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| 5. |
- Gao, Sinsia, 1966, et al.
(författare)
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Evaluation of the Integrative Algorithm for Grading Chronic Aortic and Mitral Regurgitation Severity Using the Current American Society of Echocardiography Recommendations: To Discriminate Severe from Moderate Regurgitation.
- 2018
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Ingår i: Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography. - : Elsevier BV. - 1097-6795. ; 31:9
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Tidskriftsartikel (refereegranskat)abstract
- The recently published integrative algorithms for echocardiographic grading of native aortic regurgitation (AR) and mitral regurgitation (MR) by the American Society of Echocardiography are consensus based and have not been evaluated. Thus, the aims of the present study were to investigate the feasibility of individual parameters and to evaluate the ability of the algorithms to discriminate severe from moderate regurgitation.This prospective study comprised 93 patients with chronic AR (n=45) and MR (n=48). All patients underwent echocardiography and cardiovascular magnetic resonance within 4hours. The algorithms were evaluated using two different definitions for severe regurgitation: (1) a cardiovascular magnetic resonance standard indicating future need for valve surgery and (2) a clinical standard using patients who underwent valve surgery with proven postoperative left ventricular reverse remodeling and improved functional class (AR/MR, n = 26/26).The feasibility of the criteria in the first step of the algorithm was higher (AR/MR, 95%/91%) compared with the second step using quantitative Doppler parameters (74%/57%). For the AR algorithm, sensitivity was 95% and specificity 44%, whereas for the MR algorithm, sensitivity was 73% and specificity 92%. Among patients with benefit of surgery, the algorithms correctly identified 77%, misclassified 8%, and were inconclusive in 15% of the patients with AR; the corresponding figures were 73%, 15%, and 12% in the patients with MR.Using cardiovascular magnetic resonance as reference, the recommended algorithms for grading of regurgitation have the ability to rule out severe AR and rule in severe MR. The quantitative Doppler methods are hampered by feasibility issues, and our findings suggest that the decision regarding surgical intervention in symptomatic patients with discordant or inconclusive echocardiographic grading should be based on a consolidated assessment of clinical and multimodality findings.
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| 6. |
- Lagerstrand, Kerstin M, et al.
(författare)
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Importance of through-plane heart motion correction for the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging
- 2021
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Ingår i: Magnetic Resonance Imaging. - : Elsevier BV. - 0730-725X. ; 84, s. 69-75
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To elucidate the influence of through-plane heart motion on the assessment of aortic regurgitation (AR) severity using phase contrast magnetic resonance imaging (PC-MRI). Approach: A patient cohort with chronic AR (n = 34) was examined with PC-MRI. The regurgitant volume (RVol) and fraction (RFrac) were extracted from the PC-MRI data before and after through-plane heart motion correction and was then used for assessment of AR severity. Results: The flow volume errors were strongly correlated to aortic diameter (R = 0.80, p < 0.001) with median (IQR 25%;75%): 16 (14; 17) ml for diameter>40mm, compared with 9 (7; 10) ml for normal aortic size (p < 0.001). RVol and RFrac were underestimated (uncorrected:64 +/- 37 ml and 39 +/- 17%; corrected:76 +/- 37 ml and 44 +/- 15%; p < 0.001) and similar to 20% of the patients received lower severity grade without correction. Conclusion: Through-plane heart motion introduces relevant flow volume errors, especially in patients with aortic dilatation that may result in underestimation of the severity grade in patients with chronic AR.
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| 7. |
- Meltzer, Carin, et al.
(författare)
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Surveillance of small, solid pulmonary nodules at digital chest tomosynthesis: data from a cohort of the pilot Swedish CArdioPulmonary bioImage Study (SCAPIS)
- 2021
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 62:3, s. 348-359
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Tidskriftsartikel (refereegranskat)abstract
- Background Digital tomosynthesis (DTS) might be a low-dose/low-cost alternative to computed tomography (CT). Purpose To investigate DTS relative to CT for surveillance of incidental, solid pulmonary nodules. Material and Methods Recruited from a population study, 106 participants with indeterminate solid pulmonary nodules on CT underwent surveillance with concurrently performed CT and DTS. Nodule size on DTS was assessed by manual diameter measurements and semi-automatic nodule segmentations were independently performed on CT. Measurement agreement was analyzed according to Bland-Altman with 95% limits of agreement (LoA). Detection of nodule volume change > 25% by DTS in comparison to CT was evaluated with receiver operating characteristics (ROC). Results A total of 81 nodules (76%) were assessed as measurable on DTS by two independent observers. Inter- and intra-observer LoA regarding change in average diameter were +/- 2 mm. Calculation of relative volume change on DTS resulted in wide inter- and intra-observer LoA in the order of +/- 100% and +/- 50%. Comparing relative volume change between DTS and CT resulted in LoA of -58% to 67%. The area under the ROC curve regarding the ability of DTS to detect volumetric changes > 25% on CT was 0.58 (95% confidence interval [CI] = 0.40-0.76) and 0.50 (95% CI = 0.35-0.66) for the two observers. Conclusion The results of the present study show that measurement variability limits the agreement between DTS and CT regarding nodule size change for small solid nodules.
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| 8. |
- Molnar, David, et al.
(författare)
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Artificial intelligence based automatic quantification of epicardial adipose tissue suitable for large scale population studies
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- To develop a fully automatic model capable of reliably quantifying epicardial adipose tissue (EAT) volumes and attenuation in large scale population studies to investigate their relation to markers of cardiometabolic risk. Non-contrast cardiac CT images from the SCAPIS study were used to train and test a convolutional neural network based model to quantify EAT by: segmenting the pericardium, suppressing noise-induced artifacts in the heart chambers, and, if image sets were incomplete, imputing missing EAT volumes. The model achieved a mean Dice coefficient of 0.90 when tested against expert manual segmentations on 25 image sets. Tested on 1400 image sets, the model successfully segmented 99.4% of the cases. Automatic imputation of missing EAT volumes had an error of less than 3.1% with up to 20% of the slices in image sets missing. The most important predictors of EAT volumes were weight and waist, while EAT attenuation was predicted mainly by EAT volume. A model with excellent performance, capable of fully automatic handling of the most common challenges in large scale EAT quantification has been developed. In studies of the importance of EAT in disease development, the strong co-variation with anthropometric measures needs to be carefully considered.
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| 9. |
- Pesonen, Ida, et al.
(författare)
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High prevalence of interstitial lung abnormalities in middle-aged never-smokers
- 2023
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Ingår i: ERJ Open Research. - : European Respiratory Society. - 2312-0541. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Interstitial lung abnormalities (ILA) are incidental findings on chest computed tomography (CT). These patterns can present at an early stage of fibrotic lung disease. Our aim was to estimate the prevalence of ILA in the Swedish population, in particular in never-smokers, and find out its association with demographics, comorbidities and symptoms.METHODS: Participants were recruited to the Swedish CArdioPulmonary BioImage Study (SCAPIS), a population-based survey including men and women aged 50-64 years performed at six university hospitals in Sweden. CT scan, spirometry and questionnaires were performed. ILA were defined as cysts, ground-glass opacities, reticular abnormality, bronchiectasis and honeycombing.FINDINGS: Out of 29 521 participants, 14 487 were never-smokers and 14 380 were men. In the whole population, 2870 (9.7%) had ILA of which 134 (0.5%) were fibrotic. In never-smokers, the prevalence was 7.9% of which 0.3% were fibrotic. In the whole population, age, smoking history, chronic bronchitis, cancer, coronary artery calcium score and high-sensitive C-reactive protein were associated with ILA. Both ILA and fibrotic ILA were associated with restrictive spirometric pattern and impaired diffusing capacity of the lung for carbon monoxide. However, individuals with ILA did not report more symptoms compared with individuals without ILA.INTERPRETATION: ILA are common in a middle-aged Swedish population including never-smokers. ILA may be at risk of being underdiagnosed among never-smokers since they are not a target for screening.
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| 10. |
- Polte, Christian Lars, et al.
(författare)
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Characterization of Chronic Aortic and Mitral Regurgitation Undergoing Valve Surgery Using Cardiovascular Magnetic Resonance.
- 2017
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Ingår i: The American journal of cardiology. - : Elsevier BV. - 1879-1913 .- 0002-9149. ; 119:12, s. 2061-2068
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Tidskriftsartikel (refereegranskat)abstract
- Grading of chronic aortic regurgitation (AR) and mitral regurgitation (MR) by cardiovascular magnetic resonance (CMR) is currently based on thresholds, which are neither modality nor quantification method specific. Accordingly, this study sought to identify CMR-specific and quantification method-specific thresholds for regurgitant volumes (RVols), RVol indexes, and regurgitant fractions (RFs), which denote severe chronic AR or MR with an indication for surgery. The study comprised patients with moderate and severe chronic AR (n= 38) and MR (n= 40). Echocardiography and CMR was performed at baseline and in all operated AR/MR patients (n= 23/25) 10 ± 1months after surgery. CMR quantification of AR: direct (aortic flow) and indirect method (left ventricular stroke volume [LVSV]- pulmonary stroke volume [PuSV]); MR: 2 indirect methods (LVSV- aortic forward flow [AoFF]; mitral inflow [MiIF]- AoFF). All operated patients had severe regurgitation and benefited from surgery, indicated by a significant postsurgical reduction in end-diastolic volume index and improvement or relief of symptoms. The discriminatory ability between moderate and severe AR was strong for RVol >40ml, RVol index >20ml/m(2), and RF >30% (direct method) and RVol >62ml, RVol index >31ml/m(2), and RF >36% (LVSV-PuSV) with a negative likelihood ratio ≤ 0.2. In MR, the discriminatory ability was very strong for RVol >64ml, RVol index >32ml/m(2), and RF >41% (LVSV-AoFF) and RVol >40ml, RVol index >20ml/m(2), and RF >30% (MiIF-AoFF) with a negative likelihood ratio < 0.1. In conclusion, CMR grading of chronic AR and MR should be based on modality-specific and quantification method-specific thresholds, as they differ largely from recognized guideline criteria, to assure appropriate clinical decision-making and timing of surgery.
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| 11. |
- Polte, Christian Lars, et al.
(författare)
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Mitral regurgitation quantification by cardiovascular magnetic resonance: a comparison of indirect quantification methods
- 2015
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Ingår i: The International Journal of Cardiovascular Imaging. - : Springer Science and Business Media LLC. - 1569-5794 .- 1573-0743. ; 31:6, s. 1223-31
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Tidskriftsartikel (refereegranskat)abstract
- Quantification of mitral regurgitation (MR) using cardiovascular magnetic resonance can be achieved by three indirect methods. The aims of the study were to determine their agreement, observer variability and effect on grading MR severity. The study comprised 16 healthy volunteers and 36 MR patients. Quantification was performed using the 'standard' [left ventricular stroke volume (LVSV)-aortic forward flow (AoFF)], 'volumetric' [LVSV-right ventricular stroke volume (RVSV)] and 'flow' method [mitral inflow (MiIF)-AoFF]. In healthy volunteers without MR, LVSV was larger than AoFF (mean difference ±SD: 12 ± 6 ml, P < 0.0001). Only small differences were found between LVSV-RVSV (3 ± 6 ml) and MiIF-AoFF (1 ± 5 ml). In patients, mitral regurgitant volumes (MRVs)/fractions (MRFs) were larger (P < 0.0001) using the 'standard' method (90 ± 31 ml/51 ± 11%) compared with the 'volumetric' (76 ± 30 ml/42 ± 11%) and 'flow' method (70 ± 32 ml/44 ± 15%). Inter-observer variability was lowest for the 'flow' and highest for the 'volumetric' method, while intra-observer variability was similar for all three methods. In 29 operated patients with severe MR, MRVs were above the guideline threshold (≥60 ml) in 100, 86 and 83% of the cases, and MRFs were above the threshold (≥50%) in 76, 32 and 48% of the cases, when using the 'standard', 'volumetric' and 'flow' method respectively. In conclusion, the choice of method can affect the grading of MR severity and thereby eventually the clinical decision-making and timing of surgery.
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| 12. |
- Thoren, Fredrik, 1959, et al.
(författare)
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CT colonography: implementation, indications, and technical performance - a follow-up national survey.
- 2019
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Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 60:3, s. 271-277
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Tidskriftsartikel (refereegranskat)abstract
- Background Computed tomography colonography (CTC) is an accepted complement or alternative to optical colonoscopy (OC) but its implementation is incompletely analyzed, and technical performance varies between centers. Purpose To evaluate implementation, indications, and technical performance of CTC in Sweden and to evaluate compliance to international guidelines. Material and Methods A structured, self-assessed questionnaire regarding implementation and technical performance of CTC was sent to all eligible radiology departments in Sweden. Eighty-six out of 89 departments replied. Comparisons were made with similar national surveys from 2004 and 2009. Results The number of centers performing CTC gradually increased from 23 in 2004 to 77 in 2016. In parallel, centers performing barium enema (BE) examinations have decreased from 89 in 2004 to 13 in 2016. Main reasons stated for still performing BE were lack of resources regarding CTC/OC. Main reasons for not performing CTC were lack of suitable software, lack of machine/reading time, and lack of experience. The majority of centers follow international CTC guidelines. An important exception is fecal tagging, which was implemented in only 63% of the centers. Incomplete OC remains a major indication for CTC, while preoperative CTC in colorectal cancer and follow-up after diverticulitis have emerged as new indications. Conclusion CTC today is well implemented in routine healthcare but still lacking in capacity. Indications have expanded over time, and most departments perform "state of the art" CTC, although fecal tagging is incompletely implemented.
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| 13. |
- Torén, Kjell, 1952, et al.
(författare)
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Vital capacity and COPD: the Swedish CArdioPulmonary bioImage Study (SCAPIS)
- 2016
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Ingår i: International Journal of Chronic Obstructive Pulmonary Disease. - : Informa UK Limited. - 1178-2005. ; 11:1, s. 927-933
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Tidskriftsartikel (refereegranskat)abstract
- Background: Spirometric diagnosis of chronic obstructive pulmonary disease (COPD) is based on the ratio of forced expiratory volume in 1 second (FEV1)/vital capacity (VC), either as a fixed value <0.7 or below the lower limit of normal (LLN). Forced vital capacity (FVC) is a proxy for VC. The first aim was to compare the use of FVC and VC, assessed as the highest value of FVC or slow vital capacity (SVC), when assessing the FEV1/VC ratio in a general population setting. The second aim was to evaluate the characteristics of subjects with COPD who obtained a higher SVC than FVC. Methods: Subjects (n=1,050) aged 50-64 years were investigated with FEV1, FVC, and SVC after bronchodilation. Global Initiative for Chronic Obstructive Lung Disease (GOLD) COPDFVC was defined as FEV1/FVC <0.7, GOLDCOPD(VC) as FEV1/VC <0.7 using the maximum value of FVC or SVC, LLNCOPDFVC as FEV1/FVC below the LLN, and LLNCOPDVC as FEV1/VC below the LLN using the maximum value of FVC or SVC. Results: Prevalence of GOLDCOPD(FVC) was 10.0% (95% confidence interval [CI] 8.2-12.0) and the prevalence of LLNCOPDFVC was 9.5% (95% CI 7.8-11.4). When estimates were based on VC, the prevalence became higher; 16.4% (95% CI 14.3-18.9) and 15.6% (95% CI 13.5-17.9) for GOLDCOPD(VC) and LLNCOPDVC, respectively. The group of additional subjects classified as having COPD based on VC, had lower FEV1, more wheeze and higher residual volume compared to subjects without any COPD. Conclusion: The prevalence of COPD was significantly higher when the ratio FEV1/VC was calculated using the highest value of SVC or FVC compared with using FVC only. Subjects classified as having COPD when using the VC concept were more obstructive and with indications of air trapping. Hence, the use of only FVC when assessing airflow limitation may result in a considerable under diagnosis of subjects with mild COPD.
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| 14. |
- Truedsson, Frida, et al.
(författare)
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Importance of complex blood flow in the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging.
- 2021
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Ingår i: The international journal of cardiovascular imaging. - : Springer Science and Business Media LLC. - 1875-8312 .- 1569-5794 .- 1573-0743. ; 37, s. 3561-3572
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate if and how complex flow influences the assessment of aortic regurgitation (AR) using phase contrast MRI in patients with chronic AR. Patients with moderate (n=15) and severe (n=28) chronic AR were categorized into non-complex flow (NCF) or complex flow (CF) based on the presence of systolic backward flow volume. Phase contrast MRI was performed repeatedly at the level of the sinotubular junction (Ao1) and 1cm distal to the sinotubular junction (Ao2). All AR patients were assessed to have non-severe AR or severe AR (cut-off values: regurgitation volume (RVol)≥60ml and regurgitation fraction (RF)≥50%) in both measurement positions. The repeatability was significantly lower, i.e. variation was larger, for patients with CF than for NCF (≥12±12% versus≥6±4%, P≤0.03). For patients with CF, the repeatability was significantly lower at Ao2 compared to Ao1 (≥21±20% versus≥12±12%, P≤0.02), as well as the assessment of regurgitation (RVol: 42±34ml versus 54±42ml, P<0.001; RF: 30±18% versus 34±16%, P=0.01). This was not the case for patients with NCF. The frequency of patients that changed in AR grade from severe to non-severe when the position of the measurement changed from Ao1 to Ao2 was higher for patients with CF compared to NCF (RVol: 5/26 (19%) versus 1/17 (6%), P=0.2; RF: 4/26 (15%) versus 0/17 (0%), P=0.09). Our study shows that complex flow influences the quantification of chronic AR, which can lead to underestimation of AR severity when using PC-MRI.
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| 15. |
- Vikgren, Jenny, 1957, et al.
(författare)
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Visual and Quantitative Evaluation of Emphysema: A Case-Control Study of 1111 Participants in the Pilot Swedish CArdioPulmonary BioImage Study (SCAPIS)
- 2020
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332 .- 1878-4046. ; 27:5, s. 636-643
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: Emphysema is a hallmark of chronic obstructive pulmonary disease. The primary aim of this study was to investigate inter- and intraobserver agreement of visual assessment of mild emphysema in low-dose multidetector computed tomography of subjects in the pilot SCAPIS in order to certify consistent detection of mild emphysema. The secondary aim was to investigate the performance of quantitative densitometric measurements in the cohort. Materials and Methods: Participants with emphysema (n = 100, 56 males and 44 females) reported in the electronic case report form of pilot SCAPIS and 100 matched controls (gender, age, height, and weight) without emphysema were included. To assess interobserver variability the randomized examinations were evaluated by two thoracic radiologists. For intraobserver variability three radiologists re-evaluated randomized examinations which they originally evaluated. The results were evaluated statistically by Krippendorff's α. The dataset was also assessed quantitively for % lung attenuation value −950 HU (LAV950), mean lung density and total lung volume by commercially available software. Results: Emphysema was visually scored as mild and Krippendorff's α was ≥0.8 for both the inter- and intraobserver agreement regarding presence of emphysema and approaching 0.8 regarding presence and extent of emphysema by location in the upper lobes. Mean LAV950 was not different between the emphysematous and the nonemphysematous participants; 8.3% and 8.4%, respectively. Conclusion: The inter- and intraobserver agreement for visual detection of mild emphysema in low-dose multidetector computed tomography was good. Surprisingly, quantitative analysis could not reliably identify participants with mild emphysema, which hampers the use of automatic evaluation. © 2019 The Association of University Radiologists
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| 16. |
- Arvidsson, Jonathan, 1986, et al.
(författare)
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Automated estimation of in-plane nodule shape in chest tomosynthesis images
- 2015
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Ingår i: International Federation for Medical and Biological Engineering Proceedings. - Cham : Springer International Publishing. - 1680-0737. - 9783319129679 ; 48, s. 20-23
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to develop an automated segmentation method for lung nodules in chest tomo-synthesis images. A number of simulated nodules of different sizes and shapes were created and inserted in two different locations into clinical chest tomosynthesis projections. The tomosynthesis volumes were then reconstructed using standard cone beam filtered back projection, with 1 mm slice interval. For the in-plane segmentation, the central plane of each nodule was selected. The segmentation method was formulated as an optimization problem where the nodule boundary corresponds to the minimum of the cost function, which is found by dynamic programming. The cost function was composed of terms related to pixel intensities, edge strength, edge direction and a smoothness constraint. The segmentation results were evaluated using an overlap measure (Dice index) of nodule regions and a distance measure (Hausdorff distance) between true and segmented nodule. On clinical images, the nodule segmentation method achieved a mean Dice index of 0.96 ± 0.01, and a mean Hausdorff distance of 0.5 ± 0.2 mm for isolated nodules and for nodules close to other lung structures a mean Dice index of 0.95 ± 0.02 and a mean Hausdorff distance of 0.5 ± 0.2 mm. The method achieved an acceptable accuracy and may be useful for area estimation of lung nodules.
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| 17. |
- Ásgeirsdóttir, Helga, et al.
(författare)
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Depiction of anatomic structures of relevance for scoring of cystic fibrosis changes by chest tomosynthesis and computed tomography
- 2014
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Ingår i: Journal of Cystic Fibrosis. 37th European Cystic Fibrosis Conference, 11-14 June 2014, Gothenburg, Sweden. ; 13:Suppl. 2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: Chest radiography (CR) and computed tomography (CT) are commonly used for imaging of patients with cystic fibrosis, and scoring is applied to assess disease severity. Chest tomosynthesis (CTS) is a new imaging modality providing better anatomic visualization than CR at radiation doses and costs lower than CT. Objective: To compare visibility and size of anatomic structures of relevance for scoring in CTS and CT images. Methods: 21 adult patients with cystic fibrosis were examined both with CTS (VolumeRAD; GE Healthcare) and volumetric CT (LightSpeed Pro 16, LightSpeed VCT, Discovery CT750HD; GE healthcare and Somatom Definition, Siemens Medical Solutions). The average effective dose for a standard patient was 0.13 and 4.5 mSv for CTS and CT, respectively. Comparison of visibility and manual measurements of diameters of the central and peripheral bronchi and their accompanying artery, as well as bronchial wall thickness (BWT), were performed in a non-blinded fashion. Results: All central structures could be evaluated. Mean difference in diameter of central bronchi, accompanying artery and BWT between CTS and CT was −0.6 (SD 0.6), −0.7 (SD 0.7) and −0.4 (SD 0.2) mm, respectively. Peripheral structures were more difficult to assess by CTS. Peripheral bronchial diameter, BWT and diameter of accompanying artery could be assessed by CTS in 20, 15 and 4 cases, respectively and mean difference between measurements was −0.5 (SD 0.5), −0.3 (SD 0.3) and −0.4 (SD 0.4) mm, respectively. Conclusion: This study indicates that peripheral structures are more difficult to evaluate by CTS and that CTS slightly underestimate size of structures in comparison to CT
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| 18. |
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| 19. |
- 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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| 20. |
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| 21. |
- Asplund, Sara, 1976, et al.
(författare)
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Learning aspects and potential pitfalls regarding detection of pulmonary nodules in chest tomosynthesis and proposed related quality criteria.
- 2011
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Ingår i: Acta radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 52:5, s. 503-512
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Tidskriftsartikel (refereegranskat)abstract
- Background In chest tomosynthesis, low-dose projections collected over a limited angular range are used for reconstruction of an arbitrary number of section images of the chest, resulting in a moderately increased radiation dose compared to chest radiography. Purpose To investigate the effects of learning with feedback on the detection of pulmonary nodules for observers with varying experience of chest tomosynthesis, to identify pitfalls regarding detection of pulmonary nodules, and present suggestions for how to avoid them, and to adapt the European quality criteria for chest radiography and computed tomography (CT) to chest tomosynthesis. Material and Methods Six observers analyzed tomosynthesis cases for presence of nodules in a jackknife alternative free-response receiver-operating characteristics (JAFROC) study. CT was used as reference. The same tomosynthesis cases were analyzed before and after learning with feedback, which included a collective learning session. The difference in performance between the two readings was calculated using the JAFROC figure of merit as principal measure of detectability. Results Significant improvement in performance after learning with feedback was found only for observers inexperienced in tomosynthesis. At the collective learning session, localization of pleural and subpleural nodules or structures was identified as the main difficulty in analyzing tomosynthesis images. Conclusion The results indicate that inexperienced observers can reach a high level of performance regarding nodule detection in tomosynthesis after learning with feedback and that the main problem with chest tomosynthesis is related to the limited depth resolution.
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| 22. |
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| 23. |
- Astengo, Marco, et al.
(författare)
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Ability of noninvasive criteria to predict hemodynamically significant aortic obstruction in adults with coarctation of the aorta.
- 2017
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Ingår i: Congenital heart disease. - : Computers, Materials and Continua (Tech Science Press). - 1747-0803 .- 1747-079X. ; 12:2, s. 174-180
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Tidskriftsartikel (refereegranskat)abstract
- Coarctation of the aorta (CoA) is a common condition. Adult patients with newly diagnosed CoA and patients with recurring or residual CoA require evaluation of the severity of aortic obstruction. Cardiac catheterization is considered the gold standard for the evaluation of hemodynamically significant CoA. The European Society of Cardiology (ESC) Guidelines for the management of grown-up congenital heart disease (GUCH) include noninvasive criteria for identifying significant CoA. Our aim was to investigate the ability of the Class I and Class IIa ESC recommendations to identify significant CoA at cardiac catheterization.Sixty-six adult patients with native or recurrent CoA underwent diagnostic cardiac catheterization at the GUCH unit at the Sahlgrenska University Hospital in Gothenburg from October 1998 to November 2013. Clinical and imaging data, as well as data about cardiac catheterization were retrospectively collected from patient records.The Class I ESC recommendations predicted significant CoA with a sensitivity of 0.57, a specificity of 0.63, a positive predictive value of 0.67, and a negative predictive value of 0.53. The combination of Class I and Class IIa recommendations predicted significant CoA with a sensitivity of 0.75, a specificity of 0.42, a positive predictive value of 0.66 and a negative predictive value of 0.52.the noninvasive criteria proposed by the ESC guidelines to identify subjects with significant CoA performed poorly in our dataset. Further research is needed to develop more accurate, noninvasive criteria to evaluate CoA severity and thereby reduce the number of unnecessary cardiac catheterizations.
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| 24. |
- Baubeta Fridh, Erik, et al.
(författare)
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Comparison of Magnetic Resonance Angiography and Digital Subtraction Angiography for the Assessment of Infrapopliteal Arterial Occlusive Lesions, Based on the TASC II Classification Criteria
- 2020
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Ingår i: Diagnostics (Basel). - : MDPI. - 2075-4418. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- This paper aimed to study the agreement and repeatability, both intra- and interobserver, of infrapopliteal lesion assessment with magnetic resonance angiography (MRA), using the TransAtlantic Inter-Society Consensus (TASC) II criteria, with perioperative digital subtraction angiography (DSA) as a reference. Sixty-eight patients with an MRA preceding an endovascular infrapopliteal revascularization were included. Preoperative MRAs and perioperative DSAs were evaluated in random order by three independent observers using the TASC II classification. The results were analyzed using visual grading characteristics (VGC) analysis and Krippendorffs alpha. No systematic difference was found between modalities: area under the VGC curve (AUC(VGC)) = 0.48 (p = 0.58) or intraobserver; AUC(VGC) for Observer 1 and 2 respectively, 0.49 (p = 0.85) and 0.53 (p = 0.52) for MRA compared with 0.54 (p = 0.30) and 0.49 (p = 0.81) for DSA. Interobserver differences were seen: AUC(VGC) of 0.63 (p < 0.01) for DSA and 0.80 (p < 0.01) for MRA. These results were confirmed using Krippendorffs alpha for the three observers showing 0.13 (95% confidence interval (CI) -0.07-0.31) for MRA and 0.39 (95% CI 0.23-0.53) for DSA. Poor interobserver agreement was also found in the choice of a target vessel on preoperative MRA: Krippendorffs alpha = 0.19 (95% CI 0.01-0.36). In conclusion, infrapopliteal lesions can be reliably determined on preoperative MRA, but interobserver variability regarding the choice of a target vessel is a major concern that appears to affect the overall TASC II grade.
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| 25. |
- Bech-Hanssen, Odd, 1956, et al.
(författare)
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Characterization of complex flow patterns in the ascending aorta in patients with aortic regurgitation using conventional phase-contrast velocity MRI.
- 2018
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Ingår i: The international journal of cardiovascular imaging. - : Springer Science and Business Media LLC. - 1875-8312 .- 1569-5794 .- 1573-0743. ; 34:3, s. 419-429
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Tidskriftsartikel (refereegranskat)abstract
- Ascending aorta (AA) flow displacement (FD) is a surrogate for increased wall shear stress. We prospectively studied the flow profile in the AA in patients with aortic regurgitation (AR), to identify predictors of FD and investigate whether magnetic resonance imaging (MRI) phase-contrast flow rate curves (PC-FRC) contain quantitative information related to FD. Forty patients with chronic moderate (n=14) or severe (n=26) AR (21 (53%) with bicuspid aortic valve) and 22 controls were investigated. FD was determined from phase-contrast velocity profiles and defined as the distance between the center of the lumen and the "center of velocity" of the peak systolic forward flow or the peak diastolic negative flow, normalized to the lumen radius. Forward and backward volume flow was determined separately for systole and diastole. Seventy percent had systolic backward flow and 45% had diastolic forward flow in large areas of the vessel. AA dimension was an independent predictor of systolic FD while AA dimension and regurgitant volume were independent predictors of diastolic FD. Valve phenotype was not an independent predictor of systolic or diastolic FD. The linear relationships between systolic backward flow and systolic FD and diastolic forward flow and diastolic FD were strong (R=0.77 and R=0.76 respectively). Systolic backward flow and diastolic forward flow identified marked systolic and diastolic FD (≥0.35) with a positive likelihood ratio of 6.0 and 10.8, respectively. In conclusion, conventional PC-FRC data can detect and quantify FD in patients with AR suggesting the curves as a research and screening tool in larger patient populations.
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| 26. |
- Bech-Hanssen, Odd, 1956, et al.
(författare)
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Left ventricular volumes by echocardiography in chronic aortic and mitral regurgitation.
- 2016
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Ingår i: Scandinavian cardiovascular journal : SCJ. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 50:3, s. 154-161
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Tidskriftsartikel (refereegranskat)abstract
- Cut-off values for left ventricular (LV) dimensions indicating severe valve regurgitation have not been defined. The aim of the study was to establish echocardiographic cut-off values for LV dimensions indicating severe chronic aortic (AR) or mitral (MR) regurgitation.
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| 27. |
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| 28. |
- Båth, Magnus, 1974, et al.
(författare)
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Chest tomosynthesis
- 2014
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Ingår i: Tomosynthesis Imaging. Ed. Stephen Glick. - Boca Raton : CRC Press/Taylor & Francis. - 9781439878705 ; , s. 189-197
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 29. |
- Cain, Peter A, et al.
(författare)
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Age and gender specific normal values of left ventricular mass, volume and function for gradient echo magnetic resonance imaging: a cross sectional study.
- 2009
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Ingår i: BMC medical imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge about age-specific normal values for left ventricular mass (LVM), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) by cardiac magnetic resonance imaging (CMR) is of importance to differentiate between health and disease and to assess the severity of disease. The aims of the study were to determine age and gender specific normal reference values and to explore the normal physiological variation of these parameters from adolescence to late adulthood, in a cross sectional study.
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| 30. |
- Cain, Peter, et al.
(författare)
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Physiological determinants of the variation in left ventricular mass from early adolescence to late adulthood in healthy subjects
- 2005
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Ingår i: Clin Physiol Funct Imaging. - 1475-0961. ; 25:6, s. 332-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The physiological determinants of left ventricular mass (LVM) measured by cardiac magnetic resonance (CMR) imaging are not well defined as prior investigators have studied either adults or adolescents in isolation or have not strictly excluded hypertension or accounted for the effects of exercise habits, haemodynamic, demographic, or body shape characteristics. METHODS: A total of 102 healthy volunteers (12-81 years, 53 males) underwent CMR. All parameters [unstandardized and adjusted for body surface area (BSA)] were analysed according to gender and by adolescence versus adulthood (adolescents <20 years, adults > or = 20 years). The influence of haemodynamic factors, exercise, and demographic factors on LVM were determined with multivariate linear regression. Results: LVM rose during adolescence and declined in adulthood. LVM and LVMBSA were higher in males both in adults (LVM: 188 +/- 22 g versus 139 +/- 21 g, P < 0.001; LVMBSA: 94 +/- 11 g m(-2) versus 80 +/- 11 g m(-2), P < 0.001) and in adolescents when adjusted for BSA (LVM: 128 +/- 29 g versus 107 +/- 20 g, P = 0.063; LVMBSA: 82 +/- 8 g m(-2) versus 71 +/- 10 g m(-2), P = 0.025). In adults, systolic blood pressure (SBP) and self-reported physical activity increased while meridional and circumferential wall stress were constant with age. Multivariate regression analysis revealed age, gender, and BSA as the major determinants of LVM (global R2 = 0.69). CONCLUSIONS: Normal LVM shows variation over a broad age range in both genders with a rise in adolescence and subsequent decline with increasing age in adulthood despite an increase in SBP and physical activity. BSA, age, and gender were found to be major contributors to the variation in LVM in healthy adults, while haemodynamic factors, exercise, and wall stress were not.
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| 31. |
- 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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| 32. |
- Fisichella, Valeria A, 1974, et al.
(författare)
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Evaluation of image quality and lesion perception by human readers on 3D CT colonography: comparison of standard and low radiation dose
- 2010
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Ingår i: European Radiology. - 1432-1084. ; 20:3, s. 630-9
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: We compared the prevalence of noise-related artefacts and lesion perception on three-dimensional (3D) CT colonography (CTC) at standard and low radiation doses. METHODS: Forty-eight patients underwent CTC (64 x 0.625 mm collimation; tube rotation time 0.5 s; automatic tube current modulation: standard dose 40-160 mA, low dose 10-50 mA). Low- and standard-dose acquisitions were performed in the supine position, one after the other. The presence of artefacts (cobblestone and snow artefacts, irregularly delineated folds) and the presence of polyps were evaluated by five radiologists on 3D images at standard dose, the original low dose and a modified low dose, i.e. after manipulation of opacity on 3D. RESULTS: The mean effective dose was 3.9 +/- 1.3 mSv at standard dose and 1.03 +/- 0.4 mSv at low dose. The number of images showing cobblestone artefacts and irregularly delineated folds at original and modified low doses was significantly higher than at standard dose (P < 0.0001). Most of the artefacts on modified low-dose images were mild. No significant difference in sensitivity between the dose levels was found for polyps >/=6 mm. CONCLUSIONS: Reduction of the effective dose to 1 mSv significantly affects image quality on 3D CTC, but the perception of >/=6 mm lesions is not significantly impaired.
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| 33. |
- Friberg, Peter, 1956, et al.
(författare)
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Increased left ventricular mass in obese adolescents
- 2004
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 25:11, s. 987-92
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: An increase of left ventricular mass (LVM) has been reported in obese adolescents in previous studies using echocardiography. The aim of our study was to determine the extent of the increase in LVM and correlation to other risk factors using cardiac magnetic resonance imaging in obese and lean adolescents. METHODS AND RESULTS: Nineteen obese and 20 lean adolescents were recruited. Following resting blood pressure measurements and blood sampling for insulin, triglycerides, and cholesterol levels, all subjects underwent cardiac magnetic resonance examination to assess LVM. LVM adjusted for body height was 16% greater in obese compared to lean adolescents (median 66 g/m, p = 0.0042). Obese subjects had higher resting systolic blood pressures than controls (median 115 vs. 110 mmHg, p = 0.0077) and higher fasting triglyceride and insulin levels. HDL-cholesterol levels were lower in the obese group compared with the lean group. CONCLUSIONS: Obese adolescents had a higher LVM than age-matched lean subjects, which correlated mainly with body mass index and systolic blood pressure. These findings add to the established cardiovascular risk profile of obese adolescents.
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| 34. |
- Håkansson, Markus, et al.
(författare)
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Nodule detection in digital chest radiography: effect of system noise.
- 2005
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 114:1-3, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- Apart from the image content that is the reproduction of anatomy and possible lesions, an X-ray image also contains system noise due to the limited number of photons and other internal noise sources in the system (image plate artefacts, electronic noise, etc.). The aim of this study was to determine the extent to which the system noise influences the detection of subtle lung nodules in five different regions of the chest. This was done by conducting a receiver operating characteristic (ROC) study with five observers on two different sets of images; clinical chest X-ray images and images of a LucAl phantom at similar dose levels found in the different regions of the chest. In both image types, mathematically simulated nodules (with a full-width-at-fifth-maximum of 10 mm) were added to the images at varying contrast levels. As a measure of the influence of system noise on the detection of subtle lung nodules, the ratio between the contrast needed to obtain an area under the ROC curve of 0.80 in the system noise images to that needed in the clinical images was used. The contrast ratio between system noise images and clinical images ranged from approximately 0.02 (in the hilar region) to 0.18 (in the lower mediastinal region). The maximum difference in contrast needed for the corresponding system noise images, collected at the lowest and the highest dose represented in the anatomical image, was a factor of 2. These results indicate that probably no region in a chest X-ray image is limited by the number of quanta to the detector for the detection of 10 mm lung nodules when a radiation dose corresponding to a system with speed class 200 (leading to a detector dose of approximately 9 muGy behind the parenchyma) is used.
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| 35. |
- Ivarsson, Jonas, 1976, et al.
(författare)
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Arranging for better learning opportunities in radiology
- 2015
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Ingår i: Optimisation in X-ray and Molecular Imaging 2015 - the Fourth Malmö Conference on Medical Imaging, Gothenburg, Sweden, 28-30 May 2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: The study provides an example on how it is possible to design environments at the workplace that could meet learning demands implied by the introduction of novel imaging technologies in radiology (in this case tomosynthesis). The innovative aspect of this design does not result from the implementation of any specific tool for learning. Instead, advancement is achieved by a novel set-up of existing imaging technologies. Based on a number of pedagogical principles, we developed what we call a Technology enhanced Learning Session (TLS), an interactive format that allows for focused discussions between learners with different levels of expertise. Method: Interactions during a TLS were videotaped and later analysed using interaction analysis. We did not seek to explain factors affecting learning, but rather identify qualities of the arrangement that presented opportunities for professionally meaningful forms of action, i.e. enabling conditions of the TLS for displaying knowledge on how to judge radiological section images produced by the novel technology. Results: Based on the analysis we propose three principles to be considered when designing learning environments for teaching professional modes of reasoning in radiology: First, the ways in which participants with different levels of experience interact and communicate have a large impact on the outcome of the activity. By publicly displaying records of the participants’ individual assessments everyone can become involved and mistakes become dissected rather than hidden. Second, experts working on authentic cases give prominence to case specific details, disambiguation practices, and several dimensions of variation (in representations, anatomy, pathology etc.). Professional modes of reasoning, when being made publically visible, operate as instructions. Third, participants should be given shared access to visual materials: Given different setups, participants will have different possibilities of establishing shared references and partake in reasoning that build on visual details. As we have seen, the observers’ ability to notice, discuss, and investigate particular features of the radiological images became a necessary requirement for the accomplishment of their collaborative work. Conclusions: The study points to what we see as the underexplored possibilities of tailoring basic and specialist training that meets the new demands given by novel imaging technologies in radiology.
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| 36. |
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| 37. |
- Ivarsson, Jonas, 1976, et al.
(författare)
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The application of improved, structured and interactive group learning methods in diagnostic radiology
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 169:1-4, s. 416-421
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Tidskriftsartikel (refereegranskat)abstract
- This study provides an example on how it is possible to design environments in a diagnostic radiology department that could meet learning demands implied by the introduction of new imaging technologies. The innovative aspect of the design does not result from the implementation of any specific tool for learning. Instead, advancement is achieved by a novel set-up of existing technologies and an interactive format that allows for focussed discussions between learners with different levels of expertise. Consequently, the study points to what is seen as the underexplored possibilities of tailoring basic and specialist training that meet the new demands given by leading-edge technologies.
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| 38. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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A phantom study of nodule size evaluation with chest tomosynthesis and computed tomography.
- 2010
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 140-143
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate nodule size measurements with chest tomosynthesis (TS) and computed tomography (CT). A 26-mm thick phantom, composed of a Polylite block with embedded spheres of different materials and sizes (4-20 mm), was scanned by both CT and TS. Six observers without prior knowledge of the true diameters of the spheres independently measured the diameter of the spheres on the CT and TS images. Four observers were allowed to change the window settings and two of the observers used predetermined fixed viewing conditions. The mean relative errors for all observers and all measured spheres compared with the known diameter of the spheres were 1.4 % (standard deviation, SD: 5.4 %) on CT images and -1.1 % (SD: 5.0 %) on TS images. With regard to the four observers where the window settings were at the discretion of the observer, the mean relative errors were 1.4 % (SD: 6.4 %) on CT images and -1.7 % (SD: 5.7 %) on TS images. Regarding the two observers using identical viewing conditions the mean relative error was 1.5 % (SD: 2.8 %) on CT images and 0.2 % (SD: 2.6 %) on TS images. In conclusion, the study suggests that nodule size measurements on chest TS might be an alternative to measurements on CT.
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| 39. |
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| 40. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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A Retrospective Study of Chest Tomosynthesis as a Tool for Optimizing the use of Computed Tomography Resources and Reducing Patient Radiation Exposure
- 2014
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Ingår i: Academic Radiology. - : Elsevier BV. - 1076-6332. ; 21:11, s. 1427-1433
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Tidskriftsartikel (refereegranskat)abstract
- Rationale and Objectives: To investigate potential benefits and drawbacks of the clinical use of chest tomosynthesis (CTS), to what extent CTS obviates the need for chest computed tomography (CT), and what reduction in radiation dose thereby can be achieved. Materials and Methods: The Regional Ethical Review Board approved the follow-up study of patients examined with CTS as part of clinical routine. For each case, two radiologists in consensus determined whether CT would have been performed, had CTS not been an option, and whether CTS was an adequate examination. Thereafter, it was determined whether the use of CTS instead of CT in retrospect was beneficial, neutral, or detrimental for the radiological work-up. The radiation dose to the patient population was determined both for the actual clinical situation and for the alternative scenario that would result, had CTS not been available. Results: During 1 month 3.5 years before the survey, 149 patients (74 women, age 18-91 years) had undergone CTS for clinical purposes. It was judged that CT would have been performed in 100 cases, had CTS not been available, and that CTS obviated the need for CT in 80 cases. CTS was judged as beneficial, neutral, and detrimental for the radiological work-up in 85, 13, and two cases, respectively. For the entire study population, the use of CTS decreased the average effective dose from 2.7 to 0.7 mSv. Conclusions: The present study indicates that CTS may have benefits for the radiological work-up as it has the potential to both optimize the use of CT resources and reduce the effective dose to the patient population. A drawback is that CTS examinations may fail to reveal pathology visible with CT and in clinically doubtful cases further investigations including other imaging procedures should be considered.
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| 41. |
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| 42. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Chest tomosynthesis: technical and clinical perspectives.
- 2014
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Ingår i: Seminars in respiratory and critical care medicine. - : Georg Thieme Verlag KG. - 1098-9048 .- 1069-3424. ; 35:1, s. 17-26
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Tidskriftsartikel (refereegranskat)abstract
- The recent implementation of chest tomosynthesis is built on the availability of large, dose-efficient, high-resolution flat panel detectors, which enable the acquisition of the necessary number of projection radiographs to allow reconstruction of section images of the chest within one breath hold. A chest tomosynthesis examination obtains the increased diagnostic information provided by volumetric imaging at a radiation dose comparable to that of conventional chest radiography. There is evidence that the sensitivity of chest tomosynthesis may be at least three times higher than for conventional chest radiography for detection of pulmonary nodules. The sensitivity increases with increasing nodule size and attenuation and decreases for nodules with subpleural location. Differentiation between pleural and subpleural lesions is a known pitfall due to the limited depth resolution in chest tomosynthesis. Studies on different types of pathology report increased detectability in favor of chest tomosynthesis in comparison to chest radiography. The technique provides improved diagnostic accuracy and confidence in the diagnosis of suspected pulmonary lesions on chest radiography and facilitates the exclusion of pulmonary lesions in a majority of patients, avoiding the need for computed tomography (CT). However, motion artifacts can be a cumbersome limitation and breathing during the tomosynthesis image acquisition may result in severe artifacts significantly affecting the detectability of pathology. In summary, chest tomosynthesis has been shown to be superior to chest conventional radiography for many tasks and to be able to replace CT in selected cases. In our experience chest tomosynthesis is an efficient problem solver in daily clinical work.
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| 43. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Extracolonic Findings-Identification at Low-Dose CTC.
- 2021
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 195:3-4, s. 188-197
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Tidskriftsartikel (refereegranskat)abstract
- In contrast to optical colonoscopy, computed tomography colonography (CTC) has the ability to reveal pathology outside of the colon. While identification of colorectal lesions at CTC requires only limited radiation dose, the detection of abnormalities in extracolonic soft tissue requires more radiation. The purpose of this study was to investigate the influence of ultra-low-dose (ULD) CTC on the detection and characterisation of extracolonic findings. In a prospective study 49 patients with colorectal symptoms were examined with CTC adding a ULD series (mean effective dose 0.9±0.4mSv) to the normal unenhanced standard dose (SD) series (mean effective dose 3.6±1.2mSv). Five radiologists individually and blindly evaluated the ULD, followed by evaluation of the SD after ≥9weeks (median 35weeks). A ViewDEX-based examination protocol was used, including a confidence scale and a graded assessment of need for follow-up according to the CTC Reporting and Data System (C-RADS E0-E4). The reference findings comprised the combined information from CTC (ULD, SD and contrast-enhanced CTC series) and a 4-year radiological and clinical follow-up. For the overall detection of reference findings (E2-E4) we found a statistically significant difference in favour of SD. This, however, was not the case when looking at classification of possibly important/important reference findings (E3-E4). Our results suggest that CTC with ULD (0.9mSv) is comparable to SD (3.6mSv) for identification of clinically relevant extracolonic pathology, but there is a large inter-observer variability.
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| 44. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Incidental findings and their handling in the Swedish CArdioPulmonary bioimage study (SCAPIS)
- 2017
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Ingår i: Incidental Radiological Findings. - Cham : Springer International Publishing. - 0942-5373 .- 2197-4187. - 9783319425818 - 9783319425795 - 9783319826127 ; , s. 91-101
-
Bokkapitel (refereegranskat)abstract
- The Swedish CArdioPulmonary bioImage Study (SCAPIS) combines the use of new imaging technologies, large-scale proteomics/metabolomics/genomics, and epidemiological analyses to extensively characterize a Swedish cohort of 30,000 men and women aged between 50 and 64 years. Its main aims are to improve risk prediction and to optimize our ability to study mechanisms of cardiopulmonary diseases. SCAPIS is currently recruiting at six sites in Sweden, and a pilot study was conducted in 2012 to test the feasibility of the comprehensive study protocol. In the planning phase, it was recognized that the detailed phenotyping used in SCAPIS would identify a large number of clinical findings in need of medical attention. This was confirmed by evaluation of results from the pilot study. Here we focus on pulmonary nodules and asymptomatic coronary artery stenosis. These clinical features were observed in a large number of participants, and the clinical handing and prognosis related to these observations are unclear. They thus posed great challenges for the study in their practical and ethical handling. This chapter describes how we developed procedures to handle these findings based on existing evidence and expert consensus as well as deliberations on ethical issues.
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| 45. |
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| 46. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Nodule detection by chest tomosynthesis
- 2009
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Ingår i: 2nd World Congress of Thoracic Imaging and Diagnosis in Chest Disease, 30 May-2 June 2009, Valencia, Spain.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 47. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Overview of two years of clinical experience of chest tomosynthesis at Sahlgrenska University Hospital.
- 2010
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 139:1-3, s. 124-129
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Tidskriftsartikel (refereegranskat)abstract
- Since December 2006, approximately 3800 clinical chest tomosynthesis examinations have been performed at our department at Sahlgrenska University Hospital. A subset of the examinations has been included in studies of the detectability of pulmonary nodules, using computed tomography (CT) as the gold standard. Visibility studies, in which chest tomosynthesis and CT have been compared side-by side, have been used to determine the depiction potential of chest tomosynthesis. Comparisons with conventional chest radiography have been made. In the clinical setting, chest tomosynthesis has mostly been used as an additional examination. The most frequent indication for chest tomosynthesis has been suspicion of a nodule or tumour. In visibility studies, tomosynthesis has depicted over 90 % of the nodules seen on the CT scan. The corresponding figure for chest radiography has been <30 %. In the detection studies, the lesion-level sensitivity has been approximately 60 % for tomosynthesis and 20 % for chest radiography. In one of the detection studies, an analysis of all false-positive nodules was performed. This analysis showed that all findings had morphological correlates on the CT examinations. The majority of the false-positive nodules were localised in the immediate subpleural region. In conclusion, chest tomosynthesis is an improved chest radiography method, which can be used to optimise the use of CT resources, thereby reducing the radiation dose to the patient population. However, there are some limitations with chest tomosynthesis. For example, patients undergoing tomosynthesis have to be able to stand still and hold their breath firmly for 10 s. Also, chest tomosynthesis has a limited depth resolution, which may explain why pathology in the subpleural region is more difficult to interpret and artefacts from medical devices may occur.
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| 48. |
- Johnsson, Åse (Allansdotter), 1966, et al.
(författare)
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Pulmonary nodule size evaluation with chest tomosynthesis.
- 2012
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 1527-1315 .- 0033-8419. ; 265:1, s. 273-82
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To evaluate intra- and interobserver variability, as well as agreement for nodule size measurements on chest tomosynthesis and computed tomographic (CT) images. Materials and Methods: The Regional Ethical Review Board approved this study, and all participants gave written informed consent. Thirty-six segmented nodules in 20 patients were included in the study. Eight observers measured the left-to-right, inferior-to-superior, and longest nodule diameters on chest tomosynthesis and CT images. Intra- and interobserver repeatability, as well as agreement between measurements on chest tomosynthesis and CT images, were assessed as recommended by Bland and Altman. Results: The difference between the mean manual and the segmented diameter was -2.2 and -2.3 mm for left-to-right and -2.6 and -2.2 mm for the inferior-to-superior diameter for measurements on chest tomosynthesis and CT images, respectively. Intraobserver 95% limits of agreement (LOA) for the longest diameter ranged from a lower limit of -1.1 mm and an upper limit of 1.0 mm to -1.8 and 1.8 mm for chest tomosynthesis and from -0.6 and 0.9 mm to -3.1 and 2.2 mm for axial CT. Interobserver 95% LOA ranged from -1.3 and 1.5 mm to -2.0 and 2.1 mm for chest tomosynthesis and from -1.8 and 1.1 mm to -2.2 and 3.1 mm for axial CT. The 95% LOA concerning the mean of the observers' measurements of the longest diameter at chest tomosynthesis and axial CT were ±2.1 mm (mean measurement error, 0 mm). For the different observers, the 95% LOA between the modalities ranged from -2.2 and 1.6 mm to -3.2 and 2.8 mm. Conclusion: Measurements on chest tomosynthesis and CT images are comparable, because there is no evident bias between the modalities and the repeatability is similar. The LOA between measurements for the two modalities raise concern if measurements from chest tomosynthesis and CT were to be used interchangeably. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111459/-/DC1.
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| 49. |
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| 50. |
- Lagerstrand, Kerstin M, et al.
(författare)
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Reliable phase-contrast flow volume magnetic resonance measurements are feasible without adjustment of the velocity encoding parameter
- 2020
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Ingår i: Journal of Medical Imaging. - 2329-4310 .- 2329-4302. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To show that adjustment of velocity encoding (VENC) for phase-contrast (PC) flow volume measurements is not necessary in modern MR scanners with effective background velocity offset corrections. Approach: The independence on VENC was demonstrated theoretically, but also experimentally on dedicated phantoms and on patients with chronic aortic regurgitation (n = 17) and one healthy volunteer. All PC measurements were performed using a modern MR scanner, where the pre-emphasis circuit but also a subsequent post-processing filter were used for effective correction of background velocity offset errors. Results: The VENC level strongly affected the velocity noise level in the PC images and, hence, the estimated peak flow velocity. However, neither the regurgitant blood flow volume nor the mean flow velocity displayed any clinically relevant dependency on the VENC level. Also, the background velocity offset was shown to be close to zero (
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