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| 2. |
- Hellgren, Laila, et al.
(författare)
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Severe mitral regurgitation : relations between magnetic resonance imaging, echocardiography and natriuretic peptides
- 2008
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 42:1, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Assessment of the severity of mitral regurgitation by echocardiography can be technically demanding in certain patients and supplementary methods are therefore desirable. This study addressed the agreement between magnetic resonance imaging (MRI) and echocardiography, and their relations to natriuretic peptides (NT-proANP and NT-proBNP), in quantifying severe mitral regurgitation.METHODS:Eighteen patients with severe mitral regurgitation scheduled for surgery underwent MRI, echocardiography and assay of natriuretic peptides preoperatively for clinical assessment.RESULTS:MRI and echocardiography were comparable in measuring severity of regurgitation qualitatively but not quantitatively, mitral regurgitant fraction (mean difference 27.5 (11) ml). There was a correlation between increasing regurgitant fraction on MRI and increased levels of plasma NT-proANP and NT-proBNP. In echocardiography, increasing vena contracta width and increasing PISA correlated to increased levels of plasma NT-proANP and NT-proBNP. No other correlation was found between measures on MRI and echocardiography and natriuretic peptides.CONCLUSIONS:MRI and echocardiography were comparable grading the severity of mitral regurgitation with qualitative measures but not with quantitative measures. MRI might be a complement to echocardiography when a more distinct measure of the regurgitant volume is needed, as in paravalvular leakage.
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| 3. |
- Jerdhaf, Oskar, et al.
(författare)
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Evaluating Pre-Trained Language Models for Focused Terminology Extraction from Swedish Medical Records
- 2022
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Ingår i: Proceedings of the Workshop on Terminology in the 21st century. - : European Language Resources Association. - 9791095546955 ; , s. 30-32
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Konferensbidrag (refereegranskat)abstract
- In the experiments briefly presented in this abstract, we compare the performance of a generalist Swedish pre-trained language model with a domain-specific Swedish pre-trained model on the downstream task of focused terminology extraction of implant terms, which are terms that indicate the presence of implants in the body of patients. The fine-tuning is identical for both models. For the search strategy we rely on KD-Tree that we feed with two different lists of term seeds, one with noise and one without noise. Results shows that the use of a domain-specific pre-trained language model has a positive impact on focused terminology extraction only when using term seeds without noise.
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| 4. |
- Kvernby, Sofia, et al.
(författare)
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Quantitative comparison of data-driven gating and external hardware gating for 18F-FDG PET-MRI in patients with esophageal tumors
- 2021
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Ingår i: European Journal of Hybrid Imaging. - : Springer Nature. - 2510-3636. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundRespiratory motion during PET imaging reduces image quality. Data-driven gating (DDG) based on principal component analysis (PCA) can be used to identify respiratory signals. The use of DDG, without need for external devices, would greatly increase the feasibility of using respiratory gating in a routine clinical setting. The objective of this study was to evaluate data-driven gating in relation to external hardware gating and regular static image acquisition on PET-MRI data with respect to SUVmax and lesion volumes.MethodsSixteen patients with esophageal or gastroesophageal cancer (Siewert I and II) underwent a 6-min PET scan on a Signa PET-MRI system (GE Healthcare) 1.5-2 h after injection of 4 MBq/kg F-18-FDG. External hardware gating was done using a respiratory bellow device, and DDG was performed using MotionFree (GE Healthcare). The DDG raw data files and the external hardware-gating raw files were created on a Matlab-based toolbox from the whole 6-min scan LIST-file. For comparison, two 3-min static raw files were created for each patient. Images were reconstructed using TF-OSEM with resolution recovery with 2 iterations, 28 subsets, and 3-mm post filter. SUVmax and lesion volume were measured in all visible lesions, and noise level was measured in the liver. Paired t-test, linear regression, Pearson correlation, and Bland-Altman analysis were used to investigate difference, correlation, and agreement between the methods.ResultsA total number of 30 lesions were included in the study. No significant differences between DDG and external hardware-gating SUVmax or lesion volumes were found, but the noise level was significantly reduced in the DDG images. Both DDG and external hardware gating demonstrated significantly higher SUVmax (9.4% for DDG, 10.3% for external hardware gating) and smaller lesion volume (- 5.4% for DDG, - 6.6% for external gating) in comparison with non-gated static images.ConclusionsData-driven gating with MotionFree for PET-MRI performed similar to external device gating for esophageal lesions with respect to SUVmax and lesion volume. Both gating methods significantly increased the SUVmax and reduced the lesion volume in comparison with non-gated static acquisition. DDG resulted in reduced image noise compared to external device gating and static images.
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| 5. |
- Langner, Taro, et al.
(författare)
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Identifying morphological indicators of aging with neural networks on large-scale whole-body MRI
- 2020
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Ingår i: IEEE Transactions on Medical Imaging. - 0278-0062 .- 1558-254X. ; 39:5, s. 1430-1437
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Tidskriftsartikel (refereegranskat)abstract
- A wealth of information is contained in images obtained by whole-body magnetic resonance imaging (MRI). Studying the link between the imaged anatomy and properties known from outside sources has the potential to give new insights into the underlying factors that manifest themselves in individual human morphology. In this work we investigate the expression of age-related changes in the whole-body image. A large dataset of about 32,000 subjects scanned from neck to knee and aged 44–82 years from the UK Biobank study was used for a machine-based analysis. We trained a convolutional neural network based on the VGG16 architecture to predict the age of a given subject based on image data from these scans. In 10-fold cross-validation on 23,000 of these images the network reached a mean absolute error (MAE) of 2.49 years (R 2 = 0.83) and showed consistent performance on a separate test set of another 8,000 images. On a second test set of 100 images the network outperformed the averaged estimates given by three experienced radiologists, which reached an MAE of 5.58 years (R 2 = 0.08), by more than three years on average. In an attempt to explain these findings, we employ saliency analysis that opens up the image-based criteria used by the automated method to human interpretation. We aggregate the saliency into a single anatomical visualization which clearly highlights structures in the aortic arch and knee as primary indicators of age.
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| 7. |
- Linder, Gustav, et al.
(författare)
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F-18-FDG-PET/MRI in preoperative staging of oesophageal and gastroesophageal junctional cancer
- 2019
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Ingår i: Clinical Radiology. - : W B SAUNDERS CO LTD. - 0009-9260 .- 1365-229X. ; 74:9, s. 718-725
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To evaluate integrated 2-[F-18]-fluoro-2-deoxy-D-glucose (F-18-FDG) positron-emission tomography (PET)/magnetic resonance imaging (MRI), in comparison with the standard technique, integrated F-18-FDG-PET/computed tomography (CT), in preoperative staging of oesophageal or gastroesophageal junctional cancer.MATERIALS AND METHODS: In the preoperative staging of 16 patients with oesophageal or gastroesophageal junctional cancer, F-18-FDG-PET/MRI was performed immediately following the clinically indicated F-18-FDG-PET/CT. MRI-sequences included T1-weighted fat-water separation (Dixon's technique), T2-weighted, diffusion-weighted imaging (DWI), and gadolinium contrast-enhanced T1-weighted three-dimensional (3D) imaging. PET was performed with F-18-FDG. Two separate teams of radiologists conducted structured blinded readings of F-18-FDG-PET/MRI or F-18-FDG-PET/CT, which were then compared regarding tumour measurements and characteristics as well as assessment of inter-rater agreement (Cohen's kappa) for the clinical tumour, nodal and metastatic (TNM) stage.RESULTS: There were no medical complications. Comparison of tumour measurements revealed high correlations without significant differences between modalities. The maximum standardised uptake value (SUVmax) values of the primary tumour with F-18-FDG-PET/MRI had excellent correlation to those of F-18-FDG-PET/CT (0.912, Spearman's rho). Inter-rater agreement between the techniques regarding T-stage was only fair (Cohen's kappa, 0.333), arguably owing to relative over-classification of the T-stage using F-18-FDG-PET/CT. Agreements in the assessment of N- and M-stage were substantial (Cohen's kappa, 0.849 and 0.871 respectively).CONCLUSION: Preoperative staging with F-18-FDG-PET/MRI is safe and promising with the potential to enhance tissue resolution in the area of interest. F-18-FDG-PET/MRI and F-18-FDG-PET/CT correlated well for most of the measured values and discrepancies were seen mainly in the assessment of the T-stage. These results facilitate further studies investigating the role of F-18-FDG-PET/MRI in, e.g., predicting or determining the response to neoadjuvant therapy.
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| 8. |
- Nordenskjöld, Anna M., 1977-, et al.
(författare)
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Unrecognized myocardial infarction assessed by cardiac magnetic resonance imaging is associated with adverse long-term prognosis
- 2018
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 13:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Unrecognized myocardial infarctions (UMIs) are common. The study is an extension of a previous study, aiming to investigate the long-term (>5 year) prognostic implication of late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR) detected UMI in patients with suspected stable coronary artery disease (CAD) without previously diagnosed myocardial infarction (MI).Methods: In 235 patients with suspected stable CAD without previous MI, LGE-CMR imaging and coronary angiography were performed. LGE with a subendocardial component detectable in more than one imaging plane was required to indicate UMI. The stenosis grade of the coronary arteries was determined, including in the artery supplying an infarcted area. Stenosis >= 70% stenosis was considered significant. Patients were followed for 5.4 years in mean regarding a composite endpoint of cardiovascular death, MI, hospitalization due to heart failure, stable or unstable angina.Results: UMI were present in 58 of 235 patients (25%). Thirty-nine of the UMIs were located downstream of a significant coronary stenosis. During the follow-up 40 patients (17.0%) reached the composite endpoint. Of patients with UMI, 34.5% (20/58) reached the primary endpoint compared to 11.3% (20/177) of patients with no UMI (HR 3.7, 95% CI 2.0 +/- 6.9, p<0.001). The association between UMI and outcome remained (HR 2.3, 95% CI 1.2 +/- 4.4, p = 0.012) after adjustments for age, gender, extent of CAD and all other variables univariate associated with outcome. Sixteen (41%) of the patients with an UMI downstream of a significant stenosis reached the endpoint compared to four (21%) patients with UMI and no relation to a significant stenosis (HR 2.4, 95% CI 0.8 +/- 7.2, p = 0.12).Conclusion: The presence of UMI was independently associated with an increased risk of cardiovascular events during long-term follow up.
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| 9. |
- Sörensen, Jens, et al.
(författare)
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Myocardial External Efficiency in Asymptomatic Severe Primary Mitral Regurgitation Using 11C-Acetate PET
- 2023
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 64:4, s. 645-651
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Tidskriftsartikel (refereegranskat)abstract
- Subjects with asymptomatic moderate-severe or severe primary mitral regurgitation (MR) are closely observed for signs of progression or symptoms requiring surgical intervention. The role of myocardial metabolic function in progression of MR is poorly understood. We used 11C-acetate positron emission tomography (PET) to non-invasively measure myocardial external efficiency (MEE), which is the energetic ratio of external cardiac work and left ventricular oxygen consumption.Methods and Results: 47 patients in surveillance with MR and no or minimal symptoms prospectively underwent PET, echocardiography and cardiac magnetic resonance imaging (CMR) on the same day. PET was used to simultaneously measure cardiac output, LV mass and oxygen consumption to establish MEE. PET in patients were compared to healthy volunteers (n = 9). MEE and standard imaging indicators of regurgitation severity, LV volumes and function were studied as predictors of time to surgical intervention. Patients were followed median 3.0 years (interquartile range 2.0-3.8) and the endpoint was reached in 22 subjects (47%). MEE in patients reaching the endpoint (23.8±5.0%) was lower than in censored patients (28.5±4.5%, P = 0.002) and in healthy volunteers (30.1±4.9%, 0.001). MEE with a cut-off lower than 25.7% was significantly associated with the outcome (hazard ratio of 7.5 (95%CI: 2.7-20.6, p<0.0001) and retained independent significance when compared to standard imaging parameters.Conclusion: MEE independently predicted time to progression requiring valve surgery in patients with asymptomatic moderate-severe or severe primary MR. The study suggests that inefficient myocardial oxidative metabolism precedes clinically observed progression in MR.
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