| 1. |
- Broxvall, Mathias, 1976-, et al.
(författare)
-
Fast GPU based adaptive filtering of 4D echocardiography
- 2012
-
Ingår i: IEEE Transactions on Medical Imaging. - Piscataway, USA : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0062 .- 1558-254X. ; 31:6, s. 1165-1172
-
Tidskriftsartikel (refereegranskat)abstract
- Time resolved three-dimensional (3D) echocardiography generates four-dimensional (3D+time) data sets that bring new possibilities in clinical practice. Image quality of four-dimensional (4D) echocardiography is however regarded as poorer compared to conventional echocardiography where time-resolved 2D imaging is used. Advanced image processing filtering methods can be used to achieve image improvements but to the cost of heavy data processing. The recent development of graphics processing unit (GPUs) enables highly parallel general purpose computations, that considerably reduces the computational time of advanced image filtering methods. In this study multidimensional adaptive filtering of 4D echocardiography was performed using GPUs. Filtering was done using multiple kernels implemented in OpenCL (open computing language) working on multiple subsets of the data. Our results show a substantial speed increase of up to 74 times, resulting in a total filtering time less than 30 s on a common desktop. This implies that advanced adaptive image processing can be accomplished in conjunction with a clinical examination. Since the presented GPU processor method scales linearly with the number of processing elements, we expect it to continue scaling with the expected future increases in number of processing elements. This should be contrasted with the increases in data set sizes in the near future following the further improvements in ultrasound probes and measuring devices. It is concluded that GPUs facilitate the use of demanding adaptive image filtering techniques that in turn enhance 4D echocardiographic data sets. The presented general methodology of implementing parallelism using GPUs is also applicable for other medical modalities that generate multidimensional data.
|
|
| 2. |
- Dimitriou, Praxitelis, et al.
(författare)
-
Cardiovascular magnetic resonance imaging and transthoracic echocardiography in the assessment of stenotic aortic valve area : a comparative study
- 2012
-
Ingår i: Acta Radiologica. - London, United Kingdom : Royal Society of Medicine Press. - 0284-1851 .- 1600-0455. ; 53:9, s. 995-1003
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Magnetic resonance (MR) imaging and echocardiography both allow assessment of aortic valve stenosis. In MR the aortic valve area (AvA) is measured using planimetry while in transthoracic echocardiography (TTE) AvA is usually calculated by applying the continuity equation.Purpose: To compare the measured stenotic aortic valve areas using five different MR-acquisition alternatives with the corresponding area values calculated by TTE.Material and Methods: The aortic valve was imaged in 14 patients, with diagnosed aortic valve stenosis, using balanced steady state free precession (bSSFP) gradient echo (GE) and phase contrast imaging (PC). Three adjacent slices were planned to encompass the aortic valve and the aortic valve area was measured using planimetry. The two sets of complex valued images generated by the PC sequence formed three kinds of images that could be used for aortic valve area measurements: the magnitude image (PC/Mag), the modulus (PCA/M), and phase difference (PCA/P) between the two complex images, respectively. The valve area from TTE was calculated using the continuity equation. A cut-off of <1.0 cm(2) was used as a criteria for severe stenosis.Results: The mean area differences between the different MR acquisitions and TTE method were -0.05 ± 0.37 cm(2) (GE), -0.18 ± 0.46 cm(2) (bSSFP), 0.27 ± 0.43 cm(2) (PC/Mag), 0.15 ± 0.32 cm(2) (PCA/P), and 0.26 ± 0.27 cm(2) (PCA/M). The valve area was significantly overestimated using PCA/M that, in turn, implied a significant underestimation of the aortic valve stenosis severity compared to the assessments using TTE.Conclusion: The smallest area valve difference between TTE and an MR-acquisition alternative is obtained with gradient echo images. The use of PCA/M leads to significant differences in planimetry measurements of the aortic valve orifice and the gradation of the stenosis severity compared to TTE.
|
|
| 3. |
- Egerlid, Rigmor, et al.
(författare)
-
Correlation of aortic-, mitral- and tricuspid annuli amplitudes and velocities at rest with left ventricular stroke volume in young healthy subjects : an echocardiographic study
- 2014
-
Ingår i: Experimental and Clinical Cardiology. - Bern, Switzerland : Cardiology Academic Press. - 1918-1515. ; 20:1, s. 2655-2664
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To study the correlation of the aortic-, mitral-, and tricuspid annuli and their amplitudes and velocities with the left ventricular stroke volume (LVSV) in young healthy subjects at rest using echocardiography.Methods: Twenty four healthy subjects with mean age 24 years were examined with echocardiography. The systolic, early and late diastolic velocities of the aortic-, mitral- and tricuspid annuli were measured with pulsed wave tissue Doppler and quantitative two-dimensional color Doppler tissue imaging as well as their amplitudes.Results: There was only one significant correlation found between the measured parameters and LVSV, a finding that can be statistically random. All other correlations were not significant.Conclusion: In young healthy individuals at rest the correlation between the amplitudes and velocities of the aortic-, mitral- and tricuspid annuli and LVSV is weak.
|
|
| 4. |
- Jorstig, Stina Hellstrandh, 1978-, et al.
(författare)
-
Calculation of right ventricular stroke volume in short-axis MR images using the equation of the tricuspid plane
- 2012
-
Ingår i: Clinical Physiology and Functional Imaging. - Malden, USA : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:1, s. 5-11
-
Tidskriftsartikel (refereegranskat)abstract
- Short-axis (SA) magnetic resonance (MR) images are commonly planned parallel to the left atrioventricular valve. This orientation leads to oblique slices of the right ventricle (RV) with subsequent difficulties in separating the RV from the right atrium in the SA images. The insertion points of the tricuspid valve (TV) in the myocardium can be clearly identified in the right ventricle long axis (RVLA) and four-chamber (4CH) views. The purpose of this study was to develop a method that transfers the position of the tricuspid plane, as seen in the RVLA and 4CH views, to the SA images to facilitate the separation of the RV from the atrium. This methodology, termed Dissociating the Right Atrium from the Ventricle Volume (DRAW), was applied in 20 patients for calculations of right ventricular stroke volume (RVSV). The RVSV using DRAW (RVSVDRAW) was compared to left ventricular stroke volumes (LVSV) obtained from flow measurements in the ascending aorta. The RVSV was also determined using the conventional method (RVSVCONV) where the stack of images from the SA views are summarized, and a visual decision is made of the most basal slice to be included in the RV. The mean difference between RVSVDRAW and LVSV was 0.1 +/- 12.7 ml, while the mean difference between RVSVCONV and LVSV was 0.33 +/- 14.3 ml. Both the intra- and interobserver variability were small using the DRAW methodology, 0.6 +/- 3.5 and 1.7 +/- 2.7 ml, respectively. In conclusion, the DRAW method can be used to facilitate the separation of the RV and the atrium.
|
|
| 5. |
|
|
| 6. |
- Loiske, Karin, 1978-
(författare)
-
Echocardiographic measurements of the heart : with focus on the right ventricle
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Echocardiography is a well established technique when evaluating the size and function of the heart. One of the most common ways to measure the size of the right ventricle (RV) is to measure the RV outflow tract 1(RVOT1). Several ways to measure RVOT1 are described in the literature.These ways were compared with echocardiography on 27 healthy subjects.The result showed significant differences in RVOT1, depending on the way it was measured, concluding that the same site, method and body positionshould be used when comparing RVOT1 in the same subject over time.One parameter to evaluate the RV diastolic function (RVDF) is to measure the RV isovolumetric relaxation time (RV-IVRT), a sensitive marker ofRV dysfunction. There are different ways to measure this. In this thesis two ways of measuring RV-IVRT and their time intervals were compared in 20 patients examined with echocardiography. There was a significant difference between the two methods indicating that they are not measuring the same interval.Another way to assess the RVDF is to measure the maximal early diastolicvelocity (MDV) in the long-axis direction. MDV can be measured bydifferent methods, hence 29 patients were examined and MDV was measured according to two methods. There was a good correlation but a poor agreement between the two methods meaning that reference values cannot be used interchangeably.Takotsubo cardiomyopathy is characterized by apical wall motion abnormalities without coronary stenosis. The pathology of this condition remains unclear. To evaluate biventricular changes in systolic long-axisfunction and diastolic parameters in the acute phase and after recovery, 13 patients were included and examined with echocardiography at admission and after recovery. The results showed significant biventricular improvementof systolic long-axis function while most diastolic parameters remainedunchanged.
|
|
| 7. |
- Loiske, Karin, 1978-, et al.
(författare)
-
Echocardiographic measurements of the right ventricle : right ventricular outflow tract 1
- 2010
-
Ingår i: Clinical research in cardiology. - Berlin : Springer. - 1861-0684 .- 1861-0692. ; 99:7, s. 429-435
-
Tidskriftsartikel (refereegranskat)abstract
- The size of the ventricles of the heart is important to establish during the clinical echocardiographic examination. Due to the complex anatomy of the right ventricle, it is difficult to measure its size at times. One of the most frequently used ways is to measure the right ventricular outflow tract (RVOT1), probably due to its good reproducibility. However, in the literature different ways are described to measure RVOT1, both at different sites and using different methods such as M-mode and 2D. The first aim of the present study was to exam if there is a significant difference in the outcome of RVOT1 using different sites and methods to measure it. The second aim was to study if there is a significant difference between the usually preferred left lateral decubitus position during the echocardiographic examination and the supine decubitus position, which the echocardiographer sometimes can be compelled to use if the patient is unable to lie in the left lateral decubitus position
|
|
| 8. |
- Loiske, Karin, 1978-, et al.
(författare)
-
Left and right ventricular systolic long-axis function and diastolic function in patients with takotsubo cardiomyopathy
- 2011
-
Ingår i: Clinical Physiology and Functional Imaging. - Oxford : Wiley. - 1475-0961 .- 1475-097X. ; 31:3, s. 203-208
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: Takotsubo cardiomyopathy is characterized by apical wall motion abnormalities without coronary stenosis. Limited information is available on the genesis of the underlying reversible contractile disorder. Our objective in this prospective study was to investigate biventricular changes in systolic long-axis function and diastolic parameters in the acute phase and after recovery.Methods and results: Thirteen consecutive patients were examined by echocardiography and coronary angiography at admission and again by echocardiography after 3 months. Amplitudes, systolic and diastolic velocities of the mitral and tricuspid annuli and conventional diastolic parameters were measured. Systolic long-axis shortening of the left ventricle (LV) and right ventricle (RV) improved from 9·6 ± 2·2 mm to 11·2 ± 1·9 mm (P = 0·02) and from 21·3 ± 3·6 mm to 24·1 ± 2·8 mm (P = 0·02), respectively. LV systolic, early and late diastolic velocities measured by pulsed-wave tissue Doppler also improved, while additional conventional diastolic parameters of the LV and RV diastolic function were unchanged.Conclusions: Takotsubo cardiomyopathy temporarily affects systolic LV and RV function, while most diastolic parameters remain unchanged
|
|
| 9. |
- Nygren, Britt-Marie, 1956-, et al.
(författare)
-
Comparison between aortic valve area obtained by planimetry and by using the continuity equation : a transthoracic echocardiographic study
- 2014
-
Ingår i: Experimental and Clinical Cardiology. - : Cardiology Academic Press. - 1918-1515. ; 20:1, s. 2665-2673
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: In patients with aortic stenosis the valve area is usually obtained by transthoracic echocardiography (TTE) and the continuity equation. The method is time consuming and another way to obtain the area is to trace the valves (planimetry).In the present study the both methods are compared.Methods: 34 consecutive patients with known aortic stenosis were included and examined by TTE. The aortic valve area was obtained using planimetry in the short axis view and by using the continuity equation.Results: There was no significant difference between the two methods (p=0.16) and the correlation was rather good (r=0.60; p<0.01). The agreement was better in the lower ranges of areas (<1.1 cm2) than in the higher ranges (>1.1 cm2).Conclusions: The agreement between the both methods is rather good in the lower ranges of areas (<1.1 cm2), but worse in the higher ranges of areas (>1.1 cm2). The difference between the areas in the lower ranges can be up to 0.3 cm2, a difference that can be the difference between thoracic surgery or not. It is therefore best to still use the continuity equation during TTE.
|
|
| 10. |
- Nygren, Britt-Marie, 1956-, et al.
(författare)
-
The Aortic, Mitral and Tricuspid Annuli and Their Velocities : A Comparative Echocardiographic Study
- 2014
-
Ingår i: Journal of Clinical & Experimental Cardiology. - : OMICS Publishing Group. - 2155-9880 .- 2155-9880. ; 5:8
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: The velocities at the mitral (MA) and tricuspid (TA) annuli have earlier been studied by using both colour coded tissue Doppler imaging (TVI) and pulsed wave tissue Doppler imaging (PW DTI) but the velocities at the aortic annulus (AA) and the both other annuli have only been examined using TVI and not PW DTI in one study before. Therefore the aim of the present study was to compare the systolic (s´)-, early (e´)- and late (a´) diastolic velocities at the three different annuli with both methods.Design: 24 healthy subjects were examined by echocardiography and the velocities at the annuli were measured using PW DTI and TVI.Results: For all the velocities there was a statistically significant difference (p<0.001) between the two methods, the velocities obtained by PW DTI being higher. However some heterogeneity of the mean velocity differences between methods were noted by annuli and site, but PW DTI always showing highest mean levels. There were also statistically significant velocity differences between different sites and annuli. There was a good-very good intra- and inter observer reproducibility of measuring the velocities at the aortic annulus.Conclusion: The velocities were significantly higher using PW DTI than using TVI at the different annuli, probably mainly due to the way the respective method is measuring the velocities. In addition there was shown some heterogeneity of the mean velocity differences and statistically significant velocity differences between different sites and annuli.The both methods need different reference values and could not be used interchangeably. The findings could be of importance in special cases where the interaction between the three different annuli and sites is of importance, but including the velocities at all the three different sites in a clinical routine echocardiographic examination will often not be necessary.
|
|
