| 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. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
An unusual cause of high threshold values at pacemaker implantation
- 1997
-
Ingår i: Pacing and Clinical Electrophysiology. - : John Wiley & Sons. - 0147-8389 .- 1540-8159. ; 20:Part: 1, s. 366-7
-
Tidskriftsartikel (refereegranskat)abstract
- An 81-year old man with third-degree AV block and weakness underwent an unsuccessful attempt to DDD pacemaker implant caused by hypothyroidism. Administration of thyroxin until he was euthyroid permitted implantation with normal stimulation thresholds.
|
|
| 5. |
- Emilsson, Kent, 1963-
(författare)
-
Can the amplitude of mitral annulus motion be used in the assessment of left ventricular systolic function in patients with left ventricular wall thickness in the upper limit of normal to mild hypertrophy?
- 2003
-
Ingår i: Experimental and clinical cardiology. - 1205-6626. ; 8:1, s. 29-30
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Mitral annulus motion (MAM) obtained by echocardiography can be used in the assessment of left ventricular systolic function (LVSF). However, it has been shown that the amplitude of MAM is decreased in patients with left ventricular wall thickness (LVWT) greater than 14 mm.OBJECTIVE: To study if the amplitude of MAM can be used in the assessment of LVSF in patients with LVWT in the upper limit of normal to mild hypertrophy (12 mm to 14 mm).METHODS: Eighteen consecutive patients with LVWT of 12 mm to 14 mm were compared to 18 age- and sex-matched patients with LVWT less than 12 mm.RESULTS: There was no significant difference between the amplitude of MAM in the two groups.CONCLUSIONS: MAM can be used in the assessment of LVSF in patients with LVWT in the upper limit of normal to mild hypertrophy and be related to reference values.
|
|
| 6. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
Comparison between angiographic right coronary artery motion and echocardiographic tricuspid annulus motion
- 2004
-
Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 38:2, s. 85-92
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare echocardiographic M-mode measurements of tricuspid annulus motion (TAM) with angiographic M-mode measurements of right coronary artery motion (RAM).DESIGN: Twenty-four patients were included and examined by echocardiography before the angiographic examination. The amplitudes and the velocities of TAM and the atrial contribution to the total amplitude of TAM were measured. The obtained values were compared with angiographic M-mode measurements of RAM at a proximal and a distal site of the second segment of the right coronary artery.RESULTS: There was no significant difference between several of the echocardiographic M-mode measurements of TAM and the angiographic M-mode measurements of RAM. However, the agreement was rather poor for some variables.CONCLUSION: Different parameters obtained from echocardiographic TAM are not interchangeable with values from angiographic RAM. If measurements of RAM are to be used in the assessment of right ventricular (RV) function further studies are needed to examine the correlation and agreement between RAM and different methods of measuring RV function, i.e. radionuclide angiography or magnetic resonance imaging.
|
|
| 7. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
Comparison between aortic annulus motion and mitral annulus motion obtained using echocardiography
- 2006
-
Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:5, s. 257-262
-
Tidskriftsartikel (refereegranskat)abstract
- Earlier studies have shown that the aortic root, in analogy with the mitral annulus, moves towards the left ventricular apex during systole. However, there are no earlier studies comparing the amplitude of the aortic annulus motion (AAM) with that of the mitral annulus (MAM), which was the main aim of the study. Another aim was to study the intra- and interobserver reproducibility (IIOR) of measuring AAM with M-mode and 2-D echocardiography as it is not obvious which of the methods that should be used. Twenty-one healthy subjects were examined by echocardiography. AAM and MAM were measured at different sites. IIOR was measured in 10 of the subjects. There was no significant difference between average AAM (15.3 +/- 1.5 mm) and average MAM (15.6 +/- 1.5 mm) and there was a rather good agreement between the variables. There was also no significant difference between AAM at the septal site (16.3 +/- 2 mm) and average MAM, but a significant difference between AAM at the lateral site (14.2 +/- 1.6 mm) and average MAM (P<0.001) and between the both sites of measuring AAM (P<0.001). The significant difference between the two sites of measuring AAM may have anatomical reasons but may also depend on difficulties in measuring AAM at the septal site where it has lower reproducibility than at the lateral site. IIOR of measuring AAM was good when using M-mode but poor when using 2-D echocardiography and AAM should preferably be measured using M-mode and not using 2-D echocardiography.
|
|
| 8. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
Comparison between aortic, mitral and tricuspid annular velocities measured with quantitative two-dimensional color Doppler tissue imaging in healthy subjects.
- 2007
-
Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 27:5, s. 275-83
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare the systolic, early and late diastolic velocities of the aortic, mitral and tricuspid annuli in healthy subjects and to study the intraobserver and interobserver reproducibility (IIOR) of measuring the velocities at the aortic annulus.METHODS: Twenty healthy subjects with mean age 28 years were investigated with quantitative two-dimensional color Doppler tissue imaging and the systolic, early and late diastolic velocities were measured at the aortic, mitral and tricuspid annuli.RESULTS: The mitral annulus had significant higher systolic velocity and early diastolic velocity than the aortic annulus. The late diastolic velocity was significant lower at the aortic annulus compared with the both other annuli. At the different sites of the annuli the highest systolic velocity and early diastolic velocity were measured at the lateral site of the mitral annulus, whereas the lowest systolic velocity was measured at the septal site of the same annulus. The lowest early diastolic velocity was found at the septal site of the aortic annulus. The highest late diastolic velocity was measured at the lateral site of the tricuspid annulus and the lowest at the lateral site of the aortic annulus.CONCLUSIONS: The mitral annulus has statistical significant higher systolic and early diastolic velocities than the aortic annulus. There are significant differences in velocities between several of the different sites of the annuli. IIOR of measuring the systolic and early diastolic velocities of the aortic annulus is good.
|
|
| 9. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
Comparison between circumflex artery motion and mitral annulus motion.
- 2001
-
Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 35:5, s. 318-325
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare mitral annulus motion (MAM) with circumflex artery motion (CXM) and the motion amplitude at an endocardial site (representing MAM) with an epicardial site (representing CXM) at the most basal lateral part of the atrioventricular plane (AVP).DESIGN: MAM and CXM were obtained in 28 patients examined by echocardiography and coronary angiography. The motion amplitude epicardially and endocardially was recorded by echocardiography in 13 patients with normal ejection fraction (EF) (> or = 0.50) and in 13 patients with decreased EF (<0.50).RESULTS: CXM was higher than MAM in most patients with normal EF but lower than MAM in most patients with decreased EF. The motion amplitude epicardially was significantly higher (p < 0.001) than endocardially in patients with normal EF. while there was no significant difference in patients with decreased EF.CONCLUSION: CXM represents the motion of the epicardial part of the AVP and differs from MAM, which represents the endocardial part of the wall. This must be considered when CXM is used for assessment of left ventricular systolic function.
|
|
| 10. |
- Emilsson, Kent, 1963-, et al.
(författare)
-
Comparison between maximal early diastolic velocity in long-axis direction obtained by M-mode echocardiography and by tissue Doppler in the assessment of right ventricular diastolic function
- 2005
-
Ingår i: Clinical Physiology and Functional Imaging. - Oxford : Blackwell. - 1475-0961 .- 1475-097X. ; 25:3, s. 178-182
-
Tidskriftsartikel (refereegranskat)abstract
- Recently the maximal early diastolic velocity in long-axis direction of the right ventricle (RV) obtained by tissue Doppler imaging (MDV TDI) has been introduced in the assessment of RV diastolic function (RVDF). There are reasons to think that also the maximal early diastolic velocity in long-axis direction of the RV obtained using M-mode echocardiography (MDV TAM) could be used to assess RVDF. Therefore, 29 patients were examined with echocardiography and MDV TAM and MDV TDI were measured and compared. A good correlation (r = 0.76, P< 0.001) was found between MDV TAM and MDV TDI indicating that MDV TAM might be used in the assessment of RVDF. However, the velocities obtained by MDV TDI (126.7 &PLUSMN; 38.9 mm s(-1)) were significantly (P< 0.001) higher than the velocities obtained by MDV TAM (78.3 &PLUSMN; 27.8 mm s(-1)) and the agreement between MDV TAM and MDV TDI was rather poor probably mainly due to differences in the measuring technique. This means that reference values cannot be used interchangeably between MDV TAM and MDV TDI. If MDV TAM is going to be used in the assessment of RVDF new reference values have to be produced if today's technique and recommendations to measure MDV TAM and MDV TDI are used. However, as most new echocardiographs are equipped with PW-TDI technology it seems preferable to use this technique and compare obtained values with already established reference values.
|
|
