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Sigfridsson, Andreas
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Publications (10 of 55) Show all publications
Petersson, S., Sigfridsson, A., Dyverfeldt, P., Carlhäll, C.-J. & Ebbers, T. (2016). Retrospectively Gated Intra-cardiac 4D Flow MRI using Spiral Trajectories. Magnetic Resonance in Medicine, 75(1), 196-206
Open this publication in new window or tab >>Retrospectively Gated Intra-cardiac 4D Flow MRI using Spiral Trajectories
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2016 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 75, no 1, p. 196-206Article in journal (Refereed) Published
Abstract [en]

Background: Four-dimensional (4D) flow MRI is a powerful tool for the quantification of blood flow and enables calculation of a range of unique hemodynamic parameters. However, the application of cardiac 4D flow MRI is limited by long scan times (20-40 minutes). The high efficiency of spiral readouts can be used to reduce scan times without sacrificing SNR. The aim of this work was to develop and validate a retrospectively gated 4D flow MRI sequence using spiral readouts for the measurement of intra-cardiac velocities.

Methods: A retrospectively ECG gated 4D flow sequence using stacks of spiral readouts was implemented on a clinical 1.5 T MRI scanner. The spiral 4D flow MRI sequence was validated in-vivo by comparisons with a two-dimensional (2D) through-plane velocity measurement and a conventional Cartesian 4D flow acquisition (SENSE factor 2) in 7 healthy volunteers (age 27 ± 3 years, four men) and 2 patients (age 19 and 52, women, only spiral 4D flow and 2D). Net volume flow was estimated from all three acquisition approaches and compared using one-way ANOVA. A quantitative pathline based validation was performed on the Cartesian and the spiral 4D flow MRI acquisitions by comparing the left ventricular inflow and outflow (two-tailed paired t-tests).

Results: The scan time of the spiral 4D flow sequence was 44±6% of the Cartesian counterpart. Compared to time-resolved 2D flow in the aorta, the spiral and Cartesian 4D flow acquisitions provided similarly good data, as there was no significant difference between the net volume flow for all acquisitions (Spiral: 89±14 ml, Cartesian: 93±11 ml, 2D: 93±18 ml, p=0.878). There was no significant difference between pathline-based calculations of inflow and outflow with either Cartesian (In: 88±15, Out: 85±16, p = 0.168) or spiral (In: 93±17 ml, Out: 84±18, p = 0.055) 4D flow acquisitions.

Conclusions: Retrospectively gated spiral cardiac 4D flow MRI permits more than two-fold reduction in scan time compared to conventional Cartesian 4D flow MRI without notable loss in data quality. The time-savings offered by spiral trajectories could provide a step towards the expanded clinical use of 4D flow MRI.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-101103 (URN)10.1002/mrm.25612 (DOI)000367739200019 ()
Note

Funding agencies: European Research Council [310612]; Swedish Research Council; Swedish Heart and Lung foundation

Available from: 2013-11-19 Created: 2013-11-19 Last updated: 2017-05-03Bibliographically approved
Petersson, S., Dyverfeldt, P., Sigfridsson, A., Lantz, J., Carlhäll, C.-J. & Ebbers, T. (2013). Quantification of Stenotic Flow Using Spiral 3D Phase-Contrast MRI.
Open this publication in new window or tab >>Quantification of Stenotic Flow Using Spiral 3D Phase-Contrast MRI
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2013 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Purpose: To evaluate the feasibility of spiral 3D phase contrast MRI for the assessment of velocity, volume flow rate, peak velocity and turbulent kinetic energy in stenotic flow.

Materials and Methods: A-stack-of-spirals 3D phase contrast MRI sequence was evaluated in-vitro against a conventional Cartesian sequence. Measurements were made in a flow phantom with a 75% stenosis. Both spiral and Cartesian imaging were performed using different scan orientations and flow rates. Volume flow rate, peak velocity and turbulent kinetic energy (TKE) were computed for both methods. For further validation, the estimated TKE was compared to computational fluid dynamics (CFD) data.

Results: The volume flow rate, peak velocity and TKE obtained with spiral 4D flow MRI agreed well with Cartesian data and CFD data. As expected, the short echo time of the spiral sequence resulted in less prominent displacement artifacts compared to the Cartesian sequence. However, both spiral and Cartesian flow rate estimates were sensitive to displacement when the flow was oblique to the encoding directions.

Conclusion: Spiral 3D phase contrast MRI appears favorable for the assessment of stenotic flow. The spiral sequence was more than three times faster and less sensitive to displacement artifacts when compared to a conventional Cartesian sequence.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-101107 (URN)
Available from: 2013-11-19 Created: 2013-11-19 Last updated: 2013-12-17Bibliographically approved
Sigfridsson, A., Petersson, S., Carlhäll, C. & Ebbers, T. (2012). Four-dimensional flow MRI using spiral acquisition. Magnetic Resonance in Medicine, 68(4), 1065-1073
Open this publication in new window or tab >>Four-dimensional flow MRI using spiral acquisition
2012 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 68, no 4, p. 1065-1073Article in journal (Refereed) Published
Abstract [en]

Time-resolved three-dimensional phase-contrast MRI is an important tool for physiological as well as clinical studies of blood flow in the heart and vessels. The application of the technique is, however, limited by the long scan times required. In this work, we investigate the feasibility of using spiral readouts to reduce the scan time of four-dimensional flow MRI without sacrificing quality. Three spiral approaches are presented and evaluated in vivo and in vitro against a conventional Cartesian acquisition. In vivo, the performance of each method was assessed in the thoracic aorta in 10 volunteers using pathline-based analysis and cardiac output analysis. Signal-to-noise ratio and background phase errors were investigated in vitro. Using spiral readouts, the scan times of a four-dimensional flow acquisition of the thoracic aorta could be reduced 23-fold, with no statistically significant difference in pathline validity or cardiac output. The shortened scan time improves the applicability of four-dimensional flow MRI, which may allow the technique to become a part of a clinical workflow for cardiovascular functional imaging.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2012
Keywords
cine three-dimensional flow, phase contrast, spiral, pathline
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-84888 (URN)10.1002/mrm.23297 (DOI)000309203500008 ()
Note

Funding Agencies|Swedish Research Council||Swedish Heart-Lung Foundation||

Available from: 2012-11-01 Created: 2012-10-26 Last updated: 2017-12-07Bibliographically approved
Kindberg, K., Haraldsson, H., Sigfridsson, A., Engvall, J., Ingels, N. B., Ebbers, T. & Karlsson, M. (2012). Myocardial strains from 3D displacement encoded magnetic resonance imaging. BMC Medical Imaging, 12(9)
Open this publication in new window or tab >>Myocardial strains from 3D displacement encoded magnetic resonance imaging
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2012 (English)In: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 12, no 9Article in journal (Refereed) Published
Abstract [en]

Background

The ability to measure and quantify myocardial motion and deformation provides a useful tool to assist in the diagnosis, prognosis and management of heart disease. The recent development of magnetic resonance imaging methods, such as harmonic phase analysis of tagging and displacement encoding with stimulated echoes (DENSE), make detailed non-invasive 3D kinematic analyses of human myocardium possible in the clinic and for research purposes. A robust analysis method is required, however.

Methods

We propose to estimate strain using a polynomial function which produces local models of the displacement field obtained with DENSE. Given a specific polynomial order, the model is obtained as the least squares fit of the acquired displacement field. These local models are subsequently used to produce estimates of the full strain tensor.

Results

The proposed method is evaluated on a numerical phantom as well as in vivo on a healthy human heart. The evaluation showed that the proposed method produced accurate results and showed low sensitivity to noise in the numerical phantom. The method was also demonstrated in vivo by assessment of the full strain tensor and to resolve transmural strain variations.

Conclusions

Strain estimation within a 3D myocardial volume based on polynomial functions yields accurate and robust results when validated on an analytical model. The polynomial field is capable of resolving the measured material positions from the in vivo data, and the obtained in vivo strains values agree with previously reported myocardial strains in normal human hearts.

Place, publisher, year, edition, pages
BioMed Central, 2012
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:liu:diva-90358 (URN)10.1186/1471-2342-12-9 (DOI)000321344800001 ()
Available from: 2013-03-25 Created: 2013-03-25 Last updated: 2017-12-06
Kindberg, K., Haraldsson, H., Sigfridsson, A., Sakuma, H., Ebbers, T. & Karlsson, M. (2012). Temporal 3D Lagrangian strain from 2D slice followed cine DENSE MRI. Clinical Physiology and Functional Imaging, 32(2), 139-144
Open this publication in new window or tab >>Temporal 3D Lagrangian strain from 2D slice followed cine DENSE MRI
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2012 (English)In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 32, no 2, p. 139-144Article in journal (Refereed) Published
Abstract [en]

A quantitative analysis of myocardial mechanics is fundamental to the understanding of cardiac function, diagnosis of heart disease and assessment of therapeutic intervention. In the clinical situation, where limited scan time often is important, a detailed analysis of the myocardium in a specific region might be more applicable than a full 3D measurement of the entire left ventricle. This paper presents a method to obtain temporal evolutions of transmural 3D Lagrangian strains from two intersecting 2D planes of slice followed cine displacement encoding with stimulated echoes (DENSE) data using a bilinear-cubic polynomial element to resolve strain from the displaced myocardial positions. The method demonstrates accurate results when validated in an analytical model, and has been applied to in vivo data acquired on a 3 T magnetic resonance (MR) system from a healthy volunteer to quantify systolic strains at the anterior-basal region of left ventricular myocardium. The in vivo results agree within experimental accuracy with values reported in the literature.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2012
Keywords
Myocardium; kinematics; magnetic resonance; transmural
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-60200 (URN)10.1111/j.1475-097X.2011.01068.x (DOI)000299734400010 ()
Available from: 2010-10-07 Created: 2010-10-07 Last updated: 2017-12-12
Dyverfeldt, P., Sigfridsson, A., Knutsson, H. & Ebbers, T. (2011). A novel MRI framework for the quantification of any moment of arbitrary velocity distributions. Magnetic Resonance in Medicine, 65(3), 725-731
Open this publication in new window or tab >>A novel MRI framework for the quantification of any moment of arbitrary velocity distributions
2011 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 65, no 3, p. 725-731Article in journal (Refereed) Published
Abstract [en]

MRI can measure several important hemodynamic parameters but might not yet have reached its full potential. The most common MRI method for the assessment of flow is phase-contrast MRI velocity mapping that estimates the mean velocity of a voxel. This estimation is precise only when the intravoxel velocity distribution is symmetric. The mean velocity corresponds to the first raw moment of the intravoxel velocity distribution. Here, a generalized MRI framework for the quantification of any moment of arbitrary velocity distributions is described. This framework is based on the fact that moments in the function domain (velocity space) correspond to differentials in the Fourier transform domain (kv-space). For proof-of-concept, moments of realistic velocity distributions were estimated using finite difference approximations of the derivatives of the MRI signal. In addition, the framework was applied to investigate the symmetry assumption underlying phase-contrast MRI velocity mapping; we found that this assumption can substantially affect phase-contrast MRI velocity estimates and that its significance can be reduced by increasing the velocity encoding range.

Place, publisher, year, edition, pages
John Wiley and Sons, Ltd, 2011
Keywords
phase-contrast magnetic resonance imaging, blood flow velocity, turbulent flow, cardiovascular physiology, Fourier transform, moments
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-66863 (URN)10.1002/mrm.22649 (DOI)000287929800014 ()
Available from: 2011-03-22 Created: 2011-03-21 Last updated: 2017-12-11
Dyverfeldt, P., Escobar Kvitting, J.-P., Carlhäll, C. J., Boano, G., Sigfridsson, A., Hermansson, U., . . . Ebbers, T. (2011). Hemodynamic aspects of mitral regurgitation assessed by generalized phase-contrast MRI. Journal of Magnetic Resonance Imaging, 33(3), 582-588
Open this publication in new window or tab >>Hemodynamic aspects of mitral regurgitation assessed by generalized phase-contrast MRI
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2011 (English)In: Journal of Magnetic Resonance Imaging, ISSN 1053-1807, E-ISSN 1522-2586, Vol. 33, no 3, p. 582-588Article in journal (Refereed) Published
Abstract [en]

Purpose: Mitral regurgitation creates a high velocity jet into the left atrium (LA), contributing both volume andpressure; we hypothesized that the severity of regurgitation would be reflected in the degree of LA flowdistortion.

Material and Methods: Three-dimensional cine PC-MRI was applied to determine LA flow patterns andturbulent kinetic energy (TKE) in seven subjects (five patients with posterior mitral leaflet prolapse, two normalsubjects). In addition, the regurgitant volume and the time-velocity profiles in the pulmonary veins weremeasured.

Results: The LA flow in the mitral regurgitation patients was highly disturbed with elevated values of TKE.Peak TKE occurred consistently at late systole. The total LA TKE was closely related to the regurgitant volume.LA flow patterns were characterized by a pronounced vortex in proximity to the regurgitant jet. In some patients,pronounced discordances were observed between individual pulmonary venous inflows, but these could not berelated to the direction of the flow jet or parameters describing global LA hemodynamics.

Conclusion: PC-MRI permits investigations of atrial and pulmonary vein flow patterns and TKE in significantmitral regurgitation, reflecting the impact of the highly disturbed blood flow that accompanies this importantvalve disease.

Place, publisher, year, edition, pages
John Wiley and Sons, 2011
Keywords
Hemodynamics, mitral valve insufficiency, turbulent flow, phase-contrast magnetic resonance imaging, pulmonary veins, blood flow velocity
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-53190 (URN)10.1002/jmri.22407 (DOI)000287951100009 ()
Available from: 2010-01-19 Created: 2010-01-19 Last updated: 2017-12-12
Haraldsson, H., Sigfridsson, A., Sakuma, H., Engvall, J. & Ebbers, T. (2011). Influence of the FID and off-resonance effects in dense MRI. Magnetic Resonance in Medicine, 65(4), 1104-1112
Open this publication in new window or tab >>Influence of the FID and off-resonance effects in dense MRI
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2011 (English)In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 65, no 4, p. 1104-1112Article in journal (Refereed) Published
Abstract [en]

Accurate functional measurement in cardiovascular diseases is important as inaccuracy may compromise diagnostic decisions. Cardiac function can be assessed using displacement encoding with stimulated echoes, resulting in three signal components. The free induction decay (FID), arising from spins undergoing T1-relaxation, is not displacement encoded and impairs the displacement acquired. Techniques for suppressing the FID exist; however, a residual will remain. The effect of the residual is difficult to distinguish and investigate in vitro and in vivo. In this work, the influence of the FID as well as of off-resonance effects is evaluated by altering the phase of the FID in relation to the stimulated echo. The results show that the FID and off-resonance effects can impair the accuracy of the displacement measurement acquired. The influence of the FID can be avoided by using an encoded reference. We therefore recommend the assessment of this influence of the FID for each displacement encoding with stimulated echoes protocol.

Place, publisher, year, edition, pages
Wiley, 2011
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-60266 (URN)10.1002/mrm.22692 (DOI)000288612000023 ()
Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2017-12-12
Sigfridsson, A., Haraldsson, H., Ebbers, T., Knutsson, H. & Sakuma, H. (2011). In-vivo SNR in DENSE MRI: temporal and regional effects of field strength, receiver coil sensitivity, and flip angle strategies. Magnetic Resonance Imaging, 29(2), 202-208
Open this publication in new window or tab >>In-vivo SNR in DENSE MRI: temporal and regional effects of field strength, receiver coil sensitivity, and flip angle strategies
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2011 (English)In: Magnetic Resonance Imaging, ISSN 0730-725X, E-ISSN 1873-5894, Vol. 29, no 2, p. 202-208Article in journal (Refereed) Published
Abstract [en]

Aim: The influences on the SNR of DENSE MRI of field strength, receiver coil sensitivity and choice of flip angle strategy have been previously investigated individually. In this study, all of these parameters have been investigated in the same setting, and a mutual comparison of their impact on SNR is presented.

Materials and methods: Ten healthy volunteers were imaged in a 1.5T and a 3T MRI system, using standard 5 or 6 channel cardiac coils as well as 32 channel coils, with four different excitation patterns. Variation of spatial coil sensitivity was assessed by regional SNR analysis.

Results: SNR ranging from 2.8 to 30.5 was found depending on the combination of excitation patterns, coil sensitivity and field strength. The SNR at 3T was 53 ± 26% higher than at 1.5T (p<0.001), whereas spatial differences of 59 ± 26% were found in the ventricle (p<0.001). 32 channel coils provided 52 ± 29% higher SNR compared to standard 5 or 6 channel coils (p<0.001). A fixed flip angle strategy provided an excess of 50% higher SNR in half of the imaged cardiac cycle compared to a sweeping flip angle strategy, and a single phase acquisition provided a six-fold increase of SNR compared to a cine acquisition.

Conclusion: The effect of field strength and receiver coil sensitivity influences the SNR with the same order of magnitude, whereas flip angle strategy can have a larger effect on SNR. Thus, careful choice of imaging hardware in combination with adaptation of the acquisition protocol is crucial in order to realize sufficient SNR in DENSE MRI.

Place, publisher, year, edition, pages
Elsevier, 2011
Keywords
DENSE, strain, SNR, flip angle, coil sensitivity
National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-51975 (URN)10.1016/j.mri.2010.08.016 (DOI)000287390500008 ()
Note

Original Publication: Andreas Sigfridsson, Henrik Haraldsson, Tino Ebbers, Hans Knutsson and Hajime Sakuma, In-vivo SNR in DENSE MRI: temporal and regional effects of field strength, receiver coil sensitivity, and flip angle strategies, 2011, Magnetic Resonance Imaging, (29), 2, 202-208. http://dx.doi.org/10.1016/j.mri.2010.08.016 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

Available from: 2009-11-25 Created: 2009-11-25 Last updated: 2017-12-12
Dyverfeldt, P., Sigfridsson, A., Knutsson, H. & Ebbers, T. (2011). MR flow imaging beyond the mean velocity: Estimation of the skew  and kurtosis of intravoxel velocity distributions. In: ISMRM 2011: . Paper presented at ISMRM 19th Annual Meeting & Exhibition,7-13 May 2011, Montréal, Québec, Canada. International Society for Magnetic Resonance in Medicine ( ISMRM )
Open this publication in new window or tab >>MR flow imaging beyond the mean velocity: Estimation of the skew  and kurtosis of intravoxel velocity distributions
2011 (English)In: ISMRM 2011, International Society for Magnetic Resonance in Medicine ( ISMRM ) , 2011Conference paper, Poster (with or without abstract) (Other academic)
Place, publisher, year, edition, pages
International Society for Magnetic Resonance in Medicine ( ISMRM ), 2011
Keywords
MR flow skew kurtosis
National Category
Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-95765 (URN)
Conference
ISMRM 19th Annual Meeting & Exhibition,7-13 May 2011, Montréal, Québec, Canada
Projects
CMIV
Available from: 2013-07-19 Created: 2013-07-19 Last updated: 2013-09-03
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