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Gupta, Vikas
Publications (4 of 4) Show all publications
Lantz, J., Gupta, V., Henriksson, L., Karlsson, M., Persson, A., Carlhäll, C.-J. & Ebbers, T. (2019). Impact of Pulmonary Venous Inflow on Cardiac Flow Simulations: Comparison with In Vivo 4D Flow MRI. Annals of Biomedical Engineering, 47(2), 413-424
Open this publication in new window or tab >>Impact of Pulmonary Venous Inflow on Cardiac Flow Simulations: Comparison with In Vivo 4D Flow MRI
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2019 (English)In: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686, Vol. 47, no 2, p. 413-424Article in journal (Refereed) Published
Abstract [en]

Blood flow simulations are making their way into the clinic, and much attention is given to estimation of fractional flow reserve in coronary arteries. Intracardiac blood flow simulations also show promising results, and here the flow field is expected to depend on the pulmonary venous (PV) flow rates. In the absence of in vivo measurements, the distribution of the flow from the individual PVs is often unknown and typically assumed. Here, we performed intracardiac blood flow simulations based on time-resolved computed tomography on three patients, and investigated the effect of the distribution of PV flow rate on the flow field in the left atrium and ventricle. A design-of-experiment approach was used, where PV flow rates were varied in a systematic manner. In total 20 different simulations were performed per patient, and compared to in vivo 4D flow MRI measurements. Results were quantified by kinetic energy, mitral valve velocity profiles and root-mean-square errors of velocity. While large differences in atrial flow were found for varying PV inflow distributions, the effect on ventricular flow was negligible, due to a regularizing effect by mitral valve. Equal flow rate through all PVs most closely resembled in vivo measurements and is recommended in the absence of a priori knowledge.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2019
Keywords
Sensitivity analysis, Design-of-experiments, Computational fluid dynamics, In vivo measurements
National Category
Medical Image Processing Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:liu:diva-153252 (URN)10.1007/s10439-018-02153-5 (DOI)000456383600007 ()30362080 (PubMedID)2-s2.0-85055724908 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Available from: 2018-12-06 Created: 2018-12-06 Last updated: 2019-03-22Bibliographically approved
Bustamante, M., Gupta, V., Forsberg, D., Carlhäll, C., Engvall, J. & Ebbers, T. (2018). Automated multi-atlas segmentation of cardiac 4D flow MRI. Medical Image Analysis, 49, 128-140
Open this publication in new window or tab >>Automated multi-atlas segmentation of cardiac 4D flow MRI
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2018 (English)In: Medical Image Analysis, ISSN 1361-8415, E-ISSN 1361-8423, Vol. 49, p. 128-140Article in journal (Refereed) Published
Abstract [en]

Four-dimensional (4D) flow magnetic resonance imaging (4D Flow MRI) enables acquisition of time-resolved three-directional velocity data in the entire heart and all major thoracic vessels. The segmentation of these tissues is typically performed using semi-automatic methods. Some of which primarily rely on the velocity data and result in a segmentation of the vessels only during the systolic phases. Other methods, mostly applied on the heart, rely on separately acquired balanced Steady State Free Precession (b-SSFP) MR images, after which the segmentations are superimposed on the 4D Flow MRI. While b-SSFP images typically cover the whole cardiac cycle and have good contrast, they suffer from a number of problems, such as large slice thickness, limited coverage of the cardiac anatomy, and being prone to displacement errors caused by respiratory motion. To address these limitations we propose a multi-atlas segmentation method, which relies only on 4D Flow MRI data, to automatically generate four-dimensional segmentations that include the entire thoracic cardiovascular system present in these datasets. The approach was evaluated on 4D Flow MR datasets from a cohort of 27 healthy volunteers and 83 patients with mildly impaired systolic left-ventricular function. Comparison of manual and automatic segmentations of the cardiac chambers at end-systolic and end-diastolic timeframes showed agreements comparable to those previously reported for automatic segmentation methods of b-SSFP MR images. Furthermore, automatic segmentation of the entire thoracic cardiovascular system improves visualization of 4D Flow MRI and facilitates computation of hemodynamic parameters.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
4D Flow MRI, Cardiac segmentation, Multi-atlas segmentation, Heart, Magnetic resonance imaging, Automatic segmentations, Directional velocities, Hemodynamic parameters, Left ventricular function, Segmentation methods, Semiautomatic methods, Steady state free precessions, Image segmentation, adult, anatomy, article, cohort analysis, controlled study, error, female, heart cycle, heart left ventricle function, human, human tissue, major clinical study, male, motion, nuclear magnetic resonance imaging, steady state, thickness, volunteer
National Category
Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-150788 (URN)10.1016/j.media.2018.08.003 (DOI)000446286600011 ()30144652 (PubMedID)2-s2.0-85051830661 (Scopus ID)
Note

Funding details: 310612; Funding details: FP7, Seventh Framework Programme; Funding details: 621-2014-6191, VR, Vetenskapsrådet; Funding details: 223615; Funding details: 20140398; Funding text: This work was partially funded by the FP7-funded project DOPPLER-CIP [grant number 223615]; the European Union’s Seventh Framework Programme ( FP7/2007-2013 ) [grant number 310612 ]; the Swedish Research Council [grant number 621-2014-6191 ]; and the Swedish Heart and Lung Foundation [grant number 20140398 ]. 

Available from: 2018-08-31 Created: 2018-08-31 Last updated: 2018-10-17Bibliographically approved
Gupta, V., Lantz, J., Henriksson, L., Engvall, J., Karlsson, M., Persson, A. & Ebbers, T. (2018). Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration. Journal of Cardiovascular Computed Tomography, 12(2), 139-148
Open this publication in new window or tab >>Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration
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2018 (English)In: Journal of Cardiovascular Computed Tomography, ISSN 1934-5925, Vol. 12, no 2, p. 139-148Article in journal (Refereed) Published
Abstract [en]

Background Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images.

Methods Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature.

Results Comparison with manual tracking showed high accuracy (DSC: 0.99± 0.05; PTC: 0.56mm± 0.47 mm) and resulted in determinant(Jacobian) > 0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature.

Conclusions Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Cardiac computed tomography; 4D CT; Image registration; Strain analysis; Myocardial deformation; Torsion
National Category
Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-147433 (URN)10.1016/j.jcct.2018.01.005 (DOI)000428247900008 ()29402736 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, KAW 2013.0076
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2019-04-30Bibliographically approved
Lantz, J., Gupta, V., Henriksson, L., Karlsson, M., Persson, A., Carlhäll, C. & Ebbers, T. (2018). Intracardiac Flow at 4D CT: Comparison with 4D Flow MRI. Radiology, 289(1), 51-58
Open this publication in new window or tab >>Intracardiac Flow at 4D CT: Comparison with 4D Flow MRI
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2018 (English)In: Radiology, ISSN 0033-8419, E-ISSN 1527-1315, Vol. 289, no 1, p. 51-58Article in journal (Refereed) Published
Abstract [en]

Purpose

To investigate four-dimensional (4D) flow CT for the assessment of intracardiac blood flow patterns as compared with 4D flow MRI.

Materials and Methods

This prospective study acquired coronary CT angiography and 4D flow MRI data between February and December 2016 in a cohort of 12 participants (age range, 36–74 years; mean age, 57 years; seven men [age range, 36–74 years; mean age, 57 years] and five women [age range, 52–73 years; mean age, 64 years]). Flow simulations based solely on CT-derived cardiac anatomy were assessed together with 4D flow MRI measurements. Flow patterns, flow rates, stroke volume, kinetic energy, and flow components were quantified for both techniques and were compared by using linear regression.

Results

Cardiac flow patterns obtained by using 4D flow CT were qualitatively similar to 4D flow MRI measurements, as graded by three independent observers. The Cohen κ score was used to assess intraobserver variability (0.83, 0.79, and 0.70) and a paired Wilcoxon rank-sum test showed no significant change (P > .05) between gradings. Peak flow rate and stroke volumes between 4D flow MRI measurements and 4D flow CT measurements had high correlation (r = 0.98 and r = 0.81, respectively; P < .05 for both). Integrated kinetic energy quantified at peak systole correlated well (r = 0.95, P < .05), while kinetic energy levels at early and late filling showed no correlation. Flow component analysis showed high correlation for the direct and residual components, respectively (r = 0.93, P < .05 and r = 0.87, P < .05), while the retained and delayed components showed no correlation.

Conclusion

Four-dimensional flow CT produced qualitatively and quantitatively similar intracardiac blood flow patterns compared with the current reference standard, four-dimensional flow MRI.

Place, publisher, year, edition, pages
Oak Brook, IL United States: Radiological Society of North America, Inc., 2018
National Category
Fluid Mechanics and Acoustics Cardiac and Cardiovascular Systems Medical Image Processing
Identifiers
urn:nbn:se:liu:diva-149320 (URN)10.1148/radiol.2018173017 (DOI)000444990900009 ()29944089 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, Seeing Organ FunctionSwedish Heart Lung Foundation
Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2019-04-12Bibliographically approved
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