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High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI

Imaging techniques of the mitral valve have improved tremendously during the last decade, but challenges persist. The delicate changes in annulus shape and papillary muscle position throughout the cardiac cycle have significant impact on the stress distribution in the leaflets and chords, thus prese...

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Autores principales: Stephens, Sam E., Liachenko, Serguei, Ingels, Neil B., Wenk, Jonathan F., Jensen, Morten O.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576658/
https://www.ncbi.nlm.nih.gov/pubmed/28854273
http://dx.doi.org/10.1371/journal.pone.0184042
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author Stephens, Sam E.
Liachenko, Serguei
Ingels, Neil B.
Wenk, Jonathan F.
Jensen, Morten O.
author_facet Stephens, Sam E.
Liachenko, Serguei
Ingels, Neil B.
Wenk, Jonathan F.
Jensen, Morten O.
author_sort Stephens, Sam E.
collection PubMed
description Imaging techniques of the mitral valve have improved tremendously during the last decade, but challenges persist. The delicate changes in annulus shape and papillary muscle position throughout the cardiac cycle have significant impact on the stress distribution in the leaflets and chords, thus preservation of anatomically accurate positioning is critical. The aim of this study was to develop an in vitro method and apparatus for obtaining high-resolution 3D MRI images of porcine mitral valves in both the diastolic and systolic configurations with physiologically appropriate annular shape, papillary muscle positions and orientations, specific to the heart from which the valve was harvested. Positioning and mounting was achieved through novel, customized mounting hardware consisting of papillary muscle and annulus holders with geometries determined via pre-mortem ultrasonic intra-valve measurements. A semi-automatic process was developed and employed to tailor Computer Aided Design models of the holders used to mount the valve. All valve mounting hardware was 3D printed using a stereolithographic printer, and the material of all fasteners used were brass for MRI compatibility. The mounted valves were placed within a clear acrylic case, capable of holding a zero-pressure and pressurized liquid bath of a MRI-compatible fluid. Obtaining images from the valve submerged in liquid fluid mimics the natural environment surrounding the valve, avoiding artefacts due to tissue surface tension mismatch and gravitational impact on tissue shape when not neutrally buoyant. Fluid pressure was supplied by reservoirs held at differing elevations and monitored and controlled to within ±1mmHg to ensure that the valves remained steady. The valves were scanned in a 7 Tesla MRI system providing a voxel resolution of at least 80μm. The systematic approach produced 3D datasets of high quality which, when combined with physiologically accurate positioning by the apparatus, can serve as an important input for validated computational models.
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spelling pubmed-55766582017-09-15 High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI Stephens, Sam E. Liachenko, Serguei Ingels, Neil B. Wenk, Jonathan F. Jensen, Morten O. PLoS One Research Article Imaging techniques of the mitral valve have improved tremendously during the last decade, but challenges persist. The delicate changes in annulus shape and papillary muscle position throughout the cardiac cycle have significant impact on the stress distribution in the leaflets and chords, thus preservation of anatomically accurate positioning is critical. The aim of this study was to develop an in vitro method and apparatus for obtaining high-resolution 3D MRI images of porcine mitral valves in both the diastolic and systolic configurations with physiologically appropriate annular shape, papillary muscle positions and orientations, specific to the heart from which the valve was harvested. Positioning and mounting was achieved through novel, customized mounting hardware consisting of papillary muscle and annulus holders with geometries determined via pre-mortem ultrasonic intra-valve measurements. A semi-automatic process was developed and employed to tailor Computer Aided Design models of the holders used to mount the valve. All valve mounting hardware was 3D printed using a stereolithographic printer, and the material of all fasteners used were brass for MRI compatibility. The mounted valves were placed within a clear acrylic case, capable of holding a zero-pressure and pressurized liquid bath of a MRI-compatible fluid. Obtaining images from the valve submerged in liquid fluid mimics the natural environment surrounding the valve, avoiding artefacts due to tissue surface tension mismatch and gravitational impact on tissue shape when not neutrally buoyant. Fluid pressure was supplied by reservoirs held at differing elevations and monitored and controlled to within ±1mmHg to ensure that the valves remained steady. The valves were scanned in a 7 Tesla MRI system providing a voxel resolution of at least 80μm. The systematic approach produced 3D datasets of high quality which, when combined with physiologically accurate positioning by the apparatus, can serve as an important input for validated computational models. Public Library of Science 2017-08-30 /pmc/articles/PMC5576658/ /pubmed/28854273 http://dx.doi.org/10.1371/journal.pone.0184042 Text en https://creativecommons.org/publicdomain/zero/1.0/ This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 (https://creativecommons.org/publicdomain/zero/1.0/) public domain dedication.
spellingShingle Research Article
Stephens, Sam E.
Liachenko, Serguei
Ingels, Neil B.
Wenk, Jonathan F.
Jensen, Morten O.
High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title_full High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title_fullStr High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title_full_unstemmed High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title_short High resolution imaging of the mitral valve in the natural state with 7 Tesla MRI
title_sort high resolution imaging of the mitral valve in the natural state with 7 tesla mri
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576658/
https://www.ncbi.nlm.nih.gov/pubmed/28854273
http://dx.doi.org/10.1371/journal.pone.0184042
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