Physiologic motion: Dealing with cardiac, respiratory, and other sporadic motion in MRS

Research output: Contribution to journalArticle

Abstract

Physiologic motion, such as respiration and cardiac motion, affects magnetic resonance (MR) spectroscopy (MRS) in different ways. Tissue displacement on the order of the MRS voxel size leads to contamination from neighboring tissue. Bulk motion, even that involving only small displacements that occurs during the application of localization gradients and RF pulses, induces phase shifts which can lead to signal loss when averaging and to ghosting in chemical shift imaging (CSI), even at locations away from the actual motion such as the brain, spine, and breast. Cardiac muscle motion with strain-induced thickening, thinning, and rotation leads to a range of induced signal phase shifts within single MRS voxels and, hence, to intravoxel dephasing. Reducing the strength of 'crusher' gradients that are used for dephasing extraneous transverse magnetization may reduce the amount of motion-induced phase variations. Cardiac triggering with either pulse oximetry sensors or electrocardiogram (ECG), and respiratory triggering or gating with either bellows or respiratory navigators, allow the synchronization of MRS acquisitions to cardiac and respiratory cycles. These techniques minimize the effects of motion - depending on its reproducibility - by facilitating a consistent tissue location, to enable MRS acquisitions even in the moving chest, liver and heart. Remaining shot-to-shot phase variations in the data can be corrected by constructive averaging or signal rejection techniques during post-processing.

Original languageEnglish (US)
Pages (from-to)1087-1096
Number of pages10
JournaleMagRes
Volume5
Issue number2
DOIs
StatePublished - 2016

Fingerprint

Magnetic Resonance Spectroscopy
Spectroscopy
Tissue
Phase shift
Magnetic resonance spectroscopy
Crushers
Bellows
Electrocardiography
Liver
Muscle
Magnetization
Brain
Post and Core Technique
Synchronization
Contamination
Oximetry
Sensors
Processing
Myocardium
Respiration

Keywords

  • -Intravoxel phase dispersion
  • Constructive averaging
  • Double triggering
  • ECG triggering
  • Motion artifacts
  • Motion-induced phase
  • Respiratory navigator

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Biomedical Engineering
  • Biochemistry
  • Radiology Nuclear Medicine and imaging

Cite this

Physiologic motion : Dealing with cardiac, respiratory, and other sporadic motion in MRS. / Schar, Michael.

In: eMagRes, Vol. 5, No. 2, 2016, p. 1087-1096.

Research output: Contribution to journalArticle

@article{66faee6887004f73b64c0c498d153101,
title = "Physiologic motion: Dealing with cardiac, respiratory, and other sporadic motion in MRS",
abstract = "Physiologic motion, such as respiration and cardiac motion, affects magnetic resonance (MR) spectroscopy (MRS) in different ways. Tissue displacement on the order of the MRS voxel size leads to contamination from neighboring tissue. Bulk motion, even that involving only small displacements that occurs during the application of localization gradients and RF pulses, induces phase shifts which can lead to signal loss when averaging and to ghosting in chemical shift imaging (CSI), even at locations away from the actual motion such as the brain, spine, and breast. Cardiac muscle motion with strain-induced thickening, thinning, and rotation leads to a range of induced signal phase shifts within single MRS voxels and, hence, to intravoxel dephasing. Reducing the strength of 'crusher' gradients that are used for dephasing extraneous transverse magnetization may reduce the amount of motion-induced phase variations. Cardiac triggering with either pulse oximetry sensors or electrocardiogram (ECG), and respiratory triggering or gating with either bellows or respiratory navigators, allow the synchronization of MRS acquisitions to cardiac and respiratory cycles. These techniques minimize the effects of motion - depending on its reproducibility - by facilitating a consistent tissue location, to enable MRS acquisitions even in the moving chest, liver and heart. Remaining shot-to-shot phase variations in the data can be corrected by constructive averaging or signal rejection techniques during post-processing.",
keywords = "-Intravoxel phase dispersion, Constructive averaging, Double triggering, ECG triggering, Motion artifacts, Motion-induced phase, Respiratory navigator",
author = "Michael Schar",
year = "2016",
doi = "10.1002/9780470034590.emrstm1446",
language = "English (US)",
volume = "5",
pages = "1087--1096",
journal = "eMagRes",
issn = "2055-6101",
publisher = "Blackwell",
number = "2",

}

TY - JOUR

T1 - Physiologic motion

T2 - Dealing with cardiac, respiratory, and other sporadic motion in MRS

AU - Schar, Michael

PY - 2016

Y1 - 2016

N2 - Physiologic motion, such as respiration and cardiac motion, affects magnetic resonance (MR) spectroscopy (MRS) in different ways. Tissue displacement on the order of the MRS voxel size leads to contamination from neighboring tissue. Bulk motion, even that involving only small displacements that occurs during the application of localization gradients and RF pulses, induces phase shifts which can lead to signal loss when averaging and to ghosting in chemical shift imaging (CSI), even at locations away from the actual motion such as the brain, spine, and breast. Cardiac muscle motion with strain-induced thickening, thinning, and rotation leads to a range of induced signal phase shifts within single MRS voxels and, hence, to intravoxel dephasing. Reducing the strength of 'crusher' gradients that are used for dephasing extraneous transverse magnetization may reduce the amount of motion-induced phase variations. Cardiac triggering with either pulse oximetry sensors or electrocardiogram (ECG), and respiratory triggering or gating with either bellows or respiratory navigators, allow the synchronization of MRS acquisitions to cardiac and respiratory cycles. These techniques minimize the effects of motion - depending on its reproducibility - by facilitating a consistent tissue location, to enable MRS acquisitions even in the moving chest, liver and heart. Remaining shot-to-shot phase variations in the data can be corrected by constructive averaging or signal rejection techniques during post-processing.

AB - Physiologic motion, such as respiration and cardiac motion, affects magnetic resonance (MR) spectroscopy (MRS) in different ways. Tissue displacement on the order of the MRS voxel size leads to contamination from neighboring tissue. Bulk motion, even that involving only small displacements that occurs during the application of localization gradients and RF pulses, induces phase shifts which can lead to signal loss when averaging and to ghosting in chemical shift imaging (CSI), even at locations away from the actual motion such as the brain, spine, and breast. Cardiac muscle motion with strain-induced thickening, thinning, and rotation leads to a range of induced signal phase shifts within single MRS voxels and, hence, to intravoxel dephasing. Reducing the strength of 'crusher' gradients that are used for dephasing extraneous transverse magnetization may reduce the amount of motion-induced phase variations. Cardiac triggering with either pulse oximetry sensors or electrocardiogram (ECG), and respiratory triggering or gating with either bellows or respiratory navigators, allow the synchronization of MRS acquisitions to cardiac and respiratory cycles. These techniques minimize the effects of motion - depending on its reproducibility - by facilitating a consistent tissue location, to enable MRS acquisitions even in the moving chest, liver and heart. Remaining shot-to-shot phase variations in the data can be corrected by constructive averaging or signal rejection techniques during post-processing.

KW - -Intravoxel phase dispersion

KW - Constructive averaging

KW - Double triggering

KW - ECG triggering

KW - Motion artifacts

KW - Motion-induced phase

KW - Respiratory navigator

UR - http://www.scopus.com/inward/record.url?scp=85021315781&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85021315781&partnerID=8YFLogxK

U2 - 10.1002/9780470034590.emrstm1446

DO - 10.1002/9780470034590.emrstm1446

M3 - Article

AN - SCOPUS:85021315781

VL - 5

SP - 1087

EP - 1096

JO - eMagRes

JF - eMagRes

SN - 2055-6101

IS - 2

ER -