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Importance of standardizing timing of hematocrit measurement when using cardiovascular magnetic resonance to calculate myocardial extracellular volume (ECV) based on pre- and post-contrast T1 mapping

Engblom, Henrik LU ; Kanski, Mikael LU ; Kopic, Sascha LU ; Nordlund, David LU ; Xanthis, Christos G. LU ; Jablonowski, Robert LU ; Heiberg, Einar LU ; Aletras, Anthony H. LU ; Carlsson, Marcus LU and Arheden, Håkan LU (2018) In Journal of Cardiovascular Magnetic Resonance 20(1).
Abstract

Background: Cardiovascular magnetic resonance (CMR) can be used to calculate myocardial extracellular volume fraction (ECV) by relating the longitudinal relaxation rate in blood and myocardium before and after contrast-injection to hematocrit (Hct) in blood. Hematocrit is known to vary with body posture, which could affect the calculations of ECV. The aim of this study was to test the hypothesis that there is a significant increase in calculated ECV values if the Hct is sampled after the CMR examination in supine position compared to when the patient arrives at the MR department. Methods: Forty-three consecutive patients including various pathologies as well as normal findings were included in the study. Venous blood samples were drawn... (More)

Background: Cardiovascular magnetic resonance (CMR) can be used to calculate myocardial extracellular volume fraction (ECV) by relating the longitudinal relaxation rate in blood and myocardium before and after contrast-injection to hematocrit (Hct) in blood. Hematocrit is known to vary with body posture, which could affect the calculations of ECV. The aim of this study was to test the hypothesis that there is a significant increase in calculated ECV values if the Hct is sampled after the CMR examination in supine position compared to when the patient arrives at the MR department. Methods: Forty-three consecutive patients including various pathologies as well as normal findings were included in the study. Venous blood samples were drawn upon arrival to the MR department and directly after the examination with the patient remaining in supine position. A Modified Look-Locker Inversion recovery (MOLLI) protocol was used to acquire mid-ventricular short-axis images before and after contrast injection from which motion-corrected T1 maps were derived and ECV was calculated. Results: Hematocrit decreased from 44.0 ± 3.7% before to 40.6 ± 4.0% after the CMR examination (p < 0.001). This resulted in a change in calculated ECV from 24.7 ± 3.8% before to 26.2 ± 4.2% after the CMR examination (p < 0.001). All patients decreased in Hct after the CMR examination compared to before except for two patients whose Hct remained the same. Conclusion: Variability in CMR-derived myocardial ECV can be reduced by standardizing the timing of Hct measurement relative to the CMR examination. Thus, a standardized acquisition of blood sample for Hct after the CMR examination, when the patient is still in supine position, would increase the precision of ECV measurements.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ECV, Extracellular volume, Hematocrit, T1 mapping
in
Journal of Cardiovascular Magnetic Resonance
volume
20
issue
1
publisher
BioMed Central
external identifiers
  • scopus:85049209056
ISSN
1097-6647
DOI
10.1186/s12968-018-0464-9
language
English
LU publication?
yes
id
b987e551-45df-4882-a6b9-ccc1c5ab9a6e
date added to LUP
2018-07-13 14:22:20
date last changed
2018-07-14 03:00:04
@article{b987e551-45df-4882-a6b9-ccc1c5ab9a6e,
  abstract     = {<p>Background: Cardiovascular magnetic resonance (CMR) can be used to calculate myocardial extracellular volume fraction (ECV) by relating the longitudinal relaxation rate in blood and myocardium before and after contrast-injection to hematocrit (Hct) in blood. Hematocrit is known to vary with body posture, which could affect the calculations of ECV. The aim of this study was to test the hypothesis that there is a significant increase in calculated ECV values if the Hct is sampled after the CMR examination in supine position compared to when the patient arrives at the MR department. Methods: Forty-three consecutive patients including various pathologies as well as normal findings were included in the study. Venous blood samples were drawn upon arrival to the MR department and directly after the examination with the patient remaining in supine position. A Modified Look-Locker Inversion recovery (MOLLI) protocol was used to acquire mid-ventricular short-axis images before and after contrast injection from which motion-corrected T1 maps were derived and ECV was calculated. Results: Hematocrit decreased from 44.0 ± 3.7% before to 40.6 ± 4.0% after the CMR examination (p &lt; 0.001). This resulted in a change in calculated ECV from 24.7 ± 3.8% before to 26.2 ± 4.2% after the CMR examination (p &lt; 0.001). All patients decreased in Hct after the CMR examination compared to before except for two patients whose Hct remained the same. Conclusion: Variability in CMR-derived myocardial ECV can be reduced by standardizing the timing of Hct measurement relative to the CMR examination. Thus, a standardized acquisition of blood sample for Hct after the CMR examination, when the patient is still in supine position, would increase the precision of ECV measurements.</p>},
  articleno    = {46},
  author       = {Engblom, Henrik and Kanski, Mikael and Kopic, Sascha and Nordlund, David and Xanthis, Christos G. and Jablonowski, Robert and Heiberg, Einar and Aletras, Anthony H. and Carlsson, Marcus and Arheden, Håkan},
  issn         = {1097-6647},
  keyword      = {ECV,Extracellular volume,Hematocrit,T1 mapping},
  language     = {eng},
  month        = {06},
  number       = {1},
  publisher    = {BioMed Central},
  series       = {Journal of Cardiovascular Magnetic Resonance},
  title        = {Importance of standardizing timing of hematocrit measurement when using cardiovascular magnetic resonance to calculate myocardial extracellular volume (ECV) based on pre- and post-contrast T1 mapping},
  url          = {http://dx.doi.org/10.1186/s12968-018-0464-9},
  volume       = {20},
  year         = {2018},
}