Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T

Jason M Zhao; Chekesha S Clingman; M Johanna Närväinen; Risto A Kauppinen; Peter C M van Zijl

doi:10.1002/mrm.21342

Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T

Jason M Zhao, Chekesha S Clingman, M Johanna Närväinen, Risto A Kauppinen, Peter C M van Zijl

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Abstract

Knowledge of the transverse relaxation rates R2 and R2* of blood is relevant for quantitative assessment of functional MRI (fMRI) results, including calibration of blood oxygenation and measurement of tissue oxygen extraction fractions (OEFs). In a temperature controlled circulation system, these rates were measured for blood in vitro at 3T under conditions akin to the physiological state. Single spin echo (SE) and gradient echo (GRE) sequences were used to determine R2 and R2*, respectively. Both rates varied quadratically with deoxygenation, and changes in R2* were found to be due predominantly to changes in R2. These data were used to estimate intravascular blood oxygenation level dependent (BOLD) contributions during visual activation. Due to the large R2* in venous blood, intravascular SE BOLD signal changes were larger than GRE effects at echo times above 30 ms. When including extravascular effects to estimate the total BOLD effect, GRE BOLD dominated due to the large tissue volume fraction.

Original language	English
Pages (from-to)	592-7
Number of pages	6
Journal	Magnetic Resonance in Medicine
Volume	58
Issue number	3
DOIs	https://doi.org/10.1002/mrm.21342
Publication status	Published - 2007

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title = "Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T",

abstract = "Knowledge of the transverse relaxation rates R2 and R2* of blood is relevant for quantitative assessment of functional MRI (fMRI) results, including calibration of blood oxygenation and measurement of tissue oxygen extraction fractions (OEFs). In a temperature controlled circulation system, these rates were measured for blood in vitro at 3T under conditions akin to the physiological state. Single spin echo (SE) and gradient echo (GRE) sequences were used to determine R2 and R2*, respectively. Both rates varied quadratically with deoxygenation, and changes in R2* were found to be due predominantly to changes in R2. These data were used to estimate intravascular blood oxygenation level dependent (BOLD) contributions during visual activation. Due to the large R2* in venous blood, intravascular SE BOLD signal changes were larger than GRE effects at echo times above 30 ms. When including extravascular effects to estimate the total BOLD effect, GRE BOLD dominated due to the large tissue volume fraction.",

author = "Zhao, {Jason M} and Clingman, {Chekesha S} and N{\"a}rv{\"a}inen, {M Johanna} and Kauppinen, {Risto A} and {van Zijl}, {Peter C M}",

year = "2007",

doi = "10.1002/mrm.21342",

language = "English",

volume = "58",

pages = "592--7",

journal = "Magnetic Resonance in Medicine",

issn = "0740-3194",

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TY - JOUR

T1 - Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T

AU - Zhao, Jason M

AU - Clingman, Chekesha S

AU - Närväinen, M Johanna

AU - Kauppinen, Risto A

AU - van Zijl, Peter C M

PY - 2007

Y1 - 2007

N2 - Knowledge of the transverse relaxation rates R2 and R2* of blood is relevant for quantitative assessment of functional MRI (fMRI) results, including calibration of blood oxygenation and measurement of tissue oxygen extraction fractions (OEFs). In a temperature controlled circulation system, these rates were measured for blood in vitro at 3T under conditions akin to the physiological state. Single spin echo (SE) and gradient echo (GRE) sequences were used to determine R2 and R2*, respectively. Both rates varied quadratically with deoxygenation, and changes in R2* were found to be due predominantly to changes in R2. These data were used to estimate intravascular blood oxygenation level dependent (BOLD) contributions during visual activation. Due to the large R2* in venous blood, intravascular SE BOLD signal changes were larger than GRE effects at echo times above 30 ms. When including extravascular effects to estimate the total BOLD effect, GRE BOLD dominated due to the large tissue volume fraction.

AB - Knowledge of the transverse relaxation rates R2 and R2* of blood is relevant for quantitative assessment of functional MRI (fMRI) results, including calibration of blood oxygenation and measurement of tissue oxygen extraction fractions (OEFs). In a temperature controlled circulation system, these rates were measured for blood in vitro at 3T under conditions akin to the physiological state. Single spin echo (SE) and gradient echo (GRE) sequences were used to determine R2 and R2*, respectively. Both rates varied quadratically with deoxygenation, and changes in R2* were found to be due predominantly to changes in R2. These data were used to estimate intravascular blood oxygenation level dependent (BOLD) contributions during visual activation. Due to the large R2* in venous blood, intravascular SE BOLD signal changes were larger than GRE effects at echo times above 30 ms. When including extravascular effects to estimate the total BOLD effect, GRE BOLD dominated due to the large tissue volume fraction.

U2 - 10.1002/mrm.21342

DO - 10.1002/mrm.21342

M3 - Article (Academic Journal)

C2 - 17763354

SN - 0740-3194

VL - 58

SP - 592

EP - 597

JO - Magnetic Resonance in Medicine

JF - Magnetic Resonance in Medicine

IS - 3

ER -

Oxygenation and hematocrit dependence of transverse relaxation rates of blood at 3T

Abstract

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