US 11,026,606 B2Granted

Magnetic resonance imaging method to non-invasively measure blood oxygen saturation

AssigneeOhio State Innovation Foundation

InventorsOrlando P. Simonetti, Rizwan Ahmad, Lee C. Potter, Juliet Jaison Varghese

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Abstract

Methods for data acquisition and processing of magnetic resonance (MR) imaging to obtain the oxygen saturation (O2sat) of blood using a relationship between transverse relaxation time (T2) of blood and oxygen saturation. The method includes obtaining multiple images at various T2 preparation times. Next, non-linear curve fitting may be used to solve for arterial or venous O2sat. The disclosure provides a calibration-free method for accurate quantitative assessment of blood in the heart and deep vessels, even in locations having limited accessibility with other diagnostic techniques.

Claims17

Dependent claims

A method for determining oxygen saturation (O2sat) of blood using magnetic resonance (MR) image data, comprising:

acquiring multiple transverse relaxation time (T2) prepared source images, each of the source images having distinct pulse timing between refocusing pulses (τ180);
deriving multiple T2-measurements from the T2 prepared source images, wherein each T2 measurement is derived from a combination of source images all having the same τ180 and different number of refocusing pulses (n);
using the multiple measurements of blood T2 (T2b) within a same blood pool, wherein each blood T2 measurement generated using source images with unique τ180, yields one Luz-Meiboom model derived equation of the form:
(
1
-
%
⁢
⁢
SbO
2
1
⁢
0
⁢
0
)
2
=
(
1
T
2
⁢
b
-
1
T
2
⁢
O
)
(
H
⁢
c
⁢
t
)
⁢
(
1
-
H
⁢
c
⁢
t
)
⁢
τ
e
⁢
x
⁡
(
α
⁢
ω
0
)
2
⁢
(
1
-
2
⁢
τ
e
⁢
x
τ
1
⁢
8
⁢
0
⁢
tanh
⁡
(
τ
1
⁢
8
⁢
0
2
⁢
τ
e
⁢
x
)
)
taking T2b together with independent measurements of patient hematocrit (Hct);
and together with ω0, the proton resonance frequency that is fixed for the static magnetic field strength at which the measurements are acquired;
and
applying a non-linear curve fitting to a system of equations generated using multiple T2-measurements of a blood pool, each with a unique τ180, to determine all of the unknown model parameters uniquely in each patient,
wherein the unknown model parameters include at least one of % SbO2, T2O, Tex and α,
wherein % SbO2 is the unknown blood O2sat in the system of equations that correspond to the blood pool whose O2sat needs to be determined,
T2O is the T2 value of fully oxygenated blood, and
τex is the water proton exchange time between erythrocytes and plasma, and
α is a dimensionless parameter dependent on the susceptibility difference of deoxy- and oxyhemoglobin in blood.

102 more elements

A method for determining oxygen saturation (O2sat) of blood using magnetic resonance (MR) image data, comprising:

obtaining multiple transverse relaxation time (T2) prepared source images, each of the T2 source images having distinct pulse timing (τ180) and number of refocusing pulses (n);
directly using a measured signal, S, an MR signal for a given blood pool in the multiple T2 prepared source images to yield
a Luz-Meiboom (L-M) model derived equation of the form:
(
1
-
%
⁢
⁢
SbO
2
1
⁢
0
⁢
0
)
2
=
(
ln
⁡
(
S
S
0
)
-
n
⁢
τ
180
-
1
T
2
⁢
O
)
(
H
⁢
c
⁢
t
)
⁢
(
1
-
H
⁢
c
⁢
t
)
⁢
τ
e
⁢
x
⁡
(
α
⁢
ω
0
)
2
⁢
(
1
⁢
2
⁢
τ
e
⁢
x
τ
1
⁢
8
⁢
0
⁢
tanh
⁡
(
τ
1
⁢
8
⁢
0
2
⁢
τ
e
⁢
x
)
)
;
taking S together with independent measurements of patient hematocrit (Hct) and ω0, the proton resonance frequency that is fixed for the static magnetic field strength at which the measurements are acquired;
and
applying a non-linear curve fitting to a system of equations generated from the multiple T2 prepared source images, each with a unique τ180, to determine all of the unknown model parameters uniquely in each patient,
wherein the unknown model parameters include at least one of % SbO2, T2O, τex, α, and S0,
wherein % SbO2 is the unknown blood O2sat in the set of equations that correspond to venous blood or blood pool whose O2sat needs to be determined,
T20 is the T2 value of fully oxygenated blood,
τex is the water proton exchange time between erythrocytes and plasma,
α is a dimensionless parameter dependent on the susceptibility difference of deoxy- and oxyhemoglobin, and
S0 is the steady-state MR signal.

110 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/416,249Filed 26 Jan 2017 · us provisional application
Priority: 26 Jan 2016
Published: US 2017/0224259 A110 Aug 2017
Granted: 8 Jun 2021
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

A61B 5/14542
Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g.…: for…
A61B 5/055
Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves:…
G01R 33/50
NMR imaging systems: based on the determination of relaxation times , e.g. T1 measurement by IR sequences; T2 measurement by multiple-echo sequences
G01R 33/5602
Image enhancement or correction, e.g. subtraction or averaging techniques , e.g. improvement of signal-to-noise ratio and resolution: by filtering…

Family

Application62/287,116Us provisional application · filed 26 Jan 2016
US 2017/0224259 A1Pre-grant publication · published 10 Aug 2017
US 11,026,606 B2This patent

From the US filing history. Foreign family members aren’t listed.

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