System and method for whole body continuous bed motion PET scanning with bi-directional data acquisition modes
A method of conducting a multi-pass dynamic positron emission tomography (PET) scans using continuous bed motion (CBM) mode is disclosed where the method involves acquiring PET sinogram data using CBM mode as the patient bed is moving in a first direction; acquiring PET sonogram data using CBM mode as the patient bed is moving in a second direction that is opposite from the first direction; and reconstructing 3-D PET image from the acquired PET sonogram data.
1. A method of conducting a multi-pass dynamic positron emission tomography (PET) scans of a patient that has been injected with a radioactive tracer material using continuous bed motion (CBM) mode on a PET scanner that comprises a gantry and a patient bed, the method comprising:
acquiring dynamic PET sinogram data of the patient using CBM mode as the patient bed is moving in a first direction;
acquiring dynamic PET sinogram data of the patient using CBM mode as the patient bed is moving in a second direction that is opposite from the first direction; and
reconstructing 3-D PET image from the acquired dynamic PET sinogram data, wherein acquiring dynamic PET sinogram data of the patient comprises:
(a) acquiring PET sinogram data of the patient with a single bed mode;
(b) acquiring PET sinogram data using CBM mode having a constant/varying velocity;
(c) recording a plurality of bed tags while acquiring the PET sinogram data;
(d) obtaining a parameterized/fitted blood input function based on data acquired at steps (a) and (b);
(e) repeating a loop containing steps (f)-(k) for each PET scan pass;
(f) repeating a loop containing steps (g)-(k) for each image slice;
(g) determining slice entry time t s and slice exit time t e of the image slice with respect to the gantry of the PET scanner, based on equations (1) and (2):
t s (pass, z )=ƒ( z s ( z ),pass start time,bed tags,scan mode) (1),
t e (pass, z )=ƒ( z e ( z ),pass start time,bed tags,scan mode) (2),
wherein:
t s (pass,z) is the slice start time, relative to pass start time, when the slice centered at z enters the PET scanner's field of view,
t e (pass,z) is the slice end time, relative to pass start time, when the slice centered at z exits the PET scanner's field of view,
z s (z) is the z coordinate of a starting edge of the slice,
z e (z) is the z coordinate of an ending edge of the slice,
pass start time is the time, relative to the injection of the radioactive tracer material, when the current pass starts,
bed tags include time and position coordinate pairs having positions within the slice and/or nearest adjacent bed tags outside of the slice,
scan mode is one of the predetermined modes of operating the PET scanner selected by the operator, and
function ƒ can be an interpolation function for determining the start time of the slice based on the nearest bed tags before and after the start time of the slice and the nearest bed tags before and after the end time of the slice;
(h) determining slice duration s d (pass,z), the length of time the slice is within the PET scanner's field of view, is determined, according to equation (3):
s d (pass, z )= t e (pass, z )− t s (pass, z ) (3);
(i) determining a respective average acquisition time for each slice computed according to equation (4):
tav
(
pass
,
z
)
=
1
λ
*
ln
(
λ
*
s
d
(
pass
,
z
)
/
(
1
-
exp
(
-
λ
*
s
d
(
pass
,
z
)
)
,
(
4
)
wherein, t av is the time point when average activity occurs in a slice duration s d due to decay, assuming no change from kinetics, and λ is isotope decay constant for the injected radioactive tracer material;
(j) determining time of average activity relative to injection time of the radioactive tracer material as a reference time t ref , by equation (5):
t ref (pass, z )= t s (pass, z )+tav(pass, z ) (5),
wherein, t s (pass,z) is the start time of the pass relative to the injection time, and tav(pass,z) is the time of average activity within the slice centered at z based on equation (4); and
(k) determining a respective value of a blood input function c p (t) of the patient, corresponding to the reference time t ref for each respective slice, and a respective integral of the blood input function c p (t) corresponding to each respective slice.
2. The method of claim 1 , wherein the first direction is from the patient's head to feet direction.
3. A method of conducting a multi-pass dynamic positron emission tomography (PET) scans of a patient that has been injected with a radioactive tracer material using continuous bed motion (CBM) mode on a PET scanner that comprises a gantry and a patient bed, the method comprising:
injecting a radioactive tracer material into the patient
acquiring dynamic PET sinogram data of the patient using CBM mode in a first direction as the patient bed moves from an initial position to a second position;
acquiring dynamic PET sinogram data of the patient using CBM mode in a second direction that is opposite from the first direction as the patient bed moves from the second position to a third position;
acquiring dynamic PET sinogram data of the patient using CBM mode in the first direction as the patient bed moves from the third position to the second position;
acquiring dynamic PET sinogram data of the patient using CBM mode in the first direction from the second position to a fourth position; and
reconstructing 3-D PET image from the acquired dynamic PET sinogram data, wherein acquiring dynamic PET sinogram data of the patient comprises:
(a) acquiring PET sinogram data of the patient with a single bed mode;
(b) acquiring PET sinogram data using CBM mode having a constant/varying velocity;
(c) recording a plurality of bed tags while acquiring the PET sinogram data;
(d) obtaining a parameterized/fitted blood input function based on data acquired at steps (a) and (b);
(e) repeating a loop containing steps (f)-(k) for each PET scan pass;
(f) repeating a loop containing steps (g)-(k) for each image slice;
(g) determining slice entry time is and slice exit time to of the image slice with respect to the gantry of the PET scanner, based on equations (1) and (2):
t s (pass, z )=ƒ( z s ( z ),pass start time,bed tags,scan mode) (1),
t e (pass, z )=ƒ( z e ( z ),pass start time,bed tags,scan mode) (2),
wherein:
t s (pass,z) is the slice start time, relative to pass start time, when the slice centered at z enters the PET scanner's field of view,
t e (pass,z) is the slice end time, relative to pass start time, when the slice centered at z exits the PET scanner's field of view,
z s (z) is the z coordinate of a starting edge of the slice,
z e (z) is the z coordinate of an ending edge of the slice,
pass start time is the time, relative to the injection of the radioactive tracer material, when the current pass starts,
bed tags include time and position coordinate pairs having positions within the slice and/or nearest adjacent bed tags outside of the slice,
scan mode is one of the predetermined modes of operating the PET scanner selected by the operator, and
function ƒ can be an interpolation function for determining the start time of the slice based on the nearest bed tags before and after the start time of the slice and the nearest bed tags before and after the end time of the slice;
(h) determining slice duration s d (pass,z), the length of time the slice is within the PET scanner's field of view, is determined, according to equation (3):
s d (pass, z )= t e (pass, z )− t s (pass, z ) (3);
(i) determining a respective average acquisition time for each slice computed according to equation (4):
tav
(
pass
,
z
)
=
1
λ
*
ln
(
λ
*
s
d
(
pass
,
z
)
/
(
1
-
exp
(
-
λ
*
s
d
(
pass
,
z
)
)
,
(
4
)
wherein, t av is the time point when average activity occurs in a slice duration s d due to decay, assuming no change from kinetics, and λ is isotope decay constant for the injected radioactive tracer material;
(j) determining time of average activity relative to injection time of the radioactive tracer material as a reference time t ref , by equation (5):
t ref (pass, z )= t s (pass, z )+tav(pass, z ) (5),
wherein, t s (pass,z) is the start time of the pass relative to the injection time, and tav(pass,z) is the time of average activity within the slice centered at z based on equation (4); and
(k) determining a respective value of a blood input function c p (t) of the patient, corresponding to the reference time t ref for each respective slice, and a respective integral of the blood input function c p (t) corresponding to each respective slice.
4. The method of claim 3 , wherein the first direction is from the patient's head to feet direction.
5. A method of conducting a multi-pass dynamic positron emission tomography (PET) scans of a patient that has been injected with a radioactive tracer material using continuous bed motion (CBM) mode on a PET scanner that comprises a gantry and a patient bed, the method comprising:
injecting a radioactive tracer material into the patient;
acquiring dynamic PET sinogram data over a first portion of the patient's body using CBM mode as the patient bed moves in a first direction;
acquiring dynamic PET sinogram data over a second portion of the patient's body using CBM mode as the patient bed moves back and forth in the first direction then in a second direction that is opposite from the first direction; and
reconstructing 3-D PET image from the acquired dynamic PET sinogram data, wherein acquiring dynamic PET sinogram data of the patient comprises:
(a) acquiring PET sinogram data of the patient with a single bed mode;
(b) acquiring PET sinogram data using CBM mode having a constant/varying velocity;
(c) recording a plurality of bed tags while acquiring the PET sinogram data;
(d) obtaining a parameterized/fitted blood input function based on data acquired at steps (a) and (b);
(e) repeating a loop containing steps (f)-(k) for each PET scan pass;
(f) repeating a loop containing steps (g)-(k) for each image slice;
(g) determining slice entry time t s and slice exit time to of the image slice with respect to the gantry of the PET scanner, based on equations (1) and (2):
t s (pass, z )=ƒ( z s ( z ),pass start time,bed tags,scan mode) (1),
t e (pass, z )=ƒ( z e ( z ),pass start time,bed tags,scan mode) (2),
wherein:
t s (pass,z) is the slice start time, relative to pass start time, when the slice centered at z enters the PET scanner's field of view,
t e (pass,z) is the slice end time, relative to pass start time, when the slice centered at z exits the PET scanner's field of view,
z s (z) is the z coordinate of a starting edge of the slice,
z e (z) is the z coordinate of an ending edge of the slice,
pass start time is the time, relative to the injection of the radioactive tracer material, when the current pass starts,
bed tags include time and position coordinate pairs having positions within the slice and/or nearest adjacent bed tags outside of the slice,
scan mode is one of the predetermined modes of operating the PET scanner selected by the operator, and
function ƒ can be an interpolation function for determining the start time of the slice based on the nearest bed tags before and after the start time of the slice and the nearest bed tags before and after the end time of the slice;
(h) determining slice duration s d (pass,z), the length of time the slice is within the PET scanner's field of view, is determined, according to equation (3):
s d (pass, z )= t e (pass, z )− t s (pass, z ) (3);
(i) determining a respective average acquisition time for each slice computed according to equation (4):
tav
(
pass
,
z
)
=
1
λ
*
ln
(
λ
*
s
d
(
pass
,
z
)
/
(
1
-
exp
(
-
λ
*
s
d
(
pass
,
z
)
)
,
(
4
)
wherein, t av is the time point when average activity occurs in a slice duration s d due to decay, assuming no change from kinetics, and λ is isotope decay constant for the injected radioactive tracer material;
(j) determining time of average activity relative to injection time of the radioactive tracer material as a reference time t ref , by equation (5):
t ref (pass, z )= t s (pass, z )+tav(pass, z ) (5),
wherein, t s (pass,z) is the start time of the pass relative to the injection time, and tav(pass,z) is the time of average activity within the slice centered at z based on equation (4); and
(k) determining a respective value of a blood input function c p (t) of the patient, corresponding to the reference time t ref for each respective slice, and a respective integral of the blood input function c p (t) corresponding to each respective slice.
6. The method of claim 5 , wherein the first direction is from the patient's head to feet direction.
7. A method of conducting a multi-pass dynamic positron emission tomography (PET) scans of a patient that has been injected with a radioactive tracer material using continuous bed motion (CBM) mode on a PET scanner that comprises a gantry and a patient bed, the method comprising:
injecting radioactive tracer material into the patient;
(1) acquiring dynamic PET sinogram data using CBM mode in a first direction as the patient bed moves from an initial position to a second position;
(2) acquiring dynamic PET sinogram data using CBM mode in a second direction that is opposite from the first direction as the patient bed moves from the second position to a third position;
(3) acquiring dynamic PET sinogram data using CBM mode in the first direction as the patient bed moves from the third position to the second position;
repeating (2) and (3) one or more times:
(4) acquiring dynamic PET sinogram data using CBM mode in the first direction from the second position to a fourth position; and
reconstructing 3-D PET image from the acquired dynamic PET sinogram data,
wherein acquiring dynamic PET sinogram data of the patient comprises:
(a) acquiring PET sinogram data of the patient with a single bed mode;
(b) acquiring PET sinogram data using CBM mode having a constant/varying velocity;
(c) recording a plurality of bed tags while acquiring the PET sinogram data;
(d) obtaining a parameterized/fitted blood input function based on data acquired at steps (a) and (b);
(e) repeating a loop containing steps (f)-(k) for each PET scan pass;
(f) repeating a loop containing steps (g)-(k) for each image slice;
(g) determining slice entry time is and slice exit time to of the image slice with respect to the gantry of the PET scanner, based on equations (1) and (2):
t s (pass, z )=ƒ( z s ( z ),pass start time,bed tags,scan mode) (1),
t e (pass, z )=ƒ( z e ( z ),pass start time,bed tags,scan mode) (2),
wherein:
t s (pass,z) is the slice start time, relative to pass start time, when the slice centered at z enters the PET scanner's field of view,
t e (pass,z) is the slice end time, relative to pass start time, when the slice centered at z exits the PET scanner's field of view,
z s (z) is the z coordinate of a starting edge of the slice,
z e (z) is the z coordinate of an ending edge of the slice,
pass start time is the time, relative to the injection of the radioactive tracer material, when the current pass starts,
bed tags include time and position coordinate pairs having positions within the slice and/or nearest adjacent bed tags outside of the slice,
scan mode is one of the predetermined modes of operating the PET scanner selected by the operator, and
function ζ can be an interpolation function for determining the start time of the slice based on the nearest bed tags before and after the start time of the slice and the nearest bed tags before and after the end time of the slice;
(h) determining slice duration s d (pass,z), the length of time the slice is within the PET scanner's field of view, is determined, according to equation (3):
s d (pass, z )= t e (pass, z )− t s (pass, z ) (3);
(i) determining a respective average acquisition time for each slice computed according to equation (4):
tav
(
pass
,
z
)
=
1
λ
*
ln
(
λ
*
s
d
(
pass
,
z
)
/
(
1
-
exp
(
-
λ
*
s
d
(
pass
,
z
)
)
,
(
4
)
wherein, t av is the time point when average activity occurs in a slice duration s d due to decay, assuming no change from kinetics, and λ is isotope decay constant for the injected radioactive tracer material;
(j) determining time of average activity relative to injection time of the radioactive tracer material as a reference time t ref , by equation (5):
t ref (pass, z )= t s (pass, z )+tav(pass, z ) (5),
wherein, t s (pass,z) is the start time of the pass relative to the injection time, and tav(pass,z) is the time of average activity within the slice centered at z based on equation (4); and
(k) determining a respective value of a blood input function c p (t) of the patient, corresponding to the reference time t ref for each respective slice, and a respective integral of the blood input function c p (t) corresponding to each respective slice.
8. The method of claim 7 , wherein the first direction is from the patient's head to feet direction.
9. A system for processing and reconstructing dynamic positron emission tomography (PET) sinogram data, comprising:
a processor configured for executing instructions; and
a non-transitory, machine-readable storage medium encoded with program code and coupled to the processor, the storage medium comprising:
a code for controlling a PET scanner to perform the method of claim 1 .
10. The system of claim 9 , wherein the first direction is from the patient's head to feet direction.
11. A system for processing and reconstructing dynamic positron emission tomography (PET) sinogram data, comprising:
a processor configured for executing instructions; and
a non-transitory, machine-readable storage medium encoded with program code and coupled to the processor, the storage medium comprising a code for controlling a PET scanner to perform the method of claim 3 .
12. The system of claim 11 , wherein the first direction is from the patient's head to feet direction.
13. A system for processing and reconstructing dynamic positron emission tomography (PET) sinogram data, comprising:
a processor configured for executing instructions; and
a non-transitory, machine-readable storage medium encoded with program code and coupled to the processor, the storage medium comprising a code for controlling a PET scanner to perform the method of claim 5 .
14. The system of claim 13 , wherein the first direction is from the patient's head to feet direction.
15. A system for processing and reconstructing dynamic positron emission tomography (PET) sinogram data, comprising:
a processor configured for executing instructions; and
a non-transitory, machine-readable storage medium encoded with program code and coupled to the processor, the storage medium comprising a code for controlling a PET scanner to perform the method of claim 7 .
16. The system of claim 15 , wherein the first direction is from the patient's head to feet direction.