Method for quantifying myocardial blood flow from a nuclear medicine tomographic image

1 . A method for quantifying myocardial blood flow from a nuclear medicine tomographic image, comprising:

a preliminary Stage B of acquiring and reconstructing a tomographic image, comprising the following steps:

B 1 ) Acquiring a volumetric tomographic image of the heart;

B 2 ) Recording the time T, in seconds, elapsed between the start of the radiotracer administration of a step A 3 ) of administering a radiotracer to an individual and the start of the acquisition of the static tomographic image of said step B 1 );

B 3 ) Reconstructing the image acquired in said step B 1 );

wherein said preliminary Stage B is excluded from the present method;

a Stage C of processing the tomographic image; and

a Stage D of calculating the myocardial blood flow;

wherein

stage C of processing the tomographic image comprises the following steps:

C 1 ) depending on the clinical application, segmenting in the reconstructed image in step B 3 ) the left ventricle, ascending aorta or other region of interest where the blood activity concentration can be sampled with minimum interference from adjacent tissues, and segmenting the myocardium according to step C 2 );

C 2 ) depending on the clinical application, maintaining the myocardium as a single region of interest or dividing the myocardium into subregions of interest, which are selected from the group comprising: vascular territories, cardiac segments, and other combinations of voxels;

C 3 ) calculating and recording the average of the voxel values of the regions and subregions of interest segmented in said steps C 1 ) and C 2 ), according to the following equation:

V

m

=

1

N

·

∑

i

=

1

N

V

i

wherein:

V m is the mean value of the N voxel values belonging to the region of interest defined in said steps C 1 ) and C 2 );

V i is the value of a single voxel belonging to the region of interest;

and wherein said Stage D of calculation comprises the following steps:

D 1 ) adjusting the input function of said radiotracer (blood activity concentration versus time) using the following equation:

C

⁢

a

⁡

(

t

)

=

A

·

t

-

b

wherein:

Ca(t) is the mean value of activity concentration, obtained in said step C 3 ) for the left ventricle, for the ascending aorta, or for other region of interest where the blood activity concentration can be sampled with minimum interference from adjacent tissues representing the concentration of arterial activity at a time t=T;

A is the variable to be adjusted;

Tis the post-administration time of the radiotracer recorded in said step B 2 ); and

b is the power coefficient, whose value is greater than zero, and depends on the radiotracer used and the condition of the study defined in a step A 1 ) of determining the conditions under which the myocardial perfusion study will be performed;

D 2 ) calculating said coefficient A of said input function, using the equation of said step D 1 ), using the following expression:

A

=

C

⁢

a

⁡

(

T

)

·

T

b

wherein Tis the post-administration time of the radiotracer recorded in said step B 2 );

D 3 ) calculating the entry constant of the radiotracer to the myocardium, called K1, measured in [ml/min/g tissue ] using the following equation:

K

⁢

1

=

m

·

C

⁢

m

⁡

(

T

)

∫

0

T

Ca

⁡

(

t

)

⁢

dt

wherein:

m is a coefficient that depends on said radiotracer, said condition of the myocardial perfusion study of a preliminary stage A, and the population being studied; and

Cm(T) is the mean value of activity concentration, obtained in said step C 2 ) for the myocardium; and

D 4 ) iteratively calculating the myocardial blood flow, called F, measured in [ml/min/g tissue ], until a tolerance of at least 1×10 −3 ml/min/g is achieved, using the following equation:

K

⁢

1

=

F

·

(

1

-

e

-

α

+

β

·

F

F

)

wherein

α and β are coefficients dependent on said myocardial perfusion radiotracer; and

the term α+β·F is the surface permeability product of the Renkin-Crone model adapted for multiple capillaries.

2 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the left ventricle and said regions of said step C 2 ) optionally comprise the complete myocardium.

3 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) comprises the left ventricle and said regions of said step C 2 ) comprise the three vascular territories.

4 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the left ventricle and said regions of said step C 2 ) optionally comprise the 17 cardiac segments.

5 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the left ventricle and said regions of said step C 2 ) optionally comprise each voxel of the myocardium.

6 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the ascending aorta and said regions of said step C 2 ) optionally comprise the complete myocardium.

7 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the ascending aorta and said regions of said step C 2 ) optionally comprise the three vascular territories.

8 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the ascending aorta and said regions of said step C 2 ) optionally comprise the 17 cardiac segments.

9 . The method for quantifying myocardial blood flow according to claim 1 , wherein said region of said step C 1 ) optionally comprises the ascending aorta and said regions of said step C 2 ) optionally comprise each voxel of the myocardium.

10 . The method for quantifying myocardial blood flow according to claim 1 , wherein said method is carried out in a data processing system.