Determining a measuring point-in-time in a cardiac cycle for conducting magnetic resonance diffusion measurements

1. A method for determining at least one point-in-time within a cardiac cycle at which a magnetic resonance (MR) at which diffusion data from the myocardium of an examination subject are to be acquired, said method comprising:

operating an MR data acquisition unit, while an examination subject is situated therein, to acquire a sequence of MR images of the heart of the examination subject, said heart exhibiting a geometric feature represented in said MR images that is a length or a volume associated with a selected contour of the heart;

providing said MR images to a computer and, in said computer, automatically determining a time curve of a parameter of said geometric feature in said sequence, said time curve representing changing of said parameter within each cardiac cycle due to beating of said heart;

in said computer, automatically determining a mean of said parameter from said time curve, and then determining a point in time along said time curve at which said mean occurs;

emitting an electronic control signal from said computer to said MR data acquisition unit that identifies said point in time at which said mean occurs, as a designation of at least one point-in-time that said MR diffusion data of the myocardium should be acquired, and said MR data acquisition unit responding to said electronic control signal to acquire said MR diffusion data of the myocardium at said at least one point-in-time; and

in said computer, transforming the acquired MR diffusion data of the myocardium into image data, and making the image data available in electronic form, as a data file, from said computer.

2. A method as claimed in claim 1 comprising, in said computer, determining a parameter value of said parameter in each of said MR images in said sequence and determining, as said mean, the arithmetic mean of said parameter values, and designating a point-in-time in said electrical signal from said computer, at which said arithmetic mean occurs on said time curve, as said point-in-time at which said MR diffusion data of the myocardium should be acquired.

3. A method as claimed in claim 2 comprising, in said computer:

identifying a period within said time curve of said parameter within which all parameter values of said parameter are less than said arithmetic mean;

determining a first-occurring parameter value in said period and determining a preceding parameter value that occurs immediately before said first-occurring parameter value in said time curve;

identifying a first point in time that is between respective points in time at which said first-occurring parameter value and said preceding parameter value occur;

identifying a last-occurring parameter value within said period and a next parameter value that occurs immediately after said last-occurring parameter value;

identifying a second point-in-time in said time curve that is between points-in-time in said time curve at which said last-occurring parameter value and said next parameter value occur; and

emitting said first point-in-time and said second point-in-time from said computer as electronic signals that each designate a point-in-time at which said MR diffusion data of the myocardium should be acquired.

4. A method as claimed in claim 3 comprising determining said first point-in-time using a linear interpolation between said preceding parameter value and said first-occurring parameter value, and determining said second point-in-time using a linear interpolation between said last-occurring parameter value and said next parameter value.

5. A method as claimed in claim 1 comprising using, as said parameter of said geometric feature, a parameter selected from the group consisting of the endocardial contour of the myocardium, the epicardial contour of the myocardium, and the volume of the myocardium.

6. A method as claimed in claim 1 comprising operating said MR data acquisition unit to acquire said sequence of MR images with a gradient echo sequence in which magnetic field gradients are all completely refocused.

7. A method as claimed in claim 1 comprising determining said time curve of said parameter by identifying respective parameter values of said parameter in each of said MR images in said sequence, with each MR image in said sequence being situated in a single imaging layer of the heart of the examination subject.

8. A method as claimed in claim 1 comprising, in said computer:

determining said parameter by identifying a respective parameter value of said parameter in each of said MR images in said sequence; and

determining said time curve of said parameter by interpolating between the respective parameter values, and before said interpolation, adding a first-occurring parameter value at an end of the cardiac cycle, thereby causing said time curve to begin and end at equal parameter values.

9. A method as claimed in claim 8 comprising removing said added parameter value at said end of the cardiac cycle when determining said mean.

10. A method as claimed in claim 1 comprising implementing said acquisition of MR diffusion data from the myocardium at said point in time by operating said MR data acquisition unit to activate at least one diffusion gradient that encodes said MR data acquired from the myocardium at said point in time.

11. A magnetic resonance (MR) apparatus comprising:

an MR data acquisition unit;

a computer configured to operate the MR data acquisition unit, while an examination subject is situated therein, to acquire a sequence of MR images of the heart of the examination subject, said heart exhibiting a geometric feature represented in said MR images that is a length or a volume associated with a selected contour of the heart;

said computer being configured to automatically determine a time curve of a parameter of said geometric feature in said sequence, said parameter changing within each cardiac cycle due to beating of said heart;

said computer being configured to automatically determine a mean of said parameter from said time curve, and then determine a point in time along said time curve at which said mean occurs;

said computer being configured to emit an electronic signal from said computer that identifies said point in time at which said mean occurs, as a designation of at least one point-in-time that said MR data acquisition unit should be operated to acquire MR diffusion data of the myocardium of the examination subject, and said MR data acquisition unit responding to said electronic control signal to acquire said MR diffusion data of the myocardium at said at least one point-in-time; and

said computer being configured to transform the acquired MR diffusion data of the myocardium into image data, and to make the image data available in electronic form, as a data file, from said computer.

12. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a control and processing computer system of a magnetic resonance (MR) apparatus, said MR apparatus also comprising an MR data acquisition unit, and said programming instructions causing said control and processing computer system to:

operate the MR data acquisition unit, while an examination subject is situated therein, to acquire a sequence of MR images of the heart of the examination subject, said heart exhibiting a geometric feature represented in said MR images that is a length or a volume associated with a selected contour of the heart;

automatically determine a time curve of a parameter of said geometric feature in said sequence, said parameter changing within each cardiac cycle due to beating of said heart;

automatically determine a mean of said parameter from said time curve, and then determine a point in time along said time curve at which said mean occurs;

emit an electronic signal that identifies said point in time at which said mean occurs, as a designation of at least one point-in-time that said MR data acquisition unit should be operated to acquire MR diffusion data of the myocardium of the examination subject, in order to cause said MR data acquisition unit to respond to said electronic control signal to acquire said MR diffusion data of the myocardium at said at least one point-in-time; and

transform the acquired MR diffusion data of the myocardium into image data, and make the image data available in electronic form, as a data file, from said computer.