WO2009022247A1

WO2009022247A1 - Volumetric stress echocardiography slice view

Info

Publication number: WO2009022247A1
Application number: PCT/IB2008/053031
Authority: WO
Inventors: David Hull; Allen Snook; Michael Vion; Rohit Garg
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2007-08-15
Filing date: 2008-07-29
Publication date: 2009-02-19

Abstract

The present invention provides a method for displaying ultrasound data on a display comprising the steps of acquiring volumetric ultrasound data from a heart, in particular from a left ventricle at different times. Preferably the volumetric ultrasound data are acquired before and after exercise (e.g. treadmill/bicycle) or medication. On the basis of the acquired volumetric ultrasound data tomographic C-plane cuts at different depths are reconstructed. Reconstructed tomographic C-planes of corresponding dephts but of different times are displayed on a screen side-by-side. Preferably the tomographic C-planes which have been obtained at different dephts and times are displayed in an array or matrix on the display.

Description

Volumetric Stress Echocardiography Slice View

FIELD OF THE INVENTION

The present invention relates to stress echocardiography imaging techniques. In particular, the present invention relates to a method, device and a computer readable medium for displaying ultrasound data on a display. Moreover, the present invention relates to a user interface presenting a novel approach to stress echocardiography by utilizing C-plane slices obtained from volumetric images of the heart before and after stress.

BACKGROUND OF THE INVENTION

Stress echocardiography is a test that helps to diagnose heart disease by means of ultrasound images. Following exercise or other stress to the heart, the images reveal parts of the heart that may not be receiving enough blood or oxygen because of blocked arteries.

The ultrasound portion of this test is performed in the same way as an echocardiogram.

Exercise (treadmill/bicycle) or medication is used to increase the heart rate and to show how the heart works under exertion. In particular, cardiac wall motions of the left ventricle are analyzed before and after stress to detect abnormalities during systole (the contraction phase of the heart) and/or during diastole (the expansion phase of the heart). The left ventricle wall is typically divided into a plurality of segments (e.g. 16 or 17, see Fig. 4) according to the standard recommended by the American Society of Echocardiography

(ASE). In order to evaluate all 16 or 17 segments of the left ventricle there are four standardized ultrasound views suggested to acquire image data information for each left ventricular segments.

Typically an echocardiographer records two B-plane ultrasound sequences from a patient at rest, i.e. before exercise from a parasternal position (see reference number 10 in Fig. 3) in order to obtain a long axis (PLAX; parasternal long axis) and short axis (SAX; short axis) views of the left ventricle as illustrated in Figs. 2A and 2B. Thus, in order to get the two different views, the echocardiographer has to align the ultrasound head two times in the parasternal position.

Afterwards, the echocardiographer obtains two B-plane ultrasound sequences from the apical position (see reference number 2 in Fig. 3) in order to obtain the apical four- chamber (AP4) and two-chamber (AP2) views as illustrated in Figs.2C and 2D. Again, the echocardiographer has to align the ultrasound head two times, this time in the apical position.

After the four different views are obtained from the patient in the unstressed state the same or similar four views are obtained after exercise (treadmill/bicycle) or medication such that the motion of each of the 16 or 17 segments is comparable between a unstressed and stressed status of the heart. It is also common to acquire the four standardized views under various conditions such that each of the four views can be compared under different conditions. The corresponding views are then displayed and compared side-by-side on a screen, e.g. AP2 is displayed before and after exercise side-by- side on a screen, so as to identify possible wall motion abnormalities before and after stress.

However, in order to obtain comparable ultrasound pictures or movies before and after exercise, the echocardiographer has to align the transducer at the same four positions before and after stress, i.e. in the two parasternal and in the two apical position before and after stress which is quite difficult.

There is therefore a need for an improved stress echocardiography imaging technique. It is thus an object of the present invention to provide an improved method for acquiring and displaying echocardiography data. It is a further object of the invention to provide a system which helps an echocardiographer in obtaining and comparing ultrasound data, particularly stress ultrasound date. In particular, the method of the present invention should provide an improved and simplified imaging technique which enables an echocardiographer in acquiring ultrasound data in a simplified way and further provides the echocardiographer with an image technique which simplifies comparison of echocardiography views before and after stress.

SUMMARY OF THE INVENTION In order to achieve these objects, the present invention provides a method for displaying ultrasound data on a display comprising the steps of acquiring volumetric ultrasound data from a heart, in particular from a left ventricle at different times. Preferably the volumetric ultrasound data are obtained by an echocardiographer before and after exercise (e.g. treadmill/bicycle) or medication. It should be noted that the different times are not restricted to the states before and after exercise, e.g. the ultrasound data may also be obtained during exercise or at different stages of exercise, during a rest period or during different stages of medication.

Preferably the ultrasound data are acquired from one and the same position during the different possible stages. As will be evident from the following discussion, the acquiring from the apical position is preferred. However, it is also possible to obtain the ultrasound data from the parasternal position. For a further examination of particular segments ofthe heart, obtaining the data from the parasternal and the apical position is also an option.

Preferably the acquired ultrasound data are volumetric ultrasound data. On the basis ofthe acquired volumetric ultrasound data it is possible to reconstruct afterwards C-plane cuts, i.e. tomographic cuts substantially in an orthogonal direction with respect to the ultrasound propagation direction. However, the term C-plane is not restricted to orthogonal cuts; typically a C-plane is any plane between the range of 10° and 90° with respect to the ultrasound propagation direction. For instance, a 90° C-plane is illustrated in Fig. IA and IB with reference numeral 2. Figure IA and IB also illustrate with reference numeral 3 a B-plane cut which is a cut substantially in the direction of the sound propagation.

The acquiring of volumetric ultrasound data allows reconstructing at least one, preferably two three or four tomographic C-p lanes from the volumetric data at different depths from each acquired time. In particular, the acquired and stored volumetric ultrasound data allow a tomographic reconstruction in every depth in C-plane direction. Moreover, the acquired and stored volumetric ultrasound data also allow tomographic reconstructions in the B- plane direction.

Preferably the tomographic C-planes are reconstructed in two, three, four or even more different depths relative to the position of the ultrasound head. For instance, with three C- planes in appropriate depths, it is possible to view all 16 segments of the ASE standard. Four C-plane cuts, e.g. allow an examination of all 17 segments according to the other ASE standard. For some cases it may also be preferred to reconstruct only a single C- plane, e.g. in case an abnormality has been detected in a specific C-plane.

After reconstruction, the tomographic C-planes are displayed on a screen side-by-side. Preferably the different C-planes which have been obtained at different times are displayed in an array or matrix side-by-side on the display. For instance, four different tomographic C-planes before exercise may be displayed in a column. The corresponding tomographic C-plane cuts after exercise may be displayed in another column next to the first column on the display, i.e. C-planes taken at the same depth but at different times are displayed in same rows as depicted for example in Fig. 5.

Preferably the rows and columns and/or the individual pictures (or movies) are labelled with the corresponding segment names according to the ASE. This helps an echocardiographer to identify easily which segment or part of the heart is pathological.

Preferably, the volumetric data acquired at different times are at least acquired over the time span of a heart cycle such that the diastolic motions and the systolic motions of the heart can be examined. However, for some cases it may be sufficient if the time span is shorter than a complete heart cycle, e.g. in case only the systolic or only the diastolic motions of the heart are of interest. In other cases it may be preferred that the volumetric data are acquired at least over the time span of multiple heart cycles. The reconstructed tomographic C-planes may be single images. This may be advantageous in case a specific state of the heart cycle is of interest. However, in order to examine the motion of the heart, it may be preferred to reconstruct tomographic C-planes in form of movies. The reconstruction of movies provides the advantage that the movies of the tomographic C-planes from different times can be displayed synchronously with regard to the heart cycle side-by-side on the display. An echocardiographer may then easily detect a pathological motion of a heart wall when comparing the movies of the C-plane before and after stress. It may be further preferred to display the movies in loops such that the echocardiographer may see the same sequence many times which may help in detection of pathological heart wall motions.

In addition to the reconstructed tomographic C-planes, it may be further helpful to examine certain regions of the heart from a different perspective. According to the present invention it is also possible to reconstruct tomographic B-plane views from the acquired and stored volumetric data. Such a reconstructed B-plane view may be displayed together, e.g. side-by-side, with the C-planes views.

Preferably the storage and display format of the present invention is compatible with common standards, e.g the ultrasound data may be stored in the DICOM format which allows an easy exchange between most of the available ultrasound and displaying systems.

The present invention also relates to a system for an echocardiography imaging technique. The system comprises a memory for storing volumetric ultrasound data, e.g. volumetric ultrasound data from a heart acquired at different times; a processor for reconstructing at least one, preferably two, three, four or more tomographic C-planes from the volumetric data at different depths from each acquired time and a display for displaying the reconstructed tomographic C-planes acquired at different times side-by-side. Preferably the system is adapted to perform any of the above mentioned method steps. The present invention is also directed to a computer readable medium having stored therein data representing instructions executable by a programmed processor for executing the method steps as mentioned above.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. IA schematically shows the pyramid of a volumetric ultrasound scan region with indicated b- and C-planes.

Fig. IB schematically shows a scanning pyramid similar to Fig. 1 a but with multiple b- and C-planes at different depths.

Fig.2A shows the long axis view (PLAX) of the left ventricle taken from the parasternal position. Fig.2B shows the short axis view (SAX) of the left ventricle taken from the parasternal position.

Fig.2C shows the apical four-chamber (AP4) view. Fig.2D shows the apical two-chamber (AP4) view.

Fig.3 shows the torso of a human with indicated parasternal and apical regions. Fig.4 shows the bulls-eye plot with 16 segments according to the ASE.

Fig.5 shows C-planes from the apex, apical, mid and basal region of a heart in columns at different stages of exercise (rest, post exercise 1 and post exercise 2).

DETAILED DESCRIPTION OF EMBODIMENTS Stress echocardiography according to the present invention may be conducted as follows. The echocardiographer adjusts the ultrasound head or transducer 1 at the apical position, which is e.g. depicted in Fig. 3 at reference sign 20. After positioning the transducer, volumetric ultrasound data from the heart are acquired the first time when the patient is at rest. After acquiring the volumetric ultrasound data, the patient start an exercise, e.g. walking on a treadmill. Immediately after the exercise and maybe later on, the echocardiographer acquires similar volumetric ultrasound data from the same position, i.e. from the apical position.

At a next step, the method or device according to the present invention reconstructs from the acquired and stored volumetric ultrasound data four tomographic C-p lanes at different depths, e.g. from the apex, apical, mid and basal region of the heart. The reconstructed C- planes from different depths before and after exercise are displayed side-by-side on a display. In particular, the C-planes are displayed in rows and columns as depicted for example in Fig. 5. The rows correspond to different regions of the heart while the columns enable a direct comparison of corresponding segments of the heart before and after stress. Figure 5 shows an example of 12 possible tomographic slices. The tomographic C-planes are reconstructed at four different depths, namely at the apex, in the apical region, in the mid region and in the basal region of the heart. The different depths are depicted side-by- side column wise. Moreover, similar C-planes, i.e. similar depths are reconstructed in a rest position of a patient and at two different times after exercise, e.g. post exercise 1 and post exercise 2. The pictures or movies are labelled apex at rest, apex at post 1, apex at post 2, apical at rest, apical at post 1, apical at post 2, mid at rest, mid at post 1, mid at post 2, basal at rest, basal at post 1 and basal at post 2, mid 2, basal 1, basal 2. The labelling of the slices (view and stage name) will be made available to DICOM export. In this way, the operator is able to analyse efficiently and quickly the left ventricle before and after stress, from apex to base for example.

Figure 4 shows the bulls-eye plot with 16 segments according to the ASE, i.e. the three rings represent the different planes nearest the top of the heart (outer ring, basal), mid and nearest the bottom of the heart (inner ring, apical or apex).

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A method for displaying ultrasound data on a display comprising the steps: acquiring volumetric ultrasound data from an object at different times; reconstructing at least two tomographic C-planes from the volumetric data at different depths from said object from each acquired time; displaying the reconstructed tomographic C-planes of the corresponding depths but different times side-by-side on a display.

2. The method according to claim 1, wherein volumetric data are acquired at least over the time span of a heart cycle.

3. The method according to claim 1, wherein volumetric data are acquired at least over the time span of multiple heart cycles.

4. The method according to any of claims 1, wherein volumetric data are acquired from the left ventricular myocardium before and after stress of a patient from the apex side.

5. The method according to any of claims 1, wherein at least three tomographic C-planes are reconstructed in three different depths to represent the

16 segments according to the standard recommended by the American Society of Echocardiography, ASE.

6. The method according to any of claims 1 , wherein at least four tomographic C-planes are reconstructed in four different depths to represent the

17 segments according to the standard recommended by the ASE.

7. The method according to any of claims 1 , wherein at least one of the reconstructed tomographic C-planes is an image or a movie.

8. The method according to claim 7, wherein the movie(s) of the tomographic C-planes from different times are displayed synchronously with regard to the heart cycle.

9. The method according to claim 7, wherein the movie(s) are displayed in loops.

10. The method according to any of claims 1, wherein the tomographic C- planes from different depths and different times are displayed in a matrix format (in rows and columns).

11. The method according to any of claims 10, wherein the rows and columns are labelled with the corresponding segment names according to the ASE.

12. The method according to any of claims 1, wherein B-plane views are reconstructed from the volumetric data and displayed together with the C-planes.

13. A system for an echocardiography imaging technique comprising: a memory for storing volumetric ultrasound data from an object acquired at different times; a processor for reconstructing at least two tomographic C-planes from the volumetric data at different depths from said object from each acquired time; a display for displaying the reconstructed tomographic C-planes of the corresponding depths but different times side-by-side.

14. The system according to claim 13, further adapted to perform the method steps according to claim 1.

15. A computer readable medium having stored therein data representing instructions executable by a programmed processor for executing the method steps according to claim 1.