WO2008110962A1

WO2008110962A1 - Visualization of parametric maps

Info

Publication number: WO2008110962A1
Application number: PCT/IB2008/050796
Authority: WO
Inventors: Mark C. Wengler; Alexander Fischer
Original assignee: Koninklijke Philips Electronics N.V.; Philips Intellectual Property & Standards Gmbh
Priority date: 2007-03-09
Filing date: 2008-03-05
Publication date: 2008-09-18

Abstract

The invention discloses visualizing a plurality of parametric maps (102, 104, 106) of an area (103), the parametric maps visualizing parametric levels, the method comprising determining first regions (204, 206, 208) within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and determining second regions (212, 214, 216) within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and visualizing a fused map (202) of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map, in order e.g. hereby to provide an easy, fast, simple and distinctive determination of those regions where two or more maps match to each other, while also being able to see any relations between the maps.

Description

Visualization of parametric maps

FIELD OF THE INVENTION

The invention relates to visualization of parametric maps, and in particular to provide an improved comparative visualization of parametric maps.

BACKGROUND OF THE INVENTION

Biologic functional parameters can be measured either directly by certain imaging modalities or can be achieved by suitable analysis of the data measured by imaging systems.

In a resulting image each pixel or voxel, depending on the resolution, contains the measured value of the parameter in a spatial position of the pixel or voxel. For a simplified display of the resulting image, and for some applications such as radio therapy planning, neighboring pixels or voxels of similar value are merged into clusters by clustering. With a clustering method, the quasi-continuous values of the functional parameter are reduced to a smaller number of parametric levels and then displayed in a parametric map or cluster map.

In a number of cases more than only one method can be used to achieve the same or similar or even different biological and/or functional parameter. The use of e.g. different modalities, different parameters or different image analysis may lead to different results and therefore contradictory functional parameter maps are achieved in some examples. Though, the results can also be complementary.

The US patent US 6,650,928 discloses a method for facilitating an analysis of computed tomographic (CT) images. The method includes steps of: acquiring attenuation data of a patient using a CT imaging system; reconstructing images of the patient using the acquired attenuation data; mapping intensity data from at least one reconstructed image into a color image using a color mapping indicative of physiological thresholds; and displaying the color image. Embodiments in US 6,650,928 facilitate the assessment of images and differences between images for functional image data and for perfusion-related imaging data. In the view of the present inventors US 6,650,928 fails to provide easy comparative visualization of a plurality of parametric maps. The inventors of the present invention has appreciated that an improved comparative visualization of parametric maps is of benefit, and has in consequence devised the present invention.

SUMMARY OF THE INVENTION

It may be seen as an object of the present invention to provide an improved method and apparatus for comparative visualization of a plurality of parametric maps. Preferably, the invention alleviates, mitigates or eliminates one or more of the above or other disadvantages singly or in any combination. Accordingly there is provided, in a first aspect, a method of visualizing a plurality of parametric maps of an area, the parametric maps visualizing parametric levels, the method comprising determining first regions within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and determining second regions within the plurality of parametric maps that are spatially non- overlapping or have parametric levels which are substantially different, and visualizing a fused map of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map.

Thus a method in which an easy, fast, simple and distinctive determination of those regions where two or more maps match to each other, such as within a certain threshold, is provided.

As an example, more than only one method can be used to achieve the same or a similar biological parameter map, such as by using different modalities or different parameters or different image analysis. This may lead to different results, and therefore contradictory functional parameter maps are possibly achieved. Though, the results can also be complementary. Alternatively or additionally, the results may be contradictory or complementary in at least part of the maps. In any of the examples it can be difficult to distinguish which region(s) of an area resemble a certain function, which region(s) match and/or which regions of the maps do not match. By combining the plurality of maps obtained in a fused map in accordance with the described invention, there is provided a method in which an easy, fast, simple and distinctive determination of those regions where two or more maps match and where they do not match to each other, possibly within a certain threshold. Still further, there is provided a visualization of the plurality parametric maps in one map. Furthermore, an advantage by also showing the second regions in the fused map is that any possible contributions from one or more of the maps to one or more of the other maps and/or relations between the maps can be traced in the fused map.

In general for the present invention and its embodiments it is to be understood that an advantage is that an easy, fast, simple and distinctive determination of those regions where two or more maps match to each other within a certain threshold e.g. in a single view e.g. on a limited area of e.g. a computer screen is provided by the visualization of the fused map. The visualization in the fused map may be provided in a single view in a same part of a display unit. It is to be understood that the plurality of parametric maps need not be visible, such as displayed as two or more separate images on one or two computer screens, before providing the fused map, but can only be present as a digital representation, e.g. within a digital storage of an imaging system for obtaining the images. Alternatively the parametric maps or images can be referred to as cluster maps. Each map may describe a two- dimensional map or a three-dimensional map.

When, the second regions are displayed in the fused map by overlaying at least part of the one or more other maps in a way that the part is still at least partly visible, an advantage is that an effective way of simultaneously visualizing the plurality of maps in the single fused map is provided. In embodiments overlaying is provided by interlacing the second regions or by changing transparency of the second regions.

In an embodiment the regions in each of the plurality of maps where the parametric levels are substantially the same are provided with visibly distinctive codes. In general, the visible distinctive codes, the transparency of regions and/or distinctiveness between the different regions and/or maps may as examples be provided by different greyscale and/or darkness and/or luminance and/or color and/or hatch.

When, one of the plurality of maps is a combination of two of the other maps, a possible advantage is that contributions from each of the two maps to the combined map can be seen in the fused map. If furthermore one of the plurality of parametric maps is selected as a map of interest among the maps, such as selecting the map which is a combination of two of the plurality of maps, a further possible advantage is that it is possible to display the other maps relative to the map of interest.

When, each parametric level is provided within one or more boundaries, and determining the first regions within the plurality of parametric maps that spatially overlap is provided by comparing the boundaries, a possible way of determining the first regions is provided. The first or second regions may be determined in numerous ways, such as by comparing region boundaries and/or by using mathematical methods. An alternative method of determining regions is by comparing parametric levels of the same pixel or voxel in each of the plurality of maps, hereby it is known that the pixel or voxel compared is spatially overlapping and then it is only to be determined whether or not the parametric level in the particular pixel or voxel is the same in the plurality of parametric maps.

According to a second aspect of the invention there is provided an apparatus for visualizing a plurality of parametric maps of an area, the parametric maps visualizing parametric levels, the apparatus comprising a control logic arranged to determine first regions within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and to determine second regions within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and a display unit arranged to visualize a fused map of the parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map.

The control logic may determine the first and second regions in numerous ways, such as by comparing region boundaries and/or by using mathematical methods. The display unit may be a computer screen, a printer or similar apparatuses arranged to visualize the fused map. According to a third aspect of the invention, there is provided an image obtaining system, such as a CT or a PET or an MR imaging system, comprising a unit for obtaining the plurality of parametric maps of the area, and the apparatus for visualizing the plurality of parametric maps of an area according to the invention. The image obtaining system may provide substantially non-processed image data. Parametric maps are normally the result of post-processing or analysis steps carried out on the basis of the substantially non-processed image data. These post-processing or analysis steps can be carried in a part of the imaging system such as carried out by the imaging system and acquisition software linked with e.g. a scanner of the imaging system. Alternatively these post-processing and analysis steps can be provided by an independent viewing and analysis system. In a fourth aspect there is provided a computer readable code adapted to perform the method in accordance with the invention.

In general by writing that 'it is an advantage' or 'it is a possible advantage' of the present invention and referring to an advantage, it must be understood that this advantage may be seen as a possible advantage provided by the invention, but it may also be understood that the invention is particularly, but not exclusively, advantageous for obtaining the described advantage. The various aspects and advantages of the invention may be combined and coupled in any way possible within the scope of the invention.

These and other aspects, features and/or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which FIG. 1 shows three parametric maps of an area.

FIG. 2 shows a visualization of the fused map.

FIG. 3 shows an apparatus for visualizing a plurality of parametric maps and an image obtaining system.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows an example where the plurality of parametric maps comprises three maps. A first map 102 of the plurality of maps describes a functional parameter A, a second map 104 describes a functional parameter B and a third map 106 describes the functional parameter C. The parameters may be biological parameters or any other kind of parameters.

Each map describes a two-dimensional area. The area could also be three-dimensional. The area may be referred to as the area V. The parameters is represented by the three maps A(x), B(x) and C(x), where x belongs to the area V. In imaging, such as medical imaging, x may be a location of a pixel in a two-dimensional area or a voxel in a three-dimensional area. Ra, Rb and Rc is defined as three ranges of the parametric values of the parameters A, B and C respectively. The parametric values of the parametric levels in the plurality of maps in this example represent a finite set of values. In the example the parametric maps are cluster maps, and each map has four parametric levels.

In the example the third map 106 is a combined AB map combining the parametric map 102 of the functional parameter A and the parametric map 104 of the functional parameter B into a parameter C map. The combined map 106 may be used when e.g. the use of different modalities or different image analysis or different parameters leads to different results such as in the maps 102 and 104, and therefore possibly differing functional parameter maps are achieved. Though, it is to be understood that a visualization of a fused display in accordance with the invention and the embodiments of the invention, and as further described in FIG. 2, may be provided based on a plurality of maps where none of the maps is a combination of the others, such as based on only two maps, such as based on the A map and the B map. Using the fused map in accordance with the subject-matter described herein provides the possibility of tracing contributions such as from the A map and/or the B map in the combined AB map.

In this example all maps have the same finite number of parametric levels. In other examples one level may not exist or a value of one or more parametric levels may be zero. In the example shown the number of parametric levels is as described four. A first level may be called a background parametric level 108 and preferably describes a parametric level which is zero of a background in the area 103.

Regions with certain parametric levels and boundaries of such regions within the area 103 will now be explained for the A map. The explanation is also useful for the B map and the AB map when e.g. noting that a fourth parametric level in the B map is present in two regions, a region 119 with the fourth parametric level of parameter B and another region 120 with the fourth parametric level of parameter B. Therefore a region having the fourth parametric level in the B map has two boundaries.

In the A map a second parametric level 110 of the A parameter is shown inside the boundary 111 of the second parametric level region. The second parametric level 110 of the A parameter is shown with a greyscale visible code which is slightly more grey than the background. Due to the increase in greyscale a boundary of the region can be determined visibly.

Regions in different maps where the parametric level is substantially the same is provided with visibly distinctive codes 115, 125 in the different maps.

The region within the boundary 111 has a parametric level which is one level higher than the background. Similarly, a region 112 with a third parametric level of the parameter A and a region 114 with a fourth parametric level of the parameter A are shown in the figure. A right side part of the boundary 111 of the second parametric level region of the A map is shown with a black line 113 following the right side of the boundary 111.

In the parameter B map 104 a second and third parameter B levels 116 and 118 are shown. Also shown is the fourth parametric level which in the B map has two regions, a region 119 with the fourth parametric level of parameter B and a region 120 with the fourth parametric level of parameter B as described.

In the AB map the second 122, third 124 and fourth 126 levels are shown. A right side part of the second parametric level boundary of the B map is shown with a black line 117 following the right side of the second parametric level boundary of the B map. A right side part of the second parametric level region boundary of the AB map is shown with a black line 123 following the right side of the second parametric level region boundary of the AB map.

In this simple example the first, second, third and fourth parametric levels is different from each other within one map but the parametric value of each level is the same in everyone of the maps. E.g. the fourth level in each of the maps is the same, but the spatial position, i.e. also the boundaries of the four levels differ from map to map in the plurality of maps. In this example it is not needed to determine the parametric level for each level in each of the maps, because it is known on beforehand that the parametric levels are the same. A reason for the codes of the regions or levels in the different maps being different, such as that the fourth region 126 of the AB map is almost completely black and the fourth region 114 of the A map is somewhat less black, is that it is preferred that it is also possible to provide a visible distinction between the different regions of the different maps. As described elsewhere herein other ways than using a greyscale going from white to black may be used in order to distinguish, e.g., between the levels or maps.

In FIG. 2 a display of a visualization in a single fused map 202 of the three coded parametric maps described in figure 1 is shown. In the fused map 202 all three parameters A, B and C, as described in figure 1, are shown. The fused map has as a possible advantage that it simplifies an identification of spatially overlapping regions with corresponding or identical values in the plurality of different maps, possibly along with a visualization of any relations between the maps.

In particular, there is shown a visualization of the plurality of parametric maps 102, 104, 106 of the area 103. The visualization is provided by determining first regions 204, 206, 208 within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and by determining second regions within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and visualizing the fused map 202 of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map. In this example the first regions 204, 206, 208 are shown displayed with the same visible codes which the parametric levels where provided with for one of the plurality of maps. In this example the first regions are visualized in the fused map with the codes of the AB map 106. The visible codes for the first and/or the second regions to be visualized with may be based on a predetermined setting or may be provided by selecting one of the maps as a map of interest.

The second regions are displayed in the fused map by overlaying at least part of the one or more other of the plurality of maps in a way that the part is still at least partly visible, and the overlaying is in this example provided by interlacing 212, 214, 216 the second regions 212, 214, 216. An alternative to the interlacing shown is to otherwise change a transparency of the second regions. Interlacing may as another example alternatively be provided by vertical lines instead of horizontal lines. Still further an alternative may be to overlay with a hexagon pattern or other region filling patterns, provided that overlayed parts are still visible. Further second regions than the regions 212, 214 and 216 are shown in the figure without providing reference to them.

In the example of FIG. 2 it can be seen the code of the second parametric level of the A map is shown interlaced in the region 214. With a certain resolution, only every second line is shown in order to make this region 214 transparent and in order to indicate that in this particular region the parametric level and/or the spatial distribution of the second parametric levels is not the same as in the other maps.

An example of a part of such a second region is shown at 214 pointing towards a part of a second region. In this second region the spatial distribution of the second parametric level of the A map is different from the others.

Similarly, as indicated with the arrow 212 a part of a second region is shown interlaced to the right of the right side boundary 113 of the second parametric level region of the AB map. This second region 212 is visualizing a region of the second parametric level region of the B map with is not the same as the regions of the second parametric level of the A and AB map.

FIG. 3 shows an apparatus 302 and system for displaying the visualization 202 of the plurality of parametric maps of one area in a single fused map 202. The single fused map 202 may be displayed on a display unit 306, such as a computer screen, and provided along with an apparatus 308, such as a CT or a PET or an MR scanner, for obtaining the plurality of images and hereby for obtaining the plurality of parametric maps of the area. The area may be an area within a human or animal body 310. Furthermore FIG. 3 shows control logic 304 positioned within a device such as a computer for use with the system and method in accordance with the present invention and its embodiments. Possibly, each of the plurality of images for providing the plurality of parametric maps may be obtained with the scanner 308, but possibly each of the images for providing each of the plurality of parametric maps may be provided with different scanning or imaging equipment.

Although the present invention has been described in connection with preferred embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims.

In short, elsewhere it is disclosed to visualize a plurality of parametric maps 102, 104, 106 of an area 103, the parametric maps visualizing parametric levels, the method comprising determining first regions 204, 206, 208 within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and determining second regions 212, 214, 216 within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and visualizing a fused map 202 of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map, in order hereby e.g. to provide an easy, fast, simple and distinctive determination of those regions where two or more maps match to each other, while also being able to see any relations between the maps . In this section, certain specific details of the disclosed embodiment are set forth for purposes of explanation rather than limitation, so as to provide a clear and thorough understanding of the present invention. However, it should be understood readily by those skilled in this art, that the present invention may be practiced in other embodiments which do not conform exactly to the details set forth herein, without departing significantly from the spirit and scope of this disclosure. Further, in this context, and for the purposes of brevity and clarity, detailed descriptions of well-known apparatus, circuits and methodology have been omitted so as to avoid unnecessary detail and possible confusion.

In the claims, the term "comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. Thus, references to "a", "an", "first", "second" etc. do not preclude a plurality. Reference signs are included in the claims, however, the inclusion of the reference signs is only for clarity reasons and should not be construed as limiting the scope of the claims.

Claims

CLAIMS:

1. A method of visualizing a plurality of parametric maps (102, 104, 106) of an area (103), the parametric maps visualizing parametric levels, the method comprising: determining first regions (204, 206, 208) within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and - determining second regions (212, 214, 216) within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and visualizing a fused map (202) of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map.

2. A method according to claim 1, wherein the second regions are displayed in the fused map by overlaying at least a part of the one or more other of the plurality of parametric maps in a way that the part is still at least partly visible.

3. A method according to claim 2, wherein overlaying is provided by interlacing (212, 214, 216) the second regions, with respect to the first regions.

4. A method according to claim 2, wherein overlaying is provided by changing transparency of the second regions, with respect to the first regions.

5. A method according to claim 1, wherein regions in different maps where the parametric level is substantially the same is provided with visibly distinctive codes (115, 125).

6. A method according to claim 1, wherein one (106) of the plurality of maps (102, 104, 106) is a combination of two of the other maps (102, 104).

7. A method according to claim 1, wherein each parametric level is provided within one or more boundaries, and wherein determining the first regions (204, 206, 208) that spatially overlap is provided by comparing region boundaries.

8. An apparatus (302) for visualizing a plurality of parametric maps (102, 104,

106) of an area (103), the parametric maps visualizing parametric levels, the apparatus comprising: a control logic (304) arranged to determine first regions (204, 206, 208) within the plurality of parametric maps that spatially overlap and have parametric levels which are substantially the same, and to determine second regions (212, 214, 216) within the plurality of parametric maps that are spatially non-overlapping or have parametric levels which are substantially different, and a display unit (306) arranged to visualize a fused map (202) of the plurality of parametric maps by displaying the first regions in a predetermined first way and displaying the second regions in a predetermined second way in the fused map.

9. An image obtaining system, wherein the system comprises a unit for obtaining a plurality of parametric maps of an area, and an apparatus (302) according to claim 7.

10. A computer readable code adapted to perform the method according to claim 1.