Field of the Invention

The present invention relates to methods and systems for imaging biological tissue, including display of images.

Background

Numerous techniques exist for imaging biological tissue. Examples include X-ray imaging (e.g. projection radiography, including mammography; X-ray tomography, including computed tomography (CT)); gamma imaging; ultrasound imaging; MRI (magnetic resonance imaging); and PET (positron emission tomography) imaging. All of these approaches concern the acquisition of internal physiological images to provide information that can be used, for instance, to help in the diagnosis of a medical condition or to monitor a condition once diagnosed.

Once the image data has been obtained, it must be displayed in some useful format in order that a clinician can make use of it. This display of the image may be inherent in the imaging process itself. For example, in conventional X-ray projection radiography, where the transmitted X-ray radiation is incident on an X-ray sensitive film on which the image is formed and which can be viewed directly by a clinician once processed.

For other imaging techniques, and to some extent also for X-ray imaging, it is now common for the images to be produced, processed and displayed by computers. This provides great benefits in terms of image manipulation and storage for example.

All of the techniques above provide what might be referred to as 'direct' images, in the sense that they are direct spacial mappings of the imaging 'media' (transmitted X-ray, reflected ultrasound, emitted positrons, etc) detected at an image plane. The information in these images is therefore limited to that which can be deduced directly from the interaction of the imaging 'media' with the tissue being examined.

Summary of the Invention

The present invention is generally concerned with providing imaging techniques that enable the production of images with greater or alternative information content.

In a first aspect, the invention provides a method of imaging biological tissue comprising displaying an image that shows a measure of one or more predetermined tissue characteristics for a biological tissue sample, the tissue characteristic(s) having been calculated based on measurement of one or more other tissue properties or characteristics from the tissue sample. The calculated, or what might be referred to as 'indirect' images provided by embodiments of the present invention can provide alternative or additional information to a clinician when compared with the conventional imaging techniques. This is because they are not limited only to the information that can be directly deduced from the imaging 'media's' interaction with the tissue sample.

The 'indirect' images can include information derived, for example, from previously constructed computer models of tissue characteristics that can be related to the measurements taken from the tissue sample. An example would be using measurements from the tissue sample as an input to a computer model, the computer model providing a characterisation (e.g. normal / abnormal) of the tissue sample based on those inputs (as described for instance in co-pending PCT patent application number PCT/GB04/005185).

Examples of suitable measurements that can form the basis for the calculated characteristics include X-ray scatter measurements (e.g. Compton Scatter, Wide Angle Scattering (WAXS), Small Angle X-ray Scatter (SAXS) and Ultra-Low Angle X-ray Scatter (ULAX)).

Co-pending pending PCT patent application numbers PCT/GB04/005185 and PCT/GB05/001573 describe techniques, including X-ray scatter based techniques, for characterising biological tissue. The tissue characterisations obtained using these techniques could be usefully visualised in accordance with embodiments of the present invention. PCT/GB04/005185 in particular describes a multivariate modelling technique that can be used to derive tissue characteristics from measured tissue properties.

The tissue characteristic(s) illustrated by the image may give an indication, for example, as to the probability that the tissue is normal or abnormal and, in the case of abnormal, whether it is benign or malignant. Used in this way, embodiments of the invention are useful in the diagnosis of cancer, including breast cancer.

Preferably the image is spatially resolved, in the sense that it corresponds (at least approximately) to the physical form of the tissue sample that is being imaged. In this way, the image can be overlaid on other spatially resolved images, for example the conventional X-ray, CT, ultrasound, etc images referred to above.

In a preferred embodiment of the present invention the biological tissue sample comprise ex vivo body tissue of human or animal origin. Such body tissue samples may be uniform or non-uniform in biological composition and obtained via surgical procedures or veterinary procedures. Typically, these uniform or non-uniform samples removed from a patient in order to be analysed during said procedure. For instance, suitable ex vivo body tissue may include samples removed from the liver, lung, colon or from the breast.

In a second aspect, the present invention provides a method for imaging biological tissue comprising displaying a composite image that comprises at least two separately derived images of a biological tissue sample overlaid on one another. The images may be obtained by two separate types of imaging technique, but need not be. They may, for example, be separately derived where the same initial measurements taken from a tissue sample are processed in two or more different ways to arrive at two separate images (that need not ever be displayed separately) that are combined in the final image.

The invention also provides apparatus and computer systems that can be operated in accordance with the aspects of the invention above, and software to control them.

Brief Description of the Drawings

Embodiments of the invention are described below by way of example with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of an image processing system in accordance with an embodiment of the present invention;

Figure 2 illustrates schematically an image displayed by the system of figure 1.

Description of Embodiments

Figure 1 shows a system that can be used to display digital tissue sample images to, for example, clinicians. An image processing system 2 retrieves image data either from an image data store 4 or from one or more image acquisition systems (e.g. X-ray apparatus) 6. In the latter case, the image data may be acquired in real time. The data is then processed to generate images for display to users on one or more screens at client devices 8,10,12,14 (e.g. networked PCs and laptops or dedicated terminals associated with the image acquisition system(s)).

The system might be used, for example, to display images in real time to a clinician in the treatment room or operating theatre of a facility where a patient is undergoing a biological tissue imaging procedure (e.g. X-ray procedure). The image data can simultaneously be stored for subsequent access at a future time, for example by a consultant or by the patient's GP. Communication with the image processing system may be through a local area network, wide area network or via a secure Internet connection for example.

In the preferred example described here, the displayed image is a composite image. One element of the image is a digitally captured transmitted X-ray image. The second element of the image, which is overlaid on the digital X-ray image, is a visual representation of a tissue characterisation.

In this example, the tissue is characterised based on whether it has been identified as normal or abnormal and, where abnormal, the likelihood that it is malignant. This characterisation of the tissue is obtained through calculation and/or modelling based on multiple types of tissue property measurement. Preferably, the measurements used are X-ray scatter measurements (which can therefore be taken at the same time using the same apparatus as the X-ray transmission measurements). The characterisation may be obtained, for example, using the approaches described in the co-pending PCT patent applications referred to above.

Figure 2 illustrates schematically the sort of image that might be obtained. The transmitted X- ray image alone is shown in the upper image in figure 2. It has shown up a rectangular area 20 with an elliptical area 22 of a different tissue within it. It also identifies, within the elliptical area, a potentially abnormal tissue region 24.

The second image in figure 2 shows the tissue characterisation overlaid on the X-ray image. The different tissue characteristics are shown by using different shading patterns in this example, but would preferably be shown using one or more of multiple colours, grey-scale shades, contours, etc either as an alternative or in addition to the patterns.

The rectangular tissue portion 20 outside the ellipse and the majority of the ellipse are indicated as being two different types of normal tissue; adipose and normal fibrous tissue for example. The abnormal region 24 identified by the X-ray is still shown, but the image now includes the further information, based on the characterisation data, that the tissue is very likely malignant. The characterisation data has also identified a smaller, abnormal tissue region 26 that was not visible in the X-ray image alone.

To enable the overlaying of the images, the characterisation data is acquired (and stored) with associated spatial data from which the 2D or 3D location of the characterised tissue within the sample can be determined.

In use, the person viewing the images (whether in real time or subsequently using stored data) can elect whether and to what extent they view the various elements of the image. For example, they may elect just to see the X-ray transmission image initially, this image with a binary normal / abnormal characterisation overlaid, or with a fuller characterisation overlaid.

It will be appreciated that description above is given by way of example and various modifications, omissions or additions to that which has been specifically described can be made without departing from the invention. For example, whilst the invention has been illustrated above using 2D images, it is equally applicable to 3D imaging.