Biopsy guidance by image-based X-ray system and photonic needle

Abstract

A system for providing integrated guidance for positioning a biopsy device and estimating tumor size in a body has two levels of guidance: a coarse guidance and a fine guidance. The system includes a non-invasive imaging system for obtaining an image of the biopsy device in the body, for providing the coarse guidance. Furthermore, the system includes an optical element mounted on the needle for obtaining optical information discriminating tissue in the body, for providing the fine guidance.

Claims

1. A system for integrated guidance for positioning a biopsy device in a body, the system being configured for deducing tumor boundaries and comprising: an X-ray imaging device configured to provide coarse guidance, providing images of body structures, the X-ray imaging device providing X-ray information giving an estimate of a shape of a tumor, an analyze device configured to provide fine guidance, comprising an optical element and providing one-dimensional information of a tumor boundary along a needle trajectory by discriminating tissue of the body, wherein the one-dimensional information provided by the analyze device is registered in an image provided by the X-ray imaging device, and a biopsy needle being an elongate element with a tip portion, wherein the biopsy needle is adapted to be visualized by the X-ray imaging device, and wherein the optical element is in the tip portion of the biopsy needle, wherein the system is further configured to calculate a new estimate of 3D tumor size by combining the X-ray shape of the tumor with the one.sub.=dimensional information of the analyze device.

2. The system as claimed in claim 1, wherein the optical element of the analyze device comprises an optical fiber capable of emitting and receiving of light.

3. The system as claimed in claim 2, wherein the analyze device further comprises a console for spectroscopy, wherein the console and the optical fiber are connected to each other.

4. The system as claimed in claim 3, wherein the console for spectroscopy (22) is adapted to provide information from one of the group consisting of reflectance spectroscopy, fluorescence spectroscopy, autofluorescence spectroscopy, differential path length spectroscopy, Raman spectroscopy, optical coherence tomography, light scattering spectroscopy, and multi-photon fluorescence spectroscopy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other objects of the present invention are apparent from and will be elucidated with reference to the embodiments described hereinafter and will reference to the following drawings. The same or like elements are denoted by the same reference signs throughout the drawing.

(2) FIG. 1 shows a schematic drawing of taken a biopsy via the rectum under ultrasound guidance.

(3) FIG. 2 shows a schematic illustration of the system for integrated guidance for positioning a biopsy device in a body, according to an exemplary embodiment of the invention.

(4) FIG. 3A shows an exemplary optical spectrum of diffuse reflectance for a plurality of locations of a tip of a biopsy device relative to an object. FIG. 3B shows a normalized spectrum of diffuse reflectance of FIG. 3A.

(5) FIGS. 4A-4C show an exemplary visualization of different position of a biopsy device in a phantom, showing a fluoroscopic X-ray image of the biopsy device together with the corresponding optical reflectance spectrum (in the insert top left).

(6) FIG. 5 shows a cross section of a biopsy device according to an exemplary embodiment of the invention, in which the optical fibers for guidance of biopsy and inspection of biopsy are located in a hollow shaft of the biopsy device.

(7) FIG. 6 shows schematically a set-up for Raman or fluorescence spectroscopy.

(8) FIGS. 7A and 7B show two types of fiber based needles.

(9) FIG. 8 shows schematically an experimental setup for measuring the optical spectra.

(10) FIG. 9 shows another exemplary embodiment of a biopsy device.

(11) FIG. 10 shows exemplary boundaries of a tumor according to different determination methods.

(12) FIG. 11 shows absorption coefficients of different fluidic substances.

(13) FIGS. 12A and 12B show cross sectional views illustrating the relation between the distance of a biopsy device according to an embodiment of the invention, from a blood vessel and the absorption spectrum visualized by the system according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(14) FIG. 2 shows a system according to an exemplary embodiment of the invention. The system comprises an elongated biopsy device 200, an optical element 220 which is located at the tip portion of the biopsy device, an imaging device 500 for assisting the coarse guidance, an analyze device 20 for assisting the fine guidance, and a computing device 600. The analyze device includes a light source 10 and a spectrograph 22. The imaging device 500 includes a radiation source 510 and a detector array 520. The computing device includes a processor unit 620 for processing the signals coming from the imaging device 500 and from the analyze device 20, and a monitor 610 for monitoring information for assisting the guidance of the biopsy device in a body.

(15) As illustrated in FIG. 2, a system for integrated guidance for positioning a biopsy device in a body, comprises an image guided X-ray based needle guidance system 500 (for instance, a system like XperGuide of Philips Medical Systems where three-dimensional isotropic soft-tissue volumes are reconstructed from rotational acquisitions and where live fluoroscopy is co-registered with the 3D data set and superimposed on it. Combining this with 3D road-mapping technique allows needle guidance as described in “Live 3d Guidance in the Interventional Radiology Suite”, J. M. Racadio et al., Interventional radiology ARJ 2007; 189:W357-W364) and a biopsy needle device 200 containing an optical fiber, which is connected with an analyze device 20. The image guided needle navigation system provides integrated 2D/3D lesion imaging and an interactive image guided needle advancement monitoring, all of which is coupled to the optical information obtained by the needle, wherein the X-ray system 500 provides the coarse guidance, while the optical information received from the analyze device 20, provides the final precise guidance to the biopsy location. Preferably, the X-ray data together with the position of the needle is used as input for the optical reconstruction of which tissue is in front of the needle.

(16) Presented below is a short summary of the characteristics of the first embodiment of the invention:

(17) the system is able to interactively follow the biopsy needle from the incision to the target point by superimposing 2D fluro-image on 3D tissue reconstruction and provide molecular tissue information at every point along the needle trajectory that is registered to the position inside the body of the patient

(18) the region along the needle trajectory can be scanned (scan forward and scan aside) in order to provide indications on lesion existence at the molecular level

(19) preferably in reconstructing what tissue is in front of the needle the X-ray data and the position information of the needle is actively used in the optical reconstruction of what tissue is in front of the needle

(20) tumor boundaries deduced from needle scanning and from the X-ray are compared. The X-ray information gives an estimate of the shape of the tumor, but the exact boundary cannot be determined. The needle gives detailed information of the tumor boundary but this information is only obtained along the needle trajectory. By combining the X-ray shape of the tumor with the one dimensional information of the needle, a new estimate of the 3D tumor size can be calculated (see third embodiment). The newly deduced enlarged boundary will be a better estimate for the tumor boundary

(21) X-ray and needle information is further coupled to MRI images of the same area (MR data sets can be registered with the data sets produced by the X-ray machine)

(22) biopsy needle being equipped with an optical fiber is used to position the localization wire. The localization wire containing fixation means and may be equipped with a fiber.

(23) To demonstrate the invention a needle intervention will be described. The object from which the biopsy should be taken, is placed on, for example, a C-arm bed and the needle is mounted on a stepper motor that moves the needle in the axial direction (minimal steps of 0.25 micron). The needle is connected with optical fibers to a spectrometer. At least one of the fibers detects light reflected from the tissue, hence is an optical element.

(24) The needle intervention consists of acquiring X-ray and fluoroscopic X-ray images while in addition optical reflectance spectra are measured by the needle containing fibers coupled to a console that is connected to the X-ray system.

(25) After a full rotation of the C-arm around the object, it is possible to generate 3D reconstructions of the object from the X-ray information, including the position of the needle. Furthermore, advancement of the needle can be done under fluoroscopy X-ray imaging.

(26) FIG. 3A show an optical spectrum which might be achieved by an analyze device for a plurality of locations of a tip of a needle relative to an object. Said object might be a tube filled with blood. The system according to the invention was utilized in a phantom. FIGS. 3A and 3B show the results, i.e., in FIG. 3A, reflectance versus wavelength for different distance between the tip of a needle and a tube located in the phantom. Wherein, the optical spectrum is measured by a needle equipped with fibers. In FIG. 3A, the vertical axis is ‘Reflectance’ and the horizontal axis is ‘Wavelength in nm’. FIG. 3B show the normalized reflectance with respect to the signal when the needle is 32.5 mm away from the tube. Here, the vertical axis is ‘normalized reflectance’ and the horizontal axis is ‘Wavelength in nm’.

(27) FIGS. 4A-4C show three illustrations which might be shown on a monitor to assist in guiding a biopsy device. Each illustration is mainly an image of an X-ray device, having added in the up left corner an illustration of the spectrum achieved by the analyze device. The fluoroscopy image of the X-ray device allows determining the relative position of the needle (elongated black line from the middle of each illustration to up right) with respect to the phantom (dark shadow), while the spectral information clearly shows when the small tube (black contrast line from up left to down right) is approached. It allows to fine position the needle within 100 micron accuracy. Although the information of the X-ray image and the optical information are shown in a combined image, there are various other ways to present the combined information for instance by using colors.

(28) FIG. 5 shows the tip portion of a biopsy device according to an exemplary embodiment of the invention. The biopsy device 200 comprises a shaft 210 with a fiber bundle 220. Further, the shaft 210 is adapted to accommodate a needle 240 for taking a biopt. Preferably, the fiber bundle 220 is located in the shaft 210 such that the respective ends of the fibers are located in the end surfaces of the tip portion of the biopsy device. In other words, some of the fibers might end in the front surface of the biopsy device, and/or some of the fibers might end in the vicinity of the front surface at the side surface or wall surface of the biopsy device. Furthermore, there could be some fiber ends orientated in the direction to a biopt harvested by the biopsy device, and some other fiber ends orientated in the direction to the front or the side of the biopsy device, for optical guidance prior to biopsy. In FIG. 5, fibers for optical guidance prior to biopsy are denoted with reference sign 220a, and fibers for optical inspection of the biopt are denoted with reference sign 220b.

(29) It is noted, that any fiber might be used to emit and/or to receive light.

(30) FIG. 6 shows further components of the system. According to this embodiment, some of the fibers 30 are coupled by way of a lens 52 to a light source 10 outside the body and are used for excitation of the tissue in front of the shaft tip of the biopsy device 100. Part of the scattered and emitted light is collected by other fibers 40 and guided to a detector, via another lens 54, which detector could be a spectrograph 22 coupled with a CCD-camera 24, where for instance an autofluorescence or Raman spectrum is recorded. Upon inspection of the spectrum it is decided to either take a biopsy with the biopsy device 100 or to move the shaft further to another position if no anomalies in the spectrum are found.

(31) During the insertion of the biopsy device in the tissue, spectra are recorded and linked to the position of the known X-ray based needle guidance system.

(32) For interpreting the spectra measured optically, hence translating spectra into tissue properties, the X-ray data (morphology) is used. For instance the X-ray data may provide already an indication of what type of structure could be in front of the needle, the optical data need than only to confirm or select from a few possible candidate tissues. Checking what tissue matches best with the measured spectra can then be done more reliably. Another example is if we want to be inside a certain tissue. After coarse guiding the needle with the X-ray system, the needle is fine positioned until the measured optical spectra matches with the targeted tissue.

(33) In this way for various points, information is obtained of the tissue and is combined into the 3D image obtained by X-ray. The coarse guidance to the diseased tissue is performed by the X-ray images. The fine guidance is based on the optical information. When the final location is reached a biopsy can be taken. Optionally, the biopsy may be checked optically whether it contains the diseased tissue.

(34) A way to provide real-time tissue characterization is by means of optical methods. For instance optical reflectance spectroscopy or Raman spectroscopy are known to provide signatures that are tissue specific. In the reflectance spectroscopy method where tissue is illuminated with a broad band light source, the reflected scattered spectral light distribution is measured. The difference in tissue properties (i.e., difference in scattering properties of the specific tissue) is visible in the changes of the spectral light distribution compared to the original spectral distribution of the illumination source. Furthermore, optical spectroscopic imaging (i.e., extending the optical imaging from a point measurement to two-dimensional imaging) provides even more detailed tissue characterization. In this case, tissue is viewed with micron resolution allowing cellular structures to become visible allowing detailed tissue analysis. When this cellular imaging is combined with optical spectroscopy, tissue characterization can be achieved, without using staining, that comes close to what currently is being used in ex-vivo pathology.

(35) To make these methods available in a needle, the optical fiber technology is employed. By integrating fibers into the needle, optical probing at the tip of the distal end of the fiber at the tip of the needle becomes possible. The analysis can then be done at a console that is attached to the proximal end of the fiber. The console is an integral part of the integrated navigation system.

(36) FIGS. 7A and 7B show two different types of fiber based needles. In the first type (FIG. 7A) the fibers are rigidly integrated into the needle, allowing spectroscopic analysis of the tissue near the needle tip. Since the fibers are rigidly incorporated no cellular imaging is possible. In the second type (FIG. 7B), a scanning fiber is integrated into the needle. When a lens system is mounted in front of the fiber a scanning confocal microscope is established allowing microscopic imaging of tissue. In order to scan the fiber a motor must be integrated in the needle, making the system more complex than the fixed fiber.

(37) There are various optical techniques that can be coupled to these two ways of tissue inspection, wherein spectroscopy is one of them. An example is optical reflectance spectroscopy. The spectroscopic measurement on excised tissue is performed with the needle equipped with optical fibers as is shown in FIG. 8. The light source coupled to the fiber is a broadband light source. The reflectance spectra are measured with a spectrometer and recorded with, for example, a CCD-camera.

(38) FIG. 9 shows a tip portion of a biopsy device according to yet another embodiment of the invention, wherein the biopsy device 100 contains a collection of optical fibers. Although the embodiment of a biopsy device in FIG. 9 does not have a lumen, it can also be a device having a lumen. Each of the fiber entrance positions at the base of the needle (for example in FIG. 9, the positions indicated by numbers 101, 102 and 103) relates to a fiber exit position at the head of the needle (in FIG. 9 indicated by primed numbers 101′, 102′ and 103′). In this way the needle head is covered with various optical probe positions, wherein the ends of the respective fibers are orientated in the direction to the side of the biopsy device.

(39) Light is coupled by way of a lens 50 from fibers 30 into the optical fibers at the base of the biopsy device, i.e. a needle, and out of other optical fibers at the base of the biopsy device into fibers 40. A light source 10, connected to an excitation fiber 30, illuminates for instance fiber 101. The light will cross the fiber and illuminate the tissue around exit position 101′. Light scattering from this position can for instance reach position 102′ and 103′. The analyze device 20 is connected to fiber 40 that collects the light coming from each fiber (101, 102 and 103, respectively). The intensity of the light is a measure for the amount of absorption and scatter between exit position 101′ and 102′ and 103′. From these signals the tissue characteristics around the needle can be extracted. It is worth noting that this embodiment allows two-dimensional imaging of scattering and absorption properties of the tissue surrounding the needle, with a lateral resolution equal to that of the fiber-to-fiber distance. Moreover, it is also possible to perform an optical coherence scan for each fiber, which gives for each fiber a depth scan along a line. Combining these lines, a three-dimensional image of the tissue around the needle can be reconstructed, again with a lateral resolution equal to that of the fiber-to-fiber distance.

(40) A variation of this embodiment is the implementation of fluorescence imaging and/or spectroscopic measurements. In this case source 10 and fiber 30 serve as an excitation fiber, hence to excite the fluorescent molecules and collection fiber to collect the fluorescent light emitted by the molecules.

(41) Similar as discussed in the first embodiment a Raman spectroscopy can be performed, but now in principle for each fiber end position 101′, 102′, etc.

(42) Finally, it is also possible to perform diffuse optical tomography (DOT) around the needle. This allows functional imaging in a relatively large volume around the needle similar to what is done in optical mammography. In this embodiment one or more fibers are used for (sequential) illumination of the tissue. One or more other fibers are used to collect the scattered light. Using an image reconstruction algorithm it is possible to obtain a 3D map of the optical properties in a region around the needle. The main advantage of DOT is the high penetration depth compared to other optical methods: about half of the source detector distance. The most advantageous wavelength region for DOT is the near infrared (NIR). Here the penetration depth is at its maximum and the optical properties are strongly determined by important physiologic parameters like blood content and oxygen saturation. By combining DOT at different wavelengths it is possible to translate optical parameters into physiological parameters.

(43) The imaging methods mentioned above can rely on direct absorption and scattering properties of the tissue under investigation. However it is also possible to map fluorescence of tissue, by illuminating with the proper wavelength and simultaneously blocking the illumination wavelength at the detector side. The fluorescence can be endogenous or exogenous, i.e. with the aid of contrast agents. The specificity of the fluorescence detection can be improved by methods well known in the art such as fluorescence lifetime imaging.

(44) According to a further aspect of the invention the tumor boundaries might be deduced from needle information and said information might be compared with information from the x-ray system. In FIG. 10, the boundary 310 deduced from the optical information (along a line 330 resulting in boundary points B and E) is in general larger than the boundary 300 of the x-ray (resulting in cross section points C and D with line 330) because of the higher sensitivity of the method. The scale factor deduced from this is used to extend the area according to that of the X-ray. The newly deduced enlarged boundary 320 will be a better estimate for the tumor boundary and can be used by the surgeon to plan an intervention.

(45) A further embodiment is where the invention is used to guide the needle to the location of the suspicious tissue, but instead of taking a biopsy the hollow needle is used to position a localization wire. This localization wire is then used by the surgeon to find the location of the tumor to be resected.

(46) In a further embodiment the biopsy device may also be used as a device for administering drugs or a therapy (like percutaneously using RF, microwave or cryoablation) at a certain position in the body without removing tissue, for instance for injecting a fluid at the correct location of the affected body part.

(47) A further embodiment is for avoiding blood vessels.

(48) By using a contrast enhanced (CE) CT acquisition, a 3D reconstruction of both arterial and venous vessel tree will be generated in addition to the soft tissue reconstruction of the brain parenchyma. Both the soft tissue and the arterial/venous vascularisation will be evaluated in order to find a location of suspicious tissue. Using the XperGuide navigation software, the needle trajectory will be defined as well as the needle advancement monitored. The needle trajectory will be defined in such a way that the planned path does not traverse any major vessel. Due to limited accuracy of needle advancement (human error), additional feedback on actual needle position with respect to the surrounding vessels is required. This can be done by using optical spectroscopy to measure the absorption properties of the tissue directly in front of the needle tip by adding an optical fiber to the needle.

(49) FIG. 11 shows absorption spectrums, wherein the vertical axis means the absorption coefficient, and the horizontal axis means the wavelength. In this exemplary diagram, the spectrum of melanosome M, of Water W and of Blood HB is depicted. The absorption spectrum of blood HB shows characteristic peaks in the visible region around 400-600 nm. From the spectrum measured in front of the biopsy needle the presence of blood can be deduced by monitoring for these peaks in the absorption spectrum. This can be done for instance by measuring the absorption at two wavelengths: one within the absorption peak (for instance at 530 nm) and one outside the peak (for instance at 633 nm). Taking the ratio of these absorption values as blood vessel monitor signal, a blood vessel will be approached when the signal significantly changes. In this way it is not necessary to measure the absorption signal absolutely, but only relatively.

(50) Presented below is a short summary of the steps of a method according to the invention:

(51) determination of a suspicious tissue with diagnostic scans (X-ray, CT, MRI),

(52) 3D assessment of the arterial and venous vascular tree with CE CT technique, establishment of the lesion access planning,

(53) utilization of XperGuide to perform image guided monitoring of needle advancing, according to the planning in (3),

(54) depiction of blood carrying vessel structures in close proximity of the needle tip with optical methods,

(55) utilization of the optical information in order to re-adjust needle direction in order to avoid the intervening vessel structures.

(56) The first embodiment is focused on items (1)-(4). The shaft 210 of the biopsy device 200 contains at least one fiber 220 and is adapted to receive a needle 240 (see FIG. 12). The at least one fiber is used to illuminate the tissue in front of the fiber and also serves as collection fiber of the backscattered light. Part of the scattered and emitted light, collected by the fiber is guided to a spectrograph (see FIG. 6), where the absorption spectrum is recorded 400, 410 (see FIGS. 12A and 12B). In case a blood vessel is far away the absorption spectrum 400 does not reveal the absorptions peak characteristic for blood (see FIG. 12A). However, when a blood vessel approaches the tip or the needle the absorption spectrum 410 will show the absorption peak for blood. Once such a signal shows up, the needle advances in changed direction such that the peak is absent again.

(57) There are various ways to measure or quantify this signal. One way is to use two lasers sources one emitting at 550 nm and the other at 633 nm. The signal relating to 550 nm probes the peak of blood, while the signal related to 633 nm is rather insensitive. Taking the ratio of these signals as triggering signal we are insensitive for surroundings deviations.

(58) The invention and its embodiments can be applied in various clinical procedures, including: image guided brain biopsies, image guided brain ablations, image guided brain neuro-stimulations, guide the biopsy for cancer diagnosis.

(59) 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.

(60) Other 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. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

LIST OF REFERENCE SIGNS

(61) 10 light source 20 analyze device 22 spectrograph 24 CCD-camera 30 excitation fiber 40 collection fiber 50, 52, 54 lens 100, 200 biopsy device 101, 102, 103 fiber entrance position 101′, 102′, 103′ fiber exit position 210 shaft 220, 220a, 220b fiber 240 needle 300, 310, 320 boundary 330 optical information line 400, 410 absorption spectrum 500 imaging device 510 X-ray source 520 X-ray detector array 600 computing device 610 monitor 620 processor unit