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WO2014187708A1 - Processing apparatus for processing optical shape sensing data values - Google Patents

Processing apparatus for processing optical shape sensing data values Download PDF

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Publication number
WO2014187708A1
WO2014187708A1 PCT/EP2014/059832 EP2014059832W WO2014187708A1 WO 2014187708 A1 WO2014187708 A1 WO 2014187708A1 EP 2014059832 W EP2014059832 W EP 2014059832W WO 2014187708 A1 WO2014187708 A1 WO 2014187708A1
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WO
WIPO (PCT)
Prior art keywords
data values
shape sensing
optical shape
sensing data
processing
Prior art date
Application number
PCT/EP2014/059832
Other languages
French (fr)
Inventor
Eberhard Sebastian Hansis
Bernhard Johannes Brendel
Christian Haase
Dirk Schäfer
Michael Grass
Original Assignee
Koninklijke Philips N.V.
Philips Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips N.V., Philips Gmbh filed Critical Koninklijke Philips N.V.
Publication of WO2014187708A1 publication Critical patent/WO2014187708A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/06—Devices, other than using radiation, for detecting or locating foreign bodies ; determining position of probes within or on the body of the patient
    • A61B5/065—Determining position of the probe employing exclusively positioning means located on or in the probe, e.g. using position sensors arranged on the probe
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/6852—Catheters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6867—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive specially adapted to be attached or implanted in a specific body part
    • A61B5/6869—Heart
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A61B5/721—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7221—Determining signal validity, reliability or quality
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/00234—Surgical instruments, devices or methods, e.g. tourniquets for minimally invasive surgery
    • A61B2017/00238—Type of minimally invasive operation
    • A61B2017/00243—Type of minimally invasive operation cardiac
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00681—Aspects not otherwise provided for
    • A61B2017/00694—Aspects not otherwise provided for with means correcting for movement of or for synchronisation with the body
    • A61B2017/00703—Aspects not otherwise provided for with means correcting for movement of or for synchronisation with the body correcting for movement of heart, e.g. ECG-triggered
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A61B2034/2046—Tracking techniques
    • A61B2034/2061—Tracking techniques using shape-sensors, e.g. fiber shape sensors with Bragg gratings
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]

Definitions

  • the invention relates to a processing apparatus, a processing method and a processing computer program for processing optical shape sensing data values.
  • the invention relates further to an interventional system comprising the processing apparatus.
  • US 2002/0165448 Al discloses a locating system for determining the location and orientation of an invasive medical instrument relative to a reference frame.
  • a plurality of field generators generate known, distinguishable fields in response to drive signals and a plurality of sensors situated in the invasive medical instrument proximate the distal end thereof generate sensor signals in response to the fields.
  • a signal processer computes three location coordinates and three orientation coordinates of a portion of the invasive medical instrument depending on the drive and sensor signals.
  • EP 2 514 379 A1 discloses a method for positioning an intracardiac catheter, wherein position signals of the intracardiac catheter and reference signals comprising respiration information are collected and a self- adaptation de-noising technique is utilized, in order to process the reference signals and eliminate respiration fluctuations in the position signals of the intracardiac catheter.
  • Optical shape sensing is a localization technology that can be used for guidance in minimally invasive procedures, wherein one or several interventional elements are equipped with an OSS fiber for determining the location of the respective interventional instrument by OSS.
  • Cardiac interventions are one important application area, with procedures such as catheterization of the coronary arteries, ablation therapy for electrophysiology disorders, or treatment of structural heart disease. However, during the cardiac interventions the accuracy of determining the location of the respective interventional instrument can be diminished.
  • a processing apparatus for processing OSS data values comprises:
  • an optical shape sensing data values providing unit for providing OSS data values assigned to different times, wherein a respective OSS data value is indicative of a location of an element within or close to a moving object at the respective assigned time, a motion signal providing unit for providing a motion signal over time being indicative of the motion of the object,
  • a reliability determination unit for determining reliabilities of the OSS data values depending on the motion signal
  • a processing unit for processing the OSS data values depending on the determined reliabilities.
  • the processing unit can be adapted to filter the OSS data values depending on the determined reliabilities such that motion errors are reduced in the OSS data values.
  • an averaging filter may be applied to the OSS data values, wherein the OSS data values may be weighted depending on the determined reliabilities and the weighted OSS data values may be averaged, or OSS data values, for which a reliability has been determined being smaller than a threshold, may be discarded, wherein only the locations indicated by the non discarded OSS data values may be shown.
  • the determination of the reliabilities and the processing of the OSS data values depending on the reliabilities allows therefore for an improved OSS based localization, wherein a user is less confused or not confused at all by faulty location measurements.
  • the motion signal providing unit is preferentially adapted to provide an electrocardiography (ECG) signal as the motion signal.
  • ECG electrocardiography
  • the reliability determination unit is preferentially adapted to determine the reliability of a respective OSS data value depending on the motion signal at the time assigned to the respective OSS data value.
  • the reliability determination unit is preferentially adapted to derive a motion amplitude over time from the provided motion signal and to determine the reliability depending on the derived motion amplitude.
  • the reliability determination unit is adapted to determine a larger reliability, if the derived motion amplitude is smaller, and a smaller reliability, if the derived motion amplitude is larger.
  • the element is preferentially an interventional element to be arranged within the object, which is preferentially a part of a living being, wherein the optical shape sensing data values providing unit comprises an optical shape sensing fiber arranged along the interventional element for providing the OSS data values.
  • the optical shape sensing data values providing unit is adapted to provide OSS data values being indicative of locations of the element within or close to the moving object.
  • the optical shape sensing data values providing unit is preferentially also adapted to provide OSS data values being indicative of locations of the element not within or close to the object, i.e. of locations at which the OSS data values are not corrupted by the motion of the object.
  • OSS data values may be provided, which are not adversely influenced by the movement of the object, or, if the element is, for example, a catheter, wherein the tip of the catheter is close to or within the moving object, OSS data values of other parts of the catheter, which are more far away and not influenced by the motion, can also be provided by the optical shape sensing data values providing unit.
  • the processing unit is adapted to filter the OSS data values depending on the determined reliabilities, wherein a filter is applied to the OSS data values, which is adapted to reduce motion errors in the OSS data values.
  • the processing unit may be adapted to apply an averaging filter to the OSS data values, wherein the OSS data values are weighted depending on the determined reliabilities and the weighted OSS data values are averaged. It is preferred that the processing unit is adapted to weight an OSS data value with a larger weight, if the reliability determined for the OSS data value is larger, and to weight an OSS data value with a smaller weight, if the reliability determined for the OSS data value is smaller.
  • the processing unit may be adapted to assign OSS data values for which a reliability has been determined being larger than a threshold to a slow-motion phase, to assign OSS data values for which a reliability has been determined being smaller than a threshold to a high-motion phase, to weight OSS data values assigned to a slow-motion phase with a larger weight and to weight OSS data values assigned to a high- motion phase with a smaller weight.
  • the moving object is preferentially a heart of a living being, wherein the low-motion phase is preferentially the diastolic phase.
  • the processing unit is adapted to process the OSS data values by discarding OSS data values for which a reliability has been determined being smaller than a threshold. Thus, only locations may be shown, which correspond to large reliabilities, in particular, which correspond to low-motion phases of the object, wherein locations corresponding to high-motion phases may be discarded.
  • the processing apparatus further comprises an image providing unit for providing an image of the object and a display for displaying the image and a representation of the element at the locations indicated by the processed OSS data values.
  • the representation of the element is temporally consecutively displayed at locations within or close to the object indicated by the processed OSS data values. This allows displaying reliably determined locations of the element relative to the object on the display.
  • the processing unit may be adapted to process the OSS data values by assigning display properties to the OSS data values depending on the reliabilities, wherein the display may be adapted to display the representation of the element at the locations indicated by the processed OSS data values in accordance with the respective assigned display properties.
  • the display properties may be colors, intensities, et cetera. For instance, to OSS data values having a reliability being smaller than a threshold a first color like red can be assigned and to OSS data values having a reliability being larger than the threshold a second color like green can be assigned such that reliable locations are displayed with the second color and unreliable locations are displayed with the first color.
  • an interventional system for performing an interventional procedure comprising:
  • interventional element for being arranged within a living being, wherein the interventional element is equipped with an OSS fiber, and
  • a processing method for processing OSS data values comprises:
  • OSS data values assigned to different times by an optical shape sensing data values providing unit, wherein a respective OSS data value is indicative of a location of an element within or close to a moving object at the respective assigned time, providing a motion signal over time being indicative of the motion of the object by a motion signal providing unit, determining reliabilities of the OSS data values depending on the motion signal by a reliability determination unit, and
  • a processing computer program for processing OSS data values comprises program code means for causing a processing apparatus as defined in claim 1 to carry out the steps of the processing method as defined in claim 14, when the processing computer program is run on a computer controlling the processing apparatus.
  • processing apparatus of claim 1 the interventional system of claim 13, the processing method of claim 14, and the processing computer program of claim 15 have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims.
  • Fig. 1 shows schematically and exemplarily an embodiment of an interventional system for performing an interventional procedure
  • Fig. 2 illustrates schematically and exemplarily faulty and correct locations of an ablation catheter determined by using OSS
  • Fig. 3 illustrates schematically and exemplarily low-motion phases
  • Fig. 4 illustrates schematically and exemplarily a correct location of an ablation catheter determined by using OSS
  • Fig. 5 shows a flowchart exemplarily illustrating an embodiment of a processing method for processing OSS data values.
  • Fig. 1 shows schematically and exemplarily an embodiment of an interventional system for performing an interventional procedure.
  • the interventional system 1 is adapted to perform a cardiac ablation procedure.
  • the interventional system 1 comprises an interventional element 13 being, in this embodiment, an ablation catheter 13 for performing a radio frequency (RF) ablation procedure within a heart 12 of a person 18 lying on a support means like a patient table 11.
  • the tip 14 is introduced into the heart 12 and comprises ablation electrodes for applying RF ablation energy provided by an ablation current source 17.
  • RF radio frequency
  • the ablation catheter 13 is equipped with an OSS fiber, i.e. the ablation catheter 13 comprises an OSS fiber arranged along the length of the ablation catheter.
  • the OSS fiber is connected to an optical shape sensing data values providing unit 5, which is adapted to provide OSS data values over time based on OSS signals received from the OSS fiber of the ablation catheter 13.
  • the OSS data values are indicative of locations of parts of the ablation catheter 13 close to or within the moving heart 12.
  • the OSS data values may further be indicative of locations of other parts of the ablation catheter 13.
  • OSS data values may be provided being indicative of locations of parts of the ablation catheter 13 along the entire length of the ablation catheter at least within the person 18.
  • the optical shape sensing data values providing unit 5 may be adapted to use the OSS technique disclosed in, for instance, US 8,050,523 B2, or to use another known OSS technique.
  • ECG electrodes 16 are arranged on the breast of the person 18.
  • the ECG electrodes 16 are used for acquiring ECG signals to be measured by a motion signal providing unit 4 via an electrical connection 15.
  • the motion signal providing unit 4 is adapted to generate a motion signal over time being indicative of the motion of the heart 14 by measuring an ECG signal.
  • the optical shape sensing data values providing unit 5 and the motion signal providing unit 4 can be integrated in a processing apparatus 3, wherein the processing apparatus 3 can further comprise a reliability determination unit 6 for determining reliabilities for the OSS data values, wherein the reliability determination unit 6 can be adapted to determine the reliability for a respective OSS data value depending on the ECG signal at the time assigned to the respective OSS data value.
  • the reliability determination unit 6 can be adapted to derive a motion amplitude over time from the provided ECG signal and to determine the reliability depending on the derived motion amplitude.
  • the reliability determination unit 6 can be adapted to determine a motion amplitude from the ECG signal by detecting the so-called 'R-peaks' of the ECG signal, which indicate the onset of ventricular contraction. Using the R-peaks as reference, heart motion amplitudes can be inferred at each point in the cardiac cycle, for example, by employing a motion model measured on a collective of patients and stored in the motion signal providing unit.
  • the reliability determination unit 6 is adapted to determine a larger reliability, if the derived motion amplitude is smaller, and a smaller reliability, if the derived motion amplitude is larger.
  • the reliability determination unit can be adapted to determine the reliability such that it is inversely proportional to the derived motion amplitude.
  • the processing apparatus 3 further comprises a processing unit 7 for processing the OSS data values depending on the determined reliabilities.
  • the processing unit 7 is adapted to filter the OSS data values depending on the determined reliabilities, wherein a filter is applied to the OSS data values, which is adapted to reduce motion errors in the OSS data values.
  • the processing unit 7 is adapted to apply an averaging filter to the OSS data values, wherein the OSS data values are weighted depending on the determined reliabilities and the weighted OSS data values are averaged.
  • the processing unit 7 is preferentially adapted to weight an OSS data value with a larger weight, if the reliability determined for the respective OSS data value is larger, and to weight an OSS data value with a smaller weight, if the reliability determined for the respective OSS data value is smaller.
  • the processing unit 7 can be adapted to use a weight for weighting an OSS data value, which is proportional to the reliability determined for the respective OSS data value.
  • the processing unit 7 can also be adapted to assign OSS data values, for which a reliability has been determined being larger than a threshold, to a slow-motion phase, to assign OSS data values, for which a reliability has been determined being smaller than a threshold, to a high-motion phase, to weight OSS data values assigned to a slow-motion phase with a larger weight and to weight OSS data values assigned to a high- motion phase with a smaller weight.
  • the low-motion phase may be the diastolic phase
  • the other phases of the heart 12 in particular, the transition phase between the systolic phase and the diastolic phase, can be regarded as forming a high-motion phase.
  • the processing unit 7 can use adjacent or overlapping windows, in particular, a sliding window technique, wherein the filtering may be performed based on the OSS data values in the respective window. For instance, for the weighted averaging the OSS data values can be used, which are within the respective window.
  • the processing apparatus 3 further comprises an image providing unit 19 for providing an image of the heart and a display 9 for displaying the image of the heart 12 and for displaying a representation of the ablation catheter 13 at the locations indicated by the processed OSS data values.
  • the processing apparatus 3 further comprises an input 8 like a keyboard, a computer mouse, a touchpad, et cetera for allowing a user to enter, for instance, commands like a start command for starting the processing procedure for processing the OSS data values.
  • the image providing unit 19 can be a storing unit, in which the image of the heart 12, especially a segmented image of the heart 12, is stored and from which the stored image can be provided for being displayed on the display 9.
  • the image providing unit 19 can also have some processing functionality for processing a received image of the heart 12, wherein in this case the image providing unit 19 is adapted to provide the processed image.
  • the image providing unit 19 can be adapted to receive an image of the heart 12 like a computed tomography image, a magnetic resonance image, an ultrasound image, et cetera and to segment the heart in the image, in order to provide the segmented image.
  • OSS measurements can be inaccurate during periods of rapid bending of the OSS fiber and the associated rapid changes in strain. Measurements return back to usable accuracy after a brief period of relaxation. This is especially problematic in cardiac interventions, because the heart beat results in repeated rapid motion of the heart and the nearby anatomy, including any fiber optic instruments located therein, thereby causing continuously unreliable OSS measurements, which may confuse a user. This is illustrated schematically and exemplarily in Fig. 2.
  • Fig. 2 shows an image 22 of the heart 12 together with a representation 23 of the ablation catheter 13 at a location indicated by OSS data values, which have been measured while the heart 12 was in a slow-motion phase.
  • the representations 24 show locations of the ablation catheter 13 as indicated by OSS data values measured while the heart 12 was in a high-motion phase.
  • the representations 24 are arranged at wrong locations, i.e. at locations at which the ablation catheter 13 is actually not located.
  • the corresponding OSS data values provide these wrong results, because of the rapid bending of the OSS fiber of the ablation catheter 13 caused by the movement of the heart 12 in the high-motion phases.
  • the processing apparatus 3 couples the OSS sensing system, which may also be regarded as being a fiber-optic shape sensing system, with the ECG recording.
  • the OSS sensing system which may also be regarded as being a fiber-optic shape sensing system
  • the current phase in the cardiac cycle can be assessed in real-time.
  • the heart shows limited motion, while motion is pronounced, for instance, during the transition between diastolic and systolic phases.
  • the expected motion amplitude is derived from the ECG measurement and used to estimate the reliability of the respective shape measurement, i.e. of the respective OSS data value.
  • shape sensing measurements from expected low- motion phases can be given a higher weight during temporal filtering as described above.
  • the low-motion phases 25, which can be determined based on the ECG signal 20, are schematically and exemplarily illustrated in Fig. 3.
  • Fig. 4 schematically and exemplarily illustrates a representation 26 of the ablation catheter 13 at a location indicated by processed OSS data values together with the image 22 of the heart 12.
  • the representations 24 at the wrong locations are not shown anymore such that the user will not be confused by such wrongly located representations of the ablation catheter 13.
  • the processing unit 7 can be further adapted to process the OSS data values by discarding OSS data values for which a reliability has been determined being smaller than a threshold, wherein the display 9 may be adapted to display the image of the heart 12 and to display temporally consecutively a representation of the ablation catheter 13 at locations indicated by the OSS data values which have not been discarded.
  • the threshold can be defined such that OSS data values are selected only, i.e. not discarded, to which times are assigned lying in a low-motion phase. Thus, measurements from high-motion phases can be discarded entirely and not shown to the user.
  • the processing apparatus 3 can be adapted to either use a) the above described filtering of the OSS data values and the displaying of the corresponding locations or b) the selection of OSS data values and the displaying of the corresponding selected locations only.
  • the processing apparatus 3 may be adapted to allow the user to choose between these two modes.
  • the processing unit may be adapted to just filter the OSS data values, for instance, to just weightedly average the OSS data values, but to not perform the above described discarding procedure, or the processing unit may be adapted to just perform the discarding procedure, but to not filter the OSS data values, in particular, to not weightedly average the OSS data values.
  • processing unit 7 may be adapted to process the
  • OSS data values by assigning display properties to the OSS data values depending on the reliabilities, wherein the display 9 may be adapted to display the representation of the element at the locations indicated by the processed OSS data values in accordance with the respective assigned display properties.
  • the display properties may be colors, intensities, et cetera. For instance, to OSS data values having a reliability being smaller than a threshold a first color like red can be assigned and to OSS data values having a reliability being larger than the threshold a second color like green can be assigned such that reliable locations are displayed with the second color and unreliable locations are displayed with the first color on the display 9.
  • step 101 OSS data values assigned to different times are provided by the optical shape sensing data values providing unit 5, wherein a respective OSS data value is indicative of a location of the ablation catheter 13 within or close to a heart 12 at the respective assigned time.
  • step 102 the ECG signal over time is provided by the motion signal providing unit 4 and in step 103 the reliabilities are determined for the OSS data values by the reliability determination unit 6, wherein the reliability determination unit 6 determines the reliability of a respective OSS data value depending on the ECG signal at the time assigned to the respective OSS data value.
  • the processing unit 7 processes the OSS data values depending on the determined reliabilities, for instance, the processing unit 7 performs the above described weighted averaging or discarding procedures.
  • the above described processing apparatus and processing method can reduce the influence of heart motion on a shape sensing measurement. They can thereby reduce the amplitude of measurement errors from the optical shape sensing system perceived by the user. This is especially valuable for minimally invasive interventions in which a shape sensing device passes through or close to the heart. By favoring shape measurement data from low-motion phases of the heart, as derived from the simultaneously recorded ECG signal, inaccurate shape measurements can be avoided.
  • the low-motion phase is the diastolic phase
  • the low-motion phase can also include other phases like the end-systolic phase.
  • the motion is cardiac motion such that the motion signal providing unit is adapted to provide a cardiac signal being indicative of the cardiac motion
  • the motion signal providing unit is adapted to provide alternatively or additionally a corresponding other motion signal like a respiratory signal.
  • the motion signal providing unit can be adapted to use a respiratory belt or another means for providing the respiratory signal.
  • the object is a heart of a living being
  • the moving object may also be another part of a living being like another organ, or a moving technical object.
  • each motion period comprises a single low-motion phase 25 only, in other words
  • a motion period may comprise more than one low-motion phase, wherein these motion phases may not be adjacent, i.e. a high-motion phase may be in between two low-motion phases.
  • the moving object is a periodically moving object
  • the object may also be a non-periodically moving object.
  • the reliabilities can be determined by investigating the motion signal, in order to determine first times at which the motion is relatively large and second times at which the motion is relatively low, and by assigning the OSS data values, which correspond to the first times, to a smaller reliability and the OSS data values, which correspond to the second time, to a larger reliability, or the reliabilities can be determined based on the motion signal in accordance with on another procedure.
  • the reliabilities can be explicitly determined, for instance, by directly assigning reliability values to the OSS data values, or implicitly determined, for instance, by determining low- and high- motion phases and by assigning the OSS data values to the low- and high-motion phases, wherein for the OSS data values assigned to the low-motion phases implicitly a smaller reliability has been determined and for OSS data values assigned to the high-motion phases implicitly a larger reliability has been determined.
  • Procedures like the determination of the reliabilities, the filtering of OSS data values, et cetera performed by one or several units or devices can be performed by any other number of units or devices.
  • the operations and/or the control of the processing apparatus in accordance with the processing method can be implemented as program code means of a computer program and/or as dedicated hardware.
  • a computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.
  • a suitable medium such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.
  • the invention relates to a processing apparatus for processing OSS data values, wherein a motion signal like an ECG signal is used for determining reliabilities of the OSS data values and wherein the OSS data values are processed depending on the determined reliabilities.
  • reliability information can be considered, before showing OSS locations to a user.
  • an averaging filter may be applied to the OSS data values, wherein the OSS data values may be weighted depending on the determined reliabilities and the weighted OSS data values may be averaged, or OSS data values having a relatively small reliability may be discarded. This can lead to an improved OSS based localization, wherein a user is less confused or not confused at all by faulty location measurements.

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Abstract

The invention relates to a processing apparatus (1) for processing optical shape sensing (OSS) data values, wherein a motion signal like an ECG signal is used for determining reliabilities of the OSS data values and wherein the OSS data values are processed depending on the determined reliabilities. Thus, reliability information can be considered, before showing OSS locations to a user. For instance, an averaging filter may be applied to the OSS data values, wherein the OSS data values may be weighted depending on the determined reliabilities and the weighted OSS data values may be averaged, or OSS data values having a relatively small reliability may be discarded. This can lead to an improved OSS based localization, wherein a user is less confused or not confused at all by faulty lo cation measurements.

Description

Processing apparatus for processing optical shape sensing data values
FIELD OF THE INVENTION
The invention relates to a processing apparatus, a processing method and a processing computer program for processing optical shape sensing data values. The invention relates further to an interventional system comprising the processing apparatus.
BACKGROUND OF THE INVENTION
US 2002/0165448 Al discloses a locating system for determining the location and orientation of an invasive medical instrument relative to a reference frame. A plurality of field generators generate known, distinguishable fields in response to drive signals and a plurality of sensors situated in the invasive medical instrument proximate the distal end thereof generate sensor signals in response to the fields. A signal processer computes three location coordinates and three orientation coordinates of a portion of the invasive medical instrument depending on the drive and sensor signals.
EP 2 514 379 A1 discloses a method for positioning an intracardiac catheter, wherein position signals of the intracardiac catheter and reference signals comprising respiration information are collected and a self- adaptation de-noising technique is utilized, in order to process the reference signals and eliminate respiration fluctuations in the position signals of the intracardiac catheter.
Optical shape sensing (OSS) is a localization technology that can be used for guidance in minimally invasive procedures, wherein one or several interventional elements are equipped with an OSS fiber for determining the location of the respective interventional instrument by OSS. Cardiac interventions are one important application area, with procedures such as catheterization of the coronary arteries, ablation therapy for electrophysiology disorders, or treatment of structural heart disease. However, during the cardiac interventions the accuracy of determining the location of the respective interventional instrument can be diminished. SUMMARY OF THE INVENTION
It is an object of the present invention to provide a processing apparatus, a processing method and a processing computer program for processing OSS data values, which allow for an improved OSS based localization of an element within or close to a moving object. It is a further object of the present invention to provide an interventional system comprising the processing apparatus.
In a first aspect of the present invention a processing apparatus for processing OSS data values is presented, wherein the processing apparatus comprises:
an optical shape sensing data values providing unit for providing OSS data values assigned to different times, wherein a respective OSS data value is indicative of a location of an element within or close to a moving object at the respective assigned time, a motion signal providing unit for providing a motion signal over time being indicative of the motion of the object,
a reliability determination unit for determining reliabilities of the OSS data values depending on the motion signal, and
a processing unit for processing the OSS data values depending on the determined reliabilities.
This allows considering the reliability information provided for each OSS data value, before showing corresponding locations to a user. For instance, the processing unit can be adapted to filter the OSS data values depending on the determined reliabilities such that motion errors are reduced in the OSS data values. In particular, an averaging filter may be applied to the OSS data values, wherein the OSS data values may be weighted depending on the determined reliabilities and the weighted OSS data values may be averaged, or OSS data values, for which a reliability has been determined being smaller than a threshold, may be discarded, wherein only the locations indicated by the non discarded OSS data values may be shown. The determination of the reliabilities and the processing of the OSS data values depending on the reliabilities allows therefore for an improved OSS based localization, wherein a user is less confused or not confused at all by faulty location measurements.
The motion signal providing unit is preferentially adapted to provide an electrocardiography (ECG) signal as the motion signal. The reliability determination unit is preferentially adapted to determine the reliability of a respective OSS data value depending on the motion signal at the time assigned to the respective OSS data value. Moreover, the reliability determination unit is preferentially adapted to derive a motion amplitude over time from the provided motion signal and to determine the reliability depending on the derived motion amplitude. In particular, the reliability determination unit is adapted to determine a larger reliability, if the derived motion amplitude is smaller, and a smaller reliability, if the derived motion amplitude is larger.
The element is preferentially an interventional element to be arranged within the object, which is preferentially a part of a living being, wherein the optical shape sensing data values providing unit comprises an optical shape sensing fiber arranged along the interventional element for providing the OSS data values.
The optical shape sensing data values providing unit is adapted to provide OSS data values being indicative of locations of the element within or close to the moving object. The optical shape sensing data values providing unit is preferentially also adapted to provide OSS data values being indicative of locations of the element not within or close to the object, i.e. of locations at which the OSS data values are not corrupted by the motion of the object. For instance, during navigating the element to the object OSS data values may be provided, which are not adversely influenced by the movement of the object, or, if the element is, for example, a catheter, wherein the tip of the catheter is close to or within the moving object, OSS data values of other parts of the catheter, which are more far away and not influenced by the motion, can also be provided by the optical shape sensing data values providing unit.
In an embodiment the processing unit is adapted to filter the OSS data values depending on the determined reliabilities, wherein a filter is applied to the OSS data values, which is adapted to reduce motion errors in the OSS data values. In particular, the processing unit may be adapted to apply an averaging filter to the OSS data values, wherein the OSS data values are weighted depending on the determined reliabilities and the weighted OSS data values are averaged. It is preferred that the processing unit is adapted to weight an OSS data value with a larger weight, if the reliability determined for the OSS data value is larger, and to weight an OSS data value with a smaller weight, if the reliability determined for the OSS data value is smaller. In particular, the processing unit may be adapted to assign OSS data values for which a reliability has been determined being larger than a threshold to a slow-motion phase, to assign OSS data values for which a reliability has been determined being smaller than a threshold to a high-motion phase, to weight OSS data values assigned to a slow-motion phase with a larger weight and to weight OSS data values assigned to a high- motion phase with a smaller weight. The moving object is preferentially a heart of a living being, wherein the low-motion phase is preferentially the diastolic phase. In a further embodiment the processing unit is adapted to process the OSS data values by discarding OSS data values for which a reliability has been determined being smaller than a threshold. Thus, only locations may be shown, which correspond to large reliabilities, in particular, which correspond to low-motion phases of the object, wherein locations corresponding to high-motion phases may be discarded.
In a preferred embodiment the processing apparatus further comprises an image providing unit for providing an image of the object and a display for displaying the image and a representation of the element at the locations indicated by the processed OSS data values. Preferentially, the representation of the element is temporally consecutively displayed at locations within or close to the object indicated by the processed OSS data values. This allows displaying reliably determined locations of the element relative to the object on the display.
In an embodiment the processing unit may be adapted to process the OSS data values by assigning display properties to the OSS data values depending on the reliabilities, wherein the display may be adapted to display the representation of the element at the locations indicated by the processed OSS data values in accordance with the respective assigned display properties. The display properties may be colors, intensities, et cetera. For instance, to OSS data values having a reliability being smaller than a threshold a first color like red can be assigned and to OSS data values having a reliability being larger than the threshold a second color like green can be assigned such that reliable locations are displayed with the second color and unreliable locations are displayed with the first color.
In another aspect of the present invention an interventional system for performing an interventional procedure is presented, wherein the interventional system comprises:
- an interventional element for being arranged within a living being, wherein the interventional element is equipped with an OSS fiber, and
a processing apparatus as defined in claim 1.
In a further aspect of the present invention a processing method for processing OSS data values is presented, wherein the processing method comprises:
- providing OSS data values assigned to different times by an optical shape sensing data values providing unit, wherein a respective OSS data value is indicative of a location of an element within or close to a moving object at the respective assigned time, providing a motion signal over time being indicative of the motion of the object by a motion signal providing unit, determining reliabilities of the OSS data values depending on the motion signal by a reliability determination unit, and
processing the OSS data values depending on the determined reliabilities by a processing unit.
In another aspect of the present invention a processing computer program for processing OSS data values is presented, wherein the processing computer program comprises program code means for causing a processing apparatus as defined in claim 1 to carry out the steps of the processing method as defined in claim 14, when the processing computer program is run on a computer controlling the processing apparatus.
It shall be understood that the processing apparatus of claim 1, the interventional system of claim 13, the processing method of claim 14, and the processing computer program of claim 15 have similar and/or identical preferred embodiments, in particular, as defined in the dependent claims.
It shall be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.
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
In the following drawings:
Fig. 1 shows schematically and exemplarily an embodiment of an interventional system for performing an interventional procedure,
Fig. 2 illustrates schematically and exemplarily faulty and correct locations of an ablation catheter determined by using OSS,
Fig. 3 illustrates schematically and exemplarily low-motion phases,
Fig. 4 illustrates schematically and exemplarily a correct location of an ablation catheter determined by using OSS, and
Fig. 5 shows a flowchart exemplarily illustrating an embodiment of a processing method for processing OSS data values.
DETAILED DESCRIPTION OF EMBODIMENTS
Fig. 1 shows schematically and exemplarily an embodiment of an interventional system for performing an interventional procedure. In this embodiment the interventional system 1 is adapted to perform a cardiac ablation procedure. The interventional system 1 comprises an interventional element 13 being, in this embodiment, an ablation catheter 13 for performing a radio frequency (RF) ablation procedure within a heart 12 of a person 18 lying on a support means like a patient table 11. The tip 14 is introduced into the heart 12 and comprises ablation electrodes for applying RF ablation energy provided by an ablation current source 17.
The ablation catheter 13 is equipped with an OSS fiber, i.e. the ablation catheter 13 comprises an OSS fiber arranged along the length of the ablation catheter. The OSS fiber is connected to an optical shape sensing data values providing unit 5, which is adapted to provide OSS data values over time based on OSS signals received from the OSS fiber of the ablation catheter 13. The OSS data values are indicative of locations of parts of the ablation catheter 13 close to or within the moving heart 12. The OSS data values may further be indicative of locations of other parts of the ablation catheter 13. In particular, OSS data values may be provided being indicative of locations of parts of the ablation catheter 13 along the entire length of the ablation catheter at least within the person 18. For determining the OSS data values over time the optical shape sensing data values providing unit 5 may be adapted to use the OSS technique disclosed in, for instance, US 8,050,523 B2, or to use another known OSS technique.
ECG electrodes 16 are arranged on the breast of the person 18. The ECG electrodes 16 are used for acquiring ECG signals to be measured by a motion signal providing unit 4 via an electrical connection 15. Thus, the motion signal providing unit 4 is adapted to generate a motion signal over time being indicative of the motion of the heart 14 by measuring an ECG signal.
The optical shape sensing data values providing unit 5 and the motion signal providing unit 4 can be integrated in a processing apparatus 3, wherein the processing apparatus 3 can further comprise a reliability determination unit 6 for determining reliabilities for the OSS data values, wherein the reliability determination unit 6 can be adapted to determine the reliability for a respective OSS data value depending on the ECG signal at the time assigned to the respective OSS data value. In particular, the reliability determination unit 6 can be adapted to derive a motion amplitude over time from the provided ECG signal and to determine the reliability depending on the derived motion amplitude. For instance, since the relation between the heart motion and the ECG signal is well known, the reliability determination unit 6 can be adapted to determine a motion amplitude from the ECG signal by detecting the so-called 'R-peaks' of the ECG signal, which indicate the onset of ventricular contraction. Using the R-peaks as reference, heart motion amplitudes can be inferred at each point in the cardiac cycle, for example, by employing a motion model measured on a collective of patients and stored in the motion signal providing unit. In this embodiment the reliability determination unit 6 is adapted to determine a larger reliability, if the derived motion amplitude is smaller, and a smaller reliability, if the derived motion amplitude is larger. For instance, the reliability determination unit can be adapted to determine the reliability such that it is inversely proportional to the derived motion amplitude.
The processing apparatus 3 further comprises a processing unit 7 for processing the OSS data values depending on the determined reliabilities. In this embodiment the processing unit 7 is adapted to filter the OSS data values depending on the determined reliabilities, wherein a filter is applied to the OSS data values, which is adapted to reduce motion errors in the OSS data values. In particular, the processing unit 7 is adapted to apply an averaging filter to the OSS data values, wherein the OSS data values are weighted depending on the determined reliabilities and the weighted OSS data values are averaged. The processing unit 7 is preferentially adapted to weight an OSS data value with a larger weight, if the reliability determined for the respective OSS data value is larger, and to weight an OSS data value with a smaller weight, if the reliability determined for the respective OSS data value is smaller. For instance, the processing unit 7 can be adapted to use a weight for weighting an OSS data value, which is proportional to the reliability determined for the respective OSS data value. However, the processing unit 7 can also be adapted to assign OSS data values, for which a reliability has been determined being larger than a threshold, to a slow-motion phase, to assign OSS data values, for which a reliability has been determined being smaller than a threshold, to a high-motion phase, to weight OSS data values assigned to a slow-motion phase with a larger weight and to weight OSS data values assigned to a high- motion phase with a smaller weight. For instance, the low-motion phase may be the diastolic phase, whereas the other phases of the heart 12, in particular, the transition phase between the systolic phase and the diastolic phase, can be regarded as forming a high-motion phase.
If the processing unit 7 is adapted to filter the OSS data values, it can use adjacent or overlapping windows, in particular, a sliding window technique, wherein the filtering may be performed based on the OSS data values in the respective window. For instance, for the weighted averaging the OSS data values can be used, which are within the respective window.
The processing apparatus 3 further comprises an image providing unit 19 for providing an image of the heart and a display 9 for displaying the image of the heart 12 and for displaying a representation of the ablation catheter 13 at the locations indicated by the processed OSS data values. The processing apparatus 3 further comprises an input 8 like a keyboard, a computer mouse, a touchpad, et cetera for allowing a user to enter, for instance, commands like a start command for starting the processing procedure for processing the OSS data values.
The image providing unit 19 can be a storing unit, in which the image of the heart 12, especially a segmented image of the heart 12, is stored and from which the stored image can be provided for being displayed on the display 9. However, the image providing unit 19 can also have some processing functionality for processing a received image of the heart 12, wherein in this case the image providing unit 19 is adapted to provide the processed image. For instance, the image providing unit 19 can be adapted to receive an image of the heart 12 like a computed tomography image, a magnetic resonance image, an ultrasound image, et cetera and to segment the heart in the image, in order to provide the segmented image.
In general, OSS measurements can be inaccurate during periods of rapid bending of the OSS fiber and the associated rapid changes in strain. Measurements return back to usable accuracy after a brief period of relaxation. This is especially problematic in cardiac interventions, because the heart beat results in repeated rapid motion of the heart and the nearby anatomy, including any fiber optic instruments located therein, thereby causing continuously unreliable OSS measurements, which may confuse a user. This is illustrated schematically and exemplarily in Fig. 2.
Fig. 2 shows an image 22 of the heart 12 together with a representation 23 of the ablation catheter 13 at a location indicated by OSS data values, which have been measured while the heart 12 was in a slow-motion phase. The representations 24 show locations of the ablation catheter 13 as indicated by OSS data values measured while the heart 12 was in a high-motion phase. The representations 24 are arranged at wrong locations, i.e. at locations at which the ablation catheter 13 is actually not located. The corresponding OSS data values provide these wrong results, because of the rapid bending of the OSS fiber of the ablation catheter 13 caused by the movement of the heart 12 in the high-motion phases. In order to mitigate this problem, the processing apparatus 3 couples the OSS sensing system, which may also be regarded as being a fiber-optic shape sensing system, with the ECG recording. By measuring the person's ECG during the intervention, the current phase in the cardiac cycle can be assessed in real-time. During the diastolic phase the heart shows limited motion, while motion is pronounced, for instance, during the transition between diastolic and systolic phases.
Preferentially, the expected motion amplitude is derived from the ECG measurement and used to estimate the reliability of the respective shape measurement, i.e. of the respective OSS data value. Using this information shape sensing measurements from expected low- motion phases can be given a higher weight during temporal filtering as described above.
The low-motion phases 25, which can be determined based on the ECG signal 20, are schematically and exemplarily illustrated in Fig. 3. Moreover, Fig. 4 schematically and exemplarily illustrates a representation 26 of the ablation catheter 13 at a location indicated by processed OSS data values together with the image 22 of the heart 12. In comparison to the situation illustrated in Fig. 2, the representations 24 at the wrong locations are not shown anymore such that the user will not be confused by such wrongly located representations of the ablation catheter 13.
The processing unit 7 can be further adapted to process the OSS data values by discarding OSS data values for which a reliability has been determined being smaller than a threshold, wherein the display 9 may be adapted to display the image of the heart 12 and to display temporally consecutively a representation of the ablation catheter 13 at locations indicated by the OSS data values which have not been discarded. The threshold can be defined such that OSS data values are selected only, i.e. not discarded, to which times are assigned lying in a low-motion phase. Thus, measurements from high-motion phases can be discarded entirely and not shown to the user. The processing apparatus 3 can be adapted to either use a) the above described filtering of the OSS data values and the displaying of the corresponding locations or b) the selection of OSS data values and the displaying of the corresponding selected locations only. The processing apparatus 3 may be adapted to allow the user to choose between these two modes. In a further embodiment the processing unit may be adapted to just filter the OSS data values, for instance, to just weightedly average the OSS data values, but to not perform the above described discarding procedure, or the processing unit may be adapted to just perform the discarding procedure, but to not filter the OSS data values, in particular, to not weightedly average the OSS data values.
In a further embodiment the processing unit 7 may be adapted to process the
OSS data values by assigning display properties to the OSS data values depending on the reliabilities, wherein the display 9 may be adapted to display the representation of the element at the locations indicated by the processed OSS data values in accordance with the respective assigned display properties. The display properties may be colors, intensities, et cetera. For instance, to OSS data values having a reliability being smaller than a threshold a first color like red can be assigned and to OSS data values having a reliability being larger than the threshold a second color like green can be assigned such that reliable locations are displayed with the second color and unreliable locations are displayed with the first color on the display 9.
In the following an embodiment of a processing method for processing OSS data values will exemplarily be described with reference to a flowchart shown in Fig. 5.
In step 101 OSS data values assigned to different times are provided by the optical shape sensing data values providing unit 5, wherein a respective OSS data value is indicative of a location of the ablation catheter 13 within or close to a heart 12 at the respective assigned time. In step 102 the ECG signal over time is provided by the motion signal providing unit 4 and in step 103 the reliabilities are determined for the OSS data values by the reliability determination unit 6, wherein the reliability determination unit 6 determines the reliability of a respective OSS data value depending on the ECG signal at the time assigned to the respective OSS data value. In step 104 the processing unit 7 processes the OSS data values depending on the determined reliabilities, for instance, the processing unit 7 performs the above described weighted averaging or discarding procedures.
The above described processing apparatus and processing method can reduce the influence of heart motion on a shape sensing measurement. They can thereby reduce the amplitude of measurement errors from the optical shape sensing system perceived by the user. This is especially valuable for minimally invasive interventions in which a shape sensing device passes through or close to the heart. By favoring shape measurement data from low-motion phases of the heart, as derived from the simultaneously recorded ECG signal, inaccurate shape measurements can be avoided.
Although in above described embodiments the low-motion phase is the diastolic phase, in other embodiments the low-motion phase can also include other phases like the end-systolic phase.
Although in above described embodiments the motion is cardiac motion such that the motion signal providing unit is adapted to provide a cardiac signal being indicative of the cardiac motion, in other embodiments also other kinds of motion may be considered, i.e. the reliabilities may alternatively or additionally be determined based on another kind of motion like respiratory motion. In this case the motion signal providing unit is adapted to provide alternatively or additionally a corresponding other motion signal like a respiratory signal. For instance, the motion signal providing unit can be adapted to use a respiratory belt or another means for providing the respiratory signal.
Although in above described embodiments the object is a heart of a living being, in another embodiment the moving object may also be another part of a living being like another organ, or a moving technical object.
Although in the embodiment exemplarily described above with reference to Fig. 3 each motion period comprises a single low-motion phase 25 only, in other
embodiments, in which the object is a periodically moving object, a motion period may comprise more than one low-motion phase, wherein these motion phases may not be adjacent, i.e. a high-motion phase may be in between two low-motion phases.
Although in above described embodiments the moving object is a periodically moving object, in other embodiments the object may also be a non-periodically moving object.
Although in above described embodiments certain ways of determining reliabilities of OSS data values depending on the motion signal have been described, in other embodiments also other way of determining the reliabilities of the OSS data values depending on the motion signal can be used. For instance, the reliabilities can be determined by investigating the motion signal, in order to determine first times at which the motion is relatively large and second times at which the motion is relatively low, and by assigning the OSS data values, which correspond to the first times, to a smaller reliability and the OSS data values, which correspond to the second time, to a larger reliability, or the reliabilities can be determined based on the motion signal in accordance with on another procedure. The reliabilities can be explicitly determined, for instance, by directly assigning reliability values to the OSS data values, or implicitly determined, for instance, by determining low- and high- motion phases and by assigning the OSS data values to the low- and high-motion phases, wherein for the OSS data values assigned to the low-motion phases implicitly a smaller reliability has been determined and for OSS data values assigned to the high-motion phases implicitly a larger reliability has been determined.
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. A single unit or device 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.
Procedures like the determination of the reliabilities, the filtering of OSS data values, et cetera performed by one or several units or devices can be performed by any other number of units or devices. The operations and/or the control of the processing apparatus in accordance with the processing method can be implemented as program code means of a computer program and/or as dedicated hardware.
A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems.
Any reference signs in the claims should not be construed as limiting the scope.
The invention relates to a processing apparatus for processing OSS data values, wherein a motion signal like an ECG signal is used for determining reliabilities of the OSS data values and wherein the OSS data values are processed depending on the determined reliabilities. Thus, reliability information can be considered, before showing OSS locations to a user. For instance, an averaging filter may be applied to the OSS data values, wherein the OSS data values may be weighted depending on the determined reliabilities and the weighted OSS data values may be averaged, or OSS data values having a relatively small reliability may be discarded. This can lead to an improved OSS based localization, wherein a user is less confused or not confused at all by faulty location measurements.

Claims

CLAIMS:
1. A processing apparatus for processing optical shape sensing data values, wherein the processing apparatus comprises:
an optical shape sensing data values providing unit (5) for providing optical shape sensing data values assigned to different times, wherein a respective optical shape sensing data value is indicative of a location of an element (13) within or close to a moving object (12) at the respective assigned time,
a motion signal providing unit (4) for providing a motion signal (20) over time being indicative of the motion of the object (12),
a reliability determination unit (6) for determining reliabilities of the optical shape sensing data values depending on the motion signal (20), and
a processing unit (7) for processing the optical shape sensing data values depending on the determined reliabilities.
2. The processing apparatus as defined in claim 1, wherein the processing unit (7) is adapted to filter the optical shape sensing data values depending on the determined reliabilities, wherein a filter is applied to the optical shape sensing data values, which is adapted to reduce motion errors in the optical shape sensing data values.
3. The processing apparatus as defined in claim 2, wherein the processing unit (7) is adapted to apply an averaging filter to the optical shape sensing data values, wherein the optical shape sensing data values are weighted depending on the determined reliabilities and the weighted optical shape sensing data values are averaged.
4. The processing apparatus as defined in claim 3, wherein the processing unit (7) is adapted to weight an optical shape sensing data value with a larger weight, if the reliability determined for the optical shape sensing data value is larger, and to weight an optical shape sensing data value with a smaller weight, if the reliability determined for the optical shape sensing data value is smaller.
5. The processing apparatus as defined in claim 4, wherein the processing unit (7) is adapted to assign optical shape sensing data values for which a reliability has been determined being larger than a threshold to a slow-motion phase, to assign optical shape sensing data values for which a reliability has been determined being smaller than a threshold to a high-motion phase, to weight optical shape sensing data values assigned to a slow- motion phase with a larger weight and to weight optical shape sensing data values assigned to a high-motion phase with a smaller weight.
6. The processing apparatus as defined in claim 5, wherein the moving object (12) is a heart of a living being (18) and wherein the low-motion phase (25) is the diastolic phase.
7. The processing apparatus as defined in claim 1, wherein the processing unit (7) is adapted to process the optical shape sensing data values by discarding optical shape sensing data values for which a reliability has been determined being smaller than a threshold.
8. The processing apparatus as defined in claim 1, wherein the processing apparatus (3) further comprises an image providing unit (19) for providing an image (22) of the object and a display (9) for displaying the image (22) and a representation (26) of the element (13) at the locations indicated by the processed optical shape sensing data values.
9. The processing apparatus as defined in claim 8, wherein the processing unit (7) is adapted to process the optical shape sensing data values by assigning display properties to the optical shape sensing data values depending on the reliabilities, wherein the display (9) is adapted to display the representation of the element (13) at the locations indicated by the processed optical shape sensing data values in accordance with the respective assigned display properties.
10. The processing apparatus as defined in claim 1, wherein the reliability determination unit (6) is adapted to derive a motion amplitude over time from the provided motion signal and to determine the reliabilities depending on the derived motion amplitude.
11. The processing apparatus as defined in claim 10, wherein the reliability determination unit (6) is adapted to determine a larger reliability, if the derived motion amplitude is smaller, and a smaller reliability, if the derived motion amplitude is larger.
12. The processing apparatus as defined in claim 1, wherein the element (13) is an interventional element (13) to be arranged within the object (12) being a part of a living being (18), wherein the optical shape sensing data values providing unit (5) comprises an optical shape sensing fiber arranged along the interventional element (13) for providing the optical shape sensing data values.
13. An interventional system for performing an interventional procedure, the interventional system (1) comprising:
an interventional element (13) for being arranged within a living being (18), wherein the interventional element (13) is equipped with an optical shape sensing fiber, and - a processing apparatus (3) as defined in claim 1.
14. A processing method for processing optical shape sensing data values, wherein the processing method comprises:
providing optical shape sensing data values assigned to different times by an optical shape sensing data values providing unit (5), wherein a respective optical shape sensing data value is indicative of a location of an element (13) within or close to a moving object (12) at the respective assigned time,
providing a motion signal (20) over time being indicative of the motion of the object (12) by a motion signal providing unit (4),
- determining reliabilities of the optical shape sensing data values depending on the motion signal (20) by a reliability determination unit (6), and
processing the optical shape sensing data values depending on the determined reliabilities by a processing unit (7).
15. A processing computer program for processing optical shape sensing data values, the processing computer program comprising program code means for causing a processing apparatus (3) as defined in claim 1 to carry out the steps of the processing method as defined in claim 14, when the processing computer program is run on a computer controlling the processing apparatus (3).
PCT/EP2014/059832 2013-05-22 2014-05-14 Processing apparatus for processing optical shape sensing data values WO2014187708A1 (en)

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