Abstract
The invention is directed to a method of determining properties in a vessel or the heart (V) of a patient. It comprises the steps of placing an element in a vessel or the heart(V) and determining a propulsion force (2) acting on the element. Furthermore, at least one of acceleration (3) and velocity (4) of the element is determined. At least one property of a neighbouring medium of the element is determined based on the propulsion force and at least one of acceleration (3) and velocity (4) of the element.
Claims
1.-18. (canceled)
19. A system for determining properties in a vessel or the heart of a patient, comprising: an element to be placed in a vessel or the heart; means for determining a propulsion force acting on the element; means for determining at least one of acceleration and velocity; and means for determining at least one property of a neighbouring medium of the element based on the propulsion force and at least one of acceleration and velocity of the element.
20. A method for determining properties in a vessel or heart of a patient, comprising the steps: placing an element in the vessel or the heart; determining a propulsion force acting on the element; determining at least one of acceleration and velocity of the element; and determining at least one property of a neighbouring medium of the element based on the propulsion force and at least one of acceleration and velocity of the element.
21. The method according to claim 20, wherein the propulsion force is measured by a sensor in the element.
22. The method according to claim 20, further comprising the step of imaging an area of a patient where the element is located.
23. The method according to claim 22, wherein the at least one property of the neighbouring medium is determined additionally based on the imaging data.
24. The method according to claim 20, further comprising the step of determining the location of the element.
25. The method according to claim 22, further comprising the step of determining the location of the element.
26. The method according to claim 25, wherein the location is determined by means of the imaging technique.
27. The method according to claim 24, further comprising the step of saving in a memory the at least one property of the neighbouring medium as a function of the location and/or time.
28. The method according to claim 20, wherein the step of calculating the at least one property of the neighbouring medium is performed by a computer running a software code.
29. The method according to claim 20, wherein the at least one property of the neighbouring medium is one of a mechanical, hemodynamical, anatomical, and histological property.
30. The method according to claim 20, wherein the element placed in the vessel or the heart comprises a magnetic element and the step of determining the propulsion force comprises determining of the field strength of a magnetic field.
31. The method according to claim 20, further comprising the step of calculating a theoretical acceleration or velocity of the element based on the propulsion force acting on the element.
32. The method according to claim 22, wherein the element placed in the vessel or the heart comprises a magnetic element and the step of determining the propulsion force comprises determining of the field strength of a magnetic field.
33. The method according to claim 32, wherein the step of calculating a theoretical value of velocity and acceleration of the element is additionally based on the location of the element and imaging data acquired in the imaging step.
34. The method according to claim 20, further comprising the step of measuring the flow velocity of a liquid surrounding the element and additionally base the determination of the at least one property of the neighbouring medium on the flow velocity.
35. The method according to claim 20, further comprising the step of localizing the element by means of at least one detector or marker placed on the element or at a predefined location in the patient's body.
36. A computer program product for analysing the neighbouring medium of an element in a patient's body, comprising a software code adapted to, when run on a computer, perform the step of determining at least one property of a neighbouring medium of an element based on a propulsion force and at least one of an acceleration and a velocity of the element.
37. A system for determining properties of a vessel or heart, the system comprising an element carried by and/or moving actively in a bodily fluid, a measurement unit, and a calculating unit, wherein the measurement unit is adapted to determine at least one of acceleration and velocity of the element, and the calculating unit is adapted to determine at least one property of the vessel.
38. The system of claim 37, further comprising an imaging device that is adapted to image an area of a patient's body where the element is located.
Description
[0050] FIG. 1: schematically an element in a vessel.
[0051] FIG. 2: schematically an element with different forces acting on it.
[0052] FIG. 3: schematically an element in a narrowing vessel.
[0053] FIG. 4: schematically an element in a vessel and imaging devices.
[0054] FIG. 5: schematically markers located on a vessel.
[0055] FIG. 6: schematically an element in a vessel with a blood clot.
[0056] FIG. 7: schematically a system according to the invention.
[0057] FIG. 8: schematically a magnetic element.
[0058] FIG. 1 shows schematically an element 1 in a vessel V. Here, the element 1 is a moving element comprising a ferromagnetic material. Thus, a magnetic field applied by an external magnet (not shown, see FIG. 8) may guide and/or propel the element 1 inside the vessel V. Thus, it can exert force 2 on the element 1. In this case, in the hypothetical absence of influences e.g. by bodily functions such as blood flow, friction, or gravity, the exerted force 2 by the magnetic field would be the only force acting on the element 1. It thus represents the propulsion force in this example. However, due to fluid resistance, the element is also subject to a drag force. Here, the drag force is unknown and shall be determined in order to determine the fluid properties of blood and the friction on a vessel wall. However, it would also be possible to include fluid resistance and friction in the propulsion force. It is also possible to measure the effective acceleration 3 or velocity 4 of the element. Here, the acceleration 3 is e.g. measured by an accelerometer comprised in the element. Alternatively, it may for example also be measured by means of an imaging device. The effective acceleration 3 represents the difference between the force 2 and the drag force. Thus, it is possible to calculate the drag force and consequently also fluid properties of the blood and the vessel. This is particularly advantageous, of course, where the flow properties of the blood are affected by a condition.
[0059] FIG. 2 schematically represents a similar element as shown in FIG. 1. Here, the vessel V is not shown for clarity. In addition, the element has a different shape and has a cubic instead of a quasi-spherical shape. However, it also comprises a ferromagnetic material and can be propelled by a magnetic field. The state schematically shown in FIG. 2 represents an equilibrium state when the element has reached a terminal velocity 4. Hence, the propulsion force 2 and the drag force 5 have equal norm values but opposite signs. The terminal velocity 4 can thus be used to calculate parameters of the blood such as its viscosity. In a similar embodiment of the method, the magnetic field may change its direction with a certain frequency. Instead of measuring the velocity, one may measure the frequency of motion of the element and determine fluid properties of the blood from that.
[0060] FIG. 3 shows schematically a different type of element 1. It is spherical and is passively carried by a fluid in the vessel V. It further comprises a sensor that is adapted to measure the effective acceleration 3 of the element 1. Here, the vessel has a constriction causing the flow speed of the blood to temporarily increase. Thus, the accelerometer 6 detects a temporary acceleration (and deceleration in the widening region). Because the element 1 is passively carried in this example, the propulsion force is zero. Hence, the effective acceleration 3 can directly be used to determine properties of the vessel V, in this case the presence of a constriction.
[0061] FIG. 4 shows an element 1 carried by a liquid in a vessel V. For clarity, none of the propulsion means are shown in this schematic depiction, but the person skilled in the art will understand that any of the described ways of moving, steering, or guiding the device could be employed in this embodiment. Here, an imaging unit 7 having an X-ray imaging device is employed. The element 1 is visible in X-ray imaging. In addition, the blood contains a contrast agent such that the vessel system is also visible under X-rays. A Doppler imaging unit 8 is employed to visualize the flow 9 of the blood in the vessel system. Of course, the Doppler imaging unit and the X-ray imaging device may be connected to one computer each or to the same computer, for example a computer comprising a computer program product according to the invention for use of the imaging results in the calculation.
[0062] FIG. 5 shows an element 1 moving in a vessel V. Here, several detectors 10 are placed around the vessel V. They are formed by closed copper coils around the vessel. The element comprises a permanent magnet that creates a magnetic field around it. Thus, when the element 1 passes a detector 10, the moving magnetic field induces a current in the detector that can be detected. It is also possible to provide an emitting chip on the robot and receivers/detectors placed on the body, that can triangulate the robot position.
[0063] FIG. 6 shows another application of the method. Here, the element is moving in a vessel and is propelled by a magnetic field that exerts a force 2 on the element 1 via a ferromagnetic element comprised in it. However, a blood clot C has formed in the vessel V and blocks or restricts the blood flow. Consequently, the element 1 stops moving as well once it hits the blood clot C. Thus, the effective velocity of the element becomes zero, while the propulsion force 2 is non-zero. This allows for the determination of a property, in this case the presence of a blood clot. Of course, it would also be conceivable to additionally measure the effective acceleration of the element 1 which would additionally give information about the location of the blood clot C and/or its mechanical properties (a softer clot C would lead to lower negative acceleration values).
[0064] FIG. 7 shows schematically a system according to the invention. It comprises an element 1, in which a sensor 6 is arranged. The sensor shown here is adapted to measure acceleration of the element and, optionally, basic values such as temperature and pressure. The system further comprises a measurement unit 11 and an analyser unit 12. The measurement unit is in particular adapted to receive acceleration values from the sensor. However, it may also measure values based on markers or detectors 10. Although not required to perform the method, in certain embodiments it may be advantageous to measure the effective propulsion force acting on the element 1. Thus, in this non-limiting example, the measurement unit 11 is also adapted to measure a magnetic field at the location of the element, in particular by interaction with the sensor 6. The analyser unit 12 is adapted to process the values received from and by the measurement unit 11. In addition, it comprises a memory 15 to save values. For example, it may receive an effective acceleration value from the sensor 6 comprised in the element 1. In addition, the propulsion force may be known from the parameters of an external magnetic unit (see FIG. 8) or be measured by the sensor 6. In any case, the analyser unit is adapted to process these values and analyze them to determine at least one property of the vessel. The property value can optionally be saved in the memory 15. It would be conceivable to combine the system with a display adapted to show data, in particular two-dimensional and/or three-dimensional illustrations of data such as a reconstruction of the anatomy of a patient, based on the values saved in the memory. It will be understood that any of the examples and embodiments described herein may be realized with this system.
[0065] FIG. 8 shows a magnetic element 14 that may be used to propel the element 1. Here, it comprises an electromagnet that can selectively be turned on and off to create a magnetic field 14. Of course, a permanent magnet may also be employed. It would also be conceivable to use electric energy to operate an impeller, a propeller, or another propulsion means.
