# US 2014/0194757 A1 · System for distributed blood flow measurement > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0194757 A1 - Document ID: US20140194757A1 - Status: Published application - Kind: A1 - Application number: 14/117,861 - Filed: 2012-05-29 - Published: 2014-07-10 - Earliest claimed: 2011-06-01 - Assignees: Koninklijke Philips N.V. - Inventors: Gert Wim 'T Hooft; Adrien Emmanuel Desjardins; Maya Ella Barley; Raymond Chan - Web page: https://patentgrep.com/patent/US20140194757A1 ## CPC - A61B 5/0261: {using optical means, e.g. infrared light} - A61B 5/028: by thermo-dilution - A61B 5/6852: {Catheters} - G01F 1/6884: {making use of temperature dependence of optical properties} - A61B 2562/0233: Special features of optical sensors or probes classified in A61B5/00 - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME ## Abstract A medical system for minimally-invasive measurement of blood flow in an artery (AT). An interventional device (IVD) with an optical fiber (FB) comprising a plurality of temperature-sensitive optical sensor segments, e.g. Fiber Bragg Gratings, spatially distributed along its longitudinal extension is configured for insertion into an artery (AT). A temperature changer (TC) is arranged in the WD to introduce a local change in temperature (ΔT) of a bolus of blood in the artery, to allow thermal tracking over time with the optical fiber (FB). A measurement unit (MU) with a laser light source (LS) delivers light to the optical fiber (FB) and receives light reflected from the optical fiber (FB) and generates a corresponding time varying output signal. A first algorithm (A1) translates this time varying output signal into a set of temperatures corresponding to temperatures at respective positions along the optical fiber (FB). A second algorithm (A2) calculates a measure of blood flow (BF) at respective positions along the optical fiber (FB) in accordance with a temporal behavior of said set of temperatures. Such system can be used to quickly scan an artery for diagnosing stenotic regions without the need for pullbacks or injection of toxic liquids. A good spatial resolution of the blood flow measurement can be obtained in real-time. ## Claims ### Claim 1 A medical system for interventional measurement of blood flow in an artery (AT), the medical system comprising an interventional device (IVD) comprising at least one optical fiber (FB) comprising a plurality of temperature-sensitive optical sensor segments spatially distributed along its longitudinal extension, wherein the interventional device (IVD) is configured for insertion into an artery (AT) such that the optical fiber (FB) can be positioned inside the artery (AT) and be in thermal contact with blood flowing in the artery (AT), and such that the longitudinal extension of the optical fiber (FB) follows a longitudinal extension of the artery (AT), wherein the interventional device (IVD) comprises a temperature changer (TC) arranged to introduce a local change in temperature (ΔT) of a bolus of blood in the artery (AT) at a position upstream from one end of the optical fiber (FB), a measurement unit (MU) arranged for operational connection to the interventional device (IVD), wherein the measurement unit (MU) comprises a light source (LS) for delivering light to the optical fiber (FB) in the interventional device (IVD), and wherein the measurement unit (MU) is arranged to receive light reflected from the optical fiber (FB) and to generate a corresponding time varying output signal, and a processor unit (PU) for operational connection to the measurement unit (MU), wherein the processor unit (PU) is arranged to run a first processing algorithm (A1) so as to translate the time varying output signal from the measurement unit (MU) into a set of temperatures corresponding to temperatures at respective positions along the optical fiber (FB), and wherein the processor unit (PU) is arranged to run a second processing algorithm (A2) arranged to calculate a measure of blood flow (BF) at respective positions along the optical fiber (FB) in accordance with a temporal behavior of said set of temperatures. ### Claim 2 (depends on 1) System according to claim 1, wherein the measurement unit (MU) comprises an interferometer. ### Claim 3 (depends on 1) System according to claim 1, comprising a temperature control unit arranged to temporally control a temperature changing effect of the temperature changer (TC). ### Claim 4 (depends on 3) System according to claim 3, wherein the temperature control unit is arranged to control the temperature changer (TC) so as to provide a modulation of cooling or heating of the local bolus of blood at a constant frequency, and wherein the measurement unit (MU) is arranged to measure a spatially distributed temperature at said frequency. ### Claim 5 (depends on 1) System according to claim 1, wherein the temperature changer (TC) comprises a catheter (C) arranged for injection of a temporally limited bolus of liquid with a temperature different (ΔT) from a temperature of blood in the artery (AT). ### Claim 6 (depends on 1) System according to claim 1, wherein the temperature changer (TC) comprises a temperature changing element arranged for thermal contact with blood in the artery (AT), wherein the temperature changing element is arranged to cool or heat a local bolus of blood. ### Claim 7 (depends on 1) System according to claim 1, wherein the plurality of temperature-sensitive optical sensor segments comprises at least one of: Fiber Bragg Gratings, and Rayleigh based sensor segments. ### Claim 8 (depends on 1) System according to claim 1, wherein the interventional device (IVD) comprises a guidewire in which the at least one optical fiber (FB) is arranged. ### Claim 9 (depends on 1) System according to claim 1, wherein the light source (LS) comprises a laser light source arranged to provide light at different wavelengths. ### Claim 10 (depends on 9) System according to claim 9, wherein light from the light source (LS) is split into a first part delivered to the optical fiber (FB) in the interventional device (IVD) and into a second part applied to a wavelength measurement unit arranged to determine a measure of wavelength of the light from the light source (LS). ### Claim 11 (depends on 10) System according to claim 10, wherein the wavelength measurement unit comprises a gas cell (GC) with a known optical absorption spectrum, and a Mach Zehnder interferometer. ### Claim 12 (depends on 1) System according to claim 1, wherein the first processing algorithm (Al) comprises spatially resolving the output signal as a function of time from the measurement unit into a distributed temperature profile by means of Fourier analysis. ### Claim 13 (depends on 1) System according to claim 1, wherein the interventional device (IVD) and the measurement unit (MU) are arranged for interconnection by means of an optical interface so as to allow the measurement unit (MU) and the interventional device (IVD) to be spatially separated during normal use. ### Claim 14 (depends on 1) System according to claim 1, wherein the interventional device (IVD) is made of non-magnetic materials. ### Claim 15 Method for minimally-invasive measurement of blood flow in an artery, the method comprising providing an interventional device comprising at least one optical fiber comprising a plurality of temperature-sensitive optical sensor segments spatially distributed along its longitudinal extension, wherein the interventional device comprises a temperature changer, inserting the interventional device into an artery such that the optical fiber can be positioned inside the artery and be in thermal contact with blood flowing in the artery, and such that the longitudinal extension of the optical fiber follows a longitudinal extension of the artery, introducing a local change in temperature of a bolus of blood in the artery at a position upstream from one end of the optical fiber by means of the temperature changer, delivering light to the optical fiber in the interventional device, receiving light reflected from the optical fiber, translating the time varying reflected light into a set of temperatures corresponding to temperatures at respective positions along the optical fiber, and calculating a measure of blood flow at respective positions along the optical fiber in accordance with a temporal behavior of said set of temperatures.