111111
`
`1111111111111111111111111111111111111111111111111111111111111111111111111111
`US 20140200867Al
`
`(19) United States
`c12) Patent Application Publication
`LAVI et al.
`
`(10) Pub. No.: US 2014/0200867 A1
`Jul. 17, 2014
`(43) Pub. Date:
`
`(54) VASCULAR FLOW ASSESSMENT
`
`Publication Classification
`
`(71) Applicant: CathWorks Ltd, Tel-Aviv (IL)
`
`(72)
`
`Inventors: Ifat LAVI, Moshav Mishmeret (IL); Ran
`Kornowski, Ramat-HaSharon (IL); ldit
`Avrahami, Rosh HaAyin (IL); Nessi
`Benishti, Kfar-Saba (IL); Guy Lavi,
`Moshav Mishmeret (IL)
`
`(73) Assignee: CathWorks Ltd, Tel-Aviv (IL)
`
`(21) Appl. No.: 14/040,688
`
`(22) Filed:
`
`Sep.29,2013
`
`Related U.S. Application Data
`
`(60) Provisional application No. 61/752,526, filed on Jan.
`15, 2013.
`
`(51)
`
`(52)
`
`(2006.01)
`(2006.01)
`
`Int. Cl.
`G06F 19100
`G06T 17100
`U.S. Cl.
`CPC .......... G06F 1913431 (2013.01); G06T 171005
`(2013.01)
`USPC .............................................................. 703/2
`
`ABSTRACT
`(57)
`A method for vascular assessment is disclosed. The method
`comprises receiving a plurality of2D angiographic images of
`a portion of a vasculature of a subject, and processing the
`images to produce a stenotic model over the vasculature, the
`stenotic model having measurements of the vasculature at one
`or more locations along vessels of the vasculature. The
`method further comprises obtaining a flow characteristic of
`the stenotic model, and calculating an index indicative of
`vascular function, based, at least in part, on the flow charac(cid:173)
`teristic in the stenotic model.
`
`PRODUCE A STENOTIC :tv10DEL OF A SUBJECT'S
`VASCULAR SYSTEM
`
`~ "' 1910
`
`+
`OBTAIN A FLOW CHARl\.CTERISTIC OF THE STENOTIC K
`MODEL •
`+
`
`PRODUCE A SECOND MODEL OF A SIMILAR EXTENT
`
`OF THE PATIENT'S VASCULAR SYSTEM AS THE ~ -
`
`STENOTIC MODEL
`
`1915
`
`1920
`
`OBTAIN THE FLOW CHARACTERISTIC OF THE
`N0Rl'v1AL MODEL
`
`K
`
`'1925
`
`+
`CALCULATE AN TNDEX TNDTCA TTVE OF THE NEED r-- 1930
`FOR REV ASCULARIZA TION
`
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`FIGURE 1
`
`FIGURE 2
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`r---------r·------T ___________ l___________________________________
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`~
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`Patent Application Publication
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`Jul. 17, 2014 Sheet 5 of 10
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`US 2014/0200867 A1
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`CATHWORKS EXHIBIT 1005
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`CATHWORKS EXHIBIT 1005
`Page 7 of 31
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`

`

`Patent Application Publication
`
`Jul. 17, 2014 Sheet 7 of 10
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`US 2014/0200867 A1
`
`fk" - ..... 1910
`
`PRODUCE A STENOTIC MODEL OF A SUBJECT'S
`VASCULAR SYSTEM
`
`t
`OBTATN A FLOW CHARACTERISTIC OF THE STENOTIC f.*- - ...... 1915
`t
`
`MODEL
`
`PRODUCE A SECOND MODEL OF A SIMILAR EXTENT
`OF THE PATfENT'S VASCULAR SYSTElvl 1\S THE
`STENOTIC MODEL
`
`t
`
`OBTAJN THE FLOW CHARACTERISTIC OF THE
`NORMAL MODEL
`
`•
`
`CALCULATE AN INDEX INDICATIVE OF THE NEED
`FOR REVASCULARIZAT10N
`
`,.,---- 1920
`
`~ -. 1925
`
`f..V-
`
`1930
`
`FIGURE 9
`
`CAPTURE A PLURALITY OF 2D JMAGES OF THE
`SUBJECT'S VASCULAR SYSTEM
`
`t
`
`PRODUCE A TREE MODEL OF THE SUBJECT'S
`VASCULAR SYSTEM
`
`t
`
`PRODUCE A MODEL OF A FLOW CHARACTERfSTIC OF
`THE TREE MODEL
`
`-
`~ 2010
`
`~ -
`
`2015
`
`-~ 2020
`
`FIGURE 10
`
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`Patent Application Publication
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`US 2014/0200867 A1
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`2100
`
`FIGURE 11
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`Patent Application Publication
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`US 2014/0200867 A1
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`2205
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`
`COMPUTER
`2210
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`FIGURE 12A
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`Patent Application Publication
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`US 2014/0200867 AI
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`Jul. 17, 2014
`
`1
`
`VASCULAR FLOW ASSESSMENT
`
`FIELD AND BACKGROUND OF THE
`INVENTION
`
`[0001] The present invention,
`in some embodiments
`thereof, relates to vascular flow assessment and, more par(cid:173)
`ticularly, but not exclusively, to modeling vascular flow and to
`assessing vascular flow.
`[0002] Arterial stenosis is one of the most serious forms of
`arterial disease. In clinical practice, stenosis severity is esti(cid:173)
`mated by using either simple geometrical parameter, such as
`determining the percent diameter of a stenosis, or by measur(cid:173)
`ing hemodynamically based parameters, such as the pressure(cid:173)
`based myocardial Fractional Flow Reserve (FFR). FFR is an
`invasive measurement of the functional significance of coro(cid:173)
`nary stenoses. The FFR measurement technique involves
`insertion of a 0.014" guidewire equipped with a miniature
`pressure transducer located across the arterial stenosis. It
`represents the ratio between the maximal blood flow in the
`area of stenosis and the maximal blood flow in the same
`territory without stenosis. Earlier studies showed that FFR<O.
`75 is an accurate predictor of ischemia and deferral of percu(cid:173)
`taneous coronary intervention for lesions with FFR;;:0.75
`appeared to be safe.
`[0003] An FFR cut-off value of 0.8 is typically used in
`clinical practice to guide revascularization, supported by
`long-term outcome data. Typically, an FFR value in a range of
`0.75-0.8 is considered a 'grey zone' having uncertain clinical
`significance.
`[0004] Modeling vascular flow and to assessing vascular
`flow is described, for example, in U.S. published patent appli(cid:173)
`cation number 2012/0059246 of Taylor, to a "Method And
`System For Patient-Specific Modeling Of Blood Flow",
`which describes embodiments which include a system for
`determining cardiovascular information for a patient. The
`system may include at least one computer system configured
`to receive patient-specific data regarding a geometry of at
`least a portion of an anatomical structure of the patient. The
`portion of the anatomical structure may include at least a
`portion of the patient's aorta and at least a portion of a plu(cid:173)
`rality of coronary arteries emanating from the portion of the
`aorta. The at least one computer system may also be config(cid:173)
`ured to create a three-dimensional model representing the
`portion of the anatomical structure based on the patient-spe(cid:173)
`cific data, create a physics-based model relating to a blood
`flow characteristic within the portion of the anatomical struc(cid:173)
`ture, and determine a fractional flow reserve within the por(cid:173)
`tion of the anatomical structure based on the three-dimen(cid:173)
`sional model and the physics-based model.
`[0005] Additional Background Art Includes:
`[0006] U.S. Published Patent Application No. 2012/
`053918 of Taylor;
`[0007] U.S. Published Patent Application No. 2012/
`0072190 of Sharma eta!;
`[0008] U.S. Published Patent Application No. 2012/
`0053921 ofTaylor;
`[0009] U.S. Published Patent Application No. 2010/
`0220917 of Steinberg et a!;
`[0010] U.S. Published Patent Application No. 2010/
`0160764 of Steinberg eta!;
`[0011] U.S. Published Patent Application No. 2012/
`0072190 of Sharma eta!;
`[0012] U.S. Pat. No. 6,236,878 to Taylor eta!;
`[0013] U.S. Pat. No. 8,311,750 to Taylor;
`
`[0014]
`an article titled: "Determination of fractional flow
`reserve (FFR) based on scaling laws: a simulation study" by
`Jerry T. Wong and Sabee Molloi, published in Phys. Med.
`Bioi. 53 (2008) 3995-4011;
`[0015]
`an article titled: "A Scheme for Coherence-Enhanc(cid:173)
`ing Diffusion Filtering with Optimized Rotation Invariance",
`by Weickert, published in Journal ofVisual
`[0016] Communication and Image Representation; Volume
`13, Issues 1-2, March 2002, Pages 103-118 (2002);
`[0017]
`a thesis in a book titled "Anisotropic Diffusion in
`Image Processing", by J. Weickert, published by B. G. Teub(cid:173)
`ner (Stuttgart) in 1998;
`[0018]
`an article titled: "Multiscale vessel enhancement
`filtering", by A. F Frangi, W. J. Niessen, K. L. Vincken, M.A.
`Viergever, published in Medical Image Computing and Com(cid:173)
`puter-Assisted Intervention-MICCA '98;
`[0019]
`an article titled: "Determination of fractional flow
`reserve (FFR) based on scaling laws: a simulation study", by
`Jerry T Wong and Sabee Molloi, published in Phys. Med.
`Bioi. 53 (2008) 3995-4011;
`[0020]
`an article titled: "Quantification of Fractional Flow
`Reserve UsingAngiographic Image Data", by S. Molloi, J. T.
`Wong, D. A. Chalyan, and H. Le, published in 0. Dassel and
`W. C. Schlegel (Eds.): WC 2009, IFMBE Proceedings 25/II,
`pp. 901-904, 2009;
`[0021]
`an article titled: "Quantification of fractional flow
`reserve based on angiographic image data", by Jerry T. Wong,
`Huy Le, William M. Suh, David A. Chalyan, Toufan
`Mehraien, Morton J. Kern, Ghassan S. Kassab, and Sabee
`Molloi, published in Int J Cardiovasc Imaging (2012) 28:13-
`22;
`[0022]
`an article titled: "An angiographic technique for
`coronary fractional flow reserve measurement: in vivo vali(cid:173)
`dation", by Shigeho Takarada, Zhang Zhang and Sabee Mol(cid:173)
`loi, published online on 31 Aug. 2012 in Int J Cardiovasc
`Imaging;
`[0023]
`an article titled: "A new algorithm for deriving pul(cid:173)
`satile blood flow waveforms tested using stimulated dynamic
`angiographic data", by A. M. Seifalian, D. J. Hawkes, A. C.
`Colchester, and K. E. Hobbs, published in Neuroradiology,
`vol. 31, no. 3, pp. 263269, 1989;
`[0024]
`an article titled: "Validation of a quantitative radio(cid:173)
`graphic technique to estimate pulsatile blood flow waveforms
`using digital subtraction angiographic data", by A. M. Sei(cid:173)
`falian, D. J. Hawkes, C. R. Hardingham,A. C. Colchester, and
`J. F. Reidy, published in J. Biomed. Eng., vol. 13, no., 3 pp.
`225233, May 1991;
`[0025]
`an article titled: "Validation of volume blood flow
`measurements using three dimensional distance-concentra(cid:173)
`tion functions derived from digital X-ray angiograms", by D.
`J. Hawkes, A.M. Seifalian, A. C. Colchester, N. Iqbal, C. R.
`Hardingham, C. F. Bladin, and K. E. Hobbs, published in
`Invest. Radio!, vol. 29, no. 4, pp. 434442, April1994;
`[0026]
`an article titled: "Blood flow measurements using
`3D distance-concentration functions derived from digital
`X-ray angiograms", by A. M. Seifalian, D. J. Hawkes, C.
`Bladin, A. C. F. Colchester, and K. E. F. Hobbs, published in
`Cardiovascular Imaging, J. H. C. Reiber and E. E. van der
`Wall, Eds. Norwell, MA, The Netherlands: Kluwer Aca(cid:173)
`demic, 1996, pp. 425-442;
`[0027]
`an article titled: "Determination of instantaneous
`and average blood flow rates from digital angiograms of
`vessel phantoms using distance-density curves", by K. R.
`
`CATHWORKS EXHIBIT 1005
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`

`US 2014/0200867 AI
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`
`2
`
`Hoffmann, K. Doi, and L. E. Pencil, published in Invest.
`Radio!, vol. 26, no. 3, pp. 207212, March 1991;
`an article titled: "Comparison of methods for instan(cid:173)
`[0028]
`taneous angiographic blood flow measurement", by S. D.
`Shpilfoygel, R. Jahan, R.A. Close, G. R. Duckwiler, and D. J.
`Valentino, published in Med. Phys., vol. 26, no. 6, pp.
`862871, Jnne 1999;
`[0029]
`an article titled: "Quantitative angiographic blood
`flow measurement using pulsed intra-arterial injection", by
`D. W. Holdsworth, M. Drangova, and A. Fenster, published in
`Med. Phys., vol. 26, no. 10, pp. 21682175, October 1999;
`[0030]
`an article titled: "Dedicated bifurcation analysis:
`basic principles", by Joan C. Tuinenburg, Gerhard Koning,
`Andrei Rares, Johannes P. Janssen, Alexandra J. Lansky,
`Johan H. C. Reiber, published in Int J Cardiovasc Imaging
`(2011) 27:167174;
`an article titled: "Quantitative Coronary Angiogra(cid:173)
`[0031]
`phy in the Interventional Cardiology", by Salvatore Davide
`Tomasello, Luca Costanzo and Alfredo Ruggero Galassi,
`published in Advances in the Diagnosis of Coronary Athero(cid:173)
`sclerosis;
`an article titled: "New approaches for the assess(cid:173)
`[0032]
`ment of vessel sizes in quantitative (cardio-)vascular X-ray
`analysis", by Johannes P. Janssen, Andrei Rares, Joan C.
`Tuinenburg, Gerhard Koning, Alexandra J. Lansky, Johan H.
`C. Reiber, published in Int J Cardiovasc Imaging (2010)
`26:259271;
`[0033]
`an article titled: "Coronary obstructions, morphol(cid:173)
`ogy and physiologic significance Quantitative Coronary
`Arteriography" by Kirkeeide R L. ed. Reiber J H C and
`Serruys P W, published by The Netherlands: Kluwer, 1991,
`pp 229-44;
`[0034]
`an article titled: "Coronary x-ray angiographic
`reconstruction and image orientation", by Kevin Sprague,
`Maria Drangova, Glen Lehmann, Piotr Slomka, David Levin,
`Benjamin Chow and Robert deKemp, published in MedPhys,
`2006 March; 33(3):707-18;
`[0035]
`an article titled: "A New Method of Three-dimen(cid:173)
`sional Coronary Artery Reconstruction From X-Ray Angiog(cid:173)
`raphy: Validation Against a Virtual Phantom and
`[0036] Multislice Computed Tomography", by Adaman(cid:173)
`tios Andriotis, Ali Zifan, Manolis Gavaises, Panos Liatsis,
`Ioannis Pantos, Andreas Theodorakakos, Efstathios P. Efsta(cid:173)
`thopoulos, and Demosthenes Katritsis, published in Catheter
`Cardiovasc Interv, 2008, January 1; 71 (1 ):28-43;
`[0037]
`an article titled: "Noninvasive Measurement of
`Coronary Artery Blood Flow Using Combined Two-Dimen(cid:173)
`sional and Doppler Echocardiography", by Kenji Fusejima,
`MD, published in JACC Vol. 10, No. 5, November 1987:
`1024-31;
`an article titled: "New Noninvasive Method for
`[0038]
`Coronary Flow Reserve Assessment: Contrast-Enhanced
`Transthoracic Second Harmonic Echo Doppler", by Carlo
`Caiati, Cristiana Montaldo, Norma Zedda, Alessandro Bina
`and Sabino Iliceto, published in Circulation, by the American
`HeartAssociation, 1999; 99:771-778;
`an article titled: "Validation of noninvasive assess(cid:173)
`[0039]
`ment of coronary flow velocity reserve in the right coronary
`artery-A comparison of transthoracic echocardiographic
`results with intracoronary Doppler flow wire measurements",
`by Harald Lethena, Hans P Triesa, Stefan Kersting a and
`Heinz Lambertza, published in European Heart Journal
`(2003) 24, 1567-1575;
`
`an article titled: "Coronary flow: a new asset for the
`[0040]
`echo lab?" by Paolo Vocia, Francesco Pizzuto a and Francesco
`Romeob, published in European Heart Journal (2004) 25,
`1867-1879;
`[0041]
`a review paper titled: "Non-invasive assessment of
`coronary flow and coronary flow reserve by transthoracic
`Doppler echocardiography: a magic tool for the real world",
`by Patrick Meimoun and Christophe Tribouilloy, published in
`European Journal of Echocardiography (2008) 9, 449-457;
`and
`[0042]
`an article titled: "Detection, location, and severity
`assessment of left anterior descending coronary artery
`stenoses by means of contrast-enhanced transthoracic har(cid:173)
`monic echo Doppler", by Carlo Caiati, Norma Zedda, Mauro
`Cadeddu, Lijnn Chen, Cristiana Montaldo, Sabino Iliceto,
`Mario Erminia Lepera and Stefano Favale, published in Euro(cid:173)
`pean Heart Journal (2009) 30, 1797-1806.
`[0043] The disclosures of all references mentioned above
`and throughout the present specification, as well as the dis(cid:173)
`closures of all references mentioned in those references, are
`hereby incorporated herein by reference.
`
`SUMMARY OF THE INVENTION
`
`In some embodiments of the invention, one or more
`[0044]
`models of a patient's vascular system are produced.
`In some embodiments, a first model is produced
`[0045]
`from actual data collected from images of the patient's vas(cid:173)
`cular system. Optionally, the actual data includes a portion of
`the vascular system which includes at least one blood vessel
`with stenosis. In these embodiments, the first model describes
`a portion of the vasculature system which includes at least one
`blood vessel with stenosis. This model is interchangeably
`referred to as a stenotic model. Optionally, the actual data
`includes a portion of the vascular system which includes at
`least one blood vessel with stenosis and a crown. In these
`embodiments the stenotic model also includes information
`pertaining to the shape and/or volume of the crown, and
`information pertaining to blood flow and/or resistance to
`blood flow in the crown.
`In some embodiments the first model is used for
`[0046]
`calculating an index indicative of vascular function. Prefer(cid:173)
`ably, the index is also indicative of potential effect of revas(cid:173)
`cularization. For example, the index can be calculated based
`on a volume of a crown in the model and on a contribution of
`a stenosed vessel to the resistance to blood flow in the crown.
`In some embodiments of the present invention a
`[0047]
`second model is produced from the actual data, changed so
`that one or more stenoses present in the patient's vascular
`system are modeled as if they had been revascularized.
`In some embodiments the first model and the second
`[0048]
`model are compared, and the index indicative of the potential
`effect of revascularization is produced, based on comparing
`physical characteristics in the first model and in the second
`model.
`[0049]
`In some embodiments the index is a Fractional Flow
`Reserve (FFR), as known in the art.
`[0050]
`In some embodiments the index is some other mea(cid:173)
`sure which potentially correlates to efficacy of performing
`revascularization of one or more vessels, optionally at loca(cid:173)
`tions of stenosis.
`[0051] According to an aspect of some embodiments of the
`present invention there is provided a method for vascular
`assessment. The method comprises, receiving a plurality of
`2D angiographic images of a portion of a vasculature of a
`
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`3
`
`subject; and using a computer for processing the images and
`producing, within less than 60 minutes, a first vessel tree over
`a portion of the vasculature.
`[0052] According to some embodiments of the invention
`the vasculature has therein at least a catheter other than an
`angiographic catheter, and wherein the images are processed
`and the tree is produced while the catheter is in the vascula(cid:173)
`ture.
`[0053] According to some embodiments of the invention
`the method comprises using the vascular model for calculat(cid:173)
`ing an index indicative of vascular function.
`[0054] According to some embodiments of the invention
`the index is indicative of the need for revascularization.
`[0055] According to some embodiments of the invention
`the calculation is within less than 60 minutes.
`[0056] According to an aspect of some embodiments of the
`present invention there is provided a method of analyzing
`angiographic images. The method comprises: receiving a
`plurality of 2D angiographic images of a portion vasculature
`of a subject; and using a computer for processing the images
`to produce a tree model of the vasculature.
`[0057] According to an aspect of some embodiments of the
`present invention there is provided a method of treating a
`vasculature. The method comprises: capturing a plurality of
`2D angiographic images of a vascular system of a subject
`being immobilized on a treatment surface; and, while the
`subject remains immobilized: processing the images and pro(cid:173)
`ducing a vessel tree over the vascular system; identifying a
`constricted blood vessel in the tree; and inflating a stent at a
`site of the vasculature corresponding to the constricted blood
`vessel in the tree.
`[0058] According to some embodiments of the invention
`the plurality of 2D angiographic images comprise at least
`three 2D angiographic images, wherein the tree model is a 3D
`tree model.
`[0059] According to some embodiments of the invention
`the method comprises identifYing in the first vessel tree a
`stenosed vessel and a crown of the stenosed vessel, and cal(cid:173)
`culating a resistance to fluid flow in the crown; wherein the
`index is calculated based on a volume of the crown, and on a
`contribution of the stenosed vessel to the resistance to fluid
`flow.
`[0060] According to some embodiments of the invention
`the vessel tree comprises data pertaining to location, orienta(cid:173)
`tion and diameter of vessels at a plurality of points within the
`portion of the vasculature.
`[0061] According to some embodiments of the invention
`the method comprises processing the images to produce a
`second three-dimensional vessel tree over the vasculature, the
`second vessel tree corresponding to the first vessel tree in
`which a stenotic vessel is replaced with an inflated vessel;
`wherein the calculation of the index is based on the first tree
`and the second tree.
`[0062] According to some embodiments of the invention
`the method comprises processing the images to produce a
`second three-dimensional vessel tree over the vasculature, the
`second vessel tree corresponding to a portion of the vascular
`system which does not include a stenosis and which is geo(cid:173)
`metrically similar to the first vessel tree; wherein the calcu(cid:173)
`lation of the index is based on the first tree and the second tree.
`[0063] According to some embodiments of the invention
`the method comprises obtaining a Fractional Flow Ratio
`(FFR) based on the index.
`
`[0064] According to some embodiments of the invention
`the method comprises determining, based on the index, a ratio
`between maximal blood flow in an area of a stenosis and a
`maximal blood flow in a same area without stenosis.
`[0065] According to some embodiments of the invention
`the method comprises minimally invasively treating a
`stenosed vessel.
`[0066] According to some embodiments of the invention
`the treatment is executed less than one hour from the calcu(cid:173)
`lation of the index.
`[0067] According to some embodiments of the invention
`the method comprises storing the tree in a computer readable
`medium.
`[0068] According to some embodiments of the invention
`the method comprises transmitting the tree to a remote com(cid:173)
`puter.
`[0069] According to some embodiments of the invention
`the invention the method comprises capturing the 2D angio(cid:173)
`graphic images.
`[0070] According to some embodiments of the invention
`the capturing the plurality of 2D angiographic images is
`effected by a plurality of imaging devices to capture the
`plurality of 2D angiographic images.
`[0071] According to some embodiments of the invention
`the capturing the plurality of 2D angiographic images com(cid:173)
`prises synchronizing the plurality of imaging devices to cap(cid:173)
`ture the plurality of images substantially at a same phase
`during a heart beat cycle.
`[0072] According to some embodiments of the invention
`the synchronizing is according to the subject's ECG signal.
`[0073] According to some embodiments of the invention
`the method comprises: detecting corresponding image fea(cid:173)
`tures in each ofN angiographic images, where N is an integer
`greater than 1; calculating image correction parameters based
`on the corresponding image features; and based on the cor(cid:173)
`rection parameters, registering N-1 angiographic images to
`geometrically correspond to an angiographic image other
`than the N-1 angiographic images.
`[0074] According to some embodiments of the invention
`the method comprises defining a surface corresponding to a
`shape of the heart of the subject, and using the surface as a
`constraint for the detection of the corresponding image fea(cid:173)
`tures.
`[0075] According to some embodiments of the invention
`the method comprises compensating for breath and patient
`movement.
`[0076] According to an aspect of some embodiments of the
`present invention there is provided a computer software prod(cid:173)
`uct. The computer software product comprises a computer(cid:173)
`readable medium in which program instructions are stored,
`which instructions, when read by a computer, cause the com(cid:173)
`puter to receive a plurality of 2D angiographic images of a
`subject's vascular system and execute the method as delin(cid:173)
`eated above and optionally as further detailed below.
`[0077] According to an aspect of some embodiments of the
`present invention there is provided a system for vascular
`assessment. The system comprises: a plurality of imaging
`devices configured for capturing a plurality of 2D angio(cid:173)
`graphic images of a vascular system of a subject; and a com(cid:173)
`puter configured for receiving the plurality of 2D images and
`executing the method the method as delineated above and
`optionally as further detailed below.
`[0078] According to an aspect of some embodiments of the
`present invention there is provided a system for vascular
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`US 2014/0200867 AI
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`Jul. 17, 2014
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`4
`
`assessment comprising: a computer functionally connected
`to a plurality of angiographic imaging devices for capturing a
`plurality of2D images of a portion of vasculature of a subject,
`configured to: accept data from the plurality of angiographic
`imaging devices; and process the images to produce a tree
`model of the vasculature, wherein the tree model comprises
`geometric measurements of the vasculature at one or more
`locations along a vessel of at least one branch of the vascu(cid:173)
`lature.
`[0079] According to some embodiments of the invention
`the system comprises a synchronization unit configured to
`provide the plurality of angiographic imaging devices with a
`synchronization signal for synchronizing the capturing of the
`plurality of 2D images of the vasculature.
`[0080] According to some embodiments of the invention
`the computer is configured to accept a subject ECG signal,
`and to select, based on the ECG signal, 2D images corre(cid:173)
`sponding to substantially a same phase during a heart beat
`cycle.
`[0081] According to some embodiments of the invention
`the system comprises an image registration unit configured
`for: detecting corresponding image features in each of N
`angiographic images, where N is an integer greater than 1;
`calculating image correction parameters based on the corre(cid:173)
`sponding image features; and based on the correction param(cid:173)
`eters, registering N-1 angiographic images to geometrically
`correspond to an angiographic image other than the N-1
`angiographic images.
`[0082] According to some embodiments of the invention
`the computer is configured for defining a surface correspond(cid:173)
`ing to a shape of the heart of the subject, and using the surface
`as a constraint for the detection of the corresponding image
`features.
`[0083] According to some embodiments of the invention
`the computer is configured for compensating for breath and
`patient movement.
`[0084] According to some embodiments of the invention
`the compensating comprises iteratively repeating the detec(cid:173)
`tion of the corresponding image features each time for a
`different subset of angiographic images, and updating the
`image correction parameters responsively to the repeated
`detection of the corresponding image features.
`[0085] According to some embodiments of the invention N
`is greater than 2. According to some embodiments of the
`invention N is greater than 3.
`[0086] According to some embodiments of the invention
`the corresponding image features comprise at least one of a
`group consisting of an origin of the tree model, a location of
`minimal radius in a stenosed vessel, and a bifurcation of a
`vessel.
`[0087] According to some embodiments of the invention
`the tree model comprises data pertaining to location, orienta(cid:173)
`tion and diameter of vessels at a plurality of points within the
`portion of the vasculature.
`[0088] According to some embodiments of the invention
`tree model comprising measurements of the vasculature at
`one or more locations along at least one branch of the vascu(cid:173)
`lature
`[0089] According to some embodiments of the invention
`the geometric measurements of the vasculature are at one or
`more locations along a centerline of at least one branch of the
`vasculature.
`
`[0090] According to some embodiments of the invention
`the tree model comprises data pertaining to blood flow char(cid:173)
`acteristics in at one or more of the plurality of points.
`[0091] According to some embodiments of the invention
`the portion of the vasculature comprises the heart arteries.
`[0092] According to an aspect of some embodiments of the
`present invention there is provided a method for vascular
`assessment comprising: receiving a plurality of 2D angio(cid:173)
`graphic images of a portion of a vasculature of a subject, and
`processing the images to produce a stenotic model over the
`vasculature, the stenotic model having measurements of the
`vasculature at one or more locations along vessels of the
`vasculature; obtaining a flow characteristic of the stenotic
`model; and calculating an index indicative of vascular func(cid:173)
`tion, based, at least in part, on the flow characteristic in the
`stenotic model.
`[0093] According to some embodiments of the invention
`the flow characteristic of the stenotic model comprises resis(cid:173)
`tance to fluid flow.
`[0094] According to some embodiments of the invention
`the invention the method comprises identifying in the first
`stenotic model a stenosed vessel and a crown of the stenosed
`vessel, and calculating the resistance to fluid flow in the
`crown; wherein the index is calculated based on a volume of
`the crown, and on a contribution of the stenosed vessel to the
`resistance to fluid flow.
`[0095] According to some embodiments of the invention
`the flow characteristic of the stenotic model comprises fluid
`flow.
`[0096] According to some embodiments of the invention
`the stenotic model is a three-dimensional vessel tree.
`[0097] According to some embodiments of the invention
`the vessel tree comprises data pertaining to location, orienta(cid:173)
`tion and diameter of vessels at a plurality of points within the
`portion of the vasculature.
`[0098] According to some embodiments of the invention
`the processing comprises: extending the stenotic model by
`one bifurcation; calculating a new flow characteristic in the
`extended stenotic model; updating the index responsively to
`the new flow characteristic and according to a predetermined
`criterion; and iteratively repeating the extending, the calcu(cid:173)
`lating and the updating.
`[0099] According to some embodiments of the invention
`the method comprises processing the images to produce a
`second model over the vasculature, and obtaining a flow
`characteristic of the second model; wherein the calculation of
`the index is based on the flow characteristic in the stenotic
`model and on the flow characteristic in the second model.
`[0100] According to some embodiments of the invention
`the method the second model is a normal