IT202000010357A1 - EQUIPMENT FOR OPTICAL PHASE COHERENCE TOMOGRAPHY - Google Patents

Description

Description of the industrial invention entitled ?APPARATUS FOR PHASE COHERENCE OPTICAL TOMOGRAPHY?

DESCRIPTION

Scope of the invention

The present invention relates to an improved optical coherence tomography (OCT) apparatus, in particular, for diagnostic procedures involving a patient's tissue such as the wall of a biological lumen of a patient's body, for example applications intravascular (IV-OCT).

Prior art and technical problems

[0002] Optical coherence tomography ? a non-invasive, non-contact imaging technique that uses light to acquire cross-sectional and three-dimensional images from within biological tissue. Initially, OCT was mainly used to study the human retina and in some intra-vascular applications and, more recently, also in dermatology, gastroenterology and urology.

[0003] In OCT, the light waves emitted by a broadband light source are divided into a reference beam and a sample beam. The latter ? directed within the tissue and back-diffused by internal microstructured tissues. The backscattered light is made to interfere with the reference beam and the interference pattern obtained is used to measure the light echoes against the depth profile. of the fabric.

[0004] The most important improvements important features offered by OCT compared to imaging methods such as X-ray computed tomography, magnetic resonance and ultrasound-based techniques, concern the axial resolution, ie? the resolution ?A?, mainly thanks to the use of the optical frequency domain. At the moment, ? It is possible to easily obtain micrometric axial resolutions up to about 10-20 ?m.

[0005] As regards the IV-OCT, this ? has become one of the techniques pi? of coronary artery imaging, for studying atherosclerotic plaques, and for guiding semi-invasive interventional percutaneous coronary intervention procedures such as angioplasty and stenting.

[0006] As shown in Figure 1A , during these procedures, an OCT imaging wire or cable 40 is introduced and advanced from a vascular entry site 3 to a target region 21 of a portion of interest 8 of a vessel Blood 1 as an artery provided or without a synthetic graft, over a conventional angioplasty guidewire, not shown. In this way, a light beam 11 generated by a source 10 of light rays can reach the target region 21 through the cable 40 and a submillimeter probe 60 disposed at one end? distal of cord 40.

[0007] To obtain a certain axial resolution (resolution through the tissue), is a normally continuous scan performed 9? of the wavelength of light, which can? be represented schematically as a succession of light rays R having respective wavelengths ?k, k = 1 ? R, variable within a predetermined interval ? of wavelengths, which are sent to a target sector 2j,l forming the target region 2l, as shown in figure 1B, during a time T? scan in? wavelength, see also figure 1C, thus obtaining? an axial line 97j,l of the target sector 2j,l.

[0008] Furthermore, to obtain a 2D display, that is? an image 98l of a cross section of the target region 2l, a radial scan is performed 9? on 360? (scan B) of the surrounding arterial wall, through mechanically rotatable deflection means of probe 60, not shown. In other words, the scan in wavelength 9? is it repeated for each of the M target sectors 2j,l j = 1 ? M and the axial lines 97j,l j = 1 ? M are used to reconstruct the 2D image 98l of the cross section. Thus, the time required to obtain the cross-sectional image 98l of the target region 2l ? at least M<.>T?. As described more? in detail below, in the current state of the art, the maximum speed? of radial scan 9? allowed by the means of deflection currently in use? much lower than the speed? of the wavelength scan 9? permitted by currently available light ray sources 10 .

[0009] Finally, a backward 9z translation of the probe, usually concomitant, is also performed along the portion of interest 8, so as to generate a set of 3D volumetric data which includes complete microstructural information of the artery wall or of the graft synthetic 1. In other words, radial scan 9? is repeated for each of the axial positions S, i.e. for each of the target regions 2l l = 1 ? S, and the cross sections 2D 98l l = 1 ? S are merged to form a 3D image 99 of the portion of interest 8.

[0010] In this regard, significant improvements in sensitivity have been possible, up to sensitivity values? higher than 120 dB, using high performance Fourier domain techniques (FD-OCT) based on a wavelength scanning source (SS-OCT). In this case, the continuous wave source periodically performs a scan in the frequency range of interest, normally of the amplitude of 100 nm, with a speed? at least two orders of magnitude higher than the radial scan.

[0011] However, despite the improvements summarized above, currently available OCT equipment still exhibits some important performance limitations.

[0012] A first problem? the limited depth? of axial penetration, that is to say a low capacity? of penetration through the tissue under examination, normally not exceeding about 1.5 mm, mainly due to the strong backscattering of light and the high absorption coefficients inside the tissues and blood. In particular, the poor axial penetration ? particularly disadvantageous when observing a blood vessel that is been significantly remodeled due to plaque accumulation. In this case, the outline of the real lumen disappears on the OCT image and the initial examiner must mentally join the dots to define the extent of the plaque.

[0013] Further drawbacks are due to the use of moving mechanical components to perform the radial scan 9?. In particular, rotating mirrors are normally used as means of deflection of the rays, which allow a speed? at most of a few hundred Hz, or motorized translators.

[0014] First, the speed? scan can not? exceed the value that can? be achieved using mechanical components, and what? constitutes a limitation, in particular, when observing rapidly moving tissue. Are known scanning systems pi? based on MEMS, galvanometric mirrors or piezoelectric actuators, but even these solutions include mechanical parts, as well as power supply means positioned close to the scanning region, which, due to their size, cannot be contained in the generally used submillimeter endoscopes in a medical context.

[0015] Secondly, the vibrations induced by the moving components limit the available signal-to-noise ratio (SNR), and therefore lead to reliability? and a sensitivity? relatively scarce.

[0016] Thirdly, isn't it? easy to insert mechanically revolving components in a device so? small which one? an intravascular probe.

[0017] Sensitivity too? achieved by SS-OCT systems has some drawbacks in the case of specific IV-OCT applications, since? helps to limit the depth? of maximum penetration to no more? of 1.5mm.

Summary of the invention

[0018] ? therefore an object of the present invention is to provide an OCT apparatus, in particular, for intravascular applications, which has a depth? of superior axial penetration compared to that of the OCT technology currently available.

[0019] ? Another object of the invention is to provide an OCT apparatus, typically an IV-OCT apparatus, in which no moving parts are employed to perform a 360? of a light beam to direct it against the inner wall of a biological lumen such as a blood vessel, so as to overcome the limitations, described above, due to mechanically rotating components.

[0020] ? It is a particular object of the invention to provide an FD-OCT apparatus comprising a continuous wave with wavelength scanning (SS-OCT) source.

[0021] These and other objects are achieved by an apparatus according to the independent claims n. 1 and 4. Exemplary embodiments and variants of the apparatus are defined by the dependent claims.

[0022] A diagnostic apparatus for performing an optical coherence tomography of a target region of a patient's body tissue comprises:

- a source of light rays configured to emit a light beam;

- an optical cable having one end? proximal in communication with the source of light rays to receive the light beam from it, and an extremity? distal arranged to be introduced into the target region;

- a beam orientation device configured for:

- orient the light beam according to a plurality? of rotation angles of the beams with respect to an angular reference position integral with the optical cable, in a predetermined radial scanning time, so as to obtain a plurality? of respective oriented light rays, and directing the sequentially oriented light rays, in said radial scan time, towards a plurality? of respective target sectors of the target region;

- collect backscattered light from the target sectors in response to directed light rays,

- a photodetector arranged to receive the backscattered light from the beam steerer, and configured to interferometrically compare the backscattered light with the light beam and to generate therefrom an interferometric signal;

- acquisition and processing means configured to receive the interferometric signal, to form therefrom axial profiles of the target region and to join said axial profiles forming a cross-sectional image of the tissue of the patient's body.

[0023] The tissue of the body can be, for example, the tissue of a wall of a body lumen such as a hollow organ of a human or animal body, or a blood vessel, in which case an IV-OCT apparatus is provided. In the latter case, the apparatus? also configured to perform a translational movement along an axis of the lumen, for example a backward translational movement along the interior of the lumen, and the acquisition and processing means are configured to combine a plurality of of cross-sectional images, to form a 3D image of a portion of interest of the patient's body lumen.

[0024] In one aspect of the invention,

- the optical cable comprises a beam of optical guide elements having a beam axis;

- the beam orientation device includes:

- a phase shifter device configured to - generate, at each instant of said radial scan time, a plurality? of sample light rays phased from the light beam, the phased sample light rays having respective phase shifts with respect to a reference phase of the light beam, said phase shifts forming an instantaneous combination of phase shifts, and for

- modifying said instantaneous combination of phase shifts during said radial scan time, said instantaneous combination of phase shifts being disposed in such a way that at the end? distal of the cable, an instantaneous resultant ray is formed as a combination of said phase-shifted sample light rays, said instantaneous resultant ray having a lobe of intensity? principal oriented in an instantaneous direction with respect to the beam axis;

- a fixed beam deflection device at the tip? distal, the ray deflection device having a ray deflection surface arranged to: - at any instant of said radial scan time, receive the corresponding instantaneous resultant light ray with its intensity lobe principal in a respective position on s?; And

- deflecting the resulting instantaneous light beam according to a respective angle of rotation of the rays with respect to an angular reference position integral with the optical cable, so as to form, in said radial scanning time, the oriented light rays; such that the oriented light rays are directed towards the target sectors of the target region according to the angles of rotation of the rays in said radial scan time, and the backscattered light is collected at the far end. distal in the form of backscattered light beams from the respective target sectors in response to the respective directed light beams.

[0025] In this way, an OCT apparatus is provided in which a high-speed light beam orientation system (OBS) is used to implement the radial scan. devoid of mechanical parts, in other words, the radial scan is performed without using moving components, and what? it has some important advantages over currently available optical coherence tomography systems, as described below.

[0026] In the first place, the speed? scan can? be increased up to values that largely exceed the upper speed limit? of the OCT systems of the known type, which use mechanically revolving parts such as revolving mirrors, or piezoelectric actuators. In particular, the speed radial scan can? be increased by several orders of magnitude and you can easily reach values of speed? scanning tens of MHz.

[0027] ? therefore possible an imaging more? efficient, in particular, in the case of rapidly evolving phenomena. For example, the high speed? of scanning allows new applications such as the monitoring of the elasticity? of the walls of the coronary arteries during the heartbeat, and what? it constitutes a fundamental advance to verify the correct positioning of the coronary stents after their application.

[0028] Secondly, no vibrations are associated with the operation of the light beam orientation system proposed by the invention, and this? increases the available signal-to-noise ratio thus improving the reliability? and the sensitivity? up to performance levels impossible to achieve with known OCT systems.

[0029] Thirdly, the higher speed? of scanning limits the effect of tissue movements, therefore leading to a greater accuracy of the final image.

[0030] Fourthly, the light beam orientation device ? more simple to build, and is less likely to to fail compared to traditional mechanically operated beam steering devices, which include very small moving parts. Therefore, maintenance costs and, ultimately, investment costs can be drastically reduced.

[0031] In this way, the radial scan becomes the scan more? between wavelength scan, radial scan and backward translation scan. Therefore, the speed with which the 2D cross sections are generated? limited by the scanning frequency in? wavelength instead? from the radial scan, and there? does it involve a speed? generation of cross-sections never before achieved.

[0032] In another aspect of the invention, the source of light rays configured to emit a Gaussian light beam, and ? provided an orbital angular momentum mode generator configured to transform the light beam into a mode light beam? whirling having a helical wave front, such that the oriented light rays are also oriented light rays of light in a helical mode. whirling, and the beam deflector is configured to deflect the light beams swirling in their respective oriented light rays which are also rays of light in mode? swirling.

[0033] In this way, using the vortex modes of orbital angular momentum of light, the depth? of maximum penetration of the OCT apparatus pu? be increased to outperform OCT systems using conventional Gaussian beams by 40%. In an OCT apparatus according to the invention, axial penetration values of up to 2.1 mm are therefore possible. There? ? particularly important in SS-OCT systems which, among the various alternatives, offer maximum sensitivity? for IV applications.

[0034] As known, a ray of light can propagate in mode? swirling, what? in such a way that its wavefront is not a plane figure, as in the case of a conventional Gaussian beam, but has the shape of a single or multiple helix. Wang, W.B. et al., Complex Light and Optical Forces X, 976410 (2016); Optics letters 41, no. 9 (2016), pages 2069-2072, as well as? Cochenour et al., Applied optics 55, no. 31 (2016): C34-C38 reveal that light with a certain orbital angular momentum (OAM) ? less inclined to be scattered with respect to the Gaussian rays, and that the transmission of whirling rays in the turbid media increases as the order (L) of the OAM increases, and this? does it increase the depth? of maximum penetration. As shown by C. Brunet and L.A. Rusch, Opt. Techn. fibers 35, 2-7 (2017), the modes that support OAM can propagate, as linear combinations of modes proper to the medium, in multimode optical fibers (MMF), which substantially have a core that promotes the separation between the OAM modes and therefore the their stability? during propagation.

[0035] The optical cable, and any optical guide elements contained therein, may consist of standard multimode optical fibers (MMF), which have been shown to support OAM modes. In particular, modes supporting OAM modes can propagate along multimode optical fibers as linear combinations of the medium's natural modes. Alternatively, ? Is it possible to use special multimode optical fibers pi? such as high refractive index ring vortex fibers, multi-OAM multi-ring fibers, photonic crystal fibers, supermode OAM fibers, graded-index refractive index fibers with inverse parabolic OAM modes to reach propagation distances of the order of km with remarkable stability. Basically, all of these fiber schemes have a core that promotes separation between OAM modes and thus promotes their stability. during propagation. In particular, the step MMF limits its degeneracy, showing a better isolation of the families of modes with the same orbital angular momentum values.

[0036] Alternatively, ? provided an orbital angular momentum mode generator configured to transform the Gaussian light beam into a light mode beam? swirling having a helical wave front, and the phase shifter device ? configured to generate sequentially from the light beam in mode? swirling plurality? of phase-shifted sample light rays as phase-shifted sample light rays of light in mode? swirling.

The combination of the features of the two aspects of the invention, namely the use of OAM light beams and a high speed light beam steering system (OBS) is devoid of mechanical components, leads to performances never reached by the prior art as regards both the speed? scan, both the depth? of axial penetration, and accuracy.

[0038] Preferably, the beam deflection device comprises a conical mirror arranged at the end of the beam. distal coaxially to the bundle of optical guide elements, the conical mirror having a vertex angle whose amplitude is ? choice based on the angle ? formed between the direction of the instantaneous resultant light beam and the beam axis. Preferably, the amplitude of the vertex angle ? determined by the relationship:

? = ?/2+ ?/4.

In this way, the instantaneous resultant beam hits the conical mirror on a plurality of angles. of points forming a circular trajectory, which is covered with a period equal to said radial scan time. Thus, the backscattered light rays follow the same optical paths as the respective oriented light rays in response to which the backscattered light rays are emitted at the target sectors, in the opposite direction from the target sectors at the extreme. distal.

[0039] In particular, the phase shifter device comprises:

- an optical power splitter device configured to split the light beam into a plurality? of his replies;

- an array of phase shifter modules comprising a plurality? of optical phase shifter modules, the cio? phase modulators, each arranged to receive a respective replica of said replicas, and configured to transform the replica into a phase-shifted light beam of said phase-shifted light beams.

[0040] Advantageously, the phase shifter device comprises an integrated photonic circuit comprising, as optical phase shifter modules, integrated doped optical guide elements, the doped optical guide elements being configured to receive a voltage in such a way as to modify its own refractive index accordingly. The reliability? of the apparatus is thus strengthened, thanks to the excellent stability? of the optical phase guaranteed by the photon integration.

[0041] Preferably, ? provided is a coupling device arranged to direct the phase-shifted light rays into predetermined respective optical beam guide elements, wherein the coupling device is chosen between:

- a plurality? of couplers to the grid that connect with a modality? efficiently coupling the light beam directing device with each of the optical guide elements;

- a plurality? of edge emitters with a conical profile, in order to implement a modality? of efficient coupling from each phase-shifted sample light beam provided by the light beam steering device, and the mode? supported by each of the optical guide elements.

[0042] Advantageously, the integrated optical guide elements are implemented as fast doped p-n junctions. There? allows, together with the advantages due to the absence of mechanical vibrations, to increase the speed? scans of several orders of magnitude. In particular, the p-n junction pu? operate with reverse bias. In this case, the solution can? allow an increase in speed? up to the order of GHz.

[0043] However, the coupling device can include an ad hoc photon pair of any type, provided it is configured to properly convert the mode? that propagates in the waveguide integrated in the modality? supported by the optical guide elements.

[0044] Alternatively, each of said optical phase shifter modules can including a doped optical guide portion of a respective optical guide element, the doped optical guide portion being configured to receive a voltage and to change its refractive index accordingly. In other words, in the extremity? of the catheter ? including an optical phased array, whose emitters are the extremities? of the beam guide elements. In this case, to perform radial scanning without using moving parts, the apparatus includes a light beam orientation function based on an optical phased array.

[0045] As known, a phased array ? an array of electronically phased scanned antennas to create an RF beam that can be steered electronically in different directions without moving the antennas. Optical phased arrays have also been developed in recent decades for applications such as optical sensing and high-power lasers. The use of integrated waveguide grid couplers and a 2-D array of liquid crystal phase shifter elements has greatly reduced the step between the phase shifters. Pi? Recently, sophisticated CMOS-compatible nanotechnological solutions have made it possible to create a very large number of emitters with high density? space. However, for applications such as IV-OCT, where a sub-millimeter thick probe needs to deliver/collect light to the very tip, / from the end? of the catheter along the blood vessels for about 2 meters, could it be more? convenient to use fibers or fiber bundles as phased array emitters.

[0046] In a preferred embodiment, the diagnostic apparatus is an SS-OCT apparatus, that is? an apparatus in which the source of light rays is a continuous wave source with wavelength scanning.

[0047] The typical speed? to scan a CW-SS ? included in the range 20-50 KHz, while the speed? scan rate of a typical rotating mirror ? a few hundred Hertz. Therefore, traditional IV-OCT solutions based on a moving mirror are faster than ever. of radial scanning of the order of hundreds of Hertz. On the contrary, in the present invention the speed? radial scan can? reach values between 10 and 25 MHz, which can be obtained if the phase shifters are based on doped p-n junctions. In this way, as in most commercial devices, the system will collect hundreds of axis lines per cross section, but at a speed? which, unlike conventional devices, is speed controlled scan CW-SS instead? from the speed? radial scan, therefore ? is it possible to reach a speed? radial scanning in the order of tens of KHz.

[0048] Advantageously, the optical cable includes a fiber having a refractive index profile configured to allow the propagation of modes with orbital angular momentum. To this end, in particular, the fiber ? choice between:

- a multi-OAM-mode multi-ring fiber;

- a photonic crystal fiber;

- a supermode OAM fiber;

- an air-core fiber;

- a graded-index type fiber with refractive index with inverse parabolic trend.

Brief description of the drawings

[0049] Will the invention come now shown with the following description of its particular embodiments, exemplifying but not limiting, with reference to the attached drawings in which:

? Figures 1A and 1B schematically show a conventional IV-OCT apparatus;

? figure 1C ? a flow chart showing how data is processed in a conventional IV-OCT apparatus to produce a 3D OCT image of a portion of a blood vessel of interest;

? figure 2A ? is a block diagram of an IV-OCT apparatus according to an aspect of the invention, in which a high-speed OBS system is used to implement radial scanning. free of mechanical components, wherein a beam directing device comprises a phase shifter device and a beam deflection device;

? figure 2B ? a schematic cross-sectional view of a beam deflecting device of the apparatus of FIG. 2A and a patient's lumen within which ? positioned the beam deflection device;

? figure 2C ? a block diagram showing how data is processed in the IV-OCT apparatus of Figures 2A and 2B to obtain an OCT image of a portion of a blood vessel of interest;

? the 2D figure ? a flow diagram of the acquisition and processing means of the apparatus of figure 2A;

? figure 3A ? a block diagram of an IV-OCT apparatus according to another aspect of the invention, in which ? Is there an orbital angular momentum mode generator to transform a light beam into a mode light beam? swirling;

? figure 3B ? a schematic cross-sectional view of a beam deflecting device of the apparatus of FIG. 3A and a patient's lumen within which ? positioned the beam deflection device.

? figure 4A ? a block diagram of an IV-OCT apparatus, including features of both aspects of figures 2 and 3, in which the orbital angular momentum mode generator ? disposed downstream of the phase shifter device, to treat a plurality? of Gaussian light rays with phase difference with respect to each other;

? Figure 4B illustrates the characteristics of the apparatus of figure 4A corresponding to the characteristics shown in figure 2B, for the apparatus of figure 2.

? figure 5A ? a block diagram of an IV-OCT apparatus including features of both aspects of figures 2 and 3, in which the orbital angular momentum mode generator ? arranged upstream of the phase shifting device, for treating a Gaussian light beam emitted by a light ray source;

? Figure 5B illustrates the characteristics of the apparatus of Figure 5A corresponding to the characteristics shown in Figure 2B, respectively, for the apparatus of Figure 2A.

? figure 6A ? a block diagram of an IV-OCT apparatus comprising the characteristics of the apparatus of figure 2, in which the beam deflection device comprises a conical mirror;

? Figure 6B illustrates the characteristics of the apparatus of Figure 6A corresponding to the characteristics shown in Figure 2B, respectively, for the apparatus of Figure 2A.

? figure 7A ? a block diagram of an IV-OCT apparatus having the characteristics of the apparatus of figure 2, wherein the phase shifter device comprises, among other things, an array of phase shifter modules, wherein the phase shifter device ? implemented by an integrated photonic circuit used to control beam orientation;

? Figures 7B illustrate the characteristics of the apparatus of Figure 7A corresponding to the characteristics shown in Figure 2B, respectively, for the apparatus of Figure 2A;

? figure 8A ? a block diagram of an IV-OCT apparatus having the characteristics of the apparatus of Figure 2, wherein the phase shifter device comprises among other things an array of phase shifter modules, wherein the phase shifter device also includes a plurality? of grid couplers each comprising an end micro-lens for collimating the respective phase-shifted light beams;

? Figure 8B illustrates the characteristics of the apparatus of Figure 8A corresponding to the characteristics shown in Figures 2B, respectively, for the apparatus of Figure 2A;

? figure 9A ? a block diagram of an embodiment of an apparatus as in Fig. 8A , further including an orbital angular momentum mode generator.

? Figure 9B illustrates the characteristics of the apparatus of Figure 8A corresponding to the characteristics shown in Figure 2B, respectively, for the apparatus of Figure 2A.

Detailed description of the invention

[0050] With reference to figures 2A to 3B, the apparatuses 102 and 103 for optical coherence tomography (OCT) are described, according to distinct aspects of the invention.

[0051] The OCT apparatuses 102 and 103 comprise a source 10 of light beams configured to emit a main light beam 11. Preferably, ? a splitting device 21 is provided for splitting the main light beam 11 into a sample light beam 12 and a reference light beam 18, to be used for the coherent detection of the OCT signal, as described below.

[0052] In the description, it will be done? reference to apparatuses configured to perform a 3D scan of a portion 8 of the body lumen 1 of a patient, or to perform a 3D scan of a wall of the body lumen 1. In particular, the apparatuses are suitable for intra-vascular applications (IV- OCT). However, the invention is not limited to IV-OCT applications, and pu? be used to construct tomographic images of body tissues of a patient in general.

[0053] To this end, the apparatuses 102 and 103 comprise an optical cable 40, associated with an optical catheter configured to be moved from a vascular entry site through an intravascular route, not shown, until an end distal 49 of the optical cable 40 does not reach an objective region 21 of the lumen of the patient's body 1. At the extremity? distal 49 ? placed an optical probe 60, which ? optically connected to the optical source 10 to bring light 14j obtained from the main light beam 11, for example from the sample light beam 12, to the target region 21.

[0054] Like the prior art devices shown schematically in Figures 1A-B, the light ray source 10 of the apparatuses 102 and 103 ? configured to perform a conventional scan 9? of the wavelength of the light, in order to obtain a given axial resolution of the wall of the lumen of the body 1 when the light 14j is released into the target region 21.

[0055] Furthermore, in order to scan the wall, the apparatuses 102 and 103 are also configured to let s? that the optical probe 60 performs a radial scan 9? of 360? (scan B) of the lumen wall 1 of the patient's body in the target region 21 at a predetermined radial scan time T, so as to allow a 2D visualization at the target region 21. For this purpose, the optical probe 60 includes a deflection device 70,70? of the spokes placed at the extremity? distal 49 of the optical cable 40, so as to be able to receive the light 13j,13? from the optical cable 40. The deflection device 70,70? of the rays? configured to sequentially divert received light 13j,13? obtaining the oriented light rays 141, 142, ? 14j, ? 14M in the respective instants tj of the radial scan time T (tM = T). The oriented light rays 14j are oriented according to respective predetermined angles of rotation ?1, ?2, ? ?j, ? ?M of the rays with respect to an angular reference position ?0 integral with the optical cable 40. Therefore, during the radial scanning time T, the light rays 14j are sent through the reflection device 70,70? of the beams to the respective target sectors 2j,l of the target region 2l spaced angularly by the angles of rotation ?j of the beams from a reference position corresponding to said angular reference position ?0.

[0056] Furthermore, the apparatuses 102 and 103 are configured to also conventionally perform a concomitant backward translation 9z of the probe 60 along the lumen of the body 1, in order to generate a set of 3D volumetric data.

[0057] The deflection device 70.70? of the rays of the optical probe 60 ? also configured to collect beams 161, 162, ? 16j, ? 16M of backscattered light reflected by objective sectors 21,l, 22,l, ? 2j,l, ? 2M,l, respectively, when the latter are struck by the oriented light beam 14j, and ? configured to deflect the 16j beams of backscattered light back through the tip? distal 49 and the optical cable 40 towards the end? proximal 41, as deflected backscattered light beams 17j or directly into a deflected backscattered light beam 17 in apparatuses 102,103, respectively, as described below.

[0058] The OCT apparatuses 102 and 103 also include a balanced photodetector 29 arranged to receive the backscattered light beam 17 and to compare it interferometrically with the main light beam 11 or, in particular, with the reference light beam 18. Furthermore, the photodetector 29 ? configured to generate an interferometric signal 19 based on this comparison. Acquisition and processing means 90 are provided configured to receive the interferometric signal 19 from the balanced photodetector 29 and to reconstruct images 98l, l = 1 ? S of cross sections of the target region 2l and, starting from these, reconstruct the 3D image 99 of the portion of interest 8.

[0059] As shown in Figure 2C, the image acquisition and processing means 90 preferably comprise an amplifier 92 configured to amplify the interferometric signal 19 with low noise, an analog-to-digital converter (ADC) 93 configured to convert an interferometric signal analog possibly amplified 19? in a digital signal 19", and a buffer 94 in which the digital signal 19" ? stored as an acquisition matrix Ak,j, where k,j are the wavelength index and the angle index, respectively. Each column of the matrix Ak,j represents the interferogram 95 for a wavelength in the wavelength range explored for a respective radial angle, ie? at a respective target sector 2j,l of the target region 2l.

[0060] More in detail, the image acquisition and processing means 90 include FFT calculation means 96 configured to perform a Fourier transform of the interferogram 95, along the axial line 97j,l for a given angle of rotation ?j of the oriented light beam 14 .

[0061] The acquisition and processing means 90 are also configured to collect consecutive axial lines 97j,l, j = 1? M for the entire radial scan of 360?, and for reconstructing the 2D cross section 98l and, through a pull-back movement of the optical probe 60, the 3D image 99 of artery 1 by stitching together consecutive cross sections 98l, l = 1 ? S, for example, by means of a helical interpolation procedure.

[0062] With reference to Figures 2A and 2B, in a first aspect of the invention, the OCT apparatus 102 comprises a system for directing the light rays without mechanical components and at a high speed. to perform the radial scanning of the target region 2l by deflecting the light 13j received by the optical cable 40 into oriented light rays 14j at the respective instants tj of the radial scanning time T, so as to direct the oriented light rays 14j towards the target sectors 2j, spaced angularly apart by angles of relative rotation ?j-?j-1 of the spokes.

[0063] For this purpose, in accordance with the first aspect of the invention, the optical cable 40 comprises a bundle 43 of optical guide elements 42i, for example optical fibers 42i.

[0064] Furthermore, in accordance with the first aspect of the invention, ? provided a phase variator device 20 to generate a plurality? of N sample light rays out of phase 12i,j, i = 1 ? N, from the sample light beam 12 at each instant tj of the radial scan time T. Each of the N phase-shifted sample light beams 12i,j has a phase shift ?i,j with respect to a reference phase ?0 of the sample light beam 12. The phase shifter device 20 and the optical cable 40 are mutually arranged in such a way that each phase-shifted sample light beam 12i,j can be directed into a predetermined respective optical fiber 42i of the beam 43.

[0065] More in detail, the phase variator device 20 ? configured to perform a phase shift of the light beam sample 12 more? ways. In other words, at any instant tj, j = 1 ? M, of the radial scan time T, is generated a plurality? of N sample light rays out of phase 12i,j, i = 1 ? N with a given instantaneous combination ?j of phase shifts ?i,j. Therefore, at every instant tj, at the extremity? distal 49 of the beam 43 are simultaneously released N phase-shifted sample light rays 12i with interference, which thus form? is an instantaneous resultant light beam 13j which has a radiation pattern with an intensity lobe principal oriented in an instantaneous direction with respect to an axis 44 of the beam 43, the instantaneous direction therefore depending on the instantaneous combination ?j of phase shifts ?i,j. At a later instant tj+1, a subsequent instantaneous resultant light ray 13j+1 ? formed by a plurality of N sample light rays phase shifted 12i,j+1, which have a different instantaneous combination ?j+1 of phase shifts ?i,j+1, and cos? away, for each value j, during the radial scan time T.

[0066] Furthermore, still in accordance with the first aspect of the invention, the beam deflection device ? a deflection device of the motionless rays 70, that is? ? fixedly placed in the optical probe 60 at the end? distal 49, preferably coaxially with beam 43, and has a beam deflection surface arranged to receive the corresponding instantaneous resultant light beam 13j from the distal end. distal 49 of the cable 40, and to deflect the resulting instantaneous light beam 13j by reflection, obtaining the respective oriented light beam 14j according to respective predetermined angles of rotation ?j with respect to the angular reference position ?0 integral with the beam 43, as shown in the figure 2B.

[0067] Therefore, in the radial scanning time T, the oriented light rays 14j are sent by the beam deflection device 70 towards the respective target sectors 2j,l of the target region 2l. In substantially the same radial scan time T, the backscattered light rays 16j are deflected back by the deflection surface of the fixed beam deflection device 70, thereby forming deflected backscattered light rays 17j which are conveyed again to the phase shifter device 20 via respective optical fibers 47i, i = 1 ? no.

[0068] In short, at the extreme? distal 49 of the optical cable 40, carrying out in an adequate and dynamic way the phase shift of the optical phase ?i,j of the outgoing phase-shifted sample light rays 12i,j (figures 2A, 6A, 7A, 8A) or 12?i,j (figure 4A , 5A, 9A) relative to each other, ? is it possible to obtain a capacity? of orientation and shaping of the resulting instantaneous light rays 13j so as to implement a continuous deflection of the rays with a specific deflection angle (e.g. 100 mrad) and a circular trajectory 55.

[0069] Furthermore, the phase variator device 20 ? also configured to combine backscattered light beams 17j into a backscattered light beam 17.

[0070] More in detail, the backscattered light rays 16j are deflected back by the beam deflection device 70 obtaining deflected backscattered light rays 17j, and then they are collected by a part of the fibers 47i which are part of the bundle 43 of fibers, the number of which is whose geometric arrangement are preferably defined by numerical analysis, in the activity? probe design.

[0071] With reference to figure 2C, with the apparatus according to the invention, the matrix Ak,j is "filled" row by row, ie? during each phase k of the wavelength scan, k = 1 ? R, a full 360° radial scan is performed. Therefore, if T? ? the time in which the source 10 of light rays ? set to scan in an interval ? of the wavelength of light, this ? also the time required to fill the matrix Ak,j, necessary to obtain the cross-sectional image 98l of the target region 2 of the portion of interest 8 (figure 1).

[0072] On the contrary, in the conventional technique, during the time T? a wavelength scan is performed for each angular position 2j-1 before investigating a subsequent angular position 2j, j = 1 ? M and therefore, with the same source 10 of light rays as above, ? MxT time needed? to acquire the matrix Ak,j in order to obtain the cross-sectional image 98l of the target region 2.

[0073] Therefore, in the invention, the image reconstruction process 981 of each cross section is ? much more faster than prior art methods. For example, in a conventional SS-OCT apparatus that collects M = 500 axial profiles for each 360° radial scan, through a 25 MHz angular scan, easily obtainable with optical phase shifters modules, the time required to acquire the matrix Ak,j would be 500 times more? brief. Consequently, considering a commercial wavelength scanning source with speed? scanning frequency of 50 KHz and a mechanically rotating mirror with a frequency of 100 Hz, a cross-section acquisition time of 10 ms could be reduced up to 200 ?s by resorting to a phase shift-based radial scanning according to the invention.

[0074] With reference to Figures 3A and 3B, in a second aspect of the invention, the OCT apparatus 103 advantageously uses light beams in the mode whirling to improve the ability? of axial penetration in depth? of the optical coherence tomography (OCT) apparatus.

[0075] In accordance with the second aspect of the invention, in the OCT apparatus 103 the source 10 of light rays ? configured to emit a main light beam Gaussian 11, and ? provided an orbital angular momentum mode (OAM) generator 30 configured to transform a Gaussian sample light beam 12 derived therefrom into a sample light beam 12? of light in mode? swirling.

[0076] At one end? of the optical probe 60 ? expected a deflection device 70? of the rays to deflect the sample light beam 12?,13? of light in mode? swirling in light rays oriented 14j of light in mode? whirling, in respective instants tj of the radial scanning time T, ie in the light rays 14j of light in mode? swirling oriented towards the target sectors 2j,l. The deflection device 70? of the rays can? be a conventional deflection device, as currently used in OCT techniques, for example a mirror arranged to rotate at a speed? of rotation ? around its own axis of rotation 71, or another deflection device of a known type, for example MEMS, galvanometric mirrors or piezoelectric actuators.

[0077] In some embodiments which have features of both aspects of the invention, the deflection device 70? of the rays can? be a beam deflection device 70 as described above with reference to Figs. 2A and 2B . These embodiments will be described later in detail below, with reference to figures 4A-5B, 9A and 9B.

In substantially the same radial scan time T, the backscattered light beams 16j are deflected back by the deflection device 70? of the rays, forming cos? a beam 17 of backscattered light directed towards the photodetector 29 through the optical cable 40.

[0079] Figures 4A and 4B refer to an OCT apparatus 104 according to an embodiment of the invention, in which both the characteristics of the first aspect (figures 2A and 2B) and the characteristics of the second aspect (figures 3A- 3B) of the invention. With respect to the OCT apparatus 102 of figure 2A, the OCT apparatus 104 comprises an OAM generator 30 disposed downstream of the phase shifter device 20. The OAM generator 30 ? configured to transform phase-shifted sample light rays 12i,j into phase-shifted sample light rays 12'i,j, i = 1 ? N of light in mode? whirling, at every instant tj, j = 1 ? M, of the radial scan time T. Thus, the orienter beam deflection device 70? the sample light rays out of phase 13'i,j of light in mode? whirling thus obtaining the respective light rays oriented 14'j of light in modality? whirling, and the target-sectors 2j,l of the target-region 2l will be irradiated by the respective light rays in the mode? swirling.

[0080] Figures 5A and 5B refer to an OCT apparatus 105 according to another embodiment of the invention which includes both features of the first aspect (figures 2A and 2B), and characteristics of the second aspect (figures 3A-3B) of the 'invention. In the OCT 105 apparatus, the OAM 30 generator ? arranged upstream of the phase shifter device 20. As in the OCT apparatus 103 (Figure 3A), the OAM generator apparatus 30 is configured to transform the sample Gaussian light beam 12 derived from the main light beam 11 emitted by the source 10 of bright in the light beam sample 12? of light in mode? swirling. In this case, the phase variator device 20 ? configured to sequentially generate the plurality? of light rays sample out of phase 12'i, j of light in mode? swirling from the light beam sample 12? of light in mode? swirling. Therefore, also in this case the deflection device 70 of the orienting rays? the sample light rays out of phase 13'i,j of light in mode? whirling thus obtaining the respective light rays oriented 14'j of light in modality? whirling, and the target sectors 2j,l of the target region 2l will be irradiated by the respective light rays in the mode? swirling.

[0081] In the case of the apparatuses 103, 104 and 105 of figures 3A, 4A and 5A, the optical cable 40 or the fibers 42i and 47i, respectively, are configured to support OAM propagation, for example they can be standard multimode optical fibers ( MMF) or even special MMF fibers pi? such as high refractive index ring vortex fibers, multi-OAM multi-ring fiber, photonic crystal fibers, supermode OAM fibers, air-core fibers, and graded-index refractive index fibers with inverse parabolic shape.

[0082] With reference to Figures 6A and 6B , in an OCT diagnostic apparatus 106 in accordance with the first aspect of the invention, the beam deflection device ? a conical mirror 70 placed at the end? distal 49 of the optical cable 40. The conical mirror 70 is preferably arranged coaxially with respect to the bundle 43, in other words the axis 72 of the conical mirror 70 substantially coincides with the longitudinal axis 44 of the bundle 43.

[0083] In this way, the resulting instantaneous light rays 13j, j = 1 ? M released by the optical cable 40 at the end? distal 49 at different instants tj of the radial scanning time T strike the conical mirror 70 at different points of a circular trajectory 55, i.e. in a section of the conical mirror 70 obtained with a plane perpendicular to the axis 72 of the conical mirror 70. Therefore, at every instant t1, t2, ? tj, ? tM, the resulting instantaneous light rays 131, 132, ? 13j, ? 13M are deflected radially, that is? are deflected perpendicularly to the axis 72, so as to form the respective radially deflected spokes 141, 142, ? 14j, ? 14M oriented according to respective predetermined angles of rotation ?1, ?2, ? ?j, ? ?M of the rays with respect to the angular reference position ?0, describing an angle of 360? around axis 72. In this way, the radial scan of 360 is performed? (scan B) of the target region 21 of the body lumen of patient 1, in which the target sectors 21,1, 22,1, ? 2j,l, ? 2M,l are irradiated in sequence.

[0084] Preferably, the conical mirror 70 has a vertex angle whose amplitude ? ? choice based on the angle ? between the direction of the instantaneous resultant beam 13j and the beam axis 44. In particular, the amplitude ? ? choice based on the relationship:

? = ?/2 ?/4.

[0085] It is also possible to use static mirrors other than the conical mirror 70, in particular conical mirrors having an axisymmetric surface, provided that are arranged so as to transform the resulting instantaneous rays 13j into radially deflected rays 14j.

[0086] With reference to figure 7A, an OCT apparatus 107 is described in accordance with the first aspect of the invention, in which the optical phase shifter device 20, which comprises an array 23 of optical phase shifter modules, ? implemented by an integrated photonic circuit configured to control the beam orientation process.

[0087] Downstream of the first optical power splitter device 21, which can being included in the integrated circuit 20, the phase shifter device 20 also includes a second optical power splitter device 22, configured to split the sample light beam 12 into a plurality of? of N replicas 12i, i = 1 ? N of this.

The array 23 of optical phase shifter modules comprises a plurality of of optical phase shifter modules 23i, i = 1 ? No, what? phase modulators which are optically coupled with the respective optical fibers 47i of the bundle 43 by means of a coupler device 24. At a given instant tj of the radial scan time T, each optical phase shifter module 23i ? configured to transform a replica 12i into a respective phase-shifted sample light beam 12i,j. Therefore, each 42i optical fiber ? arranged to guide a respective sample light beam 12i,j received by the respective optical power divider element 22i. In particular, the integrated phase shifter modules 23i are implemented as fast doped p-n junctions which can operate under reverse bias, with the previously explained advantages.

[0088] The backscattered light 17j can return to the input of the integrated photonic circuit 20 through a dual path, with respect to the one performed in transmission. The optical phase ?i,j of each received signal is again controlled by the phase shifter modules 27j, net of their initial calibration with a reference target, ie? a mirror, before being mated together.

[0089] The OCT apparatus 108 of figures 8A and 8B ? a variant of the OCT apparatus 107, in which the coupling device 24 of the phase shifter device 20 advantageously comprises a plurality of of grid couplers 24i which connect each output of the phase shifter module array 23 with a respective optical fiber 42i of the bundle 43. Each grid coupler 24i advantageously comprises a terminal micro-lens 25i for collimating the respective sample light rays 12i, j in each of the optical fibers 42i.

[0090] Alternatively, to correctly connect each output of the array 23 of phase shifter modules with a respective optical fiber 42i, the coupling device 24 can? be made up of appropriate mode taper to convert the mode? that propagates in the waveguide integrated in the modality? supported by 42i optical fibers. As a further alternative, ? Is it possible to use any kind of ad-hoc photon pair designed to suitably convert the mode? that propagates in the waveguide integrated in the modality? supported by 42i optical fibers. The same also applies to the backscattered light 17j to be conveyed by the fibers 47i into the input of the phase shifter module array 27.

[0091] An OCT apparatus 109, shown in figures 9A and 9B, is a variant of the OCT apparatus 108 of figures 8A and 8B which also includes the characteristics of the second aspect of the invention, i.e. an angular momentum mode generator 30 disposed downstream of the phase shifter device 20 as in figure 4A. Each 25i micro-lens ? optically connected with the orbital angular momentum mode generator 30 configured to transform each phase-shifted sample light beam 12i,j into a respective phase-shifted sample light beam 12'i,j of ? vortex propagating an orbital angular momentum, having a helical wavefront.

[0092] The grid couplers 24i and possibly the respective micro-lenses 25i are optically connected to the respective fibers 42i of the fiber bundle 43 of the optical cable 40 via suitable free-space optics, so that each light beam 12i, j phase-shifted sample 12i,j (figure 8) or the sample phase-shifted light rays 12'i,j of light in mode? vorticosa propagating an orbital angular momentum (figure 9) are coupled at the input to a core of the respective fiber 42i.

[0093] The bundle 43 of fibers ? configured to direct sample 12i,j or 12'i,j light beams to one end? of the optical probe 60 and to collect a backscattered light 16j, consisting of a plurality of backscattered rays 16j coming from the respective target sectors 2j,l of the target region 2l under examination, in this case, a portion of the blood vessel 1 of a patient.

[0094] Due to the size of the free space optics used, the bundle 43 of fibers will be? of the fan type as shown throughout the set of images, i.e., the fibers 42i are thin-coated fibers that are spaced apart at the ends. proximal 41 of the wire or of the optical cable 40, and which are progressively gathered in a smaller packing structure? tight going towards the extremity? distal 49 of the optical cable 40, so as to keep the thickness of the latter within 1 mm.

[0095] Again with reference to figure 9A, the OCT apparatus 109, as like any other OCT apparatus 101-108 previously described, pu? be a SS-OCT apparatus in which ? provided a continuous wave source with wavelength scanning (CW-SS) 10 configured to linearly scan the interval ? of wavelengths of the main light ray emitted 10 in a predetermined time T? scan in wavelength, variable between 20 ?s and 50 ?s.

[0096] Furthermore, the source 10 of light rays ? connected optically, preferably by pig-tailing the fibers, to the integrated photonic circuit 20, which preferably has the form of a silicon-on-insulator integrated circuit, to direct the main light beam into the integrated circuit 20.

[0097] In some embodiments, not shown, the angle ?M within which the radial scan is performed can be other than a 360° angle if needed. Does the size of each target sector 2j,l depend on the number N of the phase shifter modules, i.e. on the number of elements of the optical phased array which implement the OBS, on the mutual distance between the 42i fibers at the extremity? distal 49, by their geometry, by their distribution and by further parameters which are evident to the person skilled in the field of optical phased arrays and of the field to which the invention refers.

[0098] The above description of embodiments of the invention? able to show the invention from the conceptual point of view so that others, using the prior art, will be able to modify and/or adapt these specific embodiments in various applications without further research and without departing from the inventive concept and, therefore, it is intended that such adaptations and modifications will be considered equivalent to the specific embodiments. The means and materials for achieving the various functions described may be of various kinds without thereby departing from the scope of the invention. It is understood that the expressions or terminology used are for purely descriptive purposes and, therefore, not limiting.

Claims (10)

1. A diagnostic apparatus (102,104,105,106,107,108,109) for performing an optical coherence tomography of a target region (21) of a patient's body tissue (1), said diagnostic apparatus comprising: - a source (10) of light rays configured to emitting a light beam (11); - an optical cable (40) having one end? proximal end (41) in communication with said source (10) of light rays to receive said light beam (11) from it, and one end? distal (49) arranged to be introduced into said target region (21); - a beam orientation device configured for: - directing said light beam (11) according to a plurality? of rotation angles (?j) of the beams with respect to an angular reference position (?0) integral with said optical cable (40), in a predetermined radial scanning time (T), so as to obtain a plurality? of respective oriented light rays (14j) and directing said oriented light rays (14j) in sequence, in said radial scanning time (T), towards a plurality? of respective target sectors (2j,l) of said target region (2l); - collecting the backscattered light (17) from said target sectors (2j,l) in response to said directed light rays (14j), - a photodetector (29) arranged to receive said backscattered light (17) from said beam directing device, and configured to interferometrically compare said backscattered light (17) with said light beam (11,18) and generate therefrom an interferometric signal (19); - acquisition and processing means (90) configured to receive said interferometric signal (19), to form starting from it axial profiles (97j,l) of said target region (2l), and to join said axial profiles (97j,l) forming a cross-sectional image (98l) of said body tissue of said patient (1), characterized by the fact that: - said optical cable (40) comprises a bundle (43) of optical guide elements (42i), said bundle (43) having a beam axis (44); - said beam orientation device comprises: - a phase shifter device (20) configured for - generate, in every instant of said radial scan time, a plurality? of phase-shifted sample light rays (12i,j) starting from said light beam (11), said phase-shifted sample light rays (12i,j) having respective phase shifts (?i,j) with respect to a reference phase (?0) of said light beam (11), said phase shifts (?i,j) forming an instantaneous combination (?j) of phase shifts, and for - modifying said instantaneous combination (?j) of phase shifts during said radial scanning time (T), said instantaneous combination (?j) of phase shifts being arranged in such a way that at said end? distal (49) of said cable (40) an instantaneous resultant light beam (13j) is formed as a combination of said phase-shifted sample light rays (12i,j), said instantaneous resultant beam (13j) having a lobe of intensity? principal oriented in an instantaneous direction with respect to said beam axis (44); - a deflection device (70) of the rays arranged fixed at said end? distal (49), said spoke deflection device (70) having a spoke deflection surface arranged to: - at each instant of said radial scanning time (T), receiving the corresponding instantaneous resulting light beam (13j) in a respective position on itself?; and for - deflecting said instantaneous resulting light beam (13j) according to a respective rotation angle (?j) of the rays of said rotation angles around said optical cable (40), so as to form, in said radial scanning time ( T), called oriented light rays (14j); in such a way that said oriented light rays (14j) are directed towards said target sectors (2j,l) of said target region (2l) according to said rotation angles (?j) of the rays in said radial scanning time (T ), and said backscattered light (17) is collected at said end? distal (49) in the form of backscattered light rays (16d) from respective objective sectors (2j,l) in response to respective said oriented light rays (14j). 2. The diagnostic apparatus (104,109) according to claim 1, wherein said source (10) of light rays ? configured to emit a Gaussian light beam (11), and ? provided is an orbital angular momentum mode generator (30) configured to transform each of said phase-shifted sample light rays (12i,j) into phase-shifted sample light rays of light in mode? vortex (12'i,j) having helical wavefronts and said deflection device (70) of the rays ? configured to deflect said phase-shifted light sample beams of light into mode? whirling (12'i,j) in said oriented light rays (14j), said oriented light rays being light rays in mode? swirling (14j). The diagnostic apparatus (105) according to claim 1, wherein said source (10) of light rays is configured to emit a Gaussian light beam (11), and ? foreseen and an orbital angular momentum mode generator (30) configured to transform said Gaussian light beam (11) into a light beam in? vortex (12?) having a helical wave front, and said phase shifter device (20) ? configured to generate sequentially from said ray of light in mode? swirling (12?) called plurality? of phase-shifted sample light rays as phase-shifted sample light rays (12'i,j) of light in mode? swirling. 4. A diagnostic apparatus (103,104,105,109) for performing an optical coherence tomography of a target region (21) of a patient's body tissue (1), said diagnostic apparatus comprising: - a light beam source (10) configured to emit a light beam (11); - an optical cable (40) having one end? proximal end (41) in communication with said source (10) of light rays to receive said light beam (11) from it, and one end? distal (49) arranged to be introduced into said target region (21); - a beam orientation device configured for: - directing said light beam (11) according to a plurality? of rotation angles (?j) of the beams with respect to an angular reference position (?0) integral with said optical cable (40), in a predetermined radial scanning time (T), so as to obtain a plurality? of respective oriented light rays (14j) and directing said oriented light rays (14j) in sequence, in said radial scanning time (T), towards a plurality? of respective target sectors (2j,l) of said target region (2l); - collecting the backscattered light (17) from said target sectors (2j,l) in response to said directed light rays (14j), - a photodetector (29) arranged to receive said backscattered light (17) from said beam directing device, and configured to interferometrically compare said backscattered light (17) with said light beam (11) and generate therefrom an interferometric signal (19); - image acquisition and processing means (90) configured to receive said interferometric signal (19) and to form starting from it axial profiles of said target region (2l), and to join said axial profiles (97j,l) forming a cross-sectional image (98l) of said tissue of the body of said patient (1), characterized in that said source (10) of light rays ? configured to emit a Gaussian light beam, and ? provided an orbital angular momentum mode generator (30) configured to transform said light beam (11) into a light beam in mode? vorticosa (12?) having a helical wave front, in such a way that said oriented light rays (14j) are also oriented light rays of light in mode? swirling, and said beam orientation device is configured to sequentially generate said plurality? of sample light rays out of phase (12i,j) starting from said light ray in mode? swirling (12?). 5. The diagnostic apparatus (104,105,109) according to claim 4, wherein: - said optical cable (40) comprises a bundle (43) of optical guide elements (42i), said bundle (43) having a beam axis (44); - said beam orientation device comprises: - a phase shifter device (20) configured for - generate, at each instant (tj) of said radial scan time (T), a plurality? of phase-shifted sample light rays (12i,j) starting from said light beam (11), said phase-shifted sample light rays (12i,j) having respective phase shifts (?i,j) with respect to a reference phase (?0) of said light beam (11), said phase shifts (?i,j) forming an instantaneous combination (?j) of phase shifts, and for - modifying said instantaneous combination (?j) of phase shifts during said radial scanning time (T), said instantaneous combination (?j) of phase shifts being arranged in such a way that at said end? distal (49) of said cable (40) an instantaneous resultant light beam (13j) is formed as a combination of said phase-shifted sample light rays (12i,j), said instantaneous resultant light beam (13j) having a lobe of intensity? principal oriented in an instantaneous direction with respect to said beam axis (44); - a deflection device (70) of the rays arranged fixed at said end? distal (49), said spoke deflection device (70) having a spoke deflection surface arranged to: - at each instant of said radial scanning time (T), receiving the corresponding instantaneous resulting light beam (13j) in a respective position on itself?; and for - deflecting said instantaneous resulting light beam (13j) according to a respective rotation angle (?j) of the rays of said rotation angles around said optical cable (40), so as to form, in said radial scanning time ( T), called oriented light rays (14j); in such a way that said oriented light rays (14j) are directed towards said target sectors (2j,l) of said target region (2l) according to said rotation angles (?j) of the rays in said radial scanning time (T ), and said backscattered light (17) is collected at said end? distal (49) in the form of backscattered light rays (16d) from respective objective sectors (2j,l) in response to respective said oriented light rays (14j). 6. The diagnostic apparatus (106,109) according to claims 1 or 5, wherein said beam deflection device comprises a conical mirror (70) disposed at said end? distal (49) coaxially to the bundle (43) of optical guide elements (42i), said conical mirror (70) having a vertex angle whose amplitude (?) ? chosen on the basis of the angle (?) formed between the direction of said instantaneous resulting light beam (13j) and the axis (44) of the beam, in particular, by means of the relation: ? = ?/2 ?/4, Where ? ? the amplitude of said angle at the vertex of said conical mirror (70), and ? ? the angle between the direction of said instantaneous resultant light beam (13j) and the axis (44) of the beam. 7. The diagnostic apparatus (107,108,109) according to claims 1 or 5, wherein said phase shifter device (20) comprises: - an optical power splitter device (22) configured to split said light beam (11) into a plurality of? of his replicas (11i); - an array (23) of phase shifter modules comprising a plurality? of optical phase shifter modules (23i), cio? phase modulators, each arranged to receive a respective replica (11i) of said replicas, and configured to transform said replica (11i) into a phase-shifted light beam (12i) of said phase-shifted light beams (12i); - a coupling device (24) arranged to direct said phase-shifted light rays (12i) into the respective predetermined optical guide elements (42i) of said beam (43). 8. The diagnostic apparatus (108,109) according to claim 7, wherein said phase shifter device (20) comprises an integrated photonic circuit (20) comprising, like said optical phase shifter modules, integrated doped optical guide elements ( 23i), said doped optical guide elements (23i) being configured to receive a voltage in such a way as to modify its own refractive index, wherein said coupling device (24) ? chosen between: - a plurality? grid couplers (24i) connecting said light beam directing device (20) with each of said optical guide elements (42i); - a plurality? of edge emitters with a conical profile, in particular, said integrated optical guide elements (23i) comprise fast doped p-n junctions, more in particular, said doped p-n junctions are arranged to operate under reverse bias, in particular, each of said optical phase shifter modules (23i) comprises an optical guide portion doped with a respective optical guide element of said optical guide elements, said doped optical guide portion being configured to receive a voltage so as to change its refractive index. 9. The diagnostic apparatus (109) according to claim 1 or 4, wherein said source (10) of light rays is a continuous wave source with wavelength scanning. 10. The diagnostic apparatus according to claims 2 or 3 or 4, wherein said optical cable (40) includes a fiber selected from: - a multi-OAM-mode multi-ring fiber; - a photonic crystal fiber; - an OAM fiber supermode; - an air-core fiber; - a graded-index type fiber with refractive index with inverse parabolic trend.