WO2009080972A2

WO2009080972A2 - Intracavity probe for nuclear magnetic resonance imaging and/or spectrometry

Info

Publication number: WO2009080972A2
Application number: PCT/FR2008/052248
Authority: WO
Inventors: Frank Pilleul; Hervé Saint-Jalmes; Olivier Beuf; Franck Jaillon; Mircea Armenean; Serge Piranda; Jean-François DELFORGE; Etienne Mahler
Original assignee: Universite Claude Bernard Lyon I; Hospices Civils De Lyon; Centre National De La Recherche Scientifique
Priority date: 2007-12-07
Filing date: 2008-12-08
Publication date: 2009-07-02
Also published as: FR2924817B1; FR2924817A1; WO2009080972A3

Abstract

The invention relates to an intracavity probe for nuclear magnetic resonance imaging and/or spectrometry of a zone of interest, comprising an elongate body (2) of longitudinal axis (X) having a distal end (4) and a proximal end (5) and having a radiofrequency sensor (7), comprising first (8) and second (9) electrically conductive loops mounted in series, each of the loops (8, 9) comprising an electrical output conductor (81, 91) and an electrical return conductor (82, 92), each of these being situated on a generatrix of a cylinder centred on the longitudinal axis (X) and having currents circulating through them respectively in opposite directions, characterized in that one of the output conductors and one of the return conductors extend in a first plane (P1) symmetrically with respect to the longitudinal axis X, while the other output conductor and the other return conductor extend in a second plane (P2) symmetrically with respect to the longitudinal axis X, the second plane (P2) intersecting the first plane (P1) to form between them an angle (α) of 50° ± 20°.

Description

ENDOCAVITARY PROBE FOR IMAGING AND / OR NUCLEAR MAGNETIC RESONANCE SPECTROMETRY

The present invention relates to the general technical field of nuclear magnetic resonance endoscopy and more specifically to an endocavity probe for imaging and / or nuclear magnetic resonance spectrometry.

The object of the invention finds particularly advantageous applications for the exploration of tissues or organs by introducing a probe inside a human or animal cavity.

The object of the invention finds applications more specifically for oesophageal, stomach, anal sphincter, vessel, urethra or prostate exploration.

The advantages of using nuclear magnetic resonance imaging are well known. In the state of the art, it has been proposed for nuclear magnetic resonance imagers, many variants of radio frequency reception probes adapted to the shape and / or size of the area of interest to be explored. In general, such a probe or antenna comprises a radio frequency sensor used to detect or receive the magnetization signal of the imaged zone.

Various endocavity probe solutions have been proposed to obtain the best signal-to-noise ratio and improved signal uniformity in the area of interest to be imaged. The analysis of known solutions leads to the conclusion that there is a need for an endocavity probe with the advantage of presenting the best compromise between the signal-to-noise ratio and the uniformity of the radiofrequency signal in the exploration region. .

In the state of the art, it is also known from document WO 2004/038442, a catheter for imaging and / or nuclear resonance spectrometry of a zone of interest, comprising a radio frequency sensor formed by a series electrical conductors parallel to each other, distributed along a cylinder and interconnected to form a zigzag structure fed with current, alternatively having an electrical conductor go and a electrical conductor back. Such a configuration makes it possible to obtain a distribution of the magnetic field in an annular region flanking the zigzag structure. Insofar as the radiofrequency magnetic field decreases in the center of the zigzag structure, such a sensor makes it possible to dispense with parasitic signals originating from this region, such as those originating, for example, from the circulation of blood. Such a catheter has an exploration region with a specific configuration limiting its applications. In addition, such a sensor does not provide an optimal signal-to-noise ratio when moving away radially. The present invention therefore aims to propose a new endocavity probe for imaging and / or nuclear magnetic resonance spectrometry designed to have a good signal-to-noise ratio and a good uniformity of the field in the explored area.

Another object of the invention is to provide an endocavity probe having a limited diameter to allow its introduction into cavities of reduced size, for comfort and good acceptance of the probe by the patient.

Another object of the invention is to provide an endocavitary probe whose small diameter keeps the anatomical shape by not stretching the tissues and thus allow a better diagnosis.

To achieve such an objective, the endocavity probe for imaging and / or nuclear magnetic resonance spectrometry of a zone of interest comprises an elongate body of longitudinal axis having a distal end and a proximal end and comprising a sensor. radio frequency, comprising a first and a second electrically conductive loop connected in series, each of the loops comprising a go electric conductor and a return electrical conductor, each located on a generatrix of a cylinder centered on the longitudinal axis, and traversed by currents flowing respectively in opposite directions. According to the invention, one of the drivers going and one of the return conductors extend in a first plane being symmetrical with respect to the longitudinal axis, while the other driver go and the other driver return s extend in a second plane by being symmetrical with respect to the axis longitudinal, the second plane secant in the foreground forming between them an angle of 50 ° ± 20 °.

Advantageously, the first and second planes define sections which are intersecting with each other. It emerges from the invention, that the electrical conductors are distributed on the circumference of the cylinder of longitudinal axis, so that the two electrical conductors are adjacent and the two electrical conductors returns are also adjacent.

According to an embodiment characteristic: - the electrical conductor go and the electrical conductor return of the first loop are interconnected by an electrical connection,

- The electrical conductor go and the return electrical conductor of the second loop are interconnected by an electrical connection, the electrical conductor of the return of the first loop being connected to the electrical conductor go of the second loop by an electrical connection.

According to an alternative embodiment, the loops are carried by a cylindrical rigid spacer having through holes for the passage of electrical conductors back and forth, the spacer being provided at its ends, a proximal disk and a distal disc of support for electrical connections.

For example, each loop has a length of the order of 60 mm and a width of the order of 6 mm.

In the example provided, the proximal and distal disks form printed circuit boards for fixing and connecting electronic components allowing the tuning, adaptation and active decoupling of the sensor.

According to another variant embodiment, the loops are surrounded by a spacing envelope between the loops and the zone of interest and having a thickness of between 1 and 2 mm.

Advantageously, the probe comprises a disposable sleeve wrapping the distal end of the body to the proximal end of the body.

For example, the spacer envelope is made by a layer of non-magnetic material covering the spacer and / or the disposable sleeve. According to a feature of the invention, the disposable sleeve is held in position on the body at its distal and proximal ends with respectively distal and proximal stops.

Preferably, the disposable sleeve comprises a filling duct for a balloon formed by a portion of the disposable sleeve, the duct being connected externally to an inflation balloon.

For example, the proximal end of the body is provided with a connecting piece for a protective tube of the connection cable of the radio frequency sensor. According to an alternative embodiment, the probe comprises a proximal abutment threaded and fixed on the disposable sleeve.

Various other characteristics appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the subject of the invention. Figure 1 is a longitudinal sectional view of an endocavity probe according to the invention.

Figure 2 is a cross-sectional view taken along the line IHI of FIG. 1.

FIG. 3 is a diagram illustrating a preferred variant of positioning of the constituent loops of the radio frequency sensor equipping the probe according to the invention.

Figure 4 is a view similar to FIG. 2 showing a characteristic detail of the probe according to the invention.

Figures 5 and 6 are respectively details A and B of the probe illustrated in FIG. 1.

As is more particularly apparent from FIG. 1, the subject of the invention relates to an endocavity probe 1 for imaging and / or nuclear magnetic resonance spectrometry of a zone of interest. By way of example, it may be envisaged to envisage esophageal, stomach, anal sphincter, vessel, urethra or prostate exploration. In a conventional manner, this probe 1 is intended to be used in association with imagers by nuclear magnetic resonance of all types that will not be described more precisely because they are part of the general knowledge of the skilled person.

This probe 1 is in the form of a rigid elongated body 2 having a longitudinal central axis X. The body 2 has a distal end 4 and a proximal end 5.

The probe 1 comprises a radio frequency sensor 7 adapted to detect or receive the magnetic resonance signal. As illustrated more specifically in Fîg. 2 and 3, the radiofrequency sensor 7 comprises a first electrically conductive loop 8 connected in series with a second electrically conductive loop 9. In the example embodiment illustrated, these conductive loops 8 and 9 extend in planes P1 and P2 respectively. secants between them.

As is more particularly apparent from FIG. 3, the first loop 8 comprises a forward electric conductor 81 and a return electrical conductor 82 extending parallel to each other and to the longitudinal axis X and in the first plane P1. The forward electrical conductor 81 is connected to the electrical return conductor 82. by an electrical connection 83.

The second loop 9 comprises a forward electrical conductor 91 and a return electrical conductor 92 extending parallel to each other and to the longitudinal axis X and in the second plane P2. The electrical conductor go 91 is connected to the electrical return conductor 92 by an electrical connection 93. The electrical return conductor 82 of the first loop is connected to the electrical conductor go 91 of the second loop by an electrical connection 94. The electrical conductors go 81 , 91 and the return electrical conductors 82, 92 are each located on a generatrix of a cylinder centered on the longitudinal axis X.

As is apparent from the above description, the two loops 8, 9 are therefore mounted in series. Thus, the electric current flows in the same direction in the forward conductors 81 and 91 of the two loops, while the electric current flows in the same opposite direction in the return conductors 82 and 92 of the two loops 8 and 9. Thus, for each loop 8, 9, the drivers going 81, 91 and the return conductors 82, 92 are traversed by currents flowing in opposite directions and symmetrical with respect to the longitudinal axis X.

Preferably, each loop 8 and 9 has a rectangular shape. Each loop 8 and 9 thus has a length of the order of 60 mm and a width of the order of 6 mm. In other words, the length of the electrical conductors go 81, 91 and returns 82, 92 is 60 mm while the spacing between a forward conductor 81, 91 and a return conductor respectively 82, 92 is of the order of 6 mm. For example, each conductor 81, 91, 82, 92 has a diameter of the order of 1 mm. According to a characteristic of the invention, the forward and return conductors 82 extend in a first plane P1 while the forward and return conductors 92 extend in a second plane P2 that is secant in the first plane P1 forming between they have an angle α of 50 ° ± 20 °. In the illustrated example, the forward conductor 81 and the return conductor 82 extend in the first plane Pl while the forward conductor 91 and the return conductor 92 extend in a second plane P2. The planes P1 and P2 form between them an angle α of 50 ° ± 20 °. In the illustrated example, the first loop 8 extends in the first plane P1 while the second loop 9 extends in the second plane P2. Of course, it may be envisaged that the first loop is constituted by the forward and return conductors 92, while the second loop is formed by the forward and return conductors 82 considering that the directions of the currents are unchanged with respect to the description above.

It follows from the above description that the radio frequency sensor 7 thus comprises only two loops 8 and 9, that is to say only two conductors going 81,91 (respectively first and second) and two return conductors 82,92 (respectively first and second). One of the traveling conductors (for example the first 81) and one of the return conductors (for example the first 82) extend symmetrically with respect to the longitudinal axis X, in the plane Pl while the other of the traveling conductors (namely the second 91 in the example) and the other of the return conductors (namely the second 92 in the example) extend symmetrically with respect to the longitudinal axis X, in the P2 plan. Drivers traveling back and forth are therefore distributed around the circumference of the cylinder centered on the longitudinal axis X so that the two traveling conductors are adjacent or located side by side, while the two return conductors are also adjacent or located side by side. In other words, by traversing the circumference of the cylinder in one direction, one meets successively two conductors of the same direction (for example the drivers going) then the two drivers of opposite direction (the drivers return in the example). Given the definition given above, the angle considered between two conductors of the same direction (return conductors or drivers going) is equal to 50 ° ± 20 ° with respect to the longitudinal axis X. Of course, the angle caught between two adjacent conductors of opposite direction (go conductor and return conductor) is equal to (180 ° - 50 °), that is to say 130 ° ± 20 ° with respect to the longitudinal axis X.

The implementation of a radiofrequency sensor 7 as defined above makes it possible to obtain the best compromise between the signal-to-noise ratio and the uniformity of the radiofrequency signal in the exploration region.

It must be considered that the first P1 and second P2 planes define rectangular sections which are advantageously intersecting with each other. Of course, it could be envisaged that the two electric loops 8 and 9 are located one behind the other, in the longitudinal direction X. The secant or superimposed arrangement of the loops 8, 9 between them can limit clutter of the radiofrequency sensor along the longitudinal axis X.

According to a preferred embodiment, the electrical loops 8 and 9 are carried by a rigid cylindrical spacer 15 having bores 16 opening at each end for the passage of the electrical conductors 81, 91 and return 82, 92.

As is more particularly apparent in FIG. 2, the spacer 15 has a cross section preferably circular. It must be considered that the bores 16 arranged in the rigid spacer 15 ensure the correct positioning of the electrical conductors 81, 91, 82, 92 according to a given angulation value α. The rigid spacer 15 is provided at its ends with a proximal disc 17 and a distal support disc 18 for the electrical connections 83 and 94, respectively. precisely from FIG. 4, each disc 17 is made in the form of a double-sided printed circuit in which electrical connection tracks 20 are formed between the electrical conductors going and going back loops. Advantageously, the proximal disks 17 and distal 18 form printed circuits for fixing and connecting electronic components such as capacitors and diodes for tuning, adaptation and active decoupling of the radio frequency sensor.

In the variant illustrated in FIG. 1, the rigid spacer is provided with the proximal disks 17 and distal 18, being mounted between a gripping tube 21 and an introduction tube 22 equipped at its end, an introducer tip 23 of rounded shape. For example, the tip 23 has an atromatic character. The gripping tube 21 is provided at the proximal end with a connecting piece 25 for a protective tube 26 of the electrical connection cable of the radio frequency sensor to the imager. As is more particularly apparent from FIG. 6, this nozzle 25 has a tubular shape for the passage of the connection cables of the radio frequency sensor.

According to another advantageous characteristic of the subject of the invention, the electric loops 8 and 9 are surrounded by a spacing envelope 30 between the loops and the zone of interest. This spacer envelope 30 has a thickness of between 1 and 2 mm. This envelope 30 makes it possible to guarantee the correct positioning of the loops with respect to the tissues to be imaged. This spacing envelope also makes it possible to guarantee a dynamic signal in the image adapted to ensure good reading of the image. This envelope 30 may be made of a non-magnetic material enveloping the body 2 of the probe. According to a feature of the subject of the invention, the endocavity probe comprises a disposable sleeve 31 enveloping the distal end 4 of the body to the proximal end 5 of the body. Such a sleeve 31 is therefore in the form of a sock threaded from the distal end 4 of the probe. Advantageously, the disposable sleeve 31 contributes to partially or completely achieve the spacer envelope 30. The disposable sleeve 31 is made for example of a PEEK (Polyether-Ether-Keton). The disposable sleeve 31 comprises a filling duct 33 for a balloon formed by part of the disposable sleeve and a tubular membrane sealingly mounted surrounding the sleeve. The conduit is connected at the proximal end to an external inflation balloon 35.

The disposable sleeve 31 is held in position on the body 2 of the probe, at the distal end 4 by means of a stop constituted for example by a ring 36 which surrounds the sleeve at the level of the insertion tube 22. In addition, the disposable sleeve 31 is held in position on the body at the proximal end 5, with the aid of an abutment constituted in the example, by a rib 38 formed on the connection endpiece 25 and on which is engaged a groove 39 presented by the disposable sleeve 31.

According to a preferred feature of embodiment, the endocavitary probe 1 comprises a proximal abutment 40 threaded and fixed on the disposable sleeve 31 to limit the introduction of the endocavitary probe 1.

The invention is not limited to the examples described and shown because various modifications can be made without departing from its scope.

Claims

1 - Endocavity probe for imaging and / or nuclear magnetic resonance spectrometry of an area of interest, comprising an elongate body (2) with a longitudinal axis (X) having a distal end (4) and a proximal end (5) and comprising a radio frequency sensor (7), comprising a first (8) and a second (9) electrically conductive loop connected in series, each of the loops (8, 9) comprising a forward electric conductor (81, 91) and a return electrical conductor (82, 92) each located on a generatrix of a cylinder centered on the longitudinal axis (X), and traversed by currents respectively flowing in opposite directions, characterized in that one of the conductors going and one of the return conductors extend in a first plane (Pl) being symmetrical with respect to the longitudinal axis X, while the other go conductor and the other return conductor extend in a second plane (P2 ) by being sym tric with respect to the longitudinal axis X, the second plane (P2) being secant to the first plane (Pl) forming between them an angle (α) of 50 ° ± 20 °.

2 - endocavity probe according to claim 1, characterized in that the first (Pl) and second (P2) planes define sections which are intersecting with each other. 3 - endocavitary probe according to claim 1, characterized in that the electrical conductors are distributed on the circumference of the cylinder of longitudinal axis X, so that the two electrical conductors go (81, 91) are adjacent and the two electrical conductors returns (82, 92) are also adjacent. 4 - endocavity probe according to one of claims 1 to 3, characterized in that:

- the electrical conductor go (81) and the electrical return conductor (82) of the first loop (8) are interconnected by an electrical connection (83), - the electrical conductor go (91) and the electrical conductor return (92) ) of the second loop (9) are interconnected by an electrical connection (93), the electrical return conductor (82) of the first loop being connected to the electrical conductor go (91) of the second loop by an electrical connection (94).

5 - endocavitary probe according to claim 4, characterized in that the loops (8, 9) are carried by a rigid cylindrical spacer (15) having bores (16) opening for the passage of electrical conductors back and forth, the spacer (15) being provided at its ends with a proximal disc (17) and a distal disk (18) for supporting the electrical connections.

6 - endocavitary probe according to claim 4 or 5, characterized in that each loop (8, 9) has a length of the order of 60 mm and a width of the order of 6 mm.

7 - endocavity probe according to claim 5, characterized in that the proximal disks (17) and distal (18) form printed circuits for fixing and connecting electronic components for tuning, adaptation and active decoupling of the sensor . 8 - endocavity probe according to one of claims 1 to 7, characterized in that the loops (8, 9) are surrounded by a spacer envelope (30) between the loops and the zone of interest which has a thickness of between 1 and 2 mm.

9 - endocavitary probe according to one of claims 1 to 8, characterized in that it comprises a disposable sleeve (31) enveloping the distal end of the body to the proximal end of the body.

10 - endocavitary probe according to claims 5 to 9, characterized in that the spacer casing (30) is formed by a layer of non-magnetic material covering the spacer and / or the disposable sleeve (31). 11 - endocavity probe according to claim 9 or 10, characterized in that the disposable sleeve (31) is held in position on the body at its distal and proximal ends by means of abutments (36, 38) respectively distal and proximal.

12 - endocavity probe according to one of claims 7 to 11, characterized in that the disposable sleeve (31) comprises a conduit (33) for filling a balloon formed by a portion of the disposable sleeve, the conduit being externally connected to a inflation balloon (35). 13 - endocavity probe according to claim 1, characterized in that the proximal end (5) of the body (2) is provided with a connecting piece (25) for a protective tube (26) of the sensor connection cable radio frequency.

14 - Endocavity probe according to one of claims 9 to 13, characterized in that it comprises a proximal abutment (40) threaded and fixed on the disposable sleeve (31).