Method and apparatus for positioning a surgical instrument

Presented are methods and apparatus for delivering a surgical instrument to a treatment site within the body of a subject, enabling accurate placement of surgical tools in areas not directly visible to a surgeon during a surgical procedure, while reducing or eliminating need for real-time imaging modalities to guide placement of those surgical tools. A treatment tool is guided to a treatment site by placing a guiding element at a reference site within a body of a subject, the reference site having a known spatial relationship to the treatment site, and utilizing a positioning tool to guide a treatment tool to a locus so positioned with respect to that guiding element that the spatial relationship between that guiding element and that locus is substantially similar to the spatial relationship known to exist between the reference site and the treatment site, thereby positioning the treatment tool substantially at the treatment site. Methods and apparatus for treatment of Benign Prostate Hyperplasia are also presented.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to methods and apparatus for delivering a surgical instrument to a treatment site within the body of a patient. More particularly, the present invention serves to simplify surgical procedures for treating a variety of ailments, by enabling accurate placement of surgical tools in areas not directly visible to a surgeon during a surgical procedure, while reducing or eliminating need for real-time imaging modalities to guide placement of those surgical tools. Hence, the present invention finds uses in, for example, interventional cardiology, interventional gastrology, interventional urology, interventional gynecology, endoscopy and laparoscopy, as well as other medical disciplines.

Minimally-invasive surgery has become increasingly important in recent years. Surgical treatments which once required major surgical opening of body cavities, merely to provide a surgeon with access to a desired treatment site, are now increasingly operable utilizing what is known in the art as “minimally-invasive” surgical procedures, wherein surgical tools are introduced into the body through small openings or through naturally occurring body conduits, and thence are navigated to a treatment site where they are used to perform a therapeutic act. Minimally-invasive procedures minimize trauma to the body resulting from the process of delivering surgical tools to a desired intervention site, and avoid much of the damage, at loci distant from the desired treatment site, which once accompanied most surgical procedures. Damage which once endangered patients, engendered complications, increased mortality, caused discomfort and suffering, caused extended hospitalization, and led to long and complex periods of recuperation, can now largely be avoided in many cases.

Minimally-invasive procedures are, however, by their nature, procedures wherein the surgeon has limited ability to directly observe what he is doing. Surgical tools are manipulated from outside the body, yet perform their work inside the body. Tools designed to navigate the length of body conduits, endoscopes for example, are typically provided with electronic cameras to enable the surgeon to observe the treatment site from within the body conduit.

Delivering a surgical tool to a treatment site not located within a body conduit, however, is more complex. Typically, external imaging modalities such as CT, Ultrasound, Fluoroscope, static x-rays, or MRI must be used to steer the surgical tool to its treatment site. Yet, use of such imaging modalities during a surgical procedure is often complex and in some cases quite difficult. Each known imaging modality presents certain disadvantages: extended periods of fluoroscopy, for example, require extended exposure to pathogenic x-rays. Use of MRI in the operating room, for another example, comports restrictions on the types of surgical equipment that can be utilized during MRI operation.

There is thus a widely recognized need for, and it would be highly advantageous to have, a device and method for delivering a surgical tool to a treatment site, or for confirming the position a surgical tool at a treatment site, which method and device obviate the need for, or reduce dependence on, use of imaging modalities during treatment.

Benign Prostate Hyperplasia, or “BPH”, which affects a large number of adult men, is a non-cancerous enlargement of the prostate. BPH frequently results in a gradual squeezing of the portion of the urethra that traverses the prostate, also known as the prostatic urethra. Squeezing of the prostatic urethra causes patients to experience a frequent urge to urinate because of incomplete emptying of the bladder, and a burning sensation or similar discomfort during urination. The obstruction of urinary flow can also lead to a general lack of control over urination, including difficulty initiating urination when desired, as well as difficulty in preventing urinary flow because of the residual volume of urine in the bladder, a condition known as urinary incontinence. Left untreated, the obstruction caused by BPH can lead to acute urinary retention (complete inability to urinate), serious urinary tract infections and permanent bladder and kidney damage.

Most males will eventually suffer from BPH. The incidence of BPH for men in their fifties is approximately 50% and rises to approximately 80% by the age of 80. The general aging of the United States population, as well as increasing life expectancies, is anticipated to contribute to the continued growth in the number of BPH sufferers.

Patients diagnosed with BPH generally have several options for treatment: watchful waiting, drug therapy, surgical intervention, including transurethral resection of the prostate (TURP), laser assisted prostatectomy and new less invasive thermal therapies.

Currently, of the patients suffering from BPH, the number of patients who are actually treated by surgical approaches is approximately 2% to 3%. Treatment is generally reserved for patients with intolerable symptoms or those with significant potential symptoms if treatment is withheld. A large number of the BPH patients delay discussing their symptoms or elect “watchful waiting” to see if the condition remains tolerable.

Thus, there is thus a widely recognized need for, and it would be highly advantageous to have, a device and method simplifying therapeutic intervention for relief of BPH, thereby making the procedure more attractive to potential patients and less complex and expensive for health providers, potentially resulting in a substantial increase in the number of BPH suffers who elect to receive interventional therapy.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a method for delivering a treatment tool to a treatment site within the body of a subject in need thereof, the method comprising placing a guiding element at a reference site being at a first distance from the treatment site, the treatment site being in a first direction from the reference site; and utilizing a positioning tool to guide a treatment tool to a locus so positioned that a second distance, from the guiding element to the locus, is substantially similar to the first distance, and a second direction, from the guiding element to the locus, is substantially similar to the first direction from the reference site to the treatment site, thereby positioning the treatment tool substantially at the treatment site.

According to further features in preferred embodiments of the invention described below, the positioning tool is a mechanical device operable to position the treatment tool at the second distance from the guiding element and in the second direction from the guiding element, or an electro-mechanical device operable to position the treatment tool at the second distance from the guiding element and in the second direction from the guiding element, or a position-reporting device operable to report distance and direction from the guiding element to the treatment tool, thereby providing information enabling a surgeon to position the treatment tool at a the second distance from the guiding element and in the direction from the guiding element.

According to further features in preferred embodiments of the invention described below, the method further comprises using a catheter to place the guiding element at the reference site. Preferably the guiding element is integrated with the catheter. Preferably the reference site is a selected portion of a natural body conduit such as a urethra, a blood vessel, a bronchial tube, an intestine, or a colon.

Preferably 17 the positioning tool comprises a template having an aperture sized and shaped to permit passage of the treatment tool. The aperture may be sized and shaped to orient the treatment tool in a predetermined direction, which may be perpendicular to the template. Preferably the template comprises a plurality of apertures, each aperture sized and shaped to permit passage of a treatment tool.

Preferably the guiding element is a guiding segment which is substantially straight and has a length in excess of 1 cm.

Preferably, the method further comprises orienting the template to be perpendicular to a long axis of the guiding segment.

Preferably, the catheter comprises a plurality of joints lockable at fixed angles, or a plurality of variable joints joining rigid segments, each of the variable joints is operable to report an angle at which segments adjacent thereto are joined.

The method may further comprise orienting the template with respect to the guiding segment by attaching the template to the catheter at an angle calculated as a function of a sum of the reported angles of the plurality of variable joints.

The method may further comprise orienting the plane of the template by selecting a template position which minimizes a signal, received at a sensor mounted on the template, which signal originates at a signal transmitter proximate to the guiding segment.

The method may further comprise centering the template with respect to the guiding segment by selecting a template position which equalizes strengths of signals received at a plurality of sensors monitored on the template, which signals originate at a signal transmitter proximate to the guiding segment.

According to another aspect of the present invention there is provided a method for treating tissue at a treatment site within the body of a subject, comprising delivering a treatment tool to a treatment site within the body of a subject, by placing a guiding element at a reference site at a first distance from the treatment site, the treatment site being in a first direction from the reference site; and utilizing a positioning tool to guide a treatment tool to a locus so positioned that a second distance, from the guiding element to the locus, is substantially similar to the first distance, and a second direction, from the guiding element to the locus, is substantially similar to the first direction, thereby positioning the treatment tool substantially at the treatment site; and utilizing the treatment tool to treat the tissue at the treatment site.

According to further features in preferred embodiments of the invention described below, the method further comprises utilizing the treatment tool to ablating prostate tissue. The treatment site may be a volume of tissue situated less than a selected maximum distance from the guiding element and more than a selected minimum distance from the guiding element. The guiding element may be a guiding segment having a length in excess of 1 cm.

According to yet another aspect of the present invention there is provided a method for treating Benign Prostate Hyperplasia by ablating prostate tissue proximate to, but not contiguous to, a prostatic urethra, comprising:

a) utilizing a catheter to introduce into a prostatic urethra a substantially straight guiding segment oriented in a first orientation;

b) orienting a template having a plurality of apertures spaced around a central point, so that the template is perpendicular to the first orientation;

c) centering the template with respect to the guiding segment in such a way that a line, in the first orientation, extending from the guiding segment to the template, would intersect the template at the central point;

d) deploying a plurality of treatment tools through the plurality of apertures; and

e) utilizing at least some of the treatment tools to ablate tissue of the prostate, thereby treating Benign Prostate Hyperplasia by ablating prostate tissue proximate to, but not contiguous to, a prostatic urethra.

According to still another aspect of the present invention there is provided an apparatus for delivering a treatment tool to a treatment site within the body of a subject, comprising:

a) a guiding element operable to be placed at a reference site at a first distance from the treatment site, the treatment site being in a first direction from the reference site; and

b) a positioning tool operable to guide a treatment tool to a locus so positioned that a second distance, from the guiding element to the locus, is substantially similar to the first distance, and a second direction, from the guiding element to the locus, is substantially similar to the first direction from the reference site to the treatment site.

According to further features in preferred embodiments of the invention described below, the positioning tool is a mechanical device operable to position the treatment tool at the second distance from the guiding element and in the second direction from the guiding element, or an electro-mechanical device operable to position the treatment tool at the second distance from the guiding element and in the second direction from the guiding element, or a position-reporting device operable to report distance and direction from the guiding element to the treatment tool, thereby providing information enabling a surgeon to position the treatment tool at a the second distance from the guiding element and in the direction from the guiding element.

According to further features in preferred embodiments of the invention described below, the apparatus comprises a catheter operable to place the guiding element at the reference site. Preferably the guiding element is integrated with the catheter. Preferably the apparatus further comprises a treatment tool operable to ablate tissue. Preferably the guiding element is a guiding segment having a length in excess of 1 cm. Preferably the positioning tool comprises a template having an aperture sized and shaped to permit passage of the treatment tool. The aperture may be sized and shaped to orient the treatment tool in a predetermined direction, preferably perpendicular to the template.

Preferably, the template comprises a plurality of apertures, each aperture sized and shaped to permit passage of a treatment tool.

Preferably, the guiding element is a guiding segment which is substantially straight and has a length in excess of 1 cm.

Preferably the apparatus further comprises orienting means for orienting the template in an orientation perpendicular to a long axis of the guiding segment.

According to further features in preferred embodiments of the invention described below, the catheter comprises a plurality of joints lockable at fixed angles, or a plurality of variable joints joining rigid segments, each of the variable joints is operable to report an angle at which segments adjacent thereto are joined.

The apparatus may further comprise a servomotor operable to orient the template perpendicularly to the guiding segment. The servomotor may be operable to orient the template with respect to the catheter at an angle calculated as a function of a sum of the reported angles of the plurality of variable joints.

Preferably, the guiding element comprises a signal transmitter and the template comprises a signal sensor. The signal sensor may be operable to report a signal whose strength is a function of an angle of orientation of the template with respect to the guiding segment. The signal sensor may be operable to report a signal whose strength is at a minimum when the template is perpendicular to the guiding segment.

The apparatus may further comprise a plurality of sensors operable to receive a signal generated by the signal transmitter. Preferably, the plurality of sensors is operable to report substantially equal signal strengths when the template is both perpendicular to, and centered with respect to, the guiding element.

According to further features in preferred embodiments of the invention described below, the catheter is operable to be flexible, and also operable to be stiff.

According to further features in preferred embodiments of the invention described below, the catheter comprises an inflation lumen, and the catheter is operable to be rendered stiff by introduction of pressurized fluid into the inflation lumen. The catheter may be operable to be stiffened by insertion of an insertable stiffening element.

According to further features in preferred embodiments of the invention described below, the guiding element comprises a transmitter. Preferably, the guiding element comprises a sensor operable to detect a signal transmitted by the signal transmitter and reflected from a treatment tool. Alternatively, a treatment tool comprises a sensor operable to detect a signal transmitted by the transmitter.

According to further features in preferred embodiments of the invention described below, the guiding element comprises a sensor, and a treatment tool comprising a transmitter, the sensor is operable to detect a signal transmitted by the transmitter.

According to further features in preferred embodiments of the invention described below, the apparatus further comprises a display system operable to receive information from said sensor, and a controller operable to calculate movements required to deliver said treatment tool to said treatment site, based on information provided by said sensor.

According to an additional aspect of the present invention there is provided an apparatus for delivering a treatment tool to a treatment site in the body of a subject, comprising:

b) a catheter which comprises a guiding element designed and constructed to be rendered visible by the imaging system, and to appear distinct from other objects imaged by the imaging system; and

c) a treatment tool which comprises a distal portion designed and constructed to be rendered visible by the imaging system, and to appear distinct from other objects imaged by the imaging system.

The present invention successfully addresses the shortcomings of the presently known configurations by providing a method and apparatus for delivering a treatment tool to a treatment site within the body of a patient, without requiring use of imaging modalities during the surgical operation.

The present invention further successfully addresses the shortcomings of the presently known configurations by providing methods and apparatus for treating Benign Prostate Hyperplasia which are simpler and less costly to execute than are the methods of prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a method and apparatus for positioning a surgical tool at a treatment site within the body of a patient. Specifically, the present invention can be used during a minimally-invasive surgical procedure to direct a surgical treatment tool to a desired treatment site, for diagnosis or for surgical treatment at that site, while reducing dependance on real-time use of imaging modalities during positioning of the tool.

The principles and operation of a surgical treatment tool placement system according to the present invention may be better understood with reference to the drawings and accompanying descriptions.

To enhance clarity of the following descriptions, the following terms and phrases will first be defined:

The phrase “treatment site” is used herein to refer to a tissue, organ, or portion of an organ that a surgeon desires to treat during a surgical procedure. For example, in the case of a tumor that a surgeon desires to ablate, the tumor itself and possibly a portion of surrounding tissue, at the discretion of the surgeon, would be the “treatment site”.

The phrases “surgical tool” and “treatment tool” are used herein to refer to any instrument or set of instruments used by a surgeon to diagnose or to treat tissues at the treatment site. Typically, a treatment tool is an instrument designed to transfer energy at the treatment site, such as a needle-shaped cryoprobe operable to cool tissues to cryoablation temperatures, or a probe capable of dispensing radio-frequency or microwave radiation, or a probe operable to ablate tissues through electrical heating or other forms of heating. Yet the phrase “treatment tool” is not limited to instruments for energy transfer. A diagnostic tool such as a short-distance imaging tool (e.g., local MRI) is a “treatment tool” as that phrase is used herein.

The phrase “reference site” is used herein to refer to a site within a patient's body, which site has a known spatial relationship to a treatment site within that body. Preferably, a reference site is also a site accessible to easy access from outside the body, through a body conduit for example. Thus, for example, the portion of a urethra passing through an enlarged prostate might be an appropriate reference site for an operation intended to reduce prostate volume, since that portion of the urethra has a fixed and known spatial relationship to the prostate through which it passes.

The phrase “guiding element” is used herein to refer to an object which, according to an embodiment of the present invention, is placed at (or within) a reference site, and which may be used, possibly in conjunction with additional tools, to guide a treatment tool to a treatment site, position a treatment tool at a treatment site, or verify the positioning of a treatment tool at a treatment site.

The phrase “target locus” is used herein to refer to a spatial locus, a volume defined by its spatial relationship to an installed guiding element, towards which a treatment tool is directed.

As used herein the terms “about” and “substantially similar” refer to ±10% preferably, ±5%, more preferably, ±2%, most preferably, ±0.1-1.0%.

An embodiment of the present invention involves guiding a treatment tool to a treatment site by

a) placing a guiding element at a reference site within a body of a patient, the reference site having a known spatial relationship to the treatment site, and

b) utilizing a positioning tool to guide a treatment tool to a locus so positioned with respect to that guiding element that the spatial relationship between that guiding element and that locus is substantially similar to the spatial relationship known to exist between the reference site and the treatment site,

thereby positioning the treatment tool substantially at the treatment site.

Of course, in typical use, having guided a treatment tool to a treatment site, a surgeon will generally activate that treatment tool to produce a therapeutic effect, such as ablation of tissue, at that treatment site.

As described in the following, the positioning tool is preferably a mechanical, electro-mechanical, or electronic device for positioning the treatment device at a selected distance from the guiding device and in a selected direction from the guiding device. Alternatively, the positioning tool may be a mechanical, electromechanical or electronic device for reporting the position of a treatment tool with respect to the guiding device, thereby providing information which enables a surgeon to position the treatment tool at a selected distance and position with respect to the guiding element.

In a variety of preferred embodiment described in detail below, the guiding element is mounted within a catheter, which catheter is used to deliver the guiding element to a reference site, which reference site is a selected site within a body conduit.

In the following, a variety of apparatus and methods are presented, which serve to direct a treatment tool to a locus defined with reference to a guiding element placed at a reference site, thereby delivering that treatment tool to a treatment site which a surgeon desires to treat.

Attention is now drawn toFIG. 1, which is a simplified schematic of an apparatus for delivering a treatment tool to a treatment site, according to an embodiment of the present invention.FIG. 1presents an organ112having a treatment site110, such as a tumor or other pathological tissue, which a surgeon desires to treat. A selected portion of a body conduit114passing in proximity to treatment site110is selected as a reference site125, and a catheter120is passed through conduit114. Reference site125is a site having a known spatial relationship to treatment site110, which spatial relationship may have been ascertained by inspection of images obtained, prior to the operation, through use of various well-known imaging modalities. The known spatial relationship between reference site and treatment site may also be obtained from a priori knowledge, e.g., of well-known anatomical structures.

A guiding element130, or alternatively a plurality of guiding elements130, mounted on or within catheter120, is caused to advance within conduit114until guiding element130is positioned at reference site125. Thus positioned, guiding element130has a known spatial relationship with treatment site110. Imaging modalities or various other means, some of which are mentioned in the following, may be used to accurately position guiding element130at reference site125.

Alternatively, guiding element130may be caused to move through conduit114until positioned at some proximity to treatment site110, at which time imaging modalities or other means may be utilized to determine the exact position of guiding element130, and the thus determined position of guiding element130is then designated as reference site125.

In other words, either an optimal reference site125is selected and guiding element130is maneuvered to that site125, or alternatively an approximate reference site is selected, guiding element130is maneuvered into that approximate position, and imaging modalities or other means are used to determine the position of guiding element130, which is thereafter considered to be reference site125. In either case, reference site125has a known spatial relationship to desired treatment site110, and guiding element130is positioned at reference site125.

A positioning tool150may then be used to guide a treatment tool140, optionally having a distal treatment head142, towards and into a target locus160having a selected positional relationship162with guiding element130, thereby positioning treatment head142of treatment tool140at treatment site110.

Alternatively, if treatment tool140has been positioned by other means within the body of a patient, positioning tool150may be used to confirm that treatment head142of treatment tool140is correctly positioned at treatment site110.

In a preferred procedure, a surgeon selects as reference site125a selected portion of a natural body conduit. A surgeon's knowledge of the body's natural conduit system (including lymphatic & blood vessels, arteries, veins, respiratory tracts & breathing system, gastro-intestinal tracts, urethral tracts etc.) permits him to select as reference site an easily reached part of the body whose anatomy is well understood. The spatial relationship between a selected reference site and a desired treatment site may be ascertained based on generally known physiology, and based on statistical studies of patient physiologies. Alternatively or additionally, the spatial relationship between reference site125and treatment site110pertaining in a particular patient's case may be ascertained based on studies of that patient's specific pathology, determination being made according to studies based on imaging modalities such as ultrasound, x-ray, MRI, CT, utilized prior to the surgical procedure. Alternatively or additionally, knowledge of the spatial relationship between the selected reference site and the desired treatment site may be further ascertained based on physiological information gleaned and/or physiological measurements made during the course of a surgical procedure.

Reference site125is preferably a selected portion of a naturally occurring body conduit such as conduit114. Consequently, it is generally possible to introduce guiding element130into that body conduit114, and to advance guiding element130along conduit114to a position selected as reference site125for the operation. In a preferred embodiment conduit114is accessible through the body's natural entrances, such as the mouth, the urethra, or the rectum. Alternatively, conduit114may be accessible through a percutaneous intervention giving access to the blood vessel system, or via endoscopic or limited open surgery.

In a recommended procedure, a surgeon will select as reference site a portion of an accessible conduit114that is in proximity to a desired treatment site110. Preferably, a selected conduit114will have a well-understood spatial relationship to desired treatment site110. For example, in treatment of Benign Prostate Hyperplasia (“BPH”), a well-chosen conduit114would be the urethra, since the urethra is accessible through an existing natural opening in the body, and passes within an enlarged prostate whose volume is to be reduced in a surgical procedure. In this example, an appropriate reference site would be a segment of the urethra located within the prostate. It is recommended that, for various reasons of familiarity and efficiency, a surgeon will select a consistently defined reference site for each performance of a particular type of surgical procedure. Thus, selection of a defined portion of a urethra passing through a prostate as reference site125might be standard procedure for treatment of BPH, according to a preferred embodiment of the present invention.

Although, for each patient, knowledge of the spatial relationship pertaining between a selected reference site and a desired treatment site may be gleaned from standard imaging modalities such as x-ray and fluoroscope, ultrasound, MRI, and CT, reasonably accurate spatial information may in many cases also be derived from generally known physical characteristics of human anatomical systems and their well-known pathologies. For example, in treating BPH, once a diagnosis is established, basic information about the size and location of volumes to be ablated may easily be defined in terms of the spatial relationship between those volumes to be ablated, and the position of a segment of the urethra passing through the prostate.

Attention is now drawn toFIG. 2A, which is a simplified schematic of a prostate requiring treatment for BPH, showing an elongated guiding element, according to an embodiment of the present invention.

FIG. 2Apresents an enlarged prostate200traversed by a urethra202. A catheter120is passed through urethra202. Catheter120comprises a guiding element130. In the following, a guiding element130of shaped to be long and narrow will be termed a guiding segment132. Guiding segment132extends between guiding segment proximal point134and guiding segment distal point136. In treatment for BHP, a recommended length for guiding segment132is between 0.5 cm and 8 cm, and most preferably about 2-5 cm. Optimal guiding segment length for a particular patient can be measured using a cystoscope, and placement of guiding segment132centered within the prostate portion of the urethra can be easily accomplished based on cystoscopic measurements of distances from the penis urethra entrance to the entrance and exit points of the portion of the urethra which passes through the prostate. Location of the distal exit of the urethra from within the prostate can also accurately be measured by inserting a balloon catheter into the bladder, inflating the balloon, and pulling the catheter backwards until its movement is blocked by the inflated balloon encountering the entrance of the urethra into the bladder.

FIG. 2Apresents a case in which it is possible to predetermine a target site for treatment, a reference site, and a spatial relationship between the two, with predetermination being based on generally known physiological data, including statistically established probabilities of various physical relationships, and further based on typical treatment scenarios, and further based on known patient-specific information. Thus, in a relatively simple example of treatment of BPH (presented in further detail below), where the goal of the operation is to ablate tissue contained within the prostate and not extending beyond the boundaries of the prostate, to avoid damage to anus, nerves, blood vessels and other organs external to the prostate, while also avoiding ablation of tissue close to the urethra, to avoid damage to the urethra, a treatment site definition110may be predetermined, in the abstract, as a volume of points whose distance from the urethra is greater than a selected minimum distance138, and less than a selected maximum distance139, from a selected section of the prostatic urethra. Thus, in treatment for BHP and in similar embodiments of the present invention, selection of treatment site and reference site, and determination of the appropriate distance between the two, may be largely or entirely based on knowledge of the anatomic structure of the organ and of the effective range of influence of a selected therapeutic surgical tool.

For example, in the treatment of BPH the defined treatment site may be simply a hollow cylinder having a constant parallel distance from guiding segment132, along its length. Such an operation is facilitated by use of a urethral catheter having straightening features used to straighten the urethra, thereby much simplifying the organ geometry and facilitating use of parallel insertion of ablation needles, in parallel to the direction of the urethra and at a predetermined distance therefrom, as a treatment method. Examples of catheters having such straightening features are presented hereinbelow.

Alternatively, a treatment locus may have any other shape or orientation, so long as its placement and orientation with respect to the guiding segment is known.

Attention is now drawn toFIG. 2B, which is a simplified schematic of a prostate requiring treatment for BPH, showing an elongated guiding element and a positioning device, according to an embodiment of the present invention.

FIG. 2Bpresents an enlarged prostate200requiring treatment for BPH. In addition to features common toFIGS. 2A and 2B,FIG. 2Bpresents a positioning tool150, operable to position a treatment tool140with respect to a treatment site110. As may be seen in greater detail inFIGS. 3-8, positioning tool150may be embodied as a template230formed with a set of apertures240sized and shaped to permit passage of one or more treatment tools140. Apertures240are such as to orient treatment tools140passed therethrough in determined directions. In a currently preferred embodiment, all treatment tools140passed through an aperture240of template230are directed in parallel, and are held perpendicular to template230.

Utilization of template230is shown in greater detail inFIGS. 3-8.

Attention is now drawn toFIG. 3, which presents a positioning tool150embodied as a template230, according to an embodiment of the present invention. Directional lines260indicate the direction of orientation which will be imposed on any treatment tool140(not shown) passed through an aperture240of template230. Guiding segment132is shown in a random orientation with respect to template230, as shown by guiding segment directional line133. For simplicity of exposition catheter120on which guiding section132is mounted is not shown inFIGS. 3-8.

Attention is now drawn toFIGS. 4 and 5, which represent steps in a process of aligning guiding segment132and template230with respect to each other, according to an embodiment of the present invention.FIG. 4shows a guiding segment directional line133, representing the orientation of guiding segment132. InFIG. 4template230is reoriented with respect to guiding segment132in such a way that guiding segment directional line133points to the center of template230. InFIG. 5template230is reoriented with respect to guiding segment132in such a way that guiding segment directional line133is perpendicular to template230. The steps shown inFIGS. 4 and 5may be undertaken in either order, or simultaneously.FIGS. 4 and 5illustrate a process by which template230is oriented with respect to guiding segment132in such a way that guiding segment directional line133, extending the direction of guiding segment132, when guiding segment132is installed in a selected reference site such as in the prostatic urethra, is so oriented as to intersect substantially near the center of template230, and is substantially perpendicular thereto.

Attention is now drawn toFIG. 6, which presents a treatment tool passed through an aperture of a template oriented with respect to a guiding segment installed at a reference site, according to an embodiment of the present invention.

FIG. 6presents a treatment tool140having a distal treatment head142, introduced through an aperture240of template230. Guiding segment132has been centered with template230and been made perpendicular to template230, as shown inFIGS. 4 and 5. Treatment tool140is forced to be perpendicular to template230by virtue of the form of apertures240, which are designed and constructed for this purpose. Thus, consequently, treatment tool140is held necessarily substantially parallel to guiding segment132.

Attention is now drawn toFIG. 7, which presents a plurality of treatment tools held parallel to guiding segment132, according to an embodiment of the present invention. InFIG. 7each treatment tool140is shown surrounded by an ablation volume144, that is, a volume of tissue whose ablation is assured by activation of each respective treatment tool140.

Attention is now drawn toFIG. 8, which presents the configuration shown inFIG. 7, as seen from an “end-on” perspective. It may be seen fromFIG. 8that ablation volumes144surround or partially surround, but do not intersect with, guiding element132. Note also that, as shown inFIGS. 2A and 2B, guiding element132is placed within prostatic urethra202, consequently the ablated volume of tissue surrounds, but does not include, prostatic urethra202. As noted above, the operation depicted inFIGS. 7 and 8is facilitated by use of a stiffening element accompanying guiding segment132, which assures that the portion of prostatic urethra defined as reference site125is substantially straight.

Note further distance “L” as it appears inFIGS. 2B,6,7, and8. Distance “L” is the straight-line distance from template230to guiding segment proximal point134as shown inFIG. 2B. If active treatment heads142of treatment tools140extend in length approximately the distance between guiding segment proximal point134and guiding segment distal point136, and if treatment tools140are extended through template230to a distance such that the proximal limit of their active treatment heads142extends beyond template130at a distance substantially equal to distance “L”, then the ablation volume created by activation of treatment tools130as shown inFIGS. 7 and 8will result in an ablation volume which substantially surrounds guiding segment132, and which has proximal and distal extremes substantially equidistant from template132, at a distance corresponding to the proximal and distal extreme points of guiding segment132.

Note further that, if guiding segment132is placed within prostatic urethra202and does not extend beyond the proximal and distal extremes of prostate200, then ablation volumes144, as shown byFIGS. 7 and 8, will be contained within prostate200. Ablation of ablation volumes144as shown will ablate prostate tissues, as required for treatment of BPH, yet will harm neither the prostatic urethra nor the nerve bundles, bladder, anus, nor other structures which are proximate to prostate200.

Thus,FIGS. 2B-8illustrate a device and method whereby a surgeon may successfully ablate prostate tissue to treat BPH, without requiring use of imaging modalities during an ablation procedure.

To summarize the procedure as outlined inFIG. 2B-8, a surgeon places a catheter which comprises a guiding segment within a prostatic urethra (which constitutes a reference site), orients template230so as to centered on and perpendicular to that guiding segment, then uses template230to guide one or more treatment tools140to an appropriate position and depth, at a selected distance from guiding segment132. Having thus guided treatment tools140to that defined locus, the surgeon may used treatment tools140to treat tissues at that locus, confident, without need of direct observation, that those treatment tools140are indeed positioned at a desirable, and expected, treatment site.

It is to be noted that although the discussion ofFIGS. 2A-8related particularly to treatment of BPH, the apparatus and method presented hereinabove are applicable to a wide variety of treatment applications. In particular, a reference site other than the prostatic urethra may be used, and treatment sites may be identified according to any manner of accepted medical practice, for example by inspection of images created by any one of a variety of imaging modalities.

As noted, it is a requirement of the method presented byFIGS. 2B-8that template230be appropriately oriented with respect to guiding segment132. Various techniques and devices for orienting template230with respect to guiding segment132will be presented in the following.

It is noted that alternate constructions of template230are possible. In particular, so long as some mechanism is provided to relate the distance and angular direction from a template surface to a guiding element installed at a reference site to the distance and angular direction from that template surface to a treatment site, the essential functionality of template230is preserved.

Attention is now drawn toFIG. 9, which presents a simplified schematic of an alternative construction of a positioning tool150, according to an embodiment of the present invention. An orientation tool260comprises two or more arms262A and262B, at least some of which are preferable of variable length, arms262A and262B forming a variable angle between them. Angular gradations264are provided for measuring the variable angle between arms262A and262B, and length gradations266are provided for indicating a selected variable length setting for at least one of the arms. It will be clear to one skilled in that art that orientation tool260may be used in a manner similar to template230, to deliver a distal treatment head142of a treatment tool140to a treatment site110, given a known distance of a guiding element130from orientation tool260, and a known spatial relationship between guiding element130and selected treatment site110. Simple trigonometric functions will provide answers as to the appropriate orientation of orientation tool260, a desired angle between arms262, and an appropriate length and for extending treatment tool140. Thus, placing guiding element130at reference site125, and knowing a (predetermined or observed) spatial relationship between reference site125and treatment site110, orientation tool260may first be lined up so that arm262A points toward guiding element130, then trigonometric functions used to determine a required angular setting of the angle between arms262, and to determine an appropriate length setting for arm262B. Placing a treatment tool140in arm262B, setting the desired angular setting between arms262, and then advancing treatment tool140by gradually extending arm262B until the calculated depth is reached, will have the effect of delivering distal treatment head142of treatment tool140to treatment site110.

InFIG. 9, arms262are presented as simple mechanical arms, and simple visual gradations264and266are provided to enable measurements of angle and of length. It will be clear to one skilled in the art that alternative constructions are possible, including use of an electro-mechanical or electronic angular measurement tool284, an electro-mechanical or electronic length measurement tool288, an automatic or semiautomatic controller190for executing trigonometric calculations, and a servo-motor system192, optionally controllable by controller190, to modify the angular separation of arms262and to individually shorten or lengthen arms262, as required, according to trigonometric calculations, to deliver treatment tool140to treatment site110.

Attention is now drawn toFIGS. 10-21, which present further details of devices and methods for orienting template230with respect to guiding segment132. As mentioned hereinabove, operation of the apparatus described inFIGS. 2B-8and of the apparatus described inFIG. 9requires that a template230or other positioning tool150be oriented so as to have a know orientation (preferably, centered and perpendicular, as shown inFIGS. 4 and 5) with respect to guiding element130. Yet, guiding element130is typically installed at a site inside the body, and is not directly visible to an operator.FIGS. 10-21provide various devices and methods for orienting template230with respect to guiding element130, which devices and methods do not require use of imaging modalities for their operation.

Attention is drawn toFIG. 10, which presents a simplified schematic of a multi-joint locking catheter250, according to an embodiment of the present invention. Multi-joint locking catheter250, which comprises a guiding element130formed as an extended guiding segment132, further comprises lockable joints260A and260B.

FIG. 10represents a first stage in the use of catheter250. During this first stage, joints260A and260B are free to move arbitrarily. Distal end252of catheter250is moveable as well. The resulting freedom of movement of the various parts of catheter250facilitates insertion of catheter250into a patient's urethra or into a similar body conduit. Flexibility of catheter250enables it to conform to the body's geometry during insertion.

Attention is now drawn toFIG. 11, which represents a second stage in use of multi-joint locking catheter250, according to an embodiment of the present invention. Rigidity and deterministic geometry are achieved by locking joints260A and260B, and by connecting catheter250to template230, at connecting joint270.

Attention is now drawn toFIG. 12, which represents a third stage in use of multi-joint locking catheter250, according to an embodiment of the present invention. Catheter250is now shown as connected to template230, but template230is not yet aligned perpendicularly to guiding segment130. Perpendicular alignment is the desired state, as shown and described hereinabove in the context of the discussion ofFIG. 5.

To achieve perpendicular alignment, guiding segment132is embodied as an electromagnetic field generator280, powered from either an external or an internal energy source (not shown). An electronic field sensor290, preferably mounted on template230, is capable of detecting an electromagnetic field generated by field generator280. As shown inFIG. 12, non-perpendicular orientation of template230with respect to field generator280(which is guiding segment132), is detectable as a component vector291of the detected field sensed by sensor290.

Attention is now drawn toFIG. 13, which represents a fourth stage in use of multi-joint locking catheter250, according to an embodiment of the present invention.FIG. 13differs fromFIG. 12in that template230has been rotated around joint270until detected component291of the field signal detected by sensor290disappears. Disappearance of component291of the detected signal indicates that sensor290, and with it template230, are perpendicular to field generator280embodied in guiding segment132. At this point joint270can be locked in place, and template230is fixed in perpendicular orientation to guiding segment132, as required for use of the device and method as generally described hereinabove inFIGS. 2B-8.

Attention is now drawn toFIG. 14, which presents an alternative configuration for achieving perpendicular orientation of template230with respect to guiding segment132, according to an embodiment of the present invention.

The alternative configuration presented byFIG. 14is mechanical in nature; it requires no electronic components. As will be clear from inspection ofFIG. 14, angles α, β, and δ determine the angle of template230with respect to the orientation of guiding segment132. If the sum of α, β, and δ is 90°, then template230is perpendicular to guiding segment132, and treatment tools passed through guiding apertures240of template230will be parallel to guiding segment132. Locking joints262A,262B, and270into a configuration whose sum is 90° can be achieved in various ways. The simplest manner of ensuring that joints262A,262B, and270will lock only into the required 90°-sum configuration is to enable each joint to lock only into a single angle, choosing of course angles whose sum is 90°. Alternative constructions include that of allowing the above-named joints each to lock in a plurality of possible positions, providing a visible indication of each selected position, and depending on an operator to select an appropriate combination of joint locking angles. Yet another possible configuration is to allow two of the joints to lock in multiple or indeed in random positions, to provide those joints with sensors292and294able to report their positions to a controller290, and to provide a third joint (e.g., joint270) with a servo-motor296, controllable by controller290, and which automatically positions joint270at an angle which brings the sum of angles α, β, and δ to 90°.

Attention is now drawn toFIG. 15, which presents yet another configuration for orienting a template230with respect to a guiding element130, according to an additional embodiment of the present invention.

The configuration presented byFIG. 15requires no physical contact between catheter120, containing guiding element130, and template230. IfFIG. 15is compared toFIG. 13it may be seen that joints270,262A, and262B are absent.

In the configuration shown inFIG. 15an adjustable base310is provided to support template230and to optionally lock template230in a selected position. In this embodiment, a plurality of sensors290(preferably four sensors, as will be shown hereinbelow inFIG. 16) are mounted on template230, and serve to enable an operator to orient template230to be centered and perpendicular to guiding segment132, without requiring a physical connection between template230and catheter120.

Attention is now drawn toFIGS. 16A and 16B, which provide simplified additional views of template230, showing sensors290A,290B,290C, and290D mounted thereon, according to an embodiment of the present invention.

With reference to the embodiment presented byFIGS. 15,16A and16B, in a preferred mode of operation, alignment of template230proceeds in two steps.

First, template230is rendered perpendicular to guiding segment132using the techniques presented hereinabove with reference toFIGS. 12 and 13. Guiding segment132comprises a field generator280operable to create an electromagnetic field detectable by sensors290mounted on template230.FIG. 15shows that when template230is not perpendicular to guiding segment312, a vector component291can be found in electromagnetic signals detected by sensors290. Template230can be turned on various axes until component291of the field signals detected by sensors290disappears. Disappearance of component291of the detected signal indicates that sensors290, and with them template230, are perpendicular to field generator280, hence perpendicular to guiding segment132.

Referring now toFIG. 16A, at the stage of the process presented inFIG. 16A, template230has been rendered perpendicular to guiding segment132, as shown inFIG. 5, but has not yet been centered with respected to guiding segment132, as shown inFIG. 4.

Mark320indicates the point at which a line extending in the direction in which guiding segment132is oriented (that is, a line equivalent to guiding segment directional line133ofFIGS. 3-5) would intersect template230. As shown inFIG. 16A, when template230is perpendicular to the direction of guiding segment132, and field generator280radiates an electromagnetic signal, strength of that signal as detected by the various detectors290is a function of each detector's distance from point320. Thus, inFIG. 16A, detectors290A and290B detect strong signals (as shown by arrows330A and330B), whereas detectors290C and290D detect relatively weaker signals, as indicated by arrows330C and330D. In contrast, when template230is centered with respect to guiding element132, as shown inFIG. 16B, so that point320is equidistant from each of sensors290, detected signal strength of a field generated by generator280is equally strong at each of sensors290, as is shown in the figure by the equal lengths of arrows332A,332B,332C, and332D. Thus, a second step required to complete alignment of template230with guiding segment132, according to the embodiment presented byFIGS. 15,16A and16B, is simply to move template230in its own plane (template230being already perpendicular to guiding segment132as result of minimizing vector components291of signals detected by sensors290), until equal signal strengths are detected at each of sensors290.

It is noted that the process here described is one of tilting and sliding template230in response to received electromagnetic signals. It will be clear to one skilled in the art that addition of a control unit336operable to receive signal information from sensors290, to calculate an appropriate response, and to send commands to one or more servo motors340operable to title and to slide template230, will serve to automate the process here described.

Attention is now drawn toFIG. 17, which presents a side view of the detatched-template configuration ofFIGS. 15,16A, and16B, with template230perpendicular to, and centered with respect to, guiding section132. As discussed above, field generator280generates an electromagnetic signal from within guiding segment132, which signal is detected by sensors290. Equal signal strength is detected at each detector290when template230is properly aligned as previously explained. Under these circumstances, distance “L” may be calculated as a function of detected signal strength at sensors290, since the closer field generator280is to sensors290, the stronger their detected signal will be.

Attention is now drawn toFIG. 18, which is a simplified schematic of a flexible self-stiffening catheter during insertion into a urethra of a prostate, according to a further embodiment of the present invention.

InFIG. 18, a flexible self-stiffening catheter350having a proximal connection point352is design to be attachable to a template230or to any other form of positioning tool150. Initially flexible, catheter350can easily be inserted into a urethra and advanced towards and into a prostatic portion of a urethra.

Attention is now drawn toFIG. 19, which is a simplified schematic of catheter350in stiffened state. A pressurized fluid source360supplies a pressurized fluid362(gas or liquid) to an inflation lumen364running the length of catheter350. The walls of lumen364are preferably constructed of a material, such as thin metal or low compliance nylon, which assumes a pre-determined geometry when inflated. Inflating lumen364thus forces catheter350into a shape which conforms to a pre-determined geometry, which geometry includes a straight section370designed to fit within a prostatic urethra, and an external section372whose pre-determined geometry is designed to facilitate utilization of catheter350with template230, as generally described hereinabove, or with another form of positioning device150.

Straight section370incorporates a guiding element130. It is also noted that inflation of inflation lumen364forces section370to be straight, which forces the prostatic portion of the urethra to be straight, thereby greatly facilitating treatment of tissues surrounding that prostatic urethra.

Thus, a first effect of inflating inflation lumen364is to force a prostatic urethra, into which straight section370has been placed, into a straight linear orientation, thereby creating a desirable arrangement wherein that prostatic urethra is both straightened and in a known position. A second effect of inflating inflation lumen364is to force external section372into a pre-defined geometry which enables to calculate distance “L” and brings connection point352into a known sidewise displacement from the position and direction of straight section370. Fastening connecting point352to an appropriate joint a template230(not shown), at an appropriate known angle, then enables use of that template230to guide a plurality of treatment tools140(not shown) to desired loci alongside straight section370and at a pre-planned distance therefrom, for treatment of BPH, as has been described hereinabove.

Attention is now drawn toFIGS. 20 and 21, which present, in simplified schematic, two views of a flexible catheter having an insertable stiffening element, according to a further embodiment of the present invention.

As shown inFIG. 20, a flexible stiffenable catheter390comprises an external sheath392having a stiffener lumen394, and a stiffener396insertable into stiffener lumen394. The shape, purpose, and function of catheter390is identical to that of catheter350described hereinabove, with the difference that whereas catheter350is stiffened by inflation with a fluid, catheter390is stiffened, once catheter390has been appropriately inserted into a prostatic urethra, by insertion of stiffener396into lumen394, thereby straightening the prostatic urethra and bringing catheter390into a known pre-determined geometry, thereby permitting use of catheter390for guiding placement of a treatment tool to a treatment site, as described hereinabove.

Stiffener396is of rigid or semi-rigid construction, is of a known pre-determined shape, and, in a currently preferred construction, is hollow.

Attention is now drawn toFIG. 21, which presents a simplified schematic view of catheter390in stiffened configuration, with stiffener396inserted into lumen394.

Attention is now drawn toFIG. 22, which presents a simplified schematic of a treatment tool positioning apparatus, according to a further embodiment of the present invention.

InFIG. 22, treatment tool positioning apparatus400comprises a base402connected to a jointed arm410having a plurality of freely moving joints, represented inFIG. 22as joints420A and420B, and a guiding element130, which may be formed as an elongated guiding segment132. Guiding segment132may itself include one or more moveable joints420, designated420A,420B, etc.

Each joint420comprises a position sensor430, designated430A,430B, etc. Each position sensor430is capable of sensing the angular position of its associated joint, and of reporting the detected angles electronically, either by wire or by wireless digital transmission, to a controller440. Joint415, linking arm410to base402, is similarly equipped with a position sensor418, similarly capable of reporting the angular position of joint415.

Sensors415and420might, for example, be a variable resistances whose resistance to electric current is dependent on the angle of the joint. Alternatively, these sensors might be digital devices intermittently reporting their positions over a digital data line or a wireless link.

Given known lengths of arm segments between each joint, simple trigonometry may be used to calculate position and orientation of guiding element130with respect to base402. This calculation is preferably carried out automatically by controller440.

Given a known position of guiding element130relative to base402, and a known position of a treatment site110relative to guiding element130, one may easily calculate the position of treatment site110with respect to base402. Knowing the position of treatment site110with respect to base402, an operator, utilizing various methods well known in the art, may easily guide an independently moveable treatment tool460to treatment site110, where it may be used to diagnose or to treat body tissue. Treatment tool460may be implemented, for example, as a standard industrial robotic arm470controlled by controller440, and having an extensible therapeutic head472adapted to percutaneous introduction into the body of a patient.

Attention is now drawn toFIG. 23, which is a simplified schematic of a treatment tool positioning apparatus500incorporating an energy transmitter and an energy detector, according to a preferred embodiment of the present invention.

Apparatus500comprises a transmitting catheter505suitable to be inserted in the urethra of a patient. Catheter505incorporates a guiding element130comprising a transmitter510, and preferably comprising a urethra straightening device512for straightening the prostatic portion of a urethra. Straightening device512may be a rigid section of catheter505, or a section switchable between flexible and rigid configuration, such as a section utilizing techniques presented hereinabove with reference toFIGS. 18-21.

Transmitter510may be a transmitter of electromagnetic energy514, a transmitter of acoustic energy516, or a transmitter of any other kind.

Apparatus500further comprises one or more treatment tools520. Treatment tool520comprises a distal portion522. Distal portion522of treatment tool520comprises a therapeutic element530, and a signal detection sensor540. Therapeutic element530is an element operable to produce a therapeutic or diagnostic effect, such as ablation or a short-range imaging. Signal detection sensor540is a sensor operable to detect a signal generated by transmitter510. Changes in spatial distance between transmitter510and sensor540are detectable as a change in signal strength, or in signal phase, or in the time required for a signal to travel between transmitter510and sensor540. Thus, after calibration, the described transmitter-sensor combination can be used to determine and report absolute distance between transmitter510and sensor540, which is to say, between guiding element130which comprises transmitter510, and therapeutic element530of treatment tool520, which is adjacent to, or co-located with, sensor540. Transmitter510and signal sensor540comprise internal or external power sources (not shown). Output from signal sensor540may be fed to a display system542useful to guide a surgeon in manipulating and placing treatment tool520, or may be fed to a controller544operable to calculate movements required to deliver treatment tool520to a treatment site, and to provide commands to servo motors546operable to move treatment tool520according to those commands. Display system542may comprise a computerized system for signal analysis and for display enhancement under algorithmic control.

Note that in an alternative construction, the positions of transmitter510and sensor540may be reversed, with transmitter510incorporated in treatment tool520, and sensor540incorporated in guiding element130.

Attention is now drawn toFIG. 24, which is a simplified schematic of a treatment tool positioning apparatus600incorporating an energy transmitter co-located with an energy sensor, according to an additional preferred embodiment of the present invention.

Apparatus600comprises a transmitting and receiving catheter605suitable to be inserted in the urethra of a patient. Catheter605preferably comprises a urethra straightening device612for straightening the prostatic portion of a urethra. Straightening device612may be a rigid section of catheter605, or a section switchable between flexible and rigid configuration, such as a section utilizing techniques presented hereinabove with reference toFIGS. 18-21.

Catheter605incorporates a guiding element130comprising a transmitter610and a sensor640.

Transmitter610may be a transmitter of electromagnetic energy614, a transmitter of acoustic energy616, or any other transmitter.

Apparatus600further comprises one or more treatment tools620. Treatment tool620comprises a distal portion622incorporating a therapeutic element630operable to produce a therapeutic or diagnostic effect, such as ablation or short-range imaging. Distal portion622of treatment tool620is designed and constructed so as to reflect energy transmitted by transmitter610.

Signal detection sensor640is a sensor operable to detect signals generated by transmitter610and reflected from distal portion622of treatment tool620. Changes in spatial distance between transmitter610and distal portion622are detectable as changes in signal strength, or in signal phase, or in time required for a transmitted signal to travel between transmitter610and distal portion622, to be reflected from distal portion622, and to travel back to sensor640.

Thus, after calibration, the transmitter-sensor combination of apparatus600can be used to determine and report absolute distance between transmitter610, mounted within guiding element130, and a distal portion622of a treatment tool620that reflects signals transmitted by transmitter610.

Transmitter610and signal sensor640comprise internal or external power sources (not shown). Output from signal sensor640may be fed to a display system642useful to guide a surgeon in manipulating and placing treatment tool620, or may be fed to a controller644operable to calculate movements required to deliver treatment tool620to a treatment site, and to provide commands to servo motors646operable to move treatment tool620according to those commands. Display system642may comprise a computerized system for signal analysis and for display enhancement under algorithmic control.

Attention is now drawn toFIG. 25, which is a simplified schematic of a treatment tool positioning apparatus700operable in conjunction with a conventional imaging device, according to an additional preferred embodiment of the present invention.

Apparatus700comprises a catheter705suitable to be inserted in the urethra of a patient. Catheter705preferably comprises a urethra straightening device712for straightening the prostatic portion of a urethra. Straightening device712may be a rigid section of catheter705, or a section switchable between flexible and rigid configuration, such as a section utilizing techniques presented hereinabove with reference toFIGS. 18-21.

Apparatus700is designed for use with a conventional imaging device707, such as an ultrasound imaging system. By way of example, imaging device707is represented inFIG. 25as an ultrasound transducer709inserted in an anus of a patient, for imaging a prostate of that patient.

Catheter705comprises a guiding element130, designed and constructed so as to be rendered visible by imaging system707, and so as to appear distinct from other objects imaged by imaging system707.

Apparatus700further comprises one or more treatment tools720. Treatment tool720comprises a distal portion722incorporating a therapeutic element730operable to produce a therapeutic or diagnostic effect such as ablation or short-range imaging. Furthermore, distal portion722of treatment tool720is designed and constructed so as to be visible under imaging system707, and so as to appear distinct from other objects imaged by imaging system707.

Thus, guiding element130of catheter705, and distal portion722of treatment tool720, are both distinctively visible under whatever imaging modality is provided by imaging system707. Imaging system707may consequently be used with success to direct placement of treatment tool720with respect to the position of guiding element130. Consequently, when guiding element130is placed in a reference site having a known spatial relationship to a desired treatment site, apparatus700and imaging system707may be used in conjunction to successfully position treatment tool720at that desired treatment site. If, for example, guiding element130is placed within a straightened portion of a prostatic urethra, imaging system707can easily be used to navigate the distal portion of a treatment tool720to a locus at a selected distance from that prostatic urethra, e.g., for treatment of BPH.

It is noted that, although many of the embodiments presented in the accompanying Figures and discussed hereinabove were presented in the context of treatment of a prostate, and particularly of treatment of a prostate for BPH, it is to be understood that the example of treatment of a prostate and of a BPH condition are exemplary only, and not to be construed as limiting the scope of the invention.

It is expected that during the life of this patent many relevant devices for positioning a treatment tool at a treatment site will be developed. The scope of the term “treatment tool positioning apparatus” is intended to include all such new technologies a priori.