Patent Description:
Systems and methods that identify artifacts, and in particular vessels, in the surgical field during a surgical procedure provide valuable information to the surgeon or surgical team. hospitals lose billions of dollars annually in unreimbursable costs because of inadvertent vascular damage during surgery. In addition, the involved patients face a mortality rate of up to <NUM>%, and likely will require corrective procedures and remain in the hospital for an additional nine days, resulting in tens, if not hundreds, of thousands of dollars in added costs of care. Consequently, there is significant value to be obtained from methods and systems that permit accurate determination of the presence of vessels, such as blood vessels, in the surgical field, such that these costs may be reduced or avoided.

Systems and methods that provide information regarding the presence of blood vessels in the surgical field are particularly important during minimally invasive surgical procedures. Traditionally, surgeons have relied upon tactile sensation during surgical procedures both to identify blood vessels and to avoid inadvertent damage to these vessels. Because of the shift towards minimally invasive procedures, including laparoscopic and robotic surgeries, surgeons have lost the ability to use direct visualization and the sense of touch to make determinations as to the presence of blood vessels in the surgical field. Consequently, surgeons must make the determination whether blood vessels are present in the surgical field based primarily on convention and experience. Unfortunately, anatomical irregularities frequently occur because of congenital anomalies, scarring from prior surgeries, and body habitus (e.g., obesity). Systems and methods that would permit surgeons to determine the presence and/or the characteristics of vessels in the surgical field during surgery (potentially in real time or near real time) under such conditions would be a significant advantage. Patent application <CIT> describes such a system that can be used to determine the presence of vessels during surgery.

On the other hand, while it would be advantageous to include systems and methods that provide information regarding the presence of blood vessels in the surgical field, the adoption of such systems and methods would be impeded if these systems and methods made the surgical procedure more complicated. Consequently, it is advantageous that the systems and methods do not involve significant thought on the part of the surgeon or surgical team in using the system or method for detecting or differentiating tissue or an artifact, like a vessel, or significant preparation of the surgical field or the patient for use of the system or method.

As set forth in more detail below, the present disclosure describes a user interface embodying advantageous alternatives to the existing systems and methods, which may provide for improved identification for avoidance or isolation of tissue or artifacts, such as vessels, without undue complication of the surgical instrument or surgical procedure.

According to the present invention, a surgical system includes a surgical instrument, at least one light emitter disposed at a working end of the surgical instrument, an array of light sensors disposed at the working end of the surgical instrument, individual light sensors in the array of light sensors adapted to generate a signal comprising a non-pulsatile component, and a controller coupled to the array of light sensors. The controller includes an analyzer configured to determine a curve of the non-pulsatile components of the signals of each of the individual light sensors in the array of light sensors, smooth the curve to generate a smoothed curve, calculate a derivative of the smoothed curve, invert the smoothed curve to generate an inverted smoothed curve, calculate a derivative of the inverted smoothed curve, take a difference between the derivative of the inverted smoothed curve and the derivative of the smoothed curve to generate a resultant curve, smooth the resultant curve to generate a smoothed, resultant curve, estimate zero crossings of the smoothed, resultant curve, apply a signum function to points adjacent each zero crossing, if any, to generate a result; and identify a region of interest, if any, based on the result for points adjacent each zero crossing, if any.

The disclosure will be more fully understood from the following description taken in conjunction with the accompanying drawings. Some of the figures may have been simplified by the omission of selected elements for the purpose of more clearly showing other elements. Such omissions of elements in some figures are not necessarily indicative of the presence or absence of particular elements in any of the exemplary embodiments, except as may be explicitly delineated in the corresponding written description. None of the drawings is necessarily to scale.

The embodiments described herein provide a system and method for detecting or differentiating regions of interest in a curve, which system and method also involve detecting or differentiating tissue or artifacts, such as vessels, and which system and method can be used with or in surgical systems or instruments. Such a system may include at least one light emitter disposed at a working end of the surgical instrument and an array of light sensors disposed at the working end of the surgical instrument, individual light sensors in the array of light sensors adapted to generate a signal comprising a non-pulsatile component. The system may also include a controller coupled to the array of light sensors, the controller including an analyzer. The analyzer is configured to determine a curve of the non-pulsatile components of the signals of each of the individual light sensors in the array of light sensors, smooth the curve to generate a smoothed curve, calculate a derivative of the smoothed curve, invert the smoothed curve to generate an inverted smoothed curve, calculate a derivative of the inverted smoothed curve, take a difference between the derivative of the inverted smoothed curve and the derivative of the smoothed curve to generate a resultant curve, smooth the resultant curve to generate a smoothed, resultant curve, estimate zero crossings of the smoothed, resultant curve, apply a signum function to points adjacent each zero crossing, if any, to generate a result, and identify a region of interest, if any, based on the result for points adjacent each zero crossing, if any.

Turning first to <FIG>, embodiments of such a surgical system <NUM> are illustrated, which system <NUM> may be used to determine, for example, a characteristic (e.g., presence, diameter, etc.) of a vessel, V, within a region <NUM> of tissue, T, proximate to a working end <NUM> of a surgical instrument <NUM>. It will be understood that the vessel V may be connected to other vessels with the region <NUM> of tissue T, and in addition, the vessel V may extend beyond the region <NUM> so as to be in fluid communication with other organs (e.g., the heart) also found in the body of the patient. Furthermore, while the tissue T appears in <FIG> to surround fully the vessel V (in terms of both circumference and length) to a particular depth, this need not be the case in all instances where the system <NUM> is used. For example, the tissue T may only partially surround the circumference of and/or only surround a section of the length of the vessel V, or the tissue T may overlie the vessel V in a very thin layer. As further non-limiting examples, the vessel V may be a blood vessel, and the tissue T may be connective tissue, adipose tissue and/or liver tissue.

According to the illustrated embodiments, the working end <NUM> of the surgical instrument <NUM> is also a distal end of a shaft <NUM>. Consequently, the working end and the distal end will be referred to as working end <NUM> or distal end <NUM>. The shaft <NUM> also has a proximal end <NUM>, and a grip or handle <NUM> (referred to herein interchangeably as grip <NUM>) is disposed at the proximal end <NUM> of the shaft <NUM>. The grip <NUM> is designed in accordance with the nature of the instrument <NUM>; as to the thermal ligation device illustrated in <FIG>, the grip <NUM> may be a pistol-type grip including a trigger <NUM>. As one alternative, finger rings arranged in a generally scissors-type grip may be used.

While the working or distal end <NUM> and the proximal end <NUM> with grip <NUM> are illustrated as disposed at opposite-most ends of the shaft <NUM>, it will be recognized that certain surgical instruments have working ends (where a tool tip is attached, for example) disposed on the opposite-most ends of the shaft and a gripping region disposed intermediate to the opposite working ends. In accordance with the terms "distal" and "proximal" as used herein, the working ends of such an instrument are referred to herein as the distal ends and the gripping region as the proximal end. Relative to the illustrated embodiments, however, the distal and proximal ends are located at opposite-most (or simply opposite) ends of the shaft <NUM>.

As mentioned above, according to the preferred embodiments illustrated, the surgical system <NUM> includes a sensor with at least one light emitter <NUM> (or simply the light emitter <NUM>) and one or more light sensors or detectors <NUM> (or simply the light sensors <NUM>). According to the illustrated embodiments, a controller <NUM> is coupled to the light emitter <NUM> and the light sensors <NUM>, which controller <NUM> may include a splitter <NUM> and an analyzer <NUM> as explained below.

The light emitter <NUM> is disposed at the working end <NUM> of the surgical instrument <NUM>. The light sensors <NUM> are also disposed at the working end <NUM> of the surgical instrument <NUM>. In either case, the phrase "disposed at" may refer to the placement of the emitter <NUM> or sensor <NUM> physically at the working end <NUM>, or placement of a fiber or other light guide at the working end <NUM>, which light guide is coupled to the emitter <NUM> or sensor <NUM> which then may be placed elsewhere. The system <NUM> may operate according to a transmittance-based approach, such that the light sensors <NUM> are disposed opposite and facing the light emitter(s) <NUM>, for example on opposite jaws of a surgical instrument <NUM> as illustrated in <FIG>. In addition, the system <NUM> may include a reflectance-based system (for forward-facing vessel and/or tissue detection), such that the light emitter <NUM> and the light sensors <NUM> may face in a common direction and with fixed spacing therebetween, for example on a single jaw of a two-jaw device (see <FIG>). Alternatively, the light emitter <NUM> and the light sensor <NUM> of a reflectance-based system may be constructed such that the spacing between the light emitter <NUM> and the light sensor <NUM> may be adjusted, for example by positioning the light emitter <NUM> at the end or tip of one of the jaws of a two-jaw device and the light sensor <NUM> at the end or tip of the other the jaws of the two-jaw device (see <FIG>). As to the operation of such reflectance-based systems, it is referred to PCT Application No. <CIT>.

The light emitter <NUM> may be configured to emit light of at least one wavelength. For example, the light emitter <NUM> may emit light having a wavelength of <NUM>. This may be achieved with a single element, or a plurality of elements (which elements may be arranged or configured into an array, for example, as explained in detail below). In a similar fashion, the light sensor <NUM> is configured to detect light at the at least one wavelength (e.g., <NUM>). According to the embodiments described herein, the light sensor <NUM> includes a plurality of elements, which elements are arranged or configured into an array.

According to certain embodiments, the light emitter <NUM> may be configured to emit light of at least two different wavelengths, and the light sensor <NUM> may be configured to detect light at the at least two different wavelengths. As one example, the light emitter <NUM> may emit and the light sensor <NUM> may detect light in the visible range and light in the near-infrared or infrared range. Specifically, the light emitter <NUM> may emit and the light sensor <NUM> may detect light at <NUM> and at <NUM>. Such an embodiment may be used, for example, to ensure optimal penetration of blood vessel V and the surrounding tissue T under in vivo conditions.

Depending upon the effect of changes in blood flow, light of a third wavelength may also be emitted and sensed. That is, if the method of detection is found to be sensitive to varying rates of blood flow in the vessel of interest, light at <NUM> (i.e., at the isobestic point) may be emitted and sensed to permit normalization of the results to limit or eliminate the effects of changes in blood flow rate. Additional wavelengths of light may also be used.

According to certain embodiments, each individual light sensor <NUM> is configured to generate a signal comprising a first pulsatile component and a second non-pulsatile component. It will be recognized that the first pulsatile component may be an alternating current (AC) component of the signal, while the second non-pulsatile component may be a direct current (DC) component. Where the light sensor <NUM> is in the form of an array, the pulsatile and non-pulsatile information may be generated for each element of the array, or at least for each element of the array that defines at least one row of the array.

As to the pulsatile component, it will be recognized that a blood vessel may be described as having a characteristic pulsation of approximately <NUM> pulses (or beats) per minute. While this may vary with the patient's age and condition, the range of pulsation is typically between <NUM> and <NUM> pulses (or beats) per minute. The light sensor <NUM> will produce a signal (that is passed to the controller <NUM>) with a particular AC waveform that corresponds to the movement of the blood through the vessel. In particular, the AC waveform corresponds to the light absorbed or reflected by the pulsatile blood flow within the vessel. On the other hand, the DC component corresponds principally to light absorbed, reflected and/or scattered by the tissues, and thus the vessel may appear as a "shadow" or "dip" in the curve formed of the DC signals from each of the sensors in a sensor array.

According to such embodiments, the controller <NUM> is coupled to the light sensor <NUM>, and may include a splitter <NUM> to separate the first pulsatile component from the second non-pulsatile component for each element of the light sensor array <NUM>. The controller <NUM> may also include an analyzer <NUM> to determine the presence of and/or characteristic(s) of the vessel V within the region <NUM> proximate to the working end <NUM> of the surgical instrument <NUM> based (at least in part) on the pulsatile component. According to the embodiments described herein, the analyzer may make that determination by first detecting or differentiating regions of interest in the DC signals from the light sensors <NUM> of the system <NUM>.

Before discussing the details of the determination of the regions of interest, further details of the system may be discussed with reference, for example, to the transmittance-based embodiment of <FIG>, the light emitter <NUM> may include one or more elements, as referenced above. According to an embodiment schematically illustrated in <FIG>, the light sensor <NUM> may include a first light emitter <NUM>-<NUM>, a second light emitter <NUM>-<NUM>, and a third light emitter <NUM>-<NUM>. All of the light emitters may be configured to emit light at a particular wavelength (e.g., <NUM>), or certain emitters may emit light at different wavelengths than other emitters. Each light emitter may be a light emitting diode, for example.

As to those embodiments wherein the light emitter <NUM> is in the form of an array including one or more light emitting diodes, as is illustrated in <FIG>, the diodes may be arranged in the form of a one-dimensional, two-dimensional or three-dimensional array. An example of a one-dimensional array may include disposing the diodes along a line in a single plane, while an example of a two-dimensional array may include disposing the diodes in a plurality of rows and columns in a single plane. Further example of a two-dimensional array may include disposing the diodes along a line on or in a curved surface. A three-dimensional array may include diodes disposed in more than one plane, such as in a plurality of rows and columns on or in a curved surface.

The light sensor <NUM> also may include one or more elements. Again, according to the embodiment illustrated in <FIG>, the light sensor <NUM> may include a first light sensor <NUM>-<NUM>, a second light sensor <NUM>-<NUM>, an n-th light sensor <NUM>-n, and so on. As was the case with the light emitters <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, the light sensors <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-n may be arranged in an array, and the discussion about the arrays above applied with equal force here.

In fact, where the array of light sensors <NUM> includes a row of light sensors (such as in <FIG>), the array <NUM> may be referred to in the alternative as a linear array. The individual light sensors of the array <NUM> may be disposed adjacent each other, or the light sensors may be spaced from each other. It may even be possible for the individual light sensors that define a row of light sensors to be separated from each other by light sensors that define a different row or column of the array. According to a particular embodiment, however, the array may comprise a charge coupled device (CCD), and in particular linear CCD imaging device comprising a plurality of pixels. As a further alternative, a CMOS sensor array may be used.

The system <NUM> may include hardware and software in addition to the emitter <NUM>, sensor <NUM>, and controller <NUM>. For example, where more than one emitter <NUM> is used, a drive controller may be provided to control the switching of the individual emitter elements. In a similar fashion, a multiplexer may be provided where more than one sensor <NUM> is included, which multiplexer may be coupled to the sensors <NUM> and to an amplifier. Further, the controller <NUM> may include filters and analog-to-digital conversion as may be required.

According to certain embodiments, the splitter <NUM> and the analyzer <NUM> may be defined by one or more electrical circuit components. According to other embodiments, one or more processors (or simply, the processor) may be programmed to perform the actions of the splitter <NUM> and the analyzer <NUM>. According to still further embodiments, the splitter <NUM> and the analyzer <NUM> may be defined in part by electrical circuit components and in part by a processor programmed to perform the actions of the splitter <NUM> and the analyzer <NUM>.

For example, the splitter <NUM> may include or be defined by the processor programmed to separate the first pulsatile component from the second non-pulsatile component. Further, the analyzer <NUM> may include or be defined by the processor programmed to determine the presence of (or to quantify the size of, for example) the vessel V within the region <NUM> proximate to the working end <NUM> of the surgical instrument <NUM> based on the first pulsatile component. The instructions by which the processor is programmed may be stored on a memory associated with the processor, which memory may include one or more tangible non-transitory computer readable memories, having computer executable instructions stored thereon, which when executed by the processor, may cause the one or more processors to carry out one or more actions.

As to the operation of such a transmittance-based system to determine tissue and/or artifact (e.g., a vessel, such as a blood vessel or a ureter) characteristics, which characteristics may include position and dimension (e.g., length, width, diameter, etc.) by way of example and not by way of limitation,it is referred to <CIT>, <CIT>, <CIT> and <CIT>. As to associated structure and operation that may address issues related to the operation of such systems, PCT Application Nos. <CIT>, and <CIT>, are each incorporated herein by reference in their entirety.

<FIG> illustrate an embodiment of the surgical system <NUM> in combination with embodiments of a video system <NUM>, such as may be used conventionally during minimally invasive surgery or laparoscopic surgery, for example. The video system <NUM> includes a video camera or other image capture device <NUM>, a video or other associated processor <NUM>, and a display <NUM> having a viewing screen <NUM>.

As illustrated, the video camera <NUM> is directed at the region <NUM> proximate the working ends <NUM> of two surgical instruments <NUM>. As illustrated, both of the surgical instruments <NUM> are part of an embodiment of a surgical system <NUM>, such as illustrated in <FIG> and discussed above. In this case, the instruments <NUM> each include a visual indicator <NUM>. It will be recognized, however, that according to other embodiments only one of the instruments <NUM> may include a visual indicator <NUM>. The other elements of the surgical system <NUM> are omitted for ease of illustration, although it will be noted that elements of the system <NUM>, such as the splitter <NUM> and the analyzer <NUM>, may be housed in the same physical housing as the video processor <NUM>.

The signal from the video camera <NUM> is passed to the display <NUM> via the video processor <NUM>, so that the surgeon or other member of the surgical team may view the region <NUM> as well as the working ends <NUM> of the surgical instruments <NUM>, which are typically inside the patient. Because of the proximity of the visual indicators <NUM> to the working ends <NUM>, and thus the region <NUM>, the visual indicators <NUM> are also visible on the display screen <NUM>. As mentioned previously, this advantageously permits the surgeon to receive visual cues or alarms via the visual indicators <NUM> via the same display <NUM> and on the same display screen <NUM> as the region <NUM> and the working ends <NUM>. This, in turn, limits the need of the surgeon to look elsewhere for the information conveyed via the visual indicators <NUM>.

<FIG> illustrates another embodiment of a video system <NUM> that can be used in conjunction with an embodiment of the surgical system <NUM>. According to this embodiment, the video processor <NUM> is not disposed in a housing separate from the video camera <NUM>', but is disposed in the same housing as the video camera <NUM>'. According to a further embodiment, the video processor <NUM> may be disposed instead in the same housing as the remainder of the display <NUM>' as the display screen <NUM>'. Otherwise, the discussion above relative to the embodiment of the video system <NUM> illustrated in <FIG> applies equally to the embodiment of the video system <NUM> illustrated in <FIG>.

While the user interface <NUM> advantageously permits the surgeon or surgical team to view an output from the controller <NUM>, it is possible to include other output devices with the user interface <NUM>, as illustrated in <FIG>. For example, an alert may be displayed on a video monitor <NUM> being used for the surgery (e.g., the display <NUM>, <NUM>' in <FIG>), or may cause an image on the monitor to change color or to flash, change size or otherwise change appearance. The auxiliary output may also be in the form of or include a speaker <NUM> that provides an auditory alarm. The auxiliary output also may be in the form of or may incorporate a safety lockout associated with the surgical instrument <NUM> that interrupts use of the instrument <NUM>. For example, the lockout could prevent ligation or cauterization where the surgical instrument <NUM> is a thermal ligature device. As a still further example, the auxiliary output also may be in the form of a haptic feedback system, such as a vibrator <NUM>, which may be attached to or formed integral with a handle or handpiece of the surgical instrument <NUM> to provide a tactile indication or alarm. In addition to the light emitting elements disposed at the working end <NUM> of the surgical instrument <NUM>, one or more light emitting elements may be disposed at the proximal end <NUM> of the shaft <NUM>, such as disposed on or attached to the grip or handle <NUM>, to provide a visual indication or alarm. Various combinations of these particular forms of the auxiliary output may also be used.

As mentioned above, the surgical system <NUM> may also include the surgical instrument <NUM> with the working end <NUM>, to which the user interface <NUM> and the sensor (and in preferred embodiments, the light emitter <NUM> and the light sensor <NUM>) are attached (in the alternative, removably/reversibly or permanently/irreversibly). The user interface <NUM> and sensor may instead be formed integrally (i.e., as one piece) with the surgical instrument <NUM>. As also stated, it is possible that the user interface <NUM> and sensor be attached to a separate instrument or tool that is used in conjunction with a surgical instrument or tool <NUM>.

As noted above, the surgical instrument <NUM> may be a thermal ligature device in one embodiment. In another embodiment, the surgical instrument <NUM> may simply be a grasper or grasping forceps having opposing jaws. According to still further embodiments, the surgical instrument may be other surgical instruments such as irrigators, surgical staplers, clip appliers, and robotic surgical systems, for example. According to still other embodiments, the surgical instrument may have no other function that to carry the user interface and sensor and to place them within a surgical field. The illustration of a single embodiment is not intended to preclude the use of the system <NUM> with other surgical instruments or tools <NUM>.

In the context of one or more of the systems described above, it will be recognized that preliminary to characterization of an artifact (e.g., determining a diameter for a vessel) from data received from an array of light sensors, identification of a region of interest is important. Further, it is advantageous that the identification of the region of interest be relatively robust relative to environmental factors that may influence the identification of a region of interest. In addition, it is advantageous that the identification of the region of interest minimize the computational burden of making the identification. In conjunction with the former, an identification system and method that minimizes the computational burden may also facilitate the use of the system and method in real time or near real time implementations.

As noted above, the systems <NUM> described include light emitters <NUM> and light sensors <NUM>, and that the signal from the light sensors may include a pulsatile (or AC) component and a non-pulsatile (or DC) component. The system and method for identification of a region of interest described herein utilizes the non-pulsatile, or DC, component. This DC data may be described in terms of a DC curve that includes DC data from a plurality of light sensors arranged in a array, for example a linear array, according to at least one embodiment described herein.

In general terms, the method illustrated in <FIG> may be used to determine regions of interest where a "dip" occurs in the DC curve (i.e., a region along the DC curve where the profile decreases and then increases). According to certain embodiments, all dips may be identified as regions of interest. According to other embodiments, the regions of interest then may be processed further to determine which of the regions of interest have a high (or higher) probability of being associated with a particular artifact, such as a vessel, and, in particular, a blood vessel. For example, a region of interest that exhibits a high (or higher) probability of being associated with a blood vessel may be separated from regions of interest that are associated with heterogeneous or highly absorbing tissue. In this fashion, the method may be used to localize and track the blood vessel along the sensor array in real-time.

As described with reference to <FIG>, a method <NUM> for identifying regions of interest is described, which may be used with the embodiments of the system <NUM> described above. The embodiment of the method <NUM> illustrated in <FIG> begins a block <NUM>, where the system <NUM> controls the light emitters <NUM> to emit light of one or more wavelengths. The method <NUM> continues at block <NUM>, where the light sensors <NUM> receive light and generate a signal according to the light detected. Presumably, a significant portion of the light received by the light sensors <NUM> is from the light emitters <NUM>, but it will be recognized that ambient light (i.e., light from other sources) may also contribute to the light received by the light sensors <NUM>. Further, in keeping with the discussion above, the light received by the light sensors <NUM> may include a pulsatile and a non-pulsatile component, in particular when the light is received after passing through tissue including a vessel, such as a blood vessel.

At block <NUM>, the system <NUM> separates the signal(s) received from the light sensors <NUM> into pulsatile and non-pulsatile components. For example, the splitter <NUM> may be used to separate the different components of the signal(s). Further, it will be recognized that while the method <NUM> utilizes the non-pulsatile (or DC) component, the pulsatile (or AC) component may be utilized as well by the system <NUM> in a separate method, or in conjunction with the output of the method <NUM>.

According to an embodiment of the method <NUM>, the system <NUM> smoothes DC curve, which curve may include the DC signals corresponding to each of the light sensors <NUM> along the array. In this regard, smoothing may include filtering, which filtering may include averaging as well. The smoothing of the DC curve may assist in focusing on those sensors generating signals with the most pronounced DC signal relative to other sensors.

At block <NUM>, the system <NUM> determines a derivative of the smoothed DC curve generated at block <NUM>. In particular, the system <NUM> uses a <NUM>-point numerical differentiation to determine the derivative, although other n-point numerical differentiations could be used instead. The system <NUM> uses a numerical differentiation to determine the derivative to reduce the computational burden presented by the method <NUM>.

At block <NUM>, the system <NUM> inverts the smoothed signal determined at block <NUM>. At block <NUM>, the system <NUM> determines a derivative of the inverted smoothed DC curve. As was the case with block <NUM>, the system may determine the derivative by using a <NUM>-point numerical differentiation, for example. Again, using a numerical differentiation may reduce the computational burden of the method <NUM>.

At block <NUM>, the system <NUM> subtracts the derivative determined at block <NUM> from the derivative determined at block <NUM>. The system <NUM> then smoothes the result of this subtraction at block <NUM>, referred to as the resultant curve, to generate a smoothed, resultant curve at block <NUM>. The system <NUM> then optionally interpolates the smoothed resultant curve at block <NUM> for use in the remainder of the method <NUM>; alternatively, the smoothed resultant curve can be used in the remainder of the method <NUM>.

At block <NUM>, the system <NUM> estimates the zero crossings of the smoothed (and optionally interpolated) resultant curve. The system <NUM> then applies a signum function to points adjacent the estimates zero crossings of the resultant curve at block <NUM>, and determines if the result of applying the signum function for the points adjacent present a specific pattern at block <NUM>. In particular, the system <NUM> may analyze the result for a pattern of [<NUM>, -<NUM>, <NUM>], [<NUM>, -<NUM>], [-<NUM>, <NUM>] for the points adjacent the zero crossing, suggesting a dip has occurred in the original signal curve. The system <NUM> then identifies this region as a region of interest at block <NUM>.

As is reflected in <FIG>, the system may identify more than one region of interest at block <NUM>. That is, based on the number of zero crossings and the patterns established for the points adjacent those zero crossings, the system may identify no region of interest, one region of interest, or a plurality of regions of interest. In identifying a plurality of regions of interest, the determination at block <NUM> may be repeated or may occur multiple times.

As is further reflected in the method <NUM> of <FIG>, in those circumstances where a plurality of regions of interest are determined at block <NUM>, the system <NUM> may perform additional actions at block <NUM> to select one or more of the regions of interest from the plurality of regions determined at block <NUM>. For example, in some embodiments, certain regions of interest may be selected relative to others based on the likelihood that a vessel is associated with the region; in other embodiments, all of the regions of interest may be considered, where attempting to identify different tissues, for example. The system <NUM> then will perform further analysis at block <NUM> on the one or more regions of interest, such as to determine the size (e.g., diameter or effective diameter) of the vessels associated with these regions of interest, for example according to the methods disclosed in the references.

As one example of the actions that may be performed to select one or more regions of interest from a plurality of identified regions of interest, a method <NUM> is illustrated in <FIG>, which method may be used to determine which regions of interest among a plurality of regions of interest may be more or less likely to have a vessel (e.g., a blood vessel, such as an artery or vein) associated therewith. In general terms, the method <NUM> first determines which regions of interest may overlap, and resolves whether the overlapping regions of interest should be treated as a single region of interest or as separate regions of interest. Having resolved the overlap issue, the method <NUM> then seeks to determine if each of the remaining regions of interest is more or less likely to be associated with a vessel. As noted above, it is possible that after performing the method <NUM>, multiple regions are identified as regions of interest for possible further processing.

The method <NUM> begins at block <NUM> where a determination is made whether any of the regions of interest overlap. This determination may be made whether a starting point of a region of interest lies between the starting and ending points of another region of interest and/or whether an ending point or a region of interest lies between the starting and ending points of another region of interest. The starting and ending points of a region of interest may be determined by comparing the results of the signum function, as explained above. If there are regions of interest that overlap, the method <NUM> continues to block <NUM>; if there are no regions of interest that overlap, the method <NUM> continues to block <NUM>.

Assuming that it is determined that at least two regions of interest overlap at block <NUM>, an analysis of the closeness of the regions of interest is performed at block <NUM>. In general terms, if the regions of interest are sufficiently close, such that it is unlikely that any two vessels would actually be that close in reality, the system <NUM> may treat the regions of interest as a single region of interest; otherwise, the regions may be treated as separate regions. According to one embodiment, the closeness determination may include a determination of <NUM>) the closeness between ending points of adjacent regions; <NUM>) the closeness of the starting point of one region and the ending point of the previous region; and <NUM>) the closeness between starting points of adjacent regions. That is, where D is <MAT> with the first element in each column being the starting point and the second element in each column being the ending point, the above closeness determinations (or factors) may be expressed as the following: <MAT>.

Based on the results of the analysis at block <NUM>, the method <NUM> may determine whether to identify the regions as a single region at <NUM>, and either identify multiple regions (e.g., two regions) as a single region at block <NUM> or identify the regions as separate regions at block <NUM>.

Having resolved the overlapping region issues, the method <NUM> continues with the determination of which of the remaining regions is more or less likely to be associated with an artifact, e.g., a vessel. The determination could answer either or both of these questions (i.e., more or less likely), but the purpose is to identify the more likely regions of interest for further processing. While the method <NUM> of <FIG> includes one embodiment for making this determination, other embodiments are possible for also making this determination.

According to the method <NUM>, a plurality of parameters is analyzed at block <NUM> to determine if each of the regions of interest is more likely (or less likely) to be associated with a vessel. Each of the parameters may be analyzed at block <NUM> to determine if the parameter is satisfied, or is not, by comparing the parameter against a threshold associated with the parameter, for example. After each of the parameters is compared against its respective threshold, the results of all of the comparisons may be analyzed at block <NUM> to determine if it is more likely that a vessel is present, for example by comparing the analysis performed at block <NUM> against a further criterion. The determination(s) made at block <NUM> is/are then provided as an output at block <NUM>, for example for purposes of identifying regions of interest for further processing as part of the method <NUM> of <FIG>. It will be recognized that the actions of blocks <NUM>, <NUM>, <NUM>, <NUM> may be repeated as necessary to address all of the regions of interest identified.

In the embodiment of <FIG>, the following five parameters are considered: <NUM>) width, <NUM>) the standard deviation of the derivative of the region of interest, <NUM>) the mean of the derivative of the individual values of the sensors associated with the region of interest / the standard deviation of the derivative of the individual values of the sensors associated with the region of interest, <NUM>) the minimum value from among the individual values of the sensors associated with the region of interest, and <NUM>) the standard deviation to the individual values of the sensors associated with the region of interest / the mean of the individual values. According to other embodiments, other parameters may be considered, and the total number of parameters may be more or less than five. These parameters may be determined at block <NUM> in a particular order, or may be determined simultaneously or near simultaneously. The method <NUM> may determine each parameter separately and proceed immediately to the analysis of the parameter at block <NUM>, or may determine all parameters (whether sequentially or simultaneously/near simultaneously) at block <NUM> and then proceed to block <NUM>.

At block <NUM>, the parameters determined at block <NUM> are analyzed to determine if the parameter indicates that it is more or less likely that a vessel is associated with the region of interest. For example, the width parameter may be compare with a minimum width, the minimum width representing an actual limit on the size of the vessels expected or of the vessels of interest. As noted above, the use of a threshold comparison is not the only analysis method that may be used to determine if the parameters are more or less suggestive of a vessel being present in the region of interest.

At block <NUM>, a determination is made based on the analysis at block <NUM> of each of the parameters determined at block <NUM> whether a vessel is more or less likely to be associated with a region of interest. For example, according to the present embodiment, the determination whether it is more likely that a vessel is present requires the satisfaction of all of the parameters. According to other embodiments, it may be sufficient that a simple majority of the parameters are in excess of the associated thresholds, for example. Still other embodiments may use a weighted average of the results from the parameter comparisons. In any event, after the determination is made at block <NUM>, the results are provided at block <NUM>.

After the system <NUM> has determined which regions of interest to evaluate, such as using a method such as is illustrated in <FIG>, the system <NUM> may characterize the artifact at block <NUM> of <FIG>. For example, the characterization occurring at block <NUM> may include determining if the artifact is a vessel, and if so, if the vessel is a particular type of vessel (e.g., an artery). Alternatively, the characterization occurring at block <NUM> may be between different types of tissue. As a further alternative, the characterization may include determining a dimension of the artifact: for example, where the artifact is a vessel, the dimension may be a diameter (where the vessel is considered or assumed to be circular in cross-section) or effective diameter (where the vessel is considered or assumed to be other than circular in cross-section, but the largest dimension across the vessel may be used in lieu of an actual diameter).

In this regard, the action or actions carried out by the system <NUM> at block <NUM> to determine tissue and/or artifact (e.g., a vessel, such as a blood vessel or a ureter) characteristics, which characteristics may include position and dimension (e.g., length, width, diameter, etc.), may include by way of example and not by way of limitation, for a transmittance-based system, those described in <CIT><CIT><CIT> and <CIT>.

In conclusion, although the preceding text sets forth a detailed description of different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention.

Claim 1:
A surgical system (<NUM>) including a surgical instrument (<NUM>), the surgical system (<NUM>) comprising:
at least one light emitter (<NUM>) disposed at a working end of the surgical instrument (<NUM>);
an array of light sensors (<NUM>) disposed at the working end of the surgical instrument (<NUM>), individual light sensors in the array of light sensors (<NUM>) adapted to generate a signal comprising a non-pulsatile component; and
a controller (<NUM>) coupled to the array of light sensors (<NUM>), the controller (<NUM>) comprising an analyzer (<NUM>) configured to:
determine a curve of the non-pulsatile components of the signals of each of the individual light sensors in the array of light sensors,
characterized in that
the analyzer (<NUM>) is further configured to:
smooth the curve to generate a smoothed curve;
calculate a derivative of the smoothed curve;
invert the smoothed curve to generate an inverted smoothed curve;
calculate a derivative of the inverted smoothed curve;
take a difference between the derivative of the inverted smoothed curve and the derivative of the smoothed curve to generate a resultant curve;
smooth the resultant curve to generate a smoothed, resultant curve;
estimate zero crossings of the smoothed, resultant curve;
apply a signum function to points adjacent each zero crossing, if any, to generate a result; and
identify a region of interest, if any, based on the result for points adjacent each zero crossing, if any.