U.S. patent application number 14/024009 was filed with the patent office on 2014-03-20 for method and apparatus for laser ablation under ultrasound guidance.
This patent application is currently assigned to Convergent Life Sciences, Inc.. The applicant listed for this patent is Convergent Life Sciences, Inc.. Invention is credited to Dinesh Kumar, Daniel S. Sperling, Amit Vohra.
Application Number | 20140081253 14/024009 |
Document ID | / |
Family ID | 50233964 |
Filed Date | 2014-03-20 |
United States Patent
Application |
20140081253 |
Kind Code |
A1 |
Kumar; Dinesh ; et
al. |
March 20, 2014 |
METHOD AND APPARATUS FOR LASER ABLATION UNDER ULTRASOUND
GUIDANCE
Abstract
A method and apparatus for performing minimally-invasive
image-guided laser ablation of targeted region within a tissue or
organ comprising the following: A guidance tool that can guide
laser source to a predefined target region from a planning image; A
controller that can control energy from laser source, duration of
its application and dosage of energy from laser source; and a
computer with software that can compute thermometry based on
precise location and duration of application or dosage of the laser
source. The computer receives signal from controller and can
control or shut-off laser energy.
Inventors: |
Kumar; Dinesh; (Roseville,
CA) ; Vohra; Amit; (Roseville, CA) ; Sperling;
Daniel S.; (West Orange, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Convergent Life Sciences, Inc. |
West Orange |
NJ |
US |
|
|
Assignee: |
Convergent Life Sciences,
Inc.
West Orange
NJ
|
Family ID: |
50233964 |
Appl. No.: |
14/024009 |
Filed: |
September 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61700273 |
Sep 12, 2012 |
|
|
|
Current U.S.
Class: |
606/15 ; 606/13;
606/14 |
Current CPC
Class: |
A61B 10/0241 20130101;
A61B 2017/00274 20130101; A61B 34/10 20160201; A61B 18/20 20130101;
A61B 2090/365 20160201; A61B 90/39 20160201; A61B 34/20 20160201;
A61B 10/00 20130101; A61B 90/361 20160201; A61B 2090/364 20160201;
A61B 2034/107 20160201; A61B 10/02 20130101; A61B 2090/378
20160201 |
Class at
Publication: |
606/15 ; 606/13;
606/14 |
International
Class: |
A61B 18/22 20060101
A61B018/22 |
Claims
1-34. (canceled)
35. An apparatus for performing minimally-invasive image-guided
laser ablation of targeted region within a tissue or organ
comprising: a guidance tool that can guide a laser source to a
predefined target region from a planning image; a controller that
can control the energy, duration of its application and dosage of
energy from the laser source; and a computer with software that can
compute thermometry based on precise location and duration of
application or dosage of the laser source, which receives a signal
from the controller and can control or shut-off energy from the
laser source.
36. The apparatus of claim 35, wherein the guidance tool uses
magnetic, optical, mechanical or co-registration software based
tracking.
37. The apparatus of claim 35, wherein the tissue or organ is
prostate, heart, lung, kidney, liver, bladder, ovaries, thyroid, or
brain.
38. The apparatus of claim 35, wherein the target region to be
ablated is a part of the tissue, and a part of tissue or
surrounding structure identified as a sensitive region is spared
from delivery of energy.
39. The apparatus of claim 38, wherein the part of the tissue is
identified as the sensitive region while inserting a hypodermic
needle.
40. The apparatus of claim 35, wherein thermal sensors are inserted
at various locations around the laser source to measure temperature
at various distances from the laser source and the temperature
measurements are displayed on a screen.
41. The apparatus of claim 35, wherein the software computes
thermometry using ultrasound thermometry techniques such that the
live ultrasound is analyzed for computing temperature within its
field of view.
42. The apparatus of claim 41, wherein a combination of hypodermic
and surface thermal sensor measurements, ultrasound signal analysis
and heat equations are analyzed together to provide an accurate
temperature measurement.
43. The apparatus of claim 35, wherein the software computes
thermometry using heat equations, and a duration of application and
energy delivered by the laser source, which constitute the
parameters for computing a thermal map.
44. The apparatus of claim 35, wherein the laser source is guided
under guidance of a live B-mode ultrasound image, two orthogonal
planes of ultrasound simultaneously captured, or live 3D ultrasound
images.
45. The apparatus of claim 35, wherein the software can display a
thermal map as either a colored overlay or isothermal contours
which include displaying the isocontours at temperatures of
T.sub.safety.sup.high and T.sub.ablation.sup.low, where
T.sub.safety.sup.low represents the highest temperature allowable
within safety zone, T.sub.ablation.sup.low represents the lowest
temperature needed in the ablation zone to ensure complete
ablation, and safety zone represents a region that must be spared
during the procedure.
46. The apparatus of claim 45, wherein the software can display a
thermal map overlay as either a colored overlay or isothermal
contours on a live ultrasound image.
47. The apparatus of claim 35, wherein thermal sensors are inserted
in a grid-like pattern using an external physical grid with holes
at grid points to allow insertion of needles.
48. The apparatus of claim 47, wherein the needles carry either
thermal transducers or laser sources.
49. The apparatus of claim 47, wherein a virtual grid is displayed
that is consistent with the physical grid such that each grid point
location in virtual grid matches with a corresponding grid location
in the physical world, and upon identification of the grid
locations containing the laser source, the thermal map is computed
and displayed as an overlay on the virtual grid, either as a color
coded map or as isothermal contour overlays
50. The apparatus of claim 49, wherein the virtual grid and thermal
maps are displayed as an overlay on the live ultrasound images, and
the needle is automatically detected in ultrasound images as it is
advanced to a target location.
51. A method for performing minimally-invasive image-guided laser
ablation of targeted region within a tissue or organ comprising:
guiding a laser source with a guidance tool to a predefined target
region from a planning image; controlling duration of application
and dosage of energy from the laser source with a controller, and
computing thermometry using a computer with software based on a
precise location and duration of application or dosage of the laser
source, receiving a signal from controller and producing a signal
that can control or shut-off the laser energy.
52. The method of claim 51, for prostate ablation, wherein a
transperineal grid with a matrix of holes is attached to and
calibrated to an ultrasound probe such that an ultrasound video
from the ultrasound probe has a known rigid correspondence with the
virtual grid; and one or more hollow needles are advanced through
the holes in the transperineal grid so that laser fiber can be
inserted to a target region for ablation, and hypodermic thermal
sensors are then advanced through different locations in the grid
such that some sensors are placed close to the ablation zone to
confirm ablation while some other sensors are placed close to the
safety zone to avoid reaching threshold temperatures.
53. The method of claim 51, wherein the target region and laser
fiber placements are planned using a planning image acquired before
a procedure, and the software loads the plan and maps it to a frame
of reference of a live ultrasound image, and needle for laser
guidance is then placed as per this plan through the transperineal
grid, wherein the plan for each needle is represented by {(i,
j).sub.k, D.sub.k, t.sub.k} where (i,j).sub.k represents the grid
location, D.sub.k and t.sub.k represent the depth of insertion and
time of laser application for the k-th laser source.
54. The method of claim 51, wherein information from medical
imaging modalities selected from the group consisting of PET, CT,
MRI, MRSI, Ultrasound, Echo Cardiograms and Elastography are
combined with live B-mode ultrasound image or two orthogonal planes
of simultaneously captured ultrasound image or live 3d ultrasound
image to provide guidance to one or more laser sources.
55. The method of claim 54, wherein the information is combined
between imaging modalities using computerized or cognitive image
co-registration, utilizing external markers or fiducials for
initial registration, and the computerized co-registration is
achieved using rigid registration, affine registration, elastic
registration, or a combination thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a non-provisional of U.S.
Provisional Patent Application 61/700,273, filed Sep. 12, 2012, the
entirety of which is expressly incorporated herein by
reference.
BACKGROUND OF THE INVENTION
PRIOR ART
[0002] U.S. Pat. No. 8,155,416, issued on Apr. 10, 2012 for
invention titled "Methods and apparatuses for planning, performing,
monitoring and assessing thermal ablation," discloses a thermal
ablation system using an x-ray system to measure temperature
changes throughout a volume of interest in a patient. Image data
sets captured by the x-ray system during a thermal ablation
procedure provide temperature change information for the volume
being subjected to the thermal ablation. However, the invention
does not disclose a method of using a guidance tool or tracking
method for thermal ablation. Also, there are no claims on
performing the thermal ablation under ultrasound guidance with real
time thermal monitoring or multi-modality image overlays with
thermal maps.
[0003] In their patent application Ser. No. 12/213,386 filed Jun.
18, 2008 titled "Methods and devices for image-guided manipulation
or sensing or anatomic structures", the inventors disclose devices
and methods for identifying or observing a precise location in the
body through and/or upon which medical procedures such as laser
ablation may be efficiently and safely performed. The methods
disclosed in the patent application use image guidance with
ultrasound or optical coherence tomography imaging with no
computation or display of thermal maps/thermal measurements or
tracking methods. The method disclosed does not allow for any means
to control the laser sources to localize the ablation.
[0004] U.S. Pat. No. 6,669,693, issued on Dec. 30, 2003 for
invention titled "Tissue ablation device and methods of using,"
discloses a tissue ablating device and the method of using
radiofrequency signal and monitoring with ultrasound or intra
cardiac echo device for treating cardiac arrhythmias. The patent
has no claims on providing thermal measurements, thermal maps or
overlays with other imaging modalities. The method claimed does not
provide for any control of ablation sources or use of a guidance
tool or tracking method to localize the tissue ablation.
[0005] U.S. Pat. No. 8,137,340, issued on Mar. 20, 2012 for
invention titled "Apparatus and method for soft tissue ablation
employing high power diode-pumped laser," and U.S. Pat. No.
7,313,155, issued on Dec. 25, 2007 for invention titled "High power
Q-switched laser for soft tissue ablation," disclose laser ablation
with a high power diode-pumped laser and high power Q-switched
solid-state laser respectively for ablating soft tissue with laser.
The inventions do not detail laser temperature control methods,
guidance tools or tracking methods, or method of performing
targeted tissue ablation.
BACKGROUND
[0006] A large number of medical procedures involve local tissue
ablation in order to treat a condition or ablate a malignancy. For
example, tissue ablation can be used to treat a benign condition
called benign prostate hyperplasia (BPH), as well as a malignant
condition such as prostate cancer. Thermal ablation methods find
widespread applications in such medical procedures where both,
cooling and heating methods are involved. Cryotherapy ablates the
tissue by cooling it down to a temperature where the cell necrosis
occurs while laser therapy performs cell necrosis by raising
temperature to unsafe limits for the tissue being ablated. When
trying to localize the ablation, cryotherapy suffers from the
disadvantage that the temperature gradient is very large from the
body temperature to the ablation temperature. The tissue has to be
locally cooled down to around -40 degrees Celcius to ablate, which
results in temperature gradient of 77 degrees Celcius compared to
body temperature. As a result, while the tissue is being locally
cooled, the surrounding tissue also cool down to very unsafe
temperatures. The ablation is thus hard to control and causes
irreparable damage to healthy tissue.
[0007] Tissue ablation through heating does not suffer from this
drawback since the temperature only needs to be raised from 37
degree Celcius to about 60 degree Celcius. As a result, the
ablation zone can be contained to small regions while limiting the
damage to surrounding structure. Laser ablation provides one such
method where localized heat can be provided to a target within an
organ, gland or soft tissue such that the target area can be
completely and reliably ablated while preserving important
surrounding structures. Laser energy is typically applied to the
internal tissues and structures using a hypodermic needle sleeve.
The needle is inserted to the target and a fiber, through which
laser energy is applied, is inserted through the needle to place it
at the target. The laser source is then activated and the delivered
thermal energy ablates tissue within the ablation zone. The
traditional drawback to using laser ablation is that it cannot be
performed under ultrasound guidance since traditional ultrasound
does not provide thermometry information. One compromise has been
to observe temperature of ablation using MR thermometry. However,
this method is cumbersome, very expensive, and requires prolonged
access to MR gantry, which makes it an unfeasible procedure for a
vast majority of surgeons. In addition, the learning curve to
perform a laser ablation in MR gantry can be very steep.
[0008] We solve this problem by providing methods and apparatus for
performing targeted laser ablation such that the laser energy can
be delivered very precisely and the temperature measurement can be
performed without requiring real-time analysis of MRI images.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 shows a conceptual diagram showing ablation using a
grid template.
[0010] FIG. 2 shows an overall diagram showing laser ablation using
a grid template and thermometry feedback to controller and
user.
[0011] FIG. 3 shows an overall workflow for a laser ablation device
using an external grid template and hypodermic needle based thermal
sensors.
[0012] FIG. 4 shows a method for performing laser ablation such
that the safety zone is unharmed while the ablation zone is
completely ablated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] This disclosure claims methods and apparatus for performing
targeted laser ablation for a medical procedure. The target may
include a malignancy or benign inflammation. Specifically, the
apparatus includes three essential components: i) a guidance tool
that guides laser source to target region, ii) a controller that
controls laser energy and iii) a computer with software that
computes and displays temperature measurements.
[0014] The guidance tool used for placing laser to the target
tissue may contain a tracking device such that after an initial
calibration with real world, the tracking device can be manipulated
to align a needle with the desired target within the tissue. The
only requirement for the tracking tool is to provide a trajectory
for aligning the needle.
[0015] The controller provides the interface between the computer
and the laser source. The computer monitors the temperature, and in
case of a software based tracking system, the trajectory of the
needle. The computer provides feedback to the controller to start
or stop laser energy delivery. In addition, the computer is
equipped with a display monitor that provides thermal and visual
feedback to the user.
[0016] FIGS. 1 and 2 show one particular embodiment in detail where
a brachytherapy-like grid is used to guide needles. Note that the
methodology does not change even if a tracking system is used for
guiding various needles to their targets. As shown in FIG. 1, the
apparatus includes a grid, which has pinholes at various grid
locations. Each pinhole location may be individually identified.
For example, if the rows are labeled as 1,2,3, . . . , and the
columns are labeled as a,b,c, . . . , then any pinhole can be
represented by index (i,j), where i .epsilon. {1, 2,3, . . . } and
j .epsilon. {a,b,c, . . . }.
[0017] A planning image form a previous patient visit may be used
for planning the laser ablation. The laser ablation plan that
includes the location and trajectories of laser sources, ablation
zone and the region to be spared, hereafter referred to as safety
zone, is used as the input for the procedure. The plan may be
defined such that it corresponds to the grid after the grid has
been calibrated to correspond to the frame of reference of the
planning image. For example, if a laser source k is to be inserted
through a pinhole at location (i,j) to a depth D.sub.k, and
activated for a duration of t.sub.k, then the ablation plan may be
completely represented by the set {(i, j), D.sub.k, t.sub.k}. In
addition, locations for insertion of thermal sensors may be planned
in advance based on both ablation zones and safety zones. Note that
an ablation zone may require application of more than one laser
sources simultaneously. Let T.sub.safety.sup.high and
T.sub.safety.sup.low represent the thresholds for the highest
temperature allowed in safety zone beyond which the laser source
must be shut down and the maximum temperature threshold before
laser source can be activated, respectively. Let
T.sub.ablation.sup.low represent the minimum temperature required
in ablation zone. In general,
T.sub.ablation.sup.low>T.sub.safety.sup.high>T.sub.safety.sup.low
and nominal values in tissue for T.sub.ablation.sup.low,
T.sub.safety.sup.high and T.sub.safety.sup.low are 60.degree. C.,
55.degree. C. and 50.degree. C. respectively. Then, the entire
laser ablation must be performed such that the temperature in
ablation zone reaches higher than T.sub.ablation.sup.low while the
temperature of the safety zone never reaches unsafe limits, i.e.,
more than T.sub.safety.sup.high.
[0018] FIG. 2 shows an overall scheme for a localized targeted
laser ablation. The laser source(s) and temperature sensors are
placed at the planned locations using a fixed grid, which may be
attached to an ultrasound transducer or to a guidance tool. The
needles may also be directly placed using a guidance tool under
live ultrasound guidance. The laser placement is done in two
stages: first, a hollow needle, which acts as a guide or sleeve for
the laser fiber to be inserted through, is placed to desired
location; and then, the laser fiber is inserted along the needle
such that the laser source(s) reaches the tip of the needle sleeve.
The sleeve may be removed after insertion of the laser fiber. In
addition to the laser source(s), needles are also inserted to
measure temperatures inside tissue, around the ablation zone and
around the safety zone.
[0019] The controller acts as an interface between the computer and
the hardware through temperature measurements and control of laser
delivery. Controller is connected to the output of the thermal
sensors and provides the temperature measurements to the computer.
In addition, controller takes inputs from computer to start or stop
the activation of laser source(s).
[0020] The computer has algorithms for computation and display of
thermal maps in addition to the individual thermal sensor
measurements as identified on a virtual grid displayed on a
monitor. The user may interact with the computer to define the
pinhole locations and laser plan onto the virtual grid. If live
ultrasound image is available, the virtual grid is overlaid on the
live ultrasound image and the individual needles are defined in at
least two orthogonal views containing the needles. For a prostate
procedure, the two orthogonal views would be transverse, which will
correspond with the virtual grid and contain all the pinholes in
its place and sagittal, which will contain the entire needle length
in its plane. The two views for each needle define the complete
placement of needles including locations of laser sources. The
needles and their grid locations may be manually entered by the
user or automatically computed by analyzing the ultrasound video
capture after each needle is placed. After all needles and sources
are placed, the laser ablation is performed.
[0021] As shown in FIG. 3, when patient comes for thermal ablation,
upon administration of local or general anesthesia, the surgeon
positions the patient and attaches the grid such that the grid
locations correspond to the planning image grid points. This may
require some physical adjustments based on ultrasound image or some
other body markers. For example, for prostate ablation, a
transrectal ultrasound transducer may be introduced into the rectum
of patient and the grid may be mounted using a rigid fixture on to
the probe. The probe pressure and insertion depth then can be
adjusted such that the alignment of attached grid template with the
virtual template from the planning image is ensured. In another
arrangement, external markers or fiducials may be attached on the
patient's skin such that they can be used as reference while
positioning the ablation equipment relative to a planning image
that contains tissue image in addition to the geometry or image of
the fiducials. Such a procedure is part of initial calibration
before each procedure, which may also include software based
co-registration from the planning images to a live imaging modality
such as ultrasound.
[0022] After positioning the patient and the grid or guidance tool
as per the planned procedure, the user inserts the needles for
laser sleeves into place as per the predefined plan. As mentioned
earlier, this may be done using grid under live ultrasound guidance
or ultrasound coupled with a tracking system. When the needles are
placed, the user places the laser fibers by inserting it along the
needle sleeves till the tip reaches end of the sleeve. At this
point, the sleeve may be withdrawn. Next, the user inserts the
needles containing thermal sensors around the ablation zone and
safety zones. Let T.sub.safety and T.sub.ablation. represent the
maximum temperature in safety zone and minimum temperature in
ablation zone, respectively.
[0023] FIG. 4 provides a detailed procedure for performing laser
ablation while maintaining control of temperatures experienced by
ablation and safety zones. Upon placement of the laser source(s)
and the thermal sensors, the user initializes the delivery of laser
energy. The computer starts calculating the temperature based on a
combination of ultrasound thermometry, heat equations and the
measurements at each thermal sensor. The temperatures can be
displayed as a color-coded overlay or isothermal contours such that
the temperatures in ablation and safety zones can be computed and
monitored in real-time. If the safety zone reaches high temperature
threshold T.sub.safety.sup.high before ablation is completed, the
computer automatically sends signal to controller for shutting off
the laser. The system then waits for temperature to drop below
T.sub.safety.sup.low, following which it activates the laser again.
The process is repeated till temperature reaches at least
T.sub.ablation.sup.low inside the ablation zone.
[0024] ablat /ow ion i
* * * * *