WO2004090500A2

WO2004090500A2 - Fluorescent cholangiography

Info

Publication number: WO2004090500A2
Application number: PCT/US2004/010291
Authority: WO
Inventors: Brendon Stiles; Yuman Fong; Amit Bhargava; Prasad Adusumilli
Original assignee: Sloan-Kettering Institute For Cancer Research
Priority date: 2003-04-04
Filing date: 2004-04-02
Publication date: 2004-10-21
Also published as: WO2004090500A3

Abstract

An improved method for imaging the biliary tree or portions thereof of a subject, for example a human subject, requires no exogenous materials for the imaging. The method involves exposing all or a portions of the biliary tree of the subject to light of a wavelength effective to stimulate autofluorescence of bile, and (b) observing the locations of emission from the bile, wherein the emissions of the bile provide an image of the biliary tree or exposed portions thereof. In one embodiment, no exogenous materials are introduced to the subject in connection with the imaging of the biliary tree.

Description

ELUORESCENT CHOLANGIOGRAPHY

Statement of Related Cases

[001] This application claims the benefit and priority of US Provisional Application No.

60/460,245, filed April 4, 2003 which is incoiporated herein by reference in jurisdictions permitting such incorporation.

Background of the Invention

[002] Cholesystectomy, performed either open or laparoscopically, is among the most common major surgical procedures performed in the United States today. A significant complication which can occur is iatrogenic biliary tract injury. At present, there are several methods available to identify such a biliary tract injury. The most commonly used procedure is procedure is intraoperative cholangiography (IC), in which iodinated contrast material is injected into the biliary tree. This procedure can be used to delineate complex anatomy, and to detect injuries that have already occurred, but it has not been consistently reported to decrease injury rates. Another option for imaging the biliary tract is introcorporeal ultrasound (IU), however this procedure is not in widespread use because it is very operator-dependent and requires extra equipment.

[003] Disclosures have also been made suggesting the use of bile acids, conjugated with blue staining or fluorescent compounds to image the biliary tract. Like IC, these methods require the addition of an exogenous marker to the patient. Further, they rely on the excretion of this exogenously administered substance and are therefore dependent on the dose given, the time since administration and liver function.

[004] Methods for improved identification of the biliary tract to reduce injury, and for prompt identification and localization of injuries when they occur are therefore desirable.

Summary of the Invention [005] The present invention provides an improved method for imaging the biliary tree or portions thereof of a subject, for example a human subject, which requires no exogenous materials for the imaging. The method comprises the steps of: (a) exposing all or a portions of the biliary tree of the subject to light of a wavelength effective to stimulate autofluorescence of bile, and

(b) observing the locations of emission from the bile, wherein the emissions of the bile provide an image of the biliary tree or exposed portions thereof. In one embodiment, no exogenous materials are introduced to the subject in connection with the imaging of the biliary tree.

The invention further provides for a use of imaging apparatus, such as laparoscopes, in such a method for imaging the biliary tree.

Brief Description of the Drawing [006] Fig. 1 shows an emission spectrum of murine bile, excited at an excitation wavelength of 475 nm.

Detailed Description of the Invention [007] This application relates to an improved method for monitoring for and for reducing the risk of iatrogenic biliary tract injury that may occur during surgical procedures such as cholecystectomies. In accordance with the present invention, the biliary tract is visualized during surgery using the intrinsic fluorescence, or autofluorescence, of bile. This allows more rapid evaluation than IC, and provides real-time assessment throughout the procedure, rather than a single view obtained by imaging following the introduction of the contrast material. Because of this, the method of the invention can prevent, rather than merely diagnose injuries. Furthermore, a variety of advantages flow from the fact that no external marker is required. These include (1) there is less risk of injury to the cystic or common ducts, because cystic duct catheterization is not required; (2) procedural mishaps such as leakage of dye or inadvertant slippage of cannulas are avoided; (3) the procedure of the invention may be used when mechanical cannulation of the biliary tract for the introduction of a marker is difficult or impossible to perform; and (4) there is no exposure to ionizing radiation or to iodinated contrast materials. Furthermore, the method of the invention is easy to perform with a minimal learning curve and is cost effective because it uses standard laparoscopic equipment equipped with inexpensive filters to isolate the fluorescence wave lengths. In addition, the method of the invention is not dependent on dose, time since administration of a marker, or liver function.

[008] To demonstrate the efficicacy of the invention, fluorimetry was performed on samples of mouse bile to determine excitation/emission spectra. Mice (n=7) underwent midline laparotomy and the porta hepatis was exposed. Using stereomicroscopy, photographs were taken in brightfield and fluorescent modes, without changing depth or focus. Surgical residents (n=6) evaluated matched pictures randomly, identifying the gallbladder, cystic duct, common bile duct, and whether the cystic duct joined the right hepatic duct or the common bile duct (confluence). The time taken to identify all of the structures was recorded.

[009] Fluorimetry demonstrated autofluorescence of murine bile at an excitation wavelength of 475nm, with intense emission at 480nm (Figure 1). Using fluorescent stereomicroscopy based upon these findings, the entire biliary tree (gallbladder, cystic duct, hepatic ducts and common bile ducts) were easily identified in mice. Surgical residents correctly identified the above anatomical components 98% of the time from fluorescent photographs, but only 78% of the time from brightfield photographs (p<.01). The most common misidentified structures in brightfield photographs were the confluence (45%) and cystic duct (19%), which were incorrectly identified only 2% of the time in fluorescent photographs. Identification of the anatomical structures in fluorescent photographs required only 53% of the time needed using brightfield photographs (p<.001). Fluorescent stereomicroscopy was also used to diagnose bile leak, obstruction, and complex anatomy. Anatomical structures could also be identified by fluorescence in the presence of inflammation. Similarly, biliary anatomy was easily identified using a 5mm Olympus laparoscope with fluorescent filters. By alternating between brightfield and fluorescent laparoscopy, the biliary tract could be evaluated in real-time.

[010] Based on the foregoing, it is apparent that identification of biliary anatomy from fluorescent photographs was both faster and more accurate than identification of matched specimens using brightfield photographs. Fluorescent cholangiography, based solely upon the autofluorescence of bile, can therefore be used for real-time identification of biliary anatomy during laparoscopic procedures, without added morbidity. [Oil] In one embodiment, the equipment necessary to perform the method of the present invention comprises a stereomicroscope with a light source and emission filter matched to the wavelength of the bile emission spectrum. It will be appreciated that the bile the peak in the emission spectrum is fairly broad, and that exact matching of the emission filter with the peak is not necessary provided that substantial amounts of emitted light are observable. In one specific embodiment, the invention may be performed with an Olympus Visera CLV-U40 excitation light source, to provide an excitation wavelength of 470nm ±40 nm and an Olympus Visera OTV-S7V camera processor with an emission wavelength of 500 - 510 nm.

[012] To adapt the procedure from mice to other species, all that is required is a knowledge of the emission wavelengths for the other species. In the case of humans, it is expected that the wavelengths will be similar as the wavelengths for mice, emission at 480nm and excitation at 500nm. For additional species, the emission can be determined by conventional fluorescence measurements using a scanning spectrometer to collect the spectral distribution of emission wavelengths. In the case of weak observed fluorescence, it may be necessary to obtain an excitation spectrum to ensure that the excitation light source has adequate intensity at a wavelength that produces high fluorescence.

[013] Thus, the invention provides a method for imaging the biliary tree or portions thereof of a subject, including a human subject, comprising the steps of (a) exposing a region of the biliary tree to light of a wavelength effective to stimulate autofluorescence of bile of the subject, and (b) observing the locations of emission from the bile. Since no exogenous materials are necessary for the imaging, in a preferred embodiment of the invention, no exogenous markers or labels are introduced into the biliary tree.

[014] The invention will now be further described with reference to the following, non- limiting example.

Example 1

[015] Fluorimetry was performed on samples of mouse bile to determine excitation/emission spectra. Mice (n=7) underwent midline laparotomy and the porta hepatis was exposed. Using stereomicroscopy, photographs were taken in brightfield and fluorescent modes, without changing depth or focus. Surgical residents (n=6) evaluated matched pictures randomly, identifying the gallbladder, cystic duct, common bile duct, and whether the cystic duct joined the right hepatic duct or the common bile duct (confluence). The time taken to identify all of the structures was recorded. Fluorimetry demonstrated autofluorescence of bile at an excitation wavelength of 475nm, with intense emission at 480nm, with the results as described above.

Claims

1. A method for imaging the biliary tree or portions thereof of a subject comprising the steps of:

(a) exposing all or a portions of the biliary tree of the subject to light of a wavelength effective to stimulate autofluorescence of bile, and

(b) observing the locations of emission from the bile, wherein the emissions of the bile provide an image of the biliary tree or exposed portions thereof.

2. The method of claim 1, wherein the subject is human.

3. The method of claim 2, wherein the locations of emission from the bile are observed using a stereomicroscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.

4. The method of claim 2, wherein the locations of emission from the bile are observed using a laparoscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.

5. The method of claim 1, wherein the locations of emission from the bile are observed using a stereomicroscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.

6. The method of claim 1, wherein the locations of emission from the bile are observed using a laparoscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.

7. An apparatus for use in imaging the biliary tree or portions thereof of a subject, characterized in that the apparatus exposes all or a portions of the biliary tree of the subject to light of a wavelength effective to stimulate autofluorescence of bile of the subject, and observes the locations of emission from the bile, wherein the emissions of the bile provide an image of the biliary tree or exposed portions thereof.

8. Apparatus of claim 7, wherein the apparatus is a stereomicroscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.

9. Apparatus of claim 7, wherein the apparatus is a laparoscope equipped with a light source and emission filter matched to the wavelength of bile emission of the subject.