Confocal Laser Endomicroscopy Probe Research Articles

Introduction of In Vivo Confocal Laser Endomicroscopy and Real-Time Telepathology for Remote Intraoperative Neurosurgery-Pathology Consultation.

Precise communication between neurosurgeons and pathologists is crucial for optimizing patient care, especially for intraoperative diagnoses. Confocal laser endomicroscopy (CLE) combined with a telepathology software platform (TSP) provides a novel venue for neurosurgeons and pathologists to review CLE images and converse intraoperatively in real-time. To describe the feasibility of integrating CLE and a TSP in the surgical workflow for real-time review of in vivo digital fluorescence tissue imaging in 3 patients with intracranial tumors. Although the neurosurgeon used the CLE probe to generate fluorescence images of histoarchitecture within the operative field that were displayed on monitors in the operating room, the pathologist simultaneously remotely viewed the CLE images. The neurosurgeon and pathologist discussed in real-time the histological structures of intraoperative imaging locations. The neurosurgeon placed the CLE probe at various locations on and around the tumor, in the surgical resection bed, and on surrounding brain tissue with communication through the TSP. The neurosurgeon oriented the pathologist to the location of the CLE, and the pathologist and neurosurgeon discussed the CLE images in real-time. The TSP and CLE were integrated successfully and rapidly in the operating room in all 3 cases. No patient had perioperative complications. Two novel digital neurosurgical cellular imaging technologies were combined with intraoperative neurosurgeon-pathologist communication to guide the identification of abnormal histoarchitectural tissue features in real-time. CLE with the TSP may allow rapid decision-making during tumor resection that may hold significant advantages over the frozen section process and surgical workflow in general.

Image-guided in-Vivo Needle-Based Confocal Laser Endomicroscopy in the Prostate: Safety and Feasibility Study in 2 Patients.

Purpose: To assess the safety and technical feasibility of in-vivo needle-based forward-looking confocal laser endomicroscopy in prostate tissue. Methods: For this feasibility study, 2 patients with a suspicion of prostate cancer underwent transperineal needle-based confocal laser endomicroscopy during ultrasound-guided transperineal template mapping biopsies. After intravenous administration of fluorescein, needle-based confocal laser endomicroscopy imaging was performed with a forward-looking probe (outer diameter 0.9 mm) in 2 trajectories during a manual push-forward and pullback motion. A biopsy was taken in a coregistered parallel adjacent trajectory to the confocal laser endomicroscopy trajectory for histopathologic comparison. Peri- and postprocedural adverse events, confocal laser endomicroscopy device malfunction and procedural failures were recorded. Needle-based confocal laser endomicroscopy image quality assessment, image interpretation, and histology were performed by an experienced confocal laser endomicroscopy rater and uro-pathologist, blinded to any additional information. Results: In both patients, no peri- and post-procedural adverse events were reported following needle-based confocal laser endomicroscopy. No confocal laser endomicroscopy device malfunction nor procedural failures were reported. Within 1.5 min after intravenous administration of fluorescein, needle-based confocal laser endomicroscopy image quality was sufficient for interpretation for at least 14 min, yielding more than 5000 confocal laser endomicroscopy frames per patient. The pullback confocal laser endomicroscopy recordings and most of the push-forward recordings almost only visualized erythrocytes, being classified as non-representative. During the push-forward recordings, prostate tissue was occasionally visualized in single frames, insufficient for histopathologic comparison. Prostate carcinoma was identified by biopsy in one patient (Gleason score 4 + 3 = 7, >50%), while the biopsy from the other patient showed no malignancy. Conclusion: Needle-based confocal laser endomicroscopy imaging of in-vivo prostate tissue with a forward-looking confocal laser endomicroscopy probe is safe without device malfunctions or procedural failures. Needle-based confocal laser endomicroscopy is technically feasible, but the acquired confocal laser endomicroscopy datasets are non-representative. The confocal laser endomicroscopy images’ non-representative nature is possibly caused by bleeding artifacts, movement artifacts and a lack of contact time with the tissue of interest. A different confocal laser endomicroscopy probe or procedure might yield representative images of prostatic tissue.

Rapid testing of gut permeability using oral fluorescein and confocal laser endomicroscopy in Zambian adults.

Dual sugar testing for gut permeability is time-consuming and complex. We explored the utility of fluorescein as a simple and inexpensive alternative method. We used a confocal laser endomicroscopy probe placed at the fingertip of participants who had ingested sodium fluorescein to measure the fluorescence at various time points. In 10 patients with diarrhoea, but not in 10 controls, fluorescence was detected quickly. By 6min fluorescence was detected in all diarrhoea patients but only 1 control (p=0.0004). After 15min there was no difference between the groups. This simple oral fluorescein test may be useful to study gut permeability in low-resource settings.

Confocal Laser Endomicroscopy Assessment of Pituitary Tumor Microstructure: A Feasibility Study

This is the first study to assess confocal laser endomicroscopy (CLE) use within the transsphenoidal approach and show the feasibility of obtaining digital diagnostic biopsies of pituitary tumor tissue after intravenous fluorescein injection. We confirmed that the CLE probe reaches the tuberculum sellae through the transnasal transsphenoidal corridor in cadaveric heads. Next, we confirmed that CLE provides images with identifiable histological features of pituitary adenoma. Biopsies from nine patients who underwent pituitary adenoma surgery were imaged ex vivo at various times after fluorescein injection and were assessed by a blinded board-certified neuropathologist. With frozen sections used as the standard, pituitary adenoma was diagnosed as “definitively” for 13 and as “favoring” in 3 of 16 specimens. CLE digital biopsies were diagnostic for pituitary adenoma in 10 of 16 specimens. The reasons for nondiagnostic CLE images were biopsy acquisition <1 min or >10 min after fluorescein injection (n = 5) and blood artifacts (n = 1). In conclusion, fluorescein provided sufficient contrast for CLE at a dose of 2 mg/kg, optimally 1–10 min after injection. These results provide a basis for further in vivo studies using CLE in transsphenoidal surgery.

Confocal laser endomicroscopy in diagnosing indeterminate biliary strictures and pancreatic lesions − a prospective pilot study

An accurate histopathological diagnosis of indeterminate biliary strictures and pancreatic lesions is challenging because of insufficient quali-ty of tissue specimen taken during ERCP (brush cytology), cholangioscopy (biopsies) or endosonography (EUS, FNAB). Confocal laser endomicroscopy (CLE) allows virtual histopathological diagnosis with the potential to either replace or increase the diagnostic yield of standard histopathological diagnosis in patients presenting with biliary strictures and pancreatic lesions. The aims of our prospective pilot study were to: 1. Assess the diagnostic yield of standard histopathology compared to CLE in patients referred for cholangioscopy or for EUS of the pancreas; 2. Evaluate the cost of CLE in these indications. CLE was performed (during cholangioscopy or EUS), followed by standard tissue sampling. CLE-based diagnosis was compared with standard histopathology/cytology. CLE probe was introduced through the working channel of the cholangioscope or through the FNAB needle. Atotal of 23 patients were enrolled (12 women, mean age 61 years); 13 patients underwent cholangioscopy and 10 patients underwent EUS. Cholangioscopy: CLE diagnosed correctly all 4 malignant strictures (histology 2 of them only as 2 patients had insufficient quality of the tissue specimen). Agreement between standard histopathology and CLE was achieved in 85%. EUS: All 3 cases of pancreatic cancer were correctly diagnosed by both CLE and FNAB. All remaining (premalignant and benign) lesions were also correctly diagnosed by both methods. The cost of CLE examination is higher compared to FNAB but comparable with tissue sampling during digital cholangioscopy. CLE demonstrated sufficient diagnostic accuracy in patients with indeterminate biliary strictures or pancreatic lesions and, therefore, might improve diagnostic accuracy or even replace standard histopathology in these indications.

V12-02 CONFOCAL LASER ENDOMICROSCOPY FOR BLADDER CANCER DIAGNOSIS: HOW TO DO IT & OUR PRELIMINARY RESULTS

You have accessJournal of UrologyBladder Oncology and Diversion1 Apr 2017V12-02 CONFOCAL LASER ENDOMICROSCOPY FOR BLADDER CANCER DIAGNOSIS: HOW TO DO IT & OUR PRELIMINARY RESULTS Esmée Liem, Jan Erik Freund, Theo de Reijke, Joyce Baard, Guido Kamphuis, Pilar Laguna Pes, Martijn de Bruin, and Jean de la Rosette Esmée LiemEsmée Liem More articles by this author , Jan Erik FreundJan Erik Freund More articles by this author , Theo de ReijkeTheo de Reijke More articles by this author , Joyce BaardJoyce Baard More articles by this author , Guido KamphuisGuido Kamphuis More articles by this author , Pilar Laguna PesPilar Laguna Pes More articles by this author , Martijn de BruinMartijn de Bruin More articles by this author , and Jean de la RosetteJean de la Rosette More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.3208AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Cystoscopy is the cornerstone in bladder cancer diagnosis and monitoring. Although very effective, conventional white light cystoscopy has its limitations. New techniques have been developed to improve visualisation of tumours and suspicious lesions. However, no information can be given on grade of the disease during cystoscopy or per-operatively as no histopathologic information can be obtained real time. Confocal Laser Endomicroscopy (CLE) is a unique new imaging technique. It allows in vivo optical sectioning of tissue and provides real time microscopic images with high resolution. The objective of this study is to assess if we can take ′optical biopsies′ of the bladder using CLE. METHODS We performed CLE in 19 patients with a bladder tumour, during transurethral resection of the bladder tumour (TURB). At the beginning of the procedure, after initial evaluation of the bladder, 360 ml of 0.1% Fluorescein, a fluorescent contrast agent, was administered intravesical via an indwelling catheter. After 5 minutes CLE was performed using the Cystoflex UHD R (Cellvizio, Mauna Kea, Paris, France), which has a resolution of 1 μm, a field of view of 240 μm, and an imaging depth of 50-65 μm. The CLE probe was introduced via the working channel of the cystoscope (Olympus or Storz 0 - 12°). CLE images were obtained of healthy tissue and tumours, and correlated with histopathology and analysed afterwards. After obtaining CLE images, the tumour was resected en-bloc. Tumour grade was assessed according to the WHO 2004 classification. RESULTS We were able to obtain good CLE images when the probe was correctly positioned. The probe has to be in good contact with the tissue, and perpendicular to the surface. Of the 19 patients; 2 had a benign lesion, 12 low-grade urothelial carcinoma, and 5 high-grade carcinoma. Differences in CLE images could be seen between healthy tissue and tumour (figure 1). CONCLUSIONS During TURB it was possible to take ′optical biopsies′ of the bladder. The obtained CLE images could give real time histopathologic information, and has the potential to differentiate in tumour grade during cystoscopy. These ′optical biopsies′ may assist urologist in future clinical practice in bladder cancer diagnosis and follow-up. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e1372 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Esmée Liem More articles by this author Jan Erik Freund More articles by this author Theo de Reijke More articles by this author Joyce Baard More articles by this author Guido Kamphuis More articles by this author Pilar Laguna Pes More articles by this author Martijn de Bruin More articles by this author Jean de la Rosette More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Mo1988 Outcomes of Confocal Laser Endomicroscopy Probe (pCLE) in the Management of Gastrointestinal Lesions: The Latin American Experience

Mo1988 Outcomes of Confocal Laser Endomicroscopy Probe (pCLE) in the Management of Gastrointestinal Lesions: The Latin American Experience

Fiber-Optic Confocal Laser Endomicroscopy of Small Renal Masses: Toward Real-Time Optical Diagnostic Biopsy

The incidental detection of small renal masses is increasing. However, not all require aggressive treatments as up to 20% are benign and the majority of malignant tumors harbor indolent features. Improved preoperative diagnostics are needed to differentiate tumors requiring aggressive treatment from those more suitable for surveillance. We evaluated and compared confocal laser endomicroscopy with standard histopathology in ex vivo human kidney tumors as proof of principle towards diagnostic optical biopsy. Patients with a solitary small renal mass scheduled for partial or radical nephrectomy were enrolled in study. Two kidneys were infused with fluorescein via intraoperative intravenous injection and 18 tumors were bathed ex vivo in dilute fluorescein prior to confocal imaging. A 2.6 mm confocal laser endomicroscopy probe was used to image tumors and surrounding parenchyma from external and en face surfaces after specimen bisection. Confocal laser endomicroscopy images were compared to standard hematoxylin and eosin analysis of corresponding areas. Ex vivo confocal laser endomicroscopy imaging revealed normal renal structures that correlated well with histology findings. Tumor tissue was readily distinguishable from normal parenchyma, demonstrating features unique to benign and malignant tumor subtypes. Topical fluorescein administration provided more consistent confocal laser endomicroscopy imaging than the intravenous route. Additionally, en face tumor imaging was superior to external imaging. We report what is to our knowledge the first feasibility study using confocal laser endomicroscopy to evaluate small renal masses ex vivo and provide a preliminary atlas of images from various renal neoplasms with corresponding histology. These findings serve as an initial and promising step toward real-time diagnostic optical biopsy of small renal masses.

Sa1510 Clinical Impact of Confocal LASER Endomicroscopy Probe (P - CLE) in the Management of Gastrointestinal Neoplasic and Non - Neoplasic Lesion

Sa1510 Clinical Impact of Confocal LASER Endomicroscopy Probe (P - CLE) in the Management of Gastrointestinal Neoplasic and Non - Neoplasic Lesion

Diagnosis of pancreatic cysts: EUS-guided, through-the-needle confocal laser-induced endomicroscopy and cystoscopy trial: DETECT study

The diagnosis of pancreatic cystic neoplasms (PCNs), which now depends on morphology, cytology, and fluid analysis, is still challenging. A novel confocal laser endomicroscopy probe that can be inserted through a 19-gauge FNA needle allows needle-based confocal laser endomicroscopy (nCLE), and the feasibility of nCLE has been reported in PCNs. The combination of cystoscopy by using a through-the-needle fiberoptic probe in combination with nCLE under EUS guidance may improve the diagnosis of PCNs. To assess the feasibility, safety, and diagnostic yield of the combination of cystoscopy and nCLE in the clinical diagnosis of PCNs. A prospective feasibility study. An academic tertiary referral center. Thirty patients with PCNs. EUS-guided dual through-the-needle imaging (cystoscopy and nCLE) for PCNs. Technical feasibility and safety. Associations of cystoscopy and nCLE findings with clinical diagnosis of PCNs. The procedure was technically successful with the exception of 1 probe exchange failure. In 2 patients (7%), postprocedure pancreatitis developed. Specific features associated with the clinical diagnosis of mucinous cysts were identified: mucin on cystoscopy and papillary projections and dark rings on nCLE. The sensitivity of cystoscopy was 90% (9/10), and that of nCLE was 80% (8/10), and the combination was 100% (10/10) in 18 high-certainty patients. A single-center study and lack of complete pathologic correlation. The combination of dual through-the-needle imaging (cystoscopy and nCLE) of pancreatic cysts appears to have strong concordance with the clinical diagnosis of PCN. ( NCT01447238.).

Establishing a Diagnosis in Indeterminate Pancreaticobiliary Strictures: Is Confocal Laser Endomicroscopy the Answer?

Despite the advances that have been made in diagnostic modalities during recent years, the differentiation between benign and malignant pancreaticobiliary strictures remains a significant diagnostic challenge. Conventional cancer markers are of limited diagnostic utility and radiologic assessment with cross-sectional imaging may not provide a definitive diagnosis in the absence of a mass lesion [1–3]. Endoscopic evaluation has, for many years, relied heavily on cholangiographic appearance and biliary brush cytology, which, despite a specificity approaching 100 %, shows a low sensitivity of 15–57 % for malignancy [4]. Confocal laser endomicroscopy (CLE) provides microscopic information on mucosal tissue in real time and aims to enhance the diagnostic accuracy of endoscopic examination. Employing technology designed to prevent light scattering, CLE generates highly focused images of very small mucosal areas [5, 6]. It has been used in detecting dysplasia/cancer in various settings, such as colorectal polyps, inflammatory bowel disease, and Barrett’s esophagus [7–9]. A CLE probe has been devised fitting in the working channel of a cholangioscope or in a catheter that can be inserted through the working channel of a standard duodenoscope under fluoroscopic or cholangioscopic guidance allowing examination of indeterminate biliary strictures. Fluorescein is given intravenously 2–3 min prior to mucosal imaging allowing also for visualization of blood vessels [10]. In recent years, a number of studies have attempted to determine the performance characteristics of this modality for the differentiation of benign and malignant pancreaticobiliary strictures [10–13]. Also, data from a multicenter prospective study were used to reach a consensus definition of biliary and pancreatic probe-based CLE [13]. Characteristics most suggestive of malignancy included thick dark bands ([40 lm), thick white bands ([20 lm), dark clumps, or epithelial structures, whereas thin dark or white bands were suggestive of benign lesions (Miami classification criteria). It has been shown that combining two or more criteria for malignancy significantly increases the sensitivity and predictive values of the method [13]. In the largest study investigating the performance characteristics of CLE in indeterminate biliary lesions, a total of 89 patients were included [12]. Utilizing the Miami classification criteria, CLE was found to have a sensitivity of 98 %, a specificity of 67 %, and a negative and positive predictive value of 97 and 71 %, respectively. It compared favorably with conventional histopathology that had a sensitivity, specificity, negative and positive predictive values of 45, 100, 69, and 100 %, respectively [12]. The excellent sensitivity and negative predictive value of CLE in indeterminate pancreaticobiliary strictures suggest that it could be an important adjunct to ERCP for distinguishing benign from malignant disease and that it may be used to guide biopsy sampling. Integrating this very promising new technology into every-day clinical practice involves defining not only its performance characteristics but also interobserver agreement for the perceived final diagnosis and for the different diagnostic criteria applied. In the initial validation of the Miami classification criteria, three criteria indicative of malignancy and one indicative of benign strictures showed moderate interobserver agreement as suggested by significant Fleiss kappa values between 0.40 and 0.60 [13]. Apart from these findings, however, data on interobserver E. Kalaitzakis (&) Department of Gastroenterology, Skane University Hospital, 221 85 Lund, Sweden e-mail: evangelos.kalaitzakis@medicine.gu.se; kalvag@hotmail.com

Detection of Colonic Neoplastic Lesions Using Confocal Laser Endomicroscopy and a Novel pH Sensing Fluorescent Probe

Background: Confocal laser endomicroscopy (CLE) provides real time microscopic imaging of the gastrointestinal lining. Fluorescein is the most widely used contrast-enhancing fluorophore for this technique, but fails to provide signal within neoplastic cells that may reflect a more acidic tumor microenvironment. Lysosensor dye DND 189 (LD, Invitrogen) has a fluorescence peak at pH 5.2, compared to fluorescein with a peak at pH 7. The aim of this study was to determine if LD fluorescence might be greater in tumors compared to adjacent normal cells, thereby providing “positive” signals within tumors. Methods: Mice received azoxymethane (AOM, 10 mg/kg body wt) or saline (AOM vehicle) x 6 weeks. Uncontrasted colons were visualized via colonoscopy. Mice were then injected by tail vein with LD (25, 50, or 100 μL). The CLE probe (UHD probe, Mauna Kea Techologies, Paris) was inserted per rectum and images acquired 1-2 cm from the anal verge at 1, 5, 10, 30, 60, 120, and 180 min after injection. To image tumors we used an open laparotomy approach to identify tumors from the serosal side and then position the intraluminal CLE probe directly onto the tumor. After image acquisition, colons were opened and tumors harvested to correlate histological sections with confocal images. Results: Two control mice underwent colonoscopy that revealed endoscopically normal colons. In normal colons, punctate signals were detected 5-10 minutes after injection that were only observed at the highest LD dose. These signals may originate from dye trapped in acidic lysosomes. AOM-treated mice (n=4 mice) were assessed In Vivo for tumors with CLE per rectum assisted by laparotomy. Adequate tumor images were achieved with 50 μL LD. Within 5 min, LD fluorescence was detected in all tumors, but not adjacent normal-appearing mucosa (n=6 tumors, p<0.05). In one mouse without tumors undergoing CLE an inadvertent vascular injury causing ischemia of the colon almost immediately induced marked and diffuse positive signal. Conclusions: Fluorescent dyes, sensitive to low pH, can provide positive signals within tumors in a murine model of colorectal cancer. These metabolic signals could be exploited for enhanced microscopic detection of neoplasia using dynamic contrast CLE. Furthermore, changes in tumor microenvironment pH, induced by chemotherapeutic agents, might prove useful to assess response to therapy.

Interobserver Agreement and Accuracy in Prediction of Barrett's-Associated Neoplasia Among More-Experienced and Less-Experienced Endomicroscopists

Background: Confocal laser endomicroscopy (CLE) provides real time microscopic imaging of the gastrointestinal lining. Fluorescein is the most widely used contrast-enhancing fluorophore for this technique, but fails to provide signal within neoplastic cells that may reflect a more acidic tumor microenvironment. Lysosensor dye DND 189 (LD, Invitrogen) has a fluorescence peak at pH 5.2, compared to fluorescein with a peak at pH 7. The aim of this study was to determine if LD fluorescence might be greater in tumors compared to adjacent normal cells, thereby providing “positive” signals within tumors. Methods: Mice received azoxymethane (AOM, 10 mg/kg body wt) or saline (AOM vehicle) x 6 weeks. Uncontrasted colons were visualized via colonoscopy. Mice were then injected by tail vein with LD (25, 50, or 100 μL). The CLE probe (UHD probe, Mauna Kea Techologies, Paris) was inserted per rectum and images acquired 1-2 cm from the anal verge at 1, 5, 10, 30, 60, 120, and 180 min after injection. To image tumors we used an open laparotomy approach to identify tumors from the serosal side and then position the intraluminal CLE probe directly onto the tumor. After image acquisition, colons were opened and tumors harvested to correlate histological sections with confocal images. Results: Two control mice underwent colonoscopy that revealed endoscopically normal colons. In normal colons, punctate signals were detected 5-10 minutes after injection that were only observed at the highest LD dose. These signals may originate from dye trapped in acidic lysosomes. AOM-treated mice (n=4 mice) were assessed In Vivo for tumors with CLE per rectum assisted by laparotomy. Adequate tumor images were achieved with 50 μL LD. Within 5 min, LD fluorescence was detected in all tumors, but not adjacent normal-appearing mucosa (n=6 tumors, p<0.05). In one mouse without tumors undergoing CLE an inadvertent vascular injury causing ischemia of the colon almost immediately induced marked and diffuse positive signal. Conclusions: Fluorescent dyes, sensitive to low pH, can provide positive signals within tumors in a murine model of colorectal cancer. These metabolic signals could be exploited for enhanced microscopic detection of neoplasia using dynamic contrast CLE. Furthermore, changes in tumor microenvironment pH, induced by chemotherapeutic agents, might prove useful to assess response to therapy.

Confocal laser endomicroscopy for the diagnosis of urothelial bladder neoplasia: a technology of the future?

To evaluate bladder urothelium by confocal laser endomicroscopy (CLE) and correlate microscopic findings with standard histopathology. Fresh bladder urothelium tissue specimens were topically stained with acriflavine for instantaneous microscopic imaging. A single-line laser in a handheld CLE probe delivered an excitation wavelength of 488 nm providing a high resolution of 0.7 µm and an adjustable imaging depth of 0-250 µm. Resection specimens of 18 patients were investigated with 1000-fold magnification and ex vivo findings were compared with targeted histopathology (haematoxylin and eosin staining). Typical tumour growth patterns such as altered nuclear to cytoplasmic ratio, pseudopapillar tissue stratification and neoangiogenesis were readily visible. Nuclear and subnuclear architecture of healthy bladder tissue could be discriminated against neoplastic tissue. In addition to white light cystoscopy, CLE is a promising novel tool for the in vivo microscopic visualization of bladder cancer; first results of the present study show its potential to define microscopic characteristics of bladder cancer tissue. Further in vivo studies are necessary to determine sensitivity and specificity of the technique.

In Vivo Molecular Imaging of Colorectal Cancer With Confocal Endomicroscopy by Targeting Epidermal Growth Factor Receptor

Epidermal growth factor receptor (EGFR) is a therapeutic target for colorectal cancer (CRC). However, technical challenges have limited in vivo imaging of EGFR in CRCs. Confocal laser endomicroscopy (CLE) enables accurate microscopic visualization of CRC in patients during endoscopy. We evaluated the ability to use CLE in vivo for instantaneous molecular imaging of EGFR in CRC models. Tumors were grown in mice (n = 68) from human CRC cell lines that expressed high (SW480 cells) or low (SW620 cells) levels of EGFR. Tumors were visualized in vivo with a handheld CLE probe after injection of fluorescently labeled EGFR antibodies. EGFR-specific fluorescence was graded from 0 to 3+. Neoplastic and non-neoplastic specimens from human colorectal mucosa were examined. In vivo findings were correlated with histopathology, immunohistochemistry, and fluorescence microscopy analyses. CLE analysis of cell cultures confirmed the different expression levels of EGFR between cell lines. In living animals, CLE differentiated EGFR expression levels between tumor cell limes (mean fluorescence, 1.92 +/- 0.22 [SW480] and 0.59 +/- 0.21 [SW620], P = .0004). CLE analysis of EGFR expression in human specimens allowed distinction of neoplastic from non-neoplastic tissues (mean fluorescence, 2.0 +/- 0.37 vs 0.25 +/- 0.16, respectively, P = .0035). CLE can be used for in vivo, molecular analysis of CRC and to differentiate EGFR expression patterns in xenograft tumors and human tissue samples. Because CLE can be performed during endoscopy, in vivo molecular imaging might be used in diagnosis of CRC and to predict response to targeted therapies.