Needle-based Confocal Endomicroscopy Examination of Pancreatic Masse
Needle-based Confocal Endomicroscopy Examination of Pancreatic Masse
Introduction: Pancreatic cancer is one of the most aggressive malignancies with only 5% of
 patients being alive at five years. EUS (endoscopic ultra sound) is an established, sensitive
 diagnostic tool in pancreatic cancer and for staging purposes. Additionally, EUS enables
 guided fine needle aspiration (FNA), which is currently recommended as the first-line
 procedure whenever a pathological diagnosis is required. However, EUS-FNA as a sampling
 method has its drawbacks, due to a relatively low negative predictive value. Confocal laser
 endomicroscopy has emerged in recent years as a novel method that enables in vivo microscopic
 analysis during ongoing endoscopy. Recently, confocal laser endomicroscopy has gone beyond
 the superficial luminal indications with the development of a new microprobe, i.e. a flexible
 laser probe (nCLE) that can pass through a 19-gauge needle. Combined with EUS, descriptive
 criteria for the diagnosis of pancreatic cystic neoplasm has been developed in a multicentre
 trial. However, only a limited number of cases of solid pancreatic masses have been described
 with nCLE.

 Aim and Method: To describe confocal imaging criteria for pancreatic masses, lymph nodes or
 liver metastases identified during EUS procedures performed for pancreatic cancer staging
 (EUS-nCLE), while evaluating also the feasibility and safety of nCLE examination. The
 hypothesis is that EUS-nCLE could allow targeted tissue sampling of pancreatic lesions
 resulting in more accurate diagnosis. XX patients were included all presenting with a
 clinical suspicion of pancreatic cancer or imaging studies showing a pancreatic mass. During
 the procedure an nCLE preloaded 19G FNA needle was advanced into the lesion under EUS
 guidance. A contrast agent was administered intravenously (2.5 ml fluorescein 10%). The data
 was stored digitally for post procedural analysis. Afterwards EUS-FNA was performed for
 cytology smears to enable a final pathological diagnosis. Correlations between the nCLE
 images and the conventional pathology were identified.
Background Pancreatic cancer is one of the most aggressive gastrointestinal malignancies with
 mortality rates following closely the incidence rates. The incidence is increasing and the
 prognosis is grim especially because of late diagnosis and metastatic potential. While
 surgical treatment is currently the only potential curative intervention, 80-85% of the PC
 cases are unfortunately detected in late unresectable stages of the disease. In spite of
 advances in the diagnosis and management of pancreatic cancer less than 5% of patients are
 alive at five years.

 Endoscopic ultrasound (EUS) represents a highly valuable tool in the management of pancreatic
 cancer patients. As a minimally invasive technique that enables high-resolution imaging of
 the pancreatic parenchyma and surrounding structures it is considered the method of choice
 for the detection of clinically suspected pancreatic tumors, with a negative predictive value
 close to 100%. Its diagnostic sensitivity was shown by previous studies to be superior
 compared to other imaging techniques, especially in the case of smaller tumors. Additionally
 EUS enables guided fine needle aspiration (EUS-FNA) which is currently recommended as the
 firs-line procedure whenever pathological diagnosis is required. However, EUS-FNA as a
 sampling technique has its drawbacks, mainly represented by the relatively low negative
 predictive value in diagnosing pancreatic cancer. It thus cannot reliably rule out a
 diagnosis of malignancy and patients with high clinical suspicion usually need repeated FNA.

 Confocal laser endomicroscopy has emerged in recent years as a novel technique that actually
 enables in vivo microscopic analysis during ongoing endoscopy. Endomicroscopy can be
 performed either with dedicated (eCLE) or with miniprobe-based systems (pCLE). It is a
 contrast based technique, the most widely used agent being the intravenously administered
 fluorescein. The probe-based endomicroscopy system consists of a flexible catheter probe
 representing a bundle of optical fibers linked to a micro-objective, a laser scanning unit
 and the control and acquisition software (Cellvizio; Mauna Kea Technology, Paris, France).
 The flexible confocal miniprobes were specifically designed to be passed through the working
 channels of standard endoscopes, biliary catheters or cholangioscopes and thus the pCLE
 system can be easily integrated in any endoscopy unit. The principle of the technique is
 based on a laser beam of defined wavelength being focused towards the targeted tissue and the
 recaptured signal is displayed as 'optical biopsies' in a single horizontal plane.

 The potential role of CLE has been explored in pathology of both upper and lower
 gastrointestinal tract, showing good accuracy for predicting the final histopathological
 diagnosis based on immediate evaluation of tissue and vascular patterns. Recently CLE has
 gone beyond the superficial luminal indications with the development of a new microprobe,
 i.e. a flexible probe thin enough that it can be passed through a 19-gauge needle. Thus under
 EUS guidance solid organs can be accessed for real-time microscopic information. nCLE imaging
 of abdominal organs has been so far achieved in animal models. The feasibility of the
 technique was also proved in a clinical study and descriptive criteria for the diagnosis of
 pancreatic cystic neoplasm were developed from a multicentre trial. However, only a limited
 number of cases of pancreatic solid masses have been described with nCLE.

 Aim The aim of the proposed study is to describe confocal imaging criteria for pancreatic
 masses, lymph nodes or liver metastases identified during EUS procedures performed for
 pancreatic cancer staging (EUS-nCLE), while evaluating also the feasibility and safety of
 nCLE examination. The hypothesis is that EUS-nCLE could allow targeted tissue sampling of
 pancreatic lesions resulting in more accurate diagnosis. With further validation of the
 technique real-time pathological diagnosis could be obtained with immediate initiation of the
 adequate therapy after a single investigation.

 Patients The study will prospectively include patients referred to our department for EUS and
 EUS-FNA of suspected pancreatic masses during a 12 months period. The indication for this
 investigation will be based on the patient's clinical history and previous imaging studies
 (abdominal ultrasound, CT scan, MRI).

 Patients will be selected according to the following criteria used throughout the study:

 Data collected for each participant will include:

 -  Personal data (name, surname, age, sex)

 -  EUS variables (tumor characteristics)

 -  Histological and immunohistochemical findings (final diagnosis)

 Imaging tests All patients with a suspicion (clinical, US, CT/MRI) of pancreatic masses will
 be evaluated by EUS, nCLE and EUS-FNA for pathological diagnosis.

 For EUS examination linear instruments will be used to perform complete examination of the
 pancreas.

 Tumor characteristics (echogenicity, echostructure, size, vascular invasion) will be
 described.

 The presence of regional lymph nodes will be reported with their maximal size, echogenicity,
 shape and margins.

 Identification of liver metastasis will also be looked upon.

 EUS-nCLE will be performed after EUS identification of the pancreatic tumor / lymph node /
 liver metastasis:

 The confocal microprobe will be preloaded in a 19G FNA needle as previously described and
 advanced into the lesion under EUS guidance.

 nCLE examination will follow after the intravenous administration of the contrast agent (2.5
 ml fluorescein 10%).

 Image data will be stored digitally for offline analysis. EUS-FNA will be also performed
 after image acquisition for cytology smears and cell blocks to enable a final pathological
 diagnosis Confocal images will be analyzed during the examination by the principal
 investigator, with clinical and other procedural information in mind. In a second step
 offline analysis, the correlations between representative confocal images and classical
 hematoxylin and eosin sections will be identified.

 Final diagnosis The final diagnosis will be based on EUS-FNA cytology and/or histological
 specimens in those patients that will be further referred for surgery. Pathology samples
 obtained from duodeno-pancreatectomies or caudal pancreatectomies done with curative intent,
 as well as microhistological fragments obtained through EUS-FNA biopsy will be processed by
 paraffin embedding with usual stainings (haematoxylin-eosin), with subsequent
 immune-histochemistry where necessary.

 For the patients without positive cytology or histology the diagnosis will be based on EUS
 tumor characteristics and other relevant information (clinical, imaging tests) with follow-up
 for at least six months.
Inclusion criteria

 -  Age > 18 years old, male or female

 -  Patients diagnosed with solid pancreatic masses with an indication for EUS-FNA

 -  Signed informed consent for EUS with FNA and nCLE examination

 Exclusion criteria

 -  Failure to provide informed consent

 -  Patients with a contraindication for EUS-FNA

 -  Known allergy to fluorescein

 -  Pregnant or breast-feeding patients