Endoscopic Ultrasound Elastography in Pancreatic Masses
Condition: Pancreatic Adenocarcinoma; Chronic Pancreatitis
MeSH terms: Adenocarcinoma; Pancreatitis; Pancreatitis, Chronic
Study type: Observational

Summary: 
      The aim of the study is to assess elastography during EUS examinations of focal pancreatic
      masses, and to consequently differentiate benign versus malignant pancreatic masses in a
      prospective multi-center design.
    

Detailed description: 
      Ultrasound elastography is a recent ultrasound method used for the calculation of tissue
      elasticity distribution in real-time. The method allows the reconstruction of tissue
      elasticity (i.e. the elasticity modulus) and reveals directly the physical properties of the
      tissue, consequently showing different tissue hardness patterns that are determined by
      diseases. Tissue elastography can be easily performed real-time with conventional probes,
      including the linear EUS probes used for the examination of the pancreas. The calculation of
      tissue elasticity distribution is performed in real-time and the examination results are
      represented as transparent overlay colour images overimposed on the conventional gray-scale
      B-mode images.

      Ultrasound elastography was previously used for the diagnosis of breast lesions, prostate
      cancer and thyroid nodules. However, the value of endoscopic ultrasound elastography for the
      diagnosis of pancreatic focal masses is not clear for the current moment, as some authors
      couldn't differentiate benign and malignant pancreatic tumors. Moreover, the intense fibrotic
      reaction and calcifications in chronic pancreatitis induce strain differences, and it is not
      clear if elastography is sensitive enough to detect them.

      The study protocol is based on a semi-quantitative approach of EUS elastography data (movies)
      consisting of characterization of manually user-defined regions of interest, based on the hue
      histograms of the individual focal masses. Due to the inherent bias induced by selection of
      images from a dynamic sequence of EUS elastography, we have previously reported on the
      utility of using computer-aided diagnosis by averaging images from a dynamic sequence of EUS
      elastography. A special plugin (based on the ImageJ software, NIH, Bethesda, MD, USA) is used
      to compute hue histograms on average EUS elastography images, while the hue histograms values
      for each patient (0 to 255 values) are further used to classify the patients with benign and
      malignant lesions.

      Ultrasound elastography will be performed during an usual EUS examination (7.5 MHz
      frequency), with two movies of 10 seconds recorded on the embedded HDD in order to minimize
      variability and to increase repeatability of acquisition. A two panel image with the usual
      conventional gray-scale B-mode EUS image on the right side and with the elastography image on
      the left side will be used. The region of interest will be preferably larger than the focal
      mass, in order to include the surrounding structures. In order to minimize the human bias,
      all the post-processing and computer analysis of digital movies will be performed within the
      IT Center in Craiova, with all programmers and statisticians being blinded to the clinical,
      pathological and imaging data, with the exception of the average hue histogram values
      calculated from a second region of interest manually traced around the focal mass.

      The study design is prospective, blinded and multi-center, comparing endoscopic ultrasound
      elastography (EUS-EG) results for the detection and characterization of focal pancreatic
      masses by using artificial intelligence techniques, in comparison with the gold standard
      represented by pathology. The study will be performed with the approval of the institutional
      board review of each center.
    

Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        The diagnosis of chronic pancreatitis will be based on the clinical information (history of
        alcohol abuse, previous diagnosis of chronic pancreatitis or diabetes mellitus), as well as
        a combination of imaging methods (ultrasound, CT and EUS). At least four criteria of
        chronic pancreatitis during EUS will be considered for the positive diagnosis.

        A positive cytological diagnosis will be taken as a final proof of malignancy of the
        pancreas mass. The diagnoses obtained by EUS-FNA will be further verified either by surgery
        or during a clinical follow-up of at least 6 months.
      
Biospecimen description: 
      Pathology samples obtained from duodeno-pancreatectomies or caudal pancreatectomies done with
      curative intent, as well as microhistological fragments obtained through EUS-FNA biopsy
      processed by paraffin embedding
    
Keywords: Endoscopic Ultrasound Elastography; Pancreatic adenocarcinoma; Chronic Pancreatitis