Mo1511 Feasibility Study of Tridimensional Co-Registration of Endoscopic Ultrasound and Dynamic Spiral Computer Tomography Procedures for Real-Time Evaluation of Tumor Angiogenesis

Feasibility Study of Tridimensional Co-Registration of Endoscopic Ultrasound and Dynamic Spiral Computer Tomography Procedures for Real-Time Evaluation of Tumor Angiogenesis Lucian G. Gruionu, Adrian Saftoiu, Alexandru L. Iordache, Ana Maria Ioncica, Daniela Burtea, Daniela Dumitrescu Department of Engineering, University of Craiova, Craiova, Romania; Medinsys, Craiova, Romania; Research Center of Gastroenterology and Hepatology, University of Medicine and Pharmacy Craiova, Craiova, Romania; Department of Radiology and Imaging, University of Medicine and Pharmacy Craiova, Craiova, Romania Background: Endoscopic ultrasound (EUS) and computer tomography (CT) are considered procedures of choice for the diagnosis and staging of both digestive cancers (esophago-gastric and pancreatico-biliary), but also lung cancer. CT has the advantage of a large observation field with increased accuracy for the definition of N and M stage, while EUS is performing better for the targeted assessment of T and N stage, including EUS-guided fine needle aspiration procedures that allow tissue confirmation of malignancy. A hybrid imaging procedure with co-registration of both EUS and CT during the same examination would be highly desirable for improved TNM staging, but also better description of anatomical structures, increased diagnostic confidence and shorter learning curve for linear EUS procedures. Patients and method: The aim of this feasibility study was to test a new hybrid system of real-time EUS displayed simultaneously with the corresponding dynamic CT section, reconstructed virtually based on a previously stored 3D volume data set. The images were co-registered based on electromagnetical (EM) tracking of the EUS transducer position, using a wired magnetic positioning sensor embedded and fixed into the sheet of a usual EUSFNA needle inserted and locked into the biopsy channel of the EUS scope. The initial calibration (positioning) of the needle-scope assembly relative to the 3D coordinate system was based on several external markers previously fixed, closed to the anatomic region of interest, and also evident on the CT scans. Results: The system was tested initially on a specially designed EUS phantom filled with de-aerated water and silicon inclusions simulating malignant masses, showing small errors (maximum 3 mm) during co-registration of EUS and CT images. Furthermore, the same system was also tested in 6 patients with digestive and lung cancers with good results in decreasing the time of tumor localization and identification as compared with classical EUS procedures. Also, based on the EUS system capabilities, contrast-enhanced power Doppler EUS was also visualized simultaneously with dynamic spiral CT data, allowing an excellent estimation of angiogenesis inside the tumors. Conclusion: Based on the EM tracking of the EUS transducer position and co-registration software with 3D dynamic CT reconstructions, a hybrid system of real-time EUS-CT co-registration was developed. The system should be further tested in larger clinical studies, to describe better the clinical impact of increased diagnostic confidence by direct comparisons between the same lesions based on different imaging modalities, but also to shorten the difficult learning curve of linear EUS. Mo1512 Identification of the Line Demarcating Gastric Cancer From Normal Mucosa by Magnification Endoscopy With NBI Toshihisa Takeuchi, Yuichi Kojima, Yukiko Yoda, Satoshi Tokioka, Eiji Umegaki, Kazuhide Higuchi 2nd Dep of Internal Medicine, Osaka Medical Collage, Takatsuki, Japan [Introduction] Because endoscopic submucosal dissection (ESD) in patients with gastric cancer has become widespread, it is important to accurately identify the demarcation line of gastric cancer. Until now, it has been shown that in qualitative diagnosis of gastric cancer, observation of the surface microstructure and microvascular pattern by magnified endoscopy combined with narrow-band imaging (NBI) enables differentiation of benign and malignant lesions and histological determination of the depressed-type gastric cancer. However, there is no consensus on the identification of a demarcation line of gastric cancer by magnification endoscopy combined with NBI. [Objective] To elucidate the usefulness of magnified endoscopy combined with NBI for identifying a demarcation line of gastric cancer. [Subjects and Method] We included 572 lesions from patients with early gastric cancer who received ESD from 2002 to 2009. We introduced magnified endoscopy combined with NBI from 2006, after which we identified a demarcation line of gastric cancer prior to ESD in 264 lesions and compared the pathological findings with resection samples. We examined the incidence of positive lateral resection margins (i.e., the percentage of inconsistency in the identification of a demarcation line) among the resection samples as well as the factors before and after NBI. [Results] (1) The incidence of positive lateral resection margins after NBI was 1.9%, which was significantly lower that before NBI (4.5%; p 0.05). In particular, there was no resection sample with a positive lateral resection margin in the depressed-type welldifferentiated adenocarcinomas after NBI. (2) Five samples with positive lateral resection margins obtained after NBI included lesions that progressed to IIb and those that contained undifferentiated components. Pathological examination of these lesions revealed that they were either moderately differentiated adenocarcinomas that predominantly showed structural atypia with lack of cellular atypia or undifferentiated adenocarcinomas that mainly consisted of infiltration of the middle mucosal layer. [Conclusion] Accuracy of the identification of a demarcation line of gastric cancer was improved by magnified endoscopy combined with NBI. However, it was found that some moderately differentiated and undifferentiated adenocarcinomas had limited changes in their surface microvessels and mucosal microstructure, and therefore, we could not identify the demarcation line in these lesions.