Endoprobe: A system for radionuclide‐guided endoscopy

Abstract

Methods to guide the surgical treatment of cancer utilizing handheld beta-sensitive probes in conjunction with tumor-avid radiopharmaceuticals [such as 18F-fluorodeoxyglucose (FDG)] have previously been developed. These technologies could also potentially be used to assist in minimally invasive techniques for the diagnosis of cancer. The goal of this project is to develop and test a system for performing radionuclide-guided endoscopies. This system (called Endoprobe) has four major subsystems: beta detector, position tracker, endoscope, and user interface. The beta detection unit utilizes two miniaturized solid state detectors to preferentially detect beta particles. The position tracking system allows real-time monitoring of the unit's location. The beta detector and position tracking system's receiver are mounted on the tip of an endoscope. Information from the beta detector and tracking system, in addition to the video signal from the endoscope, are combined and presented to the user via a computer interface. The system was tested in a simulated search for radiotracer-avid areas of esophageal cancer. The search for esophageal cancer was chosen because this type of cancer is often diagnosed with endoscopic procedures and has been reported to have good affinity for FDG. Accumulations of FDG in the normal organs of the abdomen were simulated by an anthropomorphic torso phantom filled with the appropriate amounts of radioactivity. A 1.5- mm-thick gelatin film containing FDG was used to simulate radiotracer uptake in the lining of normal esophagus. Esophageal lesions (both benign and malignant) were simulated by thin disks of gelatin (diameters=3.5-12 mm) containing appropriate concentrations of FDG embedded in the gelatin film simulating normal esophagus. Endoprobe facilitated visual identification and examination of the simulated lesions. The position tracking system permitted the location of the Endoprobe tip to be monitored and plotted in real time on a previously acquired positron emission tomography-computed tomography (PET-CT) image of the phantom. The detection system successfully acquired estimates of the beta flux emitted from areas chosen by the user. Indeed, Endoprobe was able to assist in distinguishing simulated FDG-avid areas as small as 3.5 mm in diameter from normal esophagus (p value <0.025). In addition to FDG, Endoprobe can be used with other positron or electron-emitting radionuclides such as IC or 131I. The next phase of this project will focus on modification of the prototype to make it more suitable for clinical use.

Physical Performance of an Intraoperative Beta Probe Dedicated to Glioma Radioguided Surgery

“…The main clinical application of radioguided cancer surgery is the sentinel lymphatic node mapping of melanomas and breast cancers with the gamma ray emitting radiopharmaceutical m Tc-labeled sulphur colloïd [13]- [15]. However, the emergence of radiopharmaceuticals labeled with positron emitters, and primarily dedicated to PET is giving rise to a renewed interest for intraoperative localization of tumor and the oncological applications are progressively expanding including detection of breast lesions, oesophageal tumors, thyroid or colon cancer [16]- [18]. Radioguided brain tumour surgery is still little-used, mainly due to the lack of dedicated miniaturized detectors [19], [20], even if new -emitting radiotracers like F-fluoroethyl-L-tyrosine, F C-choline, F-fluoro-L-phenylalanine or F-fluorothymidine which shows brain tumor to normal tissue uptake ratios ranging from 2 to 9:1 are promising agents for glioma delineation [21]- [25].…”

Development of a positron probe for localization and excision of brain tumours during surgery

“…Alongside these anatomical imaging systems, intraoperative image-guided surgery based on the detection of radioactive or fluorescent tumour-seeking tracers offers higher sensitivity and specificity for the discrimination of malignant tissues. In particular, the development of fluorinated tracers has led to the recent emergence of miniaturized detectors of positrons arising from the decay of 18 F or of the associated 511 keV annihilation γ -rays (Tipnis et al 2004, Raylman and Srinivasan 2004, Yamamoto et al 2005. Probes of this type have been successfully used for the detection of tumours labelled with 18 F-FDG in various contexts, including breast lesions, gastric tumours, melanomas and thyroid and colorectal cancers (Piert et al 2007, Gulec et al 2006, Essner et al 2001.…”

Endoscopic detection of cancer with lensless radioluminescence imaging and machine vision

“…The development of beta detectors can be categorized into pure detectors, which yield a reading at a certain spot 16 17 18 19 20 21 , and imaging devices, which give an actual picture of the radiotracer distribution 22 23 24 25 26 27 28 . The principal need for the actual imaging of the radiotracer distribution in a sample is not for the primary detection of tumors or positive lymph nodes but for the detection of residual cancer in the surgical cavity.…”