Since the early 19th
century, endoscopic techniques and clinical procedures have developed in synchrony with technological advances and the advent of new medical imaging tools. The use of endoscopic tools and devices invented during this time have allowed for an increasing number of minimally invasive imaging, diagnostic and surgical procedures. A brief timeline outlining key developments of the endoscope is shown in , which has been expanded from Berci and Forde [1
] and Sivak [2
]. The development of the endoscope shows a trend: smaller, more capable devices allowing for improved disease diagnosis and surgical intervention more deeply and into more organs, with the goals of improved patient outcomes at reasonable cost.
Timeline of technological innovations in endoscopy and minimally invasive surgery
Current techniques for endoscopic disease diagnoses throughout the GI system are based upon the use of white light endoscopy in combination with biopsy. These GI imaging and diagnostic techniques were enabled with innovations from the 1950s. Chief among endoscopic developments at this time were the use of television equipment for the acquisition of in vivo
images, the Hopkin’s rod lens system resulting in modern laproscopic imaging devices, and Hirshowitz’s development of the flexible fiberscope for gastro-endoscopy. From these inventions, the combination of in vivo
imaging and tissue state diagnosis from biopsy samples has yielded high sensitivity and specificity for disease diagnosis in accessible organs. Sivak notes that following the rapid pace of innovation in the field of endoscopy from the 1950s to the 1980s, the pace of innovation has slowed [2
The pace of innovation may yet accelerate again as investigators are pursuing advances in four areas: (1) accessing organs that are too small for current endoscopes or are distant from gastrointestinal orifices – such as the pancreas [3
], upper bilary tree [5
], and small intestine [6
]; (2) improving the speed of disease diagnosis and selection of biopsy sites during a clinical imaging procedures using non-invasive optical spectroscopic techniques [7
]; (3) improving the ability to deliver therapy during a clinical procedure to diseased tissue and; (4) reducing the cost of endoscopic tools and time from disease diagnosis to surgical intervention for clinical procedures, thus allowing for a reduction of total cost for the patient and health care system and possibly wider availability of this medical care.
The last 20 years have seen the introduction of a number of new endoscopic imaging modalities that have sought to improve the clinician’s ability to diagnose disease and image difficult to access organs. Some of these techniques include: high magnification endoscopy, high definition endoscopy, fluorescence and hyperspectral endoscopy, light scattering spectroscopy, endoscopic optical coherence tomography, narrow band imaging, confocal endoscopy, capsule endoscopy, double balloon enteroscopy, endocytoscopy, and cholangioscopy. These imaging modalities, to be useful, need to achieve diagnostic sensitivity and specificity comparable to that of the current white light imaging and biopsy techniques while being inexpensive and capable of being used by current endoscopic clinicians. The scanning fiber endoscope (SFE) is a new technology developed specifically for clinicians with the objective of matching the high-quality imaging provided by current endoscopes at 1/3 the size. In addition to being able to image previously inaccessible regions of the body, the SFE is a platform on which to build many of the new optical diagnostic techniques listed above. In this paper, the basic technology of SFE imaging is presented along with three examples, (1) tethered-capsule endoscope for unsedated imaging of the esophagus, (2) ultrathin and flexible endoscope for imaging the bile and pancreatic ducts, and (3) proof-of-concept study of combining the SFE with autofluorescence detection of disease in the colon.