Careful handling of a light cable will prolong its life span, avoiding discoloration of the ends and breakage of individual fibers. Light cable integrity is assessed by looking through one end of the cable toward a room light or window. However, over time discoloration reduces light transmission and can change the color of the light that is emitted. Broken fibers will appear as small black or gray areas. When more than 30% of the fibers are broken, replacement of the cable is recommended. Excessive bending, twisting, or crushing of light cables should be avoided to minimize fiber breakage.
Contemporary light cables are autoclavable, but manufacturers' recommendations for time and cycle should be carefully followed using an appropriate sterilizer. Light cables should always be stored alone in adequate containers in a loosely coiled position, to minimize stress on the glass fibers.
When considering fluorescence technologies, a specific light cable is mandatory due to intrinsic wavelengths' transmission ability. Depending on the configuration of the video system, one should consider “fluorescence fluid” or “fluorescence fiberoptic” light cables. Since the most common fluorescence applications in veterinary surgery use ICG, the more frequently chosen type of cable corresponds to the fiber optic version.
Endoscopic Video Cameras
The video camera system consists of the camera head, CCU, and monitor. Heads include adapters with different focal lengths that determine the displayed image size. However, image size and magnification can be adjusted more conveniently with an integrated optical zoom knob located on the camera head. Optical zoom produces a true magnified image without compromising the resolution, unlike digital zoom, which merely increases pixel size [1–5, 8, 13].
An important consideration may be the flexibility of the chosen camera for different procedures and different endoscopes. It may be prudent to consider both a variable focal distance head as well as a CCU that is compatible with all the types of scopes that might be used in practice (fiberscopes, videoendoscopes, and rigid telescopes). Multidisciplinary and versatile systems may support a broad endoscopy service for a reasonable investment. Larger practices may, however, consider having separate systems for different services [1–5].
Medical cameras contain a computer “chip,” which transforms the optical image into an electronic signal transmitted to the CCU. Recent improvements in miniaturization of complementary metal‐oxide‐semiconductor (CMOS) “chips” have led to standardization of CMOS cameras as high‐end quality devices whose performance and image quality are equivalent or superior to earlier CCD (charge‐coupled device) cameras [1–5].
Although endoscopic camera quality has previously been defined by single‐chip or three‐chip technology, it is currently more relevant to embrace HD image technology. An HD image can be produced with either a single CMOS chip or three‐chip camera, which provides a wide screen display (Figure 3.8a). The HD aspect ratio of 16 : 9 more closely approximates the human visual field than the historical 4 : 3 standard and allows the surgeon to observe instruments entering the surgical field sooner than with a traditional monitor [1–5].
However, HD cameras differ in resolution and light sensitivity, performance characteristics that affect detail recognition, color, features, and price. Some newer cameras, for example, have integrated image capturing capabilities or image processing options that enhance contrast or brighten dark areas (see Enhanced Contact Endoscopy section below). Full HD cameras deliver superior picture resolution (1920 × 1080 pixels) and progressive scanning, as opposed to interlaced scanning. The progressive scanning method simultaneously displays all 1080 lines for every frame, thus producing the smoothest, clearest image, especially when the video content is motion intensive.
New generation full HD camera heads have titanium bodies, making them light, robust, and autoclavable, in contrast to older models only sterilizable by gas or soaking [1–5, 8, 9]. Newer camera heads provide intraoperative access to customizable functions with the push of a button on the head, such as white balance, image capture, video recording, image enhancement, zoom, and many others.
For standard veterinary abdominal and thoracic MIS procedures, a CMOS single‐chip FULL HD camera head and CCU are considered the standard of care, bringing to practice the best and most affordable medical technology. Nevertheless, for specific or more advanced applications, dedicated technologies are also available.
Figure 3.8 (A) FULL HD CMOS single chip lightweight camera, 1920 × 1080 pixels. Zoom can be activated by programmed touch button in camera head. (B). 4K camera with NIR/ICG, IMAGE 1 STM 4U RUBINA.
Source: © KARL STORZ SE & Co. KG, Germany.
It is critical to remember that for endoscopic images to be displayed in HD, each component of the imaging chain must be HD compatible, from the camera head to the transmission media and systems (CCU and cables) to the monitor [1–5, 13, 17].
A major milestone toward the goal of higher image definition, using image enhancement technology, was attained with the marketing of HD television (HDTV) camera systems. The ongoing process in this huge consumer technology sector has led to a variety of 3D endoscope systems culminating in the introduction of Ultra HD systems providing the 4K standard (Figure 3.8b) with a horizontal screen display resolution of approximately 4000 pixels as opposed to 1080 with full HD.
Over the last decade, various methods and technologies to enhance contrast, and early detection of mucosal and submucosal lesions, were described and used in clinical practice. These include autofluorescence (AF), conventional chromoendoscopy (CC), and recently enhanced contact endoscopy (ECE). These technologies were developed because white light endoscopic routine evaluation might fail to identify early‐stage lesions in epithelial or subepithelial layers, or to detect accurate margins in macroscopic lesions.
ECE is based on the dynamic fusion of the conventional IEE (image‐enhanced endoscopy) with CE (contact endoscopy) – but without the need for vital staining – and thus combines the advantages of both modalities.
Currently, imaging technologies that provide detailed contrast enhancement of the mucosa and blood vessels are widely used in many human medical specialties. The major focus of current research and development in the field of endoscopic imaging technologies is on the advancement of image‐enhanced endoscopy (IEE) systems (i‐SCAN, NBI, and IMAGE1 STM). The IMAGE 1 STM (KARL STORZ Tuttlingen, Germany) is a versatile digital full HD video system, providing specific color rendering of the acquired broad visible spectrum within the HD‐camera system. Since spectral separation is obtained within the camera system and amplified by adapted color processing algorithms, the IMAGE 1 STM does not require a dedicated narrow band light source and operates with a standard light source using the whole spectrum of light information. Therefore, this system enhances the appearance of the mucosal surface structures and subepithelial vasculature by selected wavelengths of light providing five different predefined spectral ranges in addition to the standard mode with white light: CLARA, CLARA + CHROMA, CHROMA, SPECTRA A, SPECTRA B. The KARL STORZ IMAGE 1 S system was awarded the Innovation of the Year by EAES – European Association for Endoscopic Surgery, in 2014 when the product was introduced, becoming a standard since then, for modern laparoscopic and thoracoscopic surgery.
ECE is currently used in small animal endoscopy (i.e. gastrointestinal, respiratory, and urinary systems) and MIS (laparoscopy and thoracoscopy).