Early detection of premalignant lesions of the gastrointestinal tract serves as one of the major indications for endoscopy. Whether an esophag-ogastroduodenoscopy (EGD) is performed for Barrett esophagus or a colonoscopy is performed for colorectal cancer screening, the goals remain the same: identify a premalignant lesion, treat the lesion, and lower the overall risk of developing a malignancy. Although the notion of early detection and survival benefits with the use of standard endoscopy is well supported, there appears to be ample room for technological advancement.Narrow-band imaging (NBI) is a relatively new high-resolution endoscopic technology that helps identify potentially neoplastic changes of the gastrointestinal epi-thelium.

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Its use is rooted in the concept that the depth of light penetration depends upon its wavelength. As opposed to conventional white-light endoscopy (WLE), NBI utilizes 2 distinct wavelengths of light, 415 nm (blue) and 540 nm (green), with bandwidths of 20–30 nm each, limiting penetrance of the light to the mucosal surface., The blue light highlights the super-ficial capillary networks, whereas the green light focuses on the subepithelial vessels. NBI shows great promise when evaluating patients for Barrett esophagus. A recent large prospective study reported a sensitivity of 100% for identifying long-segment Barrett esophagus when NBI and directed biopsies were utilized compared to a sensitivity of only 80% when random biopsies were obtained via conventional means. The sensitivity for short-segment Barrett esophagus was 80% with NBI and directed biopsies compared to 30% with random biopsies, again favoring the NBI-directed approach.NBI can also be used to differentiate colonic adenomas from benign lesions. In a study comparing NBI, chromo-endoscopy, and WLE, NBI achieved better visualization of the colonic mucosal vascular network than conventional endoscopy. There was no significant difference between NBI and chromoendoscopy for differentiating neoplastic from nonneoplastic lesions; both techniques had a sensitivity of 100% and a specificity of 75%, though both fared better than WLE, which had a sensitivity of 83% and a specificity of 44% ( P.

Case Report #1A 52-year-old man was referred to us for surveillance of Barrett esophagus. The patient had a history of long-segment Barrett esophagus, which was confirmed by a recent EGD. Random 4-quadrant biopsies every 2 cm during standard endoscopy revealed specialized intestinal metaplasia indefinite for dysplasia. Repeat endoscopy revealed a subtle area of umbilication identified in a segment of Barrett esophagus that was noted only with NBI. Targeted biopsies of this area were again indefinite for dysplasia, a finding that was confirmed by 2 expert gastrointestinal pathologists. Given the possibility of high-grade dysplasia and intramucosal carcinoma within the nodule, flow cytometry was performed. Biopsies revealed aneuploidy, which is a potential marker for the development of adenocarcinoma.

Endoscopic mucosal resection was performed , and the histology revealed high-grade dysplasia. Clean margins were noted, and repeat biopsies of the area have been unremarkable to date. NBI detected this high-risk lesion early and gave the patient the opportunity to undergo less invasive but definitive therapy. Case Report #2A 74-year-old man was diagnosed with colon cancer of the left colon and a synchronous 2-cm tubulovillous adenoma of the rectum with high-grade dysplasia. He underwent surgical resection 3 years ago.

One year later, he experienced recurrence of a tubulovillous adenoma at the colorectal anastomosis and was treated with argon plasma coagulation. Surveillance was performed with conventional endoscopy to confirm ablation of the dysplastic tissue. Biopsies from the anastomosis revealed only granulation tissue and hyperplastic changes. Repeat surveillance with NBI allowed for localization of a focal region suspicious for recurrence of adenoma , which was confirmed by directed biopsy. The adenomatous changes identified by NBI were unappreciated with white light. The novel technology of NBI afforded the opportunity to target the area of concern and ultimately ablate the neoplastic tissue.

DiscussionThese 2 cases demonstrate the utility and practicality of NBI, which was once considered to be a research-based technology. NBI gives endoscopists the ability to identify lesions that may not be appreciated with conventional WLE.

The sensitivity and specificity of NBI for these lesions are equivalent to those of chromoendoscopy and allow for significant ease of use comparatively.A quandary arises when deciphering the significance of the various mucosal vascular patterns noted at the time of endoscopy. Several classification systems have been proposed with relatively good sensitivity and specificity; however, they lack uniformity and are fairly complex, making the technique less desirable. Hirata and associates recently proposed a less complex approach to evaluating the microvessels of colonic lesions.

They examined the clinical usefulness of NBI with magnification in the assessment of microvascular architecture of colonic lesions. The microvascular changes appreciated with this technique appeared to correlate with histologic grade, enabling the endoscopist to predict the diagnosis and ultimately select the most appropriate therapeutic intervention. Their data support the use of NBI for evaluating micro-vascular changes in colonic tissue; however, NBI appears to be useful in other areas of the gastrointestinal tract as well. We have used their methods in the evaluation of colonic lesions and have deemed them to be user-friendly and accurate.Over the last 50 years, we have witnessed an evolution in endoscopy from early rigid limited-viewing endoscopes to the current wide-angle video-magnifying endoscopes. The future will likely bring further advancement to endoscopic detection of premalignant tissue within the gastrointestinal tract. Currently, NBI with magnification appears to be part of a new revolution in endoscopic detection. This technology, in conjunction with a more straightforward and concise classification system, appears to be promising, as it allows for detailed inspection of suspicious mucosal abnormalities.

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NBI will also likely improve early detection of these lesions, as demonstrated in our 2 cases.

A Motorola Advisor alphanumeric pager used in Brazil in the 1990s, operated by TeletrimA pager (also known as a beeper) is a wireless device that receives and displays alphanumeric or voice messages. One-way pagers can only receive messages, while response pagers and two-way pagers can also acknowledge, reply to, and originate messages using an internal transmitter.Pagers operate as part of a paging system which includes one or more fixed transmitters (or in the case of response pagers and two-way pagers, one or more ), as well as a number of pagers carried by mobile users. These systems can range from a restaurant system with a single low-power transmitter, to a nationwide system with thousands of high-power base stations.Pagers were developed in the 1950s and 1960s, and became widely used by the 1980s. In the, the widespread availability of and has greatly diminished the pager industry. Nevertheless, pagers continue to be used by some emergency services and public safety personnel, because modern pager systems' coverage overlap, combined with use of satellite communications, can make paging systems more reliable than terrestrial-based cellular networks in some cases, including during natural and man-made disasters. This resilience has led public safety agencies to adopt pagers over cellular and other commercial services for critical messaging.The UK is thought to use over 10% of remaining pagers in 2017 (130,000), with an annual cost of £6.6 million., announced in February 2019 that the 130,000 pagers still in use were to be phased out.In, circa 1996, ten millions of pagers were active.

On October 1, 2019, Japan's last page provider shut down radio signals and terminated its service. Original Motorola 'Pageboy II' pager, used in New York in the late 1970s.The first telephone pager system was patented in 1949 by.One of the first practical paging services was launched in 1950 for in the area.

Physicians paid 12 per month for the service and carried a 200-gram (7 oz) pager that would receive phone messages within 40 kilometres (25 mi) of a single transmitter tower. The system was manufactured by the Reevesound Company and operated by Telanswerphone. In 1960, combined elements of 's and automobile radio technologies to create the first transistorized pager, and from that time, paging technology continued to advance, and pager adoption among emergency personnel is still popular, as of July 2016.In 1962 the Bell System—the U.S. Telephone monopoly colloquially known as 'Ma Bell'—presented its Bellboy radio paging system at the Seattle World's Fair. Bellboy was the first commercial system for personal paging. It also marked one of the first consumer applications of the (invented by in 1947), for which three Bell Labs inventors received a in Physics in 1956.

Solid-state circuitry enabled the Bellboy pager, about the size of a small TV remote device, to fit into a customer's pocket or purse, quite a feat at that time. The Bellboy was a terminal that notified the user when someone was trying to call them.

When the person received an audible signal (a buzz) on the pager, the user found a telephone and called the service centre, which informed the user of the caller's message. Bell System Bellboy radio pagers each used three relays, each relay tuned to one of 33 different frequencies, selectively ringing a particular customer when all three relays were activated at the same time—a precursor of. The protocol was developed in the mid-1990s.While Motorola announced the end of its new pager manufacturing in 2001, pagers remained in use in large hospital complexes. Another is a facility handling, where various radio transmitter or data storage devices are excluded to ensure security. First responders in rural areas with inadequate cellular coverage are often issued pagers.The resulted in overload of systems by the emergency services, and showed that pagers, with their absence of necessity to transmit an acknowledgement before showing the message, and the related capability to operate on very low signal levels, are not completely outclassed by their successors. Volunteer firefighters, EMS paramedics, and rescue squad members usually carry pagers to alert them of emergency call outs for their department. These pagers receive a special tone from a fire department radio frequency.Restaurant pagers were in wide use in the 2000s.

Customers were given a portable receiver that usually vibrates, flashes, or beeps when a table becomes free or when their meal is ready. Pagers have been popular with birdwatchers in Britain and Ireland since 1991, with companies Rare Bird Alert and Birdnet Information offering news of rare birds sent to pagers that they sell.The U.S.

Paging industry generated $2.1 billion in revenue in 2008, down from $6.2 billion in 2003. In Canada, 161,500 Canadians paid $18.5 million for pager service in 2013., one of the three major mobile carriers, announced the end to its Canadian pager service as of March 31, 2015, but rivals Bell, Rogers and PageNet intend to continue service. Timex Datalink Beepwear Pro: a wearable pager/watch featuring alphanumeric paging capability.

Part of the family of watchesMany paging network operators now allow numeric and textual pages to be submitted to the paging networks via email. This is convenient for many users, due to the widespread adoption of; but email-based message submission methods do not usually provide any way to ensure that messages have been received by the paging network.

This can result in pager messages being delayed or lost. Older forms of message submission using the involve modem connections directly to a paging network, and are less subject to these delays. For this reason, older forms of message submission retain their usefulness for disseminating highly-important alerts to users such as personnel.Common paging protocols include, GOLAY, and NTT. Past paging protocols include Two-tone. In the United States, pagers typically receive signals using the in the 900 MHz band. Commercial paging transmitters typically radiate 1000 of, resulting in a much wider coverage area per tower than a mobile phone transmitter, which typically radiates around 0.6 watts per channel.

Although 900 MHz FLEX paging networks tend to have stronger in-building coverage than mobile phone networks, commercial paging service providers will work with large institutions to install repeater equipment in the event that service is not available in needed areas of the subscribing institution's buildings. This is especially critical in hospital settings where emergency staff must be able to reliably receive pages in order to respond to patient needs.Unlike mobile phones, most one-way pagers do not display any information about whether a signal is being received or about the strength of the received signal. Since one-way pagers do not contain transmitters, one-way paging networks have no way to track whether a message has been successfully delivered to a pager. Because of this, if a one-way pager is turned off or is not receiving a usable signal at the time a message is transmitted, the message will not be received and the sender of the message will not be notified of this fact. In the mid-1990s, some paging companies began offering a service, which allowed a customer to call their pager-number, and have numeric messages read back to them. This was useful for times when the pager was off or out of the coverage area, as it would know what pages were sent to the subscriber even if the subscriber never actually received the page. Other radio bands used for pagers include the 400 MHz band, the band, and the FM commercial broadcast band (88-108 MHz).

Other paging protocols used in the VHF, 400 MHz, and 900 MHz bands include and ERMES. Pagers using the commercial FM band receive a subcarrier, called the, of a broadcast station.

On-site paging systems in hospitals, unlike wide area paging systems, are local area services. Hospitals commonly use on-site paging for communication with staff and increasingly for contacting waiting patients when their appointment is due. These offer waiting patients the opportunity to leave the waiting area, but still be contacted.Operation. The top of a Motorola 'Bravo' numeric pagerPaging systems are operated by commercial carriers, often as a subscription service, and they are also operated directly by end users as private systems. Commercial carrier systems tend to cover a larger geographical area than private systems, while private systems tend to cover their limited area more thoroughly and deliver messages faster than commercial systems. In all systems, clients send messages to pagers, an activity commonly referred to as paging.

System operators often assign unique phone numbers or email addresses to pagers (and pre-defined groups of pagers), enabling clients to page by telephone call, e-mail, and SMS. Paging systems also support various types of direct connection protocols, which sacrifice global addressing and accessibility for a dedicated communications link. Automated monitoring and escalation software clients, often used in hospitals, IT departments, and alarm companies, tend to prefer direct connections because of the increased reliability. Small paging systems, such as those used in restaurant and retail establishments, often integrate a keyboard and paging system into a single box, reducing both cost and complexity.Paging systems support several popular direct connection protocols, including, TNPP, and, as well as proprietary modem- and socket-based protocols. Additionally, organizations often integrate paging systems with their and systems, conceptually attaching pagers to a telephone extensions, and they set up to integrate pagers into other parts of their enterprise.

A paging system alerts a pager (or group of pagers) by transmitting information over an RF channel, including an address and message information. This information is formatted using a paging protocol, such as 2-tone, 5/6-tone, GOLAY, or NTT. Two-way pagers and response pagers typically use the protocol.Modern paging systems typically use multiple base transmitters to modulate the same signal on the same RF channel, a design approach called. This type of design enables pagers to select the strongest signal from several candidate transmitters using, thereby improving overall system performance.

Simulcast systems often use satellite to distribute identical information to multiple transmitters, and GPS at each transmitter to precisely time its modulation relative to other transmitters. The coverage overlap, combined with use of satellite communications, can make paging systems more reliable than terrestrial based cellular networks in some cases, including during natural and man-made disaster. This resilience has led public safety agencies to adopt pagers over cellular and other commercial services for critical messaging. Categories Pagers themselves vary from very cheap and simple beepers, to more complex personal communications equipment, falling into eight main categories.Beepers or tone-only pagers Beepers or tone-only pagers are the simplest and least expensive form of paging. They were named beepers because they originally made a beeping noise, but current pagers in this category use other forms of alert as well. Some use audio signals, others light up and some vibrate, often used in combination. The majority of restaurant pagers fall into this category.

Voice/tone Voice/Tone pagers enable pager users to listen to a recorded voice message when an alert is received. Numeric Numeric Pagers contain a numeric LCD display capable of displaying the calling phone number or other numeric information generally up to 10 digits. The display can also convey pager codes, a set of number codes corresponding to mutually understood pre-defined messages. Alphanumeric Alphanumeric pagers contain a more sophisticated LCD capable of displaying text and icons. These devices receive text messages, often through email or direct connection to the paging system. The sender must enter a message, either numeric and push # or, text & push # or a verbal message.

The pager does not automatically record the sender's number; the pager will beep but no message can be seen or heard if none has been entered. Response Response pagers are alphanumeric pagers equipped with built-in transmitters, with the ability to acknowledge/confirm messages. They also allow the user to reply to messages by way of a multiple-choice response list, and to initiate 'canned' messages from pre-programmed address and message lists. These devices are sometimes called '1.5-way pagers' or '1.7-way pagers' depending on capabilities. Two-way Two-way pagers are response pagers with built-in QWERTY keyboards. These pagers allow the user to reply to messages, originate messages, and forward messages using free-form text as well as 'canned' responses.

One-way modems One-way are controllers with integrated paging receivers, which are capable of taking local action based on messages and data they receive. Two-way modems Two-way modems have capabilities similar to one-way modems. They can also confirm messages and transmit their own messages and data. Security.

This section does not any. Unsourced material may be challenged. ( June 2009) Pagers also have advantages compared with cellular phones.

Since a one-way pager is a passive receiver only (it sends no information back to the base station), its location cannot be tracked. However, this can also be disadvantageous, as a message sent to a pager must be broadcast from every paging transmitter in the pager's service area. Thus, if a pager has nationwide service, a message sent to it could be intercepted by criminals or law enforcement agencies anywhere within the nationwide service area.In popular culture As is the case with many new technologies, the functionality of the pager shifted from necessary professional use to a social tool integrated in one's personal life.: 175 During the rise of the pager, it became the subject of various forms of media; most notably in the 1990s hip-hop scene. Upcoming mainstream artists such as, and began referencing forthcoming mobile technologies, in particular the pager. A Tribe Called Quest's single 'Skypager' directly speaks of the importance of such a wireless communication device.

'Q-Tip' conveys that the Skypager 'serves an important communicative function for a young professional with a full calendar'. 's '2-Way Freak', 's 'Beepers' and ' from Destiny's Child also make reference to pagers.Illicit drug dealers used pagers to great effect during the 1990s to conduct commerce, using them to arrange meetings with buyers. Associate superintendent for in Florida James Fleming once called them 'the most dominant symbol of the drug trade' and schools have previously forbidden students from carrying them because of the ease with which they could be 'used to arrange illegal drug sales'. See also. WhatIs.com. ^. 30 September 2019.

Archived from on 1 October 2019. Retrieved 1 October 2019. ^ Independent Panel Reviewing the Impact of Hurricane Katrina on Communications Networks (12 June 2006). Retrieved 14 January 2018. ^ Section 3.0. March 2007.

^ NFPA 1221: Standard for the Installation, Maintenance, and Use of Emergency Services Communications Systems, 2002 edition, at 1221-23 section 8.4.2.1. ^. 9 September 2017. 12 July 2018. Retrieved 12 July 2018. 23 February 2019. Retrieved 23 February 2019.

Thoughtco.com. Corporation, Bonnier (1 January 1951). Bonnier Corporation – via Google Books.

Brophy.net. Keller, A. (1964), (PDF), The Bell System Technical Journal. ^. Londonambulance.nhs.uk. ^ Tyson, Jeff, retrieved 17 January 2010. 2003 and 2008 research data used with permission.

^ Heckman, Davin (2006). ' 'Do You Know the Importance of a Sky Pager?' : Telecommunications, African-Americans, and Popular Culture'. In Anandam P. Kavoori; Noah Arceneaux (eds.).

Peter Lang Publishing. Sims, Calvin (25 September 1988). The New York Times. Retrieved 16 February 2014.External links Wikimedia Commons has media related to. —Technical information on protocols, carriers, etc.