Evaluation of a Second Generation High Definition and Narrow Band Imaging System for the Detection and Characterization of Colorectal Adenomas (EXERA III Colorectal Adenoma Study)

A second generation HDTV and NBI will be soon available. This second generation
NBI will have a brighter image than the first generation due to various
improvements in the design of the light source, video processor and CCD. As the
failure of first generation NBI to enhance adenoma detection could be partly
explained by the darkness of the images provided by NBI function, this second
generation NBI still has a potential role for detection of colonic adenomas
and this role has to be evaluated in a randomized cross-over study. The
question is to know if the combination of second generation HDTV / 170° FOV
(HD2) plus NBI second generation (NBI2) could help to better detect colorectal
adenomas in comparison to non HDTV / 140° FOV without NBI function. In order to
limit the number of patients to be included, high risk patients for colorectal
cancer will be selected. In such group mixing FOBT positive patients and
patients with a familial or personal history of colorectal neoplastic lesions,
the prevalence of patients with at least one adenoma is expected to be 35%.
The new generation HD2/NBI2 colonoscope will further more incorporate new
responsive insertion technology. This consists of a passive bending section at
the distal part and various other improvements in the insertion tube design.
The passive bending aims to help the operators to more easily negotiate acute
angulations of the colon when inserting the endoscope and to reduce the time
for insertion of the endoscope to the caecum. Further elements of responsive
insertion technology include a high force transmission design of the entire
insertion tube aiming at maximizing the push force transmission to the tip as
well as variable stiffness that allows stiffening of the insertion part during
examination to prevent recurrence of looping. Evaluation of this new responsive
insertion technology to reduce time for inserting the endoscope will be a
secondary parameter to be analyzed during this study.
This new generation HD2/NBI2 could also help to better characterize the polyps.
First generation HDTV / 170° FOV imaging has also not demonstrated any effect
to enhance adenoma and according to industry sources non HDTV / 140° FOV
imaging is still mainly used for colonoscopy in Europe. The second generation
HDTV endoscope technology consists of a dual focus optical lens / aperture in
combination with a further improved CCD design. With its new dual focus lens
system in *near focus* mode this optical system can deliver higher to first
generation HDTV *close focus* image magnification at levels identical to the
magnification level of commercially available dedicated zoom endoscopes in
*tele mode*. Also in the *far focus* mode the new dual focus scope delivers
imaging resolution clearly surpassing the level once established by first
generation HDTV endoscopes.
Characterization of a colorectal polyp during colonoscopy has 2 major potential
advantages: 1 - to determine if the polyp is neoplastic (adenoma) or not
(hyperplastic) and then to decide whether or not it is necessary to remove the
polyp or to analyze it once removed. To avoid unnecessary resection or
unnecessary analysis of polyps that are not at risk may have major implications
for reducing morbidity and procedure cost, 2 - to determine if in a neoplastic
polyp there is a deeply invasive submucosal cancer leading to avoid endoscopic
resection and favor a surgical resection. Up to now in Europe and the USA,
polyp characterization is very little done unlike in Japan: the rule is to
systematically remove all polyps except those who are obviously non-neoplastic
and less than 10mm in diameter in the rectum. Japanese operators instead
characterize polyps by zoom chromoscopy (with dye spraying). Why this
difference in practice between Japan and Western countries? 1 - Chromoscopy is
little used in the West because it is time consuming, has a certain cost
(catheter) and is well not remunerated 2 - the Western versions (color CCD, 100
series) of endoscope zoom are less easy to use than the Japanese versions
(Black and white CCD, 200 series).
As NBI is very easy to activate and as zoom magnification is not even mandatory
for NBI characterization (60) NBI function could therefore allow the West to
limit removal and histological analysis of non - risk polyps. Such policy
(called DISCARD) has already been tested with success in UK, where endoscopes
used are similar to the Japanese endoscopes (black and white CCD, 200 series)
(63). For polyps less than 10 mm in size, in-vivo optical diagnosis is
considered as an acceptable strategy to assess polyp histopathology and future
surveillance intervals. A classification of polyps using the NBI (NICE
classification) has been established between experts from Europe, Japan and
USA. This classification separates adenomatous polyps (type B) from
hyperplastic polyps (type A), and also distinguishes adenoma with massive
submucosal cancer (type C). The purpose of this study is to evaluate the
accuracy of this classification using second generation NBI and to evaluate its
role to avoid unnecessary resections or to avoid unnecessary histological
analysis. At the same time, the new dual focusing system which aims to provide
easy to obtain high magnification views for better and easier analysis will be
evaluated.

Evaluation of the effectiveness of a new system HD2/NBI2 to improve the
detection of colorectal neoplastic lesions during colonoscopy in comparison to
the former generation with currently highest share of the installed base
(nonHD-nonNBI system i.e. 160/165 series)

Multicenter cross-over randomized controlled study

Back-to-back colonoscopy with two different colonoscopy systems.

Risks of the colonoscopy procedure:
The risks of colonoscopy are well established. The procedures within this study
are consistent with usual routine colonoscopy. No new study-related
colonoscopic risks are anticipated within the study. As the patient will be
evaluated with two colonoscopy systems within the same sitting, it is
conceivable that slightly increased risks may be associated with lengthened
anesthesia or sedation time.
It is to be noted that within the European scope of this clinical study the
routine administration of anesthesia or sedative medications for colonoscopic
procedures varies widely between the investigational sites. These issues will
be appropriately addressed within the informed consent process.
Benefits from participating in the study:
Each study participant will be examined using two acknowledged colonoscopy
systems by two experienced gastroenterologists. It is expected that through
this process, an optimal identification of potentially cancerous polyps may be
obtained. At the same time, a guarantee that all potentially cancerous polyps
will be found cannot be made.