The use of narrow band imaging versus conventional colonoscopy for the detection of dysplasia and cancer in patients with longstanding ulcerative colitis. A randomized cross-over study

Patients with longstanding ulcerative colitis (UC) are at increased risk of
developing colorectal cancer. To reduce this risk, colonoscopic surveillance is
currently recommended in order to detect dysplasia and cancers at an early
stage. During surveillance colonoscopy random biopsies should be taken, since
neoplastic tissue exists mainly in flat mucosa and is grossly invisible at
conventional colonoscopy. Despite this laborious protocol the accuracy of this
method is low. The use of dye spraying (chromoendoscopy) has proven to be more
accurate for the detection of neoplasia but is labour-intensive and operator
dependent. Narrow Band Imaging (NBI) is a novel endoscopic imaging technique
with a similar effect as chromoendoscopy but without the use of dyes. This
technique may improve the detection and specification of lesions found during
colonoscopy.

1) to compare NBI and standard White Light Endoscopy (WLE) for the detection of
neoplasia during colonoscopic surveillance of patients with longstanding UC
2) To determine the accuracy of Kudo*s classification in distinguishing
neoplastic from non neoplastic lesions using NBI
3) to characterize the mucosal morphology and vascular pattern of neoplastic
and non neoplastic mucosa making use of NBI.

Patients with longstanding UC will undergo colonoscopic surveillance by both
WLE and NBI with a time interval of at least 4 weeks between the procedures.
Randomization determines the order of the two techniques. During both
procedures targeted biopsies will be taken from suspicious lesions. Only during
the second procedure additional random biopsies will be taken according to
current clinical guidelines. All detected lesions will be inspected and imaged
with NBI and the mucosal morphology and vascular pattern will be classified.
The histopathological outcome of the biopsies will be used as the gold standard
for diagnosis.

The endoscopic procedures are comparable to the standard procedure for regular
patient care with the exception of performing the endoscopy twice. The use of
NBI does not increase the risk of complications. The accepted risk of a
diagnostic colonoscopy is minimal (<0.2%).