Role of Narrow Band Imaging Endoscopy in

Treatment Strategies - Gastrointestinal Carcinoma
Role of Narrow Band Imaging Endoscopy in
Suspected Malabsorption
Amitava Goswami, Sunil Dadhich and Narendra Bhargava
Department of Gastroenterology, Dr Sampurnanand Medical College, India
Introduction
architecture in varied etiology. Study comprised one hundred and five
Narrow band imaging (NBI) is a novel endoscopic imaging technique
subjects with clinical history suggestive of malabsorption or serologic
suspicion of celiac disease.10 Diagnosis of celiac disease was established
that enables characterisation of subtle mucosal changes.1 The
using the standard European Society for Pediatric Gastroenterology,
technology consists of placing narrowband pass filters in front of
Hepatology, and Nutrition guidelines11 and histological grading
a conventional white-light source to obtain tissue illumination at
selected narrow wavelength bands. The bandwidths of the blue (415
according to the Marsh and Oberhuber classification.12
nm) and green filters (540 nm) are used in NBI. This light is maximally
absorbed by haemoglobin, enhancing the visualisation of capillary
microvasculature and giving it a dark appearance.2 Most of the studies
on NBI in the gastrointestinal tract have focussed on the oesophagus
and colon especially for the evaluation of Barrett’s oesophagus and
colorectal polyps.3,4 A limited work has been done in assessing mucosal
changes in duodenum with narrow band imaging. Moreover white
light standard endoscopy has 50% to 94% sensitivity for diagnosing
villous atrophy in celiac disease. Sensitivity is particularly lower for
NBI Endoscopy in Duodenum
Conscious sedation is usually needed before performing endoscopy.
Upper gastrointestinal endoscope compatible with narrow band
imaging, which enables magnification up to × 1.5 was used in
recent study. A 1-cm reusable black rubber cap fitted to the tip of
the endoscope can also be used to allow the endoscope to be fixed
onto the mucosa. However routine use of black rubber cap is not
a prerequisite as clear imaging can also be done without using it.
subclinical celiac disease and patchy villous atrophy.5,6
Endoscopy of the second part of the duodenum is initially performed
with white light and followed by magnification endoscopy with
NBI. At most additional 3–5 seconds is needed to switch from white
The first study on narrow band imaging-magnifying endoscopy
(NBI-ME) in villous morphology was done by Singh et al., in 2010.
7
light to NBI and for maximal focused visualisation of the mucosa
De Luca has further established the role of NBI-ME in celiac disease
to be achieved. To visualise the mucosa clearly and avoid excessive
over a wider population in Italy. Both the studies used a narrow band
peristaltic activity, an antispasmodic agent, intravenous hyoscine-
imaging endoscope with high external optical magnification (×115).
N-butylbromide (10–20 mg) is needed. A minimum of four separate
Recently from India, Dutta et al. showed a good correlation between
areas in the duodenum should be imaged and recorded.
8
duodenal villous morphology using magnification NBI with histology
in patients with suspected malabsorption syndrome.9
In the duodenum, villi are clearly seen during magnification NBI
endoscopy. We have recently proposed a classification for duodenal
Recently our group published a large prospective study to determine
mucosal changes from normal mucosa to flat mucosa. Four distinct
the correlation between NBI and histology in grading villous
varieties of villous morphological changes are graded as “NBI type
I” for normal finger-like villi, “NBI type II” for short and stubby villi or
Dr. Amitava Goswami graduated in General
Medicine in 2006 from Guwahati Medical College,
India. After gaining comprehensive training and
experience in Hepatology and Gastroenterology at
Institute of Liver and Biliary Science and Medanta
Medicity, he entered Doctorate of Medicine
course in Gastroenterology at Dr Sampurnanand
Medical College (RUHS) in 2011. He has published
6 International articles, 1 national, 2 chapters (1
textbook) and is a peer reviewer in 2 indexed journals. He is a member of
American Society of Gastrointestinal Endoscopy and his area of interest is
endoscopy, hepatology, celiac disease, infectious colitis and biliary disease.
cerebriform villi, “NBI type III” for patchy villous atrophy, and “NBI type
IV” for flat surface without villi (Figure 1).
Other Imaging Endoscopy
The Optical band imaging technology is based on the selection of
certain wavelengths from a reflected light signal that results in an
enhanced and digitally constructed image. In contrast, the narrowband imaging system achieves this goal by using filters that restrict
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Figure1. A Type I Finger like villi B and C Type II Stubbed and Cerebriform villi D Type III Patchy villous atrophy.
the bandwidth of a transmitted RGB light signal. Cammarota et al.
celiac disease in North India is 1.04% (1 in 96). Most of the reports on
did an original open, prospective, single centre trial on the potential
celiac disease have appeared from the northern part of India (Punjab,
of optimal band imaging, for predicting the duodenal villous
Haryana, Delhi, Rajasthan, Uttar Pradesh) where wheat is the staple
morphologic characteristics in patients with suspected CD. The
cereal in the diet. Based on community studies, 5–8 million people
author had showed extremely high sensitivity, specificity, positive
are expected to have celiac disease in India. Of such a large pool of
predictive value, and negative predictive value (all >90 %) and
patients, only a few thousand patients have been diagnosed as having
excellent interobserver variability (κ = 0.93). However no further
celiac disease and a large number of subjects are still undiagnosed.
13
study to assess the duodenal villous morphology has been done in
recent times with optical band imaging.
Malabsorption in Indian Subcontinent
60
It is believed that, in recent years the frequency of tropical
malabsorption has declined mainly with improvement in socioeconomic status, sanitary conditions and use of antimicrobials.
Malabsorption syndrome (MAS) is common in tropics including India.
Tropical malabsorption still constitutes 7-37 % of MAS in Indian adults.
Celiac disease and tropical malabsorption are the most common
Sometimes it is very difficult to differentiate between celiac disease
causes of MAS among Indian adults.14,15 The overall prevalence of
and tropical malabsorption. Other uncommon causes of MAS are small
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intestinal bacterial overgrowth, giardiasis, hypogammaglobulinemia,
narrow band imaging performed very well in predicting duodenal
intestinal tuberculosis, strongyloidiasis, Crohn’s disease, acquired
villous morphology and may help in carrying out targeted biopsies
immunodeficiency syndrome, amyloidosis, immuno proliferative small
and avoiding unnecessary biopsies in patients with suspected
intestinal disease and intestinal lymphangiectasia.15
malabsorption. Previously another report from India has highlighted
the role of the combination of high resolution NBI with magnification
to obtain targeted biopsy specimens from patchy villous atrophy.16
NBI in Assessing Villous Atrophy
Singh et al. published the first study of NBI on duodenal mucosal
morphology. In their study the overall sensitivity and specificity
Our study is the largest prospective study on magnifying NBI endoscopy
in correctly distinguishing the presence or absence of villi were
in assessing villous morphology in varied etiology.10 The proposed
93.3% and 97.8%, respectively, with interobserver and intraobserver
classification on NBI villous morphology has high (all >90%) sensitivity,
agreement (kappa, κ) at 0.82 and 0.86. Three years later De Luca
specificity, PPV, and NPV. The overall intra- and interobserver kappa
et al. in their study concluded that the NBI system with ME has
agreement coefficient for determining villous morphology subtypes
superior performance than conventional endoscopy in detecting
using NBI-ME as compared to histology was 0.83 and 0.89, respectively.
mucosal abnormalities on an otherwise normal-appearing duodenal
Standard white light endoscopy feature suggestive of celiac disease was
mucosa. The overall agreement between NBI-ME and histology was
seen in 70-86% while narrow band imaging with magnifying endoscopy
significantly higher when compared with SE and histology (kappa
(NBI-ME) can detect almost 100% cases of histologically diagnosed CD.
score 0.90 vs. 0.46; p=0.001) in diagnosing CD.
The mean time period required for standard endoscopy plus NBI-ME is
about 4 min 25 s ±16 s. Partial villous atrophy is usually seen either as
Recently Dutta et al. did a study to assess the morphology of
stubbed villi or cerebriform villi (see Figure 1. B & C). Most interesting
duodenal villi using magnification narrow band imaging and
findings in NBI- ME are a mixed pattern or patchy villous atrophy (see
correlate it with histology findings in patients with clinically
Figure 1. D). Targeted biopsy has a role to play in patchy villous atrophy.
suspected malabsorption syndrome. One hundred patients with
Patchy villous atrophy can be easily picked up with NBI-ME which can be
clinically suspected malabsorption were included and sixteen
missed with conventional white light endoscopy and targeted biopsy
patients had histologically confirmed villous atrophy. The sensitivity
can decrease the diagnostic delay in significant number of cases. Our
and specificity of narrow band imaging in predicting villous
study highlights the role of magnifying narrowband imaging endoscopy
atrophy was 87.5% and 95.2%, respectively, for one endoscopist.
in both celiac disease and tropical malabsorption, which constitutes a
The corresponding figures for the second endoscopist were 81.3%
major cause of malabsorption in Indian subcontinent.
and 92.9%, respectively. The interobserver agreement was very
Table 1 shows the results of these studies along with data from the
good with a kappa value of 0.87. Authors concluded magnification
Author (Country)
Year
Study Size
Endoscopic villous atrophy correlation with histology
Sensitivity Specificity
Singh (Australia)
7
2010
41 videos (10 celiac
Positive
Negative
Interobserver
predictive
predictive
Kappa
value
value
coefficient
0.82
93.3%
97.8%
93.6%
97.9%
100%
93%
89%
100%
87.5%
95.2%
95%
90.2%
and 31 normal)
De Luca (Italy)
8
2013
44 patients with
suspected celiac
disease (Single
observer)
Dutta (India)
9
2014
100 patients
0.87
with suspected
malabsorption
Goswami
(India)
10
2014
105 patients
91.2%
94.2%
0.89
with suspected
malabsorption
Table 1. Studies with narrow band imaging endoscopy in assessing duodenal villous atrophy.
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current study. All of them show very good sensitivity and specificity of
be associated with villous atrophy and hence duodenal biopsy may
magnification NBI in detecting duodenal villous atrophy. So in recent times
still be required in cases of suspected malabsorption. The increased
a good amount of work has been done to establish the efficacy of narrow
procedure time, need for sedation and added cost of the procedure
band imaging in assessing duodenal villous morphological changes.
to the patient for using NBI endoscopy is to be balanced against the
NBI may aid in the diagnosis of patients with suspected malabsorption.
potential usefulness of this procedure.
Magnifying NBI is especially helpful in getting targeted biopsy in patchy
villous atrophy and sometimes avoiding unnecessary biopsies.
Limitations of NBI Endoscopy
62
In conclusion early diagnosis of etiology of malabsorption is
undoubtedly of great importance for patients to initiate treatment
and maintenance of quality of life. Magnification NBI endoscopy
Some limitations or cautions has to be kept in mind before applying
appears to be a promising tool in assessing duodenal villous
magnifying narrow band imaging as a screening procedure in patient
morphology and is likely to play a role as a diagnostic aid in
with suspected malabsorption. All causes of malabsorption may not
evaluation of patients with suspected malabsorption.
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