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ORIGINAL ARTICLE
Diagnostic ability of magnifying endoscopy with blue laserimaging for early gastric cancer: a prospective study
Osamu Dohi1 • Nobuaki Yagi1 • Atsushi Majima1 • Yusuke Horii1 •
Tomoko Kitaichi1 • Yuriko Onozawa1 • Kentaro Suzuki1 • Akira Tomie1 •
Reiko Kimura-Tsuchiya1 • Toshifumi Tsuji1 • Nobuhisa Yamada1 •
Nobukatsu Bito1 • Tetsuya Okayama1 • Naohisa Yoshida1 • Kazuhiro Kamada1 •
Kazuhiro Katada1 • Kazuhiko Uchiyama1 • Takeshi Ishikawa1 • Tomohisa Takagi1 •
Osamu Handa1 • Hideyuki Konishi1 • Yuji Naito1 • Akio Yanagisawa2 •
Yoshito Itoh1
Received: 20 October 2015 /Accepted: 26 May 2016 / Published online: 13 June 2016
� The International Gastric Cancer Association and The Japanese Gastric Cancer Association 2016
Abstract
Background Blue laser imaging (BLI) is a new image-en-
hanced endoscopy technique that utilizes a laser light source
developed for narrow-band light observation. The aim of this
study was to evaluate the usefulness of BLI for the diagnosis
of early gastric cancer.
Methods This single center prospective study analyzed 530
patients. The patients were examinedwith both conventional
endoscopy with white-light imaging (C-WLI) and magni-
fying endoscopy with BLI (M-BLI) at Kyoto Prefectural
University of Medicine between November 2012 andMarch
2015. The diagnostic criteria for gastric cancer usingM-BLI
included an irregular microvascular pattern and/or irregular
microsurface pattern, with a demarcation line according to
the vessel plus surface classification system. Biopsies of the
lesions were taken after C-WLI andM-BLI observation. The
primary end point of this studywas to compare the diagnostic
performance between C-WLI and M-BLI.
Results We analyzed 127 detected lesions (32 cancers and
95 non-cancers). The accuracy, sensitivity, and specificity of
M-BLI diagnoses were 92.1, 93.8, and 91.6 %, respectively.
On the other hand, the accuracy, sensitivity, and specificity
of C-WLI diagnoses were 71.7, 46.9, and 80.0 %,
respectively.
Conclusions M-BLI had improved diagnostic performance
for early gastric cancer compared with C-WLI. These
results suggested that the diagnostic effectiveness of
M-BLI is similar to that of magnifying endoscopy with
narrow-band imaging (M-NBI).
Keywords Blue laser imaging � Early gastric cancer �Endoscopic diagnosis � Magnifying endoscopy � VSclassification
Introduction
Gastric cancer is the second most common cause of cancer-
associated deaths worldwide [1]. Early detection and
treatment has led to improved survival rates, with esoph-
agogastroduodenoscopy (EGD) proving to be the most
useful method of diagnosis for early gastric cancer (EGC).
However, it is often difficult to detect gastric superficial
adenocarcinomas using conventional endoscopy with
white-light imaging (C-WLI). Many clinical studies have
reported on the diagnostic performance of EGC by image-
enhanced endoscopy (IEE) techniques such as narrow-band
imaging (NBI) [2–9] or flexible spectral imaging color
enhancement (FICE) [10–12]. In particular, magnifying
endoscopy with NBI (M-NBI) is a powerful optical IEE
that has demonstrated accurate real-time diagnostic per-
formance in EGC compared with C-WLI [5, 7].
Recently, Fujifilm developed an endoscope system with a
semiconductor laser as a light source. The system includes
two types of lasers with wavelengths of 410 and 450-nm. The
450-nm laser irradiates phosphor to produce illumination
light similar to that obtained with a xenon lamp. The
& Osamu Dohi
osamu-d@koto.kpu-m.ac.jp
1 Department of Molecular Gastroenterology and Hepatology,
Graduate School of Medical Science, Kyoto Prefectural
University of Medicine, 465 Kawaramachi Hirokoji
Kamigyo-ku, Kyoto 602-8566, Japan
2 Department of Surgical Pathology, Graduate School of
Medical Science, Kyoto Prefectural University of Medicine,
Kyoto, Japan
123
Gastric Cancer (2017) 20:297–303
DOI 10.1007/s10120-016-0620-6
combination of strong 410-nm laser light, weak 450-nm laser
light, and fluorescent light enables blue laser imaging (BLI)
via narrow-band light observation. Magnifying endoscopy
with BLI (M-BLI) is useful for evaluating mucosal surface
information such as surface blood vessel and structure pat-
terns [13–16].
M-BLI has the potential to diagnose EGC as efficiently
as M-NBI because it uses narrow-band laser light com-
bined with illumination light. However, sufficient data
have not been reported regarding its diagnostic perfor-
mance for EGC. Therefore, we aimed to investigate whe-
ther M-BLI is more effective for diagnostic accuracy of
EGC when compared with C-WLI.
Patients and methods
Patients
A prospective single-center study was conducted at the
Department ofMolecular Gastroenterology andHepatology,
Kyoto Prefectural University of Medicine. A total of 530
consecutive patients with EGC or superficial esophageal
cancer underwent EGD prior to endoscopic submucosal
dissection (ESD) at the University Hospital, Kyoto Prefec-
tural University of Medicine were enrolled in this study
between November 2012 and March 2015. All patients
provided written informed consents to undergo EGD by both
C-WLI and M-BLI. If undetected lesions were found and
diagnosed as gastric adenoma or adenocarcinoma patho-
logically, ESD were performed on the day after obtaining
additional informed consent from the patients.
This study was approved by the Ethical Review Com-
mittee of the Kyoto Prefectural University of Medicine and
carried out in accordance with the Helsinki Declaration of
the World Medical Association. In addition, this study was
registered in the University Hospital Medical Information
Network Clinical Trials Registry (UMIN-CTR) as No.
UMIN000009216.
End points
The primary aim of this study was to compare the diagnostic
performance (accuracy sensitivity, specificity, positive pre-
dictive value, and negative predictive value) betweenC-WLI
and M-BLI. The secondary aim was to evaluate the features
of misdiagnosed lesions by M-BLI.
Endoscopic system and device
All procedures were carried out with optical magnifying
EG-L590ZW endoscopes and the LASEREO endoscopic
system (Fujifilm Medical Co., Tokyo, Japan). BLI can be
applied with the push of a button. In the BLI mode, the
structure enhancement function was constantly set at the
A6 level, with the color mode fixed at level 1. To obtain
magnified endoscopic images of the lesion easily, we
attached a black soft hood (MAJ-1989; Olympus Medical
Systems, Tokyo, Japan) on the tip of the scope.
Participating endoscopists
All examinations were performed by four skilled endo-
scopists who had participated in more than 100 EGC cases
of M-BLI; this minimized diagnostic variation of the
analyses.
Endoscopic examination
In practice, when an elevated or depressive lesion on the
gastric mucosa was diagnosed as cancer or there was a
suspicion of cancer, the lesion was diagnosed by C-WLI as
a target lesion. After the C-WLI diagnosis was complete,
an assistant physician immediately recorded the results in
the case notes. Next, M-BLI was performed and the results
were recorded in the case notes. Afterwards, one forceps
biopsy specimen was taken from each lesion. The follow-
ing lesions were excluded from this study in order to
evaluate the usefulness of M-BLI for diagnoses of the new
detected lesions in daily clinical situation: (1) superficial
gastric lesions with pathological diagnoses (cancer or non-
cancer) before the study, (2) gastric polyps or protruding
lesions, (3) superficial gastric lesions without detailed
observation using M-BLI, (4) superficial gastric lesions
diagnosed using C-WLI as benign with no need of biopsy,
and (5) superficial gastric lesions with indeterminate
pathological diagnoses obtained by biopsy specimen.
Diagnostic criteria
The diagnostic criteria for gastric cancer using C-WLI
were shallow, depressed, or flat elevated lesions with both
an irregular margin and an irregular mucosal area. The
endoscopic diagnostic criteria for gastric cancer using
M-BLI were defined based on previous reports of vessel
plus surface (VS) classification: the presence of either an
irregular microvascular pattern with a demarcation line, or
the presence of an irregular microsurface pattern with a
demarcation line [3].
Pathological diagnosis
Specimens of all lesions were obtained by biopsy or ESD
and were subsequently fixed with 10 % formalin and
evaluated pathologically. The pathological diagnoses were
completed by a highly experienced clinical pathologist (A.
298 O. Dohi et al.
123
Yanagisawa) who was blind to the actual magnified
endoscopic findings, which were categorized according to
the Japanese Classification of Gastric Carcinoma proposed
by the Japanese Gastric Cancer Association [17]. If there
were diagnostic differences between biopsy and ESD
specimens, the final diagnoses were evaluated according to
ESD specimens.
Statistical analysis
In a pilot study, 60 gastric lesions including 12 EGCs were
examined using both C-WLI and M-BLI. Seven of 12
EGCs (58 %) had different diagnoses between C-WLI and
M-BLI. The diagnoses of M-BLI were accurate compared
with those of C-WLI in six of seven EGCs (86 %). These
data indicated that the proportion of cancerous lesions with
a different diagnosis for the response of matched pairs was
58 %, and the proportion of cancerous lesions with an
improved diagnosis for BLI was 86 %. Accordingly, we
needed to study 15 cancerous lesions with different diag-
nostic results to be able to reject a null hypothesis that the
response difference was zero with probability (power) 0.8.
The Type I error probability associated with a study of this
null hypothesis is 0.05. Since the proportion of patients
with a different diagnosis in the response of matched pairs
was 58 %, the sample size was set to 26 cancerous lesions.
The frequency of synchronous or metachronous multiple
gastric cancers in patients with previous gastric cancers
was reported as 3–5 per 100 patient-years [18–20]. More-
over, it was reported that the frequency of synchronous or
metachronous gastric cancers was 7.7 % in patients with
esophageal cancer [21]. Therefore, we hypothesized that
the frequency of cancerous lesions would be 5.0 % for
patients with gastric cancer or esophageal cancer and cal-
culated the required size of the screening sample to be at
least 520 patients.
McNemar’s test was used to analyze the accuracy of
endoscopic diagnosis and biopsy diagnosis. The diagnostic
accuracy of each of the endoscopic findings is presented as
a percentage (95 % confidence interval). A p value of less
than 0.05 was considered statistically significant. All sta-
tistical analyses were performed using SPSS, version 15.0
(SPSS Inc., Chicago, IL, USA).
Results
Between November 2012 and March 2015, 530 patients
were enrolled in this study; 407 patients underwent EGD
for EGC prior to ESD, 123 patients underwent EGD for
superficial esophageal cancer prior to ESD. Among all
patients, 139 previously undiagnosed lesions were detected
during C-WLI in 132 patients. Among these detected
lesions, the M-BLI findings in seven lesions were inap-
propriate due to difficulties in detail observation, and three
lesions were impossible to judge for malignancy or
benignancy on pathological diagnoses, while two lesions
were diagnosed pathologically by biopsy specimens before
the study. Other than these 12 cases, the 127 lesions
comprised 32 gastric cancers, three gastric adenomas, and
92 non-tumorous tissues (86 chronic gastritis and 6
intestinal metaplasia). Resected gastric cancers included 29
well-differentiated adenocarcinomas, two moderately dif-
ferentiated adenocarcinomas, and one poorly differentiated
adenocarcinoma (Fig. 1). The clinicopathological features
of the evaluated lesions are summarized in Table 1. The
frequency of detected synchronous EGCs was 6.8 % (28
EGCs) in 407 patients with EGC prior to ESD and 3.2 % (4
EGCs) in 123 patients with superficial esophageal cancer
prior to ESD.
The outcomes of C-WLI and pathological diagnoses for
the 127 lesions are shown in Table 2. We diagnosed
cancerous lesions in 34 of 127 superficial gastric lesions
with C-WLI. However, only 15 of the 34 lesions diagnosed
as cancers with C-WLI (44.1 %) were diagnosed patho-
logically to be cancers. The outcomes of M-BLI and
pathological diagnoses for all of the 127 lesions evaluated
are shown in Table 3. We diagnosed cancerous lesions for
38 of the 127 superficial gastric lesions with M-BLI; 30 of
these 38 lesions (78.9 %) were diagnosed pathologically to
be cancers. Three of eight of the false-positive lesions were
diagnosed pathologically to be gastric adenomas. The other
five false-positive lesions were shallow depressed lesions
that were diagnosed pathologically to be chronic gastritis.
The sensitivity of M-BLI diagnoses was significantly
higher than that of C-WLI (93.8 vs. 46.9 %, respectively),
as was the specificity (80.0 vs. 91.6 %, respectively),
positive predictive value (44.1 vs. 78.9 %, respectively),
negative predictive value (81.7 vs. 97.7 %, respectively),
and accuracy (71.2 vs. 92.1 %, respectively) (Table 4).
Representative cases
Representative C-WLI and M-BLI images of gastric cancer
and non-cancerous lesions are shown in Figs. 2 and 3.
Representative case 1 is a superficial elevated lesion on the
lesser curvature of the middle gastric body. A slight
irregular mucosal lesion is visible on the lesser curvature of
the middle gastric body, but the margin of the lesion is
unclear on C-WLI (Fig. 2a). Thus, the lesion was diag-
nosed as a non-cancerous lesion by C-WLI. The demar-
cation of the lesion is clearly distinguishable because of
both the irregular microvascular pattern and the irregular
microsurface pattern on M-BLI (Fig. 2b), and was thus
diagnosed as a cancer. The lesion was diagnosed as a well-
differentiated adenocarcinoma by ESD specimens
Diagnostic ability of magnifying endoscopy with blue laser imaging for early gastric cancer:… 299
123
(Fig. 2c). Representative case 2 is a superficial depressed
lesion on the lesser curvature of the upper gastric body. A
slight irregular mucosal lesion is visible on the lesser
curvature of the middle gastric body, but the margin of the
Fig. 1 Flow chart showing
enrollment of patients and
analysis of lesions
Table 1 Clinicopathological characteristics of gastric superficial
lesions
Cancer Non-
cancer
p value
No. patients/lesions 28/32 90/95 –
Gender
Male 26 69 0.046
Female 2 21
Median age, years (range) 71 (56–86) 70 (41–91) 0.15
Median lesion size, mm (range) 10 (2–35) 5 (2–25) \0.001
Macroscopic type
Elevated type 19 35 0.044
Flat type 1 14
Depressive type 12 46
Location
U 6 7 0.061
M 18 46
L 8 42
Table 2 Endoscopic diagnoses using C-WLI for gastric superficial
lesions
Pathological diagnosis
Cancer Non-cancer
C-WLI
Cancer 15 19
Non-cancer 17 76
C-WLI conventional endoscopy with white-light imaging
Table 3 Endoscopic diagnoses using M-BLI for gastric superficial
lesions
Pathological diagnosis
Cancer Non-cancer
M-BLI
Cancer 30 8
Non-cancer 2 87
M-BLI magnifying endoscopy with blue laser imaging
Table 4 Diagnostic performance of C-WLI and M-BLI for gastric
superficial lesions
C-WLI M-BLI
% 95 % CI % 95 % CI
Sensitivity 46.9 29.1–65.3 93.8a 79.2–99.2
Specificity 80.0 70.5–87.5 91.6b 84.1–96.3
PPV 44.1 27.2–62.1 78.9 62.7–90.4
NPV 81.7 72.4–89.0 97.7 92.1–99.7
Accuracy 71.7 63.0–79.3 92.1a 86.0–96.2
C-WLI conventional endoscopy with white-light imaging, M-BLI
magnifying endoscopy with blue laser imaging, CI confidence inter-
val, PPV positive predictive value, NPV negative predictive valuea p\ 0.001 vs C-WLI, b p = 0.021 vs C-WLI
300 O. Dohi et al.
123
lesion is clear on C-WLI (Fig. 3a). Thus, the lesion was
diagnosed as a cancer by C-WLI. The demarcation of the
lesion is clearly visible because of both the irregular
microvascular pattern and the irregular microsurface pat-
tern (Fig. 3b). Thus, the lesion was diagnosed as a cancer
by M-BLI. The lesion was diagnosed as fundic and pyloric
gland mucosa with mild edema and inflammatory cell
infiltration by a biopsy specimen (Fig. 3c).
Discussion
This is the first comparative report of M-BLI being useful
for the diagnosis of EGC. In this study, M-BLI clearly
detected microvascular pattern, microsurface pattern, and
demarcation line. Thus, VS classification by M-BLI
correlated well with the pathological diagnoses. The sen-
sitivity, specificity, and accuracy of M-BLI after C-WLI
were excellent at 93.8, 91.6, and 92.1 %, respectively. In
previous reports, Ezoe et al. showed that the sensitivity,
specificity, and accuracy of M-NBI after C-WLI for the
diagnosis of small depressed lesions were excellent at 95.0,
96.8, and 96.6 %, respectively [7]. Yamada et al. showed
that the sensitivity, specificity, accuracy, positive predic-
tive value, and negative predictive value of M-NBI after
C-WLI for the diagnosis of small depressed lesions were
excellent at 95, 97, 97, 79, and 99 %, respectively [8].
Based on our findings, the M-BLI diagnoses using VS
classification were excellent, as were the M-NBI diagnoses.
Our study included both elevated and depressed lesions;
thus, the sensitivity, specificity, and accuracy of M-BLI
might be slightly lower score than that of M-NBI. In
Fig. 2 A positive case with M-BLI diagnosis (case 1). Superficial
elevated lesion on the lesser curvature of the middle gastric body.
a C-WLI image shows a slight irregular mucosal lesion with unclear
margin (arrowhead). b M-BLI image shows both irregular microvas-
cular pattern and irregular microsurface pattern with a clear
demarcation line (arrows). c Histopathological image of biopsy
specimen shows a well-differentiated adenocarcinoma. C-WLI con-
ventional endoscopy with white-light imaging, M-BLI magnifying
endoscopy with blue laser imaging
Diagnostic ability of magnifying endoscopy with blue laser imaging for early gastric cancer:… 301
123
addition, the positive predictive value of M-BLI was
slightly low at 78.9 % when compared with other scores.
Moreover, we investigated the reasons why eight non-
cancerous lesions were incorrectly diagnosed as cancers
using M-BLI. In five non-tumorous lesions, the finding of
irregular microvascular and microsurface pattern prompted
a cancer diagnosis. In three other adenomas, flat-elevated
lesions with focal irregular microsurface pattern and reg-
ular microvasuclar pattern were diagnosed as cancers using
M-BLI. The difficulty of diagnosing these lesions was a
limitation of M-BLI using VS classification.
It was previously reported that the sensitivity and
specificity of the gastrofiberscopic biopsy method for
gastric malignancies were 93.8 and 99.6 %, respectively,
and the overall accuracy for all the patients was 97.4 %
[22]. In our study, the sensitivity of M-BLI was as high as
biopsy method. When the lesion is diagnosed to be a cancer
by M-BLI, taking a biopsy specimen is highly
recommended to confirm the pathology. On the other hand,
specificity and negative predictive value of M-BLI was
high in our study. When the lesion is not suspected to be a
cancer by M-BLI, we could decrease the number of
unnecessary biopsies.
Our study has a major limitation. This study provided
only a limited evaluation of M-BLI and the VS classifi-
cation system, which is a diagnostic tool for M-NBI. We
previously reported the evaluation of endoscopic image
between M-BLI and M-NBI. M-BLI could detect
microvascular pattern and microsurface pattern the same as
M-NBI. With VS classification criteria, the accuracy of
M-NBI and M-BLI were 94.1 and 95.3 %, respectively.
There was not significantly difference in appearance of
microvascular pattern [23]. However, the number of
patients was small and the data were gathered from a single
center. Therefore, further multi-institutional studies with a
large number of cases are required to evaluate the
Fig. 3 A false-positive case with M-BLI diagnosis (case 2). Super-
ficial depressed lesion on the posterior wall of the upper gastric body.
a C-WLI image shows a reddish irregular mucosal lesion with clear
margin (arrowhead). b M-BLI image shows both irregular microvas-
cular pattern and irregular microsurface pattern with a demarcation
line (arrows). c Histopathological image of biopsy specimen shows a
fundic and pyloric gland mucosa with mild edema and inflammatory
cell infiltration. C-WLI conventional endoscopy with white-light
imaging, M-BLI magnifying endoscopy with blue laser imaging
302 O. Dohi et al.
123
diagnostic accuracy and findings using VS classification for
EGC between M-BLI and M-NBI. Thus, a multi-institu-
tional prospective study (UMIN-CTR 000007300) has
already been done and the data processing is now ongoing.
In conclusion, M-BLI had greater diagnostic perfor-
mance for early gastric cancer than C-WLI. These results
suggest that the diagnostic effectiveness of M-BLI is
similar to that of M-NBI.
Acknowledgments We thank all members of the Department of
Molecular Gastroenterology and Hepatology, Graduate School of
Medical Science, Kyoto Prefectural University of Medicine, for
helping conduct this study. We also thank Kubo Masahiro and all
personnel who assisted with operation of the Fujifilm LASEREO
system.
Compliance with ethical standards
Conflict of interest Y. Naito received collaboration research funding
from Fujifilm Medical Co., Ltd. (J132001115, J132001139). N. Yagi
and Y. Itoh were affiliated with a department that was partially funded
by Fujifilm Medical Co., Ltd. (J082003006). Fujifilm Medical Co.,
Ltd. had no role in the design, conduct, data collection, data inter-
pretation, or reportage of the study.
Human rights statement and informed consent All procedures
followed were in accordance with the ethical standards of the
responsible committee on human experimentation (The Ethical
Review Committee of the Kyoto Prefectural University of Medicine
and national) and with the Helsinki Declaration of 1964 and later
versions. Informed consent or substitute for it was obtained from all
patients included in the study.
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