Comparison
of the Imaging of Ultrathin Transnasal Endoscopy and Transoral Conventional
Endoscopy in the Same Patient with Early Esophageal Cancer
Naondo
Sohara, Satoru Kakizaki, Yasuhiro Onozato, Haruhisa Iizuka, Hiroshi Ishihara,
Shinichi Okamura, Hideaki Itoh, Masatomo Mori
Naondo Sohara, Yasuhiro Onozato, Haruhisa Iizuka,
Hiroshi Ishihara, Department of Endoscopy and Endoscopic Surgery, Shirakawa
Clinic, Maebashi, Gunma 371-0051, Japan
Satoru Kakizaki, Shinichi Okamura, Masatomo Mori, Department of Medicine and Molecular
Science, Gunma University Graduate School of Medicine, Maebashi, Gunma
371-8511, Japan
Hideaki Itoh, Department
of Pathology, Maebashi Red Cross Hospital, Maebashi, Gunma 371-0014, Japan
Correspondence to: Satoru Kakizaki, MD, PhD, Department of
Medicine and Molecular Science, Gunma University Graduate School of Medicine,
3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan.
kakizaki@showa.gunma-u.ac.jp
Telephone: +81-27-220-8127 Fax: +81-27-220-8136
Received: November 1, 2011 Revised: December 25,
2011
Accepted: January 19, 2012
Published online: February 21,
2012
ABSTRACT
AIM: The diagnostic value of ultrathin
transnasal endoscopy (UT) for early esophageal cancers (EEC) remains
controversial. To evaluate the diagnostic utility of UT in detecting EEC, we
compared the imaging of UT and transoral conventional endoscopy (CO) in the
same patient.
METHODS:
Nineteen
consecutive patients with 20 lesions were enrolled to this study. The
endoscopic findings, sensitivity and accuracy in the detection of mucosal
findings, and the sensitivity of diagnosis were compared between UT and CO in
the same subjects. The image
density from each procedure was quantified and compared with the ImageJ
software program.
RESULTS: All 20 lesions could be detected using
UT. Twelve of 20 lesions (60.0%) could be diagnosed as cancerous by UT. The
sensitivities of the mucosal findings such as the fur white coat, the vessel
irregularity and loss of glossy identified by CO were superior to those
obtained by UT. A combined examination by narrow-band imaging (NBI) yielded the
same detection rate of the brownish area.
The quantitative analyses revealed that combination diagnosis with NBI
was superior to optical imaging alone. There were no differences in the
calculated densities between UT and CO, thus demonstrating that UT was not
inferior to CO for detecting these lesions.
CONCLUSIONS: The inherent shortcomings of UT
included its poor resolution, lower light source, and lack of
magnification. The imaging
qualities and diagnostic accuracy of UT in EEC were lower than those of CO.
However, the combination of UT with NBI increased the sensitivity, and UT with
NBI could detect EEC.
© 2012 Thomson research. All rights reserved.
Keywords: Early
esophageal cancer; Ultrathin transnasal endoscopy; Narrow-band imaging
Sohara N,
Kakizaki S, Onozato Y, Iizuka H, Ishihara H, Okamura S, Itoh H, Mori M.
Comparison of the Imaging of Ultrathin Transnasal Endoscopy and Transoral
Conventional Endoscopy in the Same Patient with Early Esophageal Cancer. Journal
of Gastroenterology and Hepatology Research 2012; 1(1): 5-10
Available from:
URL: http://www.ghrnet.org/index./joghr/
INTRODUCTION
Since the report by Shaker [1] in 1994, transnasal
esophagogastroduodenoscopy has been reported worldwide as one technique that
facilitates comfortable endoscopy without the requirement for sedative
drugs. Recent technological
advances have led to the further miniaturization of the charge-coupled device
(CCD) allowing the production of thinner endoscopes [1]. Ultrathin
transnasal endoscopy (UT) has been increasingly performed in health check-up
institutions in Japan, in patients that anticipate comfortable unsedated upper
gastrointestinal endoscopy. Several studies have demonstrated that the
tolerance and acceptance of UT are better than those for transoral conventional
endoscopy (CO) in unsedated patients[2-5]. Furthermore, several
studies have demonstrated that UT is less stressful on the cardiovascular
system than CO [2, 5, 6]. However, UT has several drawbacks, such as
low image resolution, low luminous intensity and lack of magnification [7].
Using UT, several studies reported the detection rate of gastric cancer in
Japan, which was comparable to the rate using standard scopes [8, 9].
However, Hayashi et al[10] reported that the diagnostic
utility of UT may be lower than for CO for screening early gastric cancers, and
that the disadvantages of UT should be carefully considered when physicians are
evaluating patients.
Therefore, the diagnostic utility of UT for early gastric cancers
remains controversial. UT for screening early esophageal cancers (EEC) can be
more difficult than detecting early gastric cancers. A higher imaging quality
may be required to detect EEC. Furthermore, the early diagnosis of esophageal
cancers is an important determinant of outcome and quality of life. As a
result, using UT is controversial in screening for EEC.
It is well known that CO is
superior to UT in imaging quality [7]. However, few studies have performed the
comparative analyses between CO and UT using quantitative imaging tools. It is
important to analyze the imaging methods for their subjectivity and their quantitative
qualities. We herein evaluated the imaging differences between UT and CO in the
calculated densities using the ImageJ software program. The present study
evaluated the detecting utility of UT in comparison to CO in order to screen
EEC.
PATIENTS AND METHODS
Patients
and design
At our hospital, nineteen patients with twenty
lesions of EEC were treated by endoscopic submucosal dissection (ESD) from
November 2007 to October 2009. All 19 patients (17 male subjects, 2 female
subjects) underwent UT and CO. Three gastrointestinal endoscopists who had 21
years, 20 years and 17 years of experience in gastrointestinal endoscopy
respectively, compared the images. One of 3 endoscopists performed each
procedure, but all 3 endoscopists attended each procedure and saw the images
live. Furthermore, 3 endoscopists reviewed both the still images and video
images. The detection ability, accuracy of diagnosis, and mucosal findings were
decided by the consensus of the 3 gastrointestinal endoscopists. We classified
the degrees of diagnostic utility of UT as distinct, indistinct and
undetectable. Distinct; we were able to detect the lesion and accurately assess
its malignancy. Indistinct; we could detect the lesion but were unable to
accurately assess its malignancy. Undetectable; we could not detect the lesion by
UT. The location of the lesion was classified into the upper, middle, and lower
third of the esophagus. The location classification according to a clockwise
definition was also assessed.
Dimethicone (100 mg), pronase (20 000 units), and sodium bicarbonate
(1g) dissolved in 30 ml of drinking water were orally administered 15 minutes
before endoscopy to remove mucous obstacles. All patients provided written
informed consent before receiving the examination. This study was approved by the
institutional ethical committee (No., SC2007/002; date, 14 October, 2007).
Ultrathin
transnasal endoscopy and narrow-band imaging (NBI)
UT was carried out with an Olympus GIF-XP260N and CO
was performed using an Olympus GIF-H260Z (Olympus Medical Systems Corp., Tokyo,
Japan). The outer diameter of the GIF-XP260N insertion tube was 5.0 mm and the
width of vision was 120°. The tip flexion capability was 210° up, 90° down and
100° right/left. The outer diameter of the insertion tube of GIF-H260Z was 10.8
mm and the width of vision was 140°. The tip flexion capability was same as
GIF-XP260N. We used the Evis Lucera Spectrum video imaging system (Olympus) for
narrow-band imaging (NBI). The neoplastic lesion was defined as the area that
appeared brownish under NBI and was equated to the area of microvascular
proliferation in the lesion [11-15]. We carried out UT with white
light, which was followed by examination with UT with NBI, CO with white light,
CO with NBI, and CO with lugol chromoendoscopy, prior to treatment with ESD. Lugol
chromoendoscopy was as follows: through a washing pipe that was 2 mm in outer
diameter (PW-6P-1; Olympus), 20 to 30 ml of 3% Lugol solution and sprayed
uniformly over the esophageal mucosa. Mucosal findings were assessed by the
following five categories: redness, fur white coat, mucosal irregularity,
vessel irregularity and loss of glossy appearance. Representative endoscopic imaging of
mucosal findings is shown in Figure 1.
Histology
Biopsy samples and resected specimens after ESD were
obtained for histological evaluation by an experienced pathologist (H.I). The
diagnosis and classifications were in accordance with the Japan Esophageal
Society [16].
Quantitative
analyses of endoscopic findings
The densities were measured using the ImageJ software
program (National Institutes of Health, MD, USA). ImageJ software recognizes
black as 1 and white as 255. Other colors indicated a gradient numerical
parameter between 1 and 255. Briefly, the colors resembling to black show a low
score and colors that resemble white show a higher score. As shown in Figure 2,
endoscopic films obtained during the UT and CO with white-light or NBI were
scanned and measured using a computer graphics software program. The density
ratios were calculated and indicated as percentile of: – (1–density of the
tumor lesion/density of surrounding normal mucosa) ×100 %.
Statistical
analysis
The results are presented as the mean ±
SD for continuous variables. Fisher’s exact probability test for
frequency tables was used for the statistical analyses. Distributions of
continuous variables were analyzed using the Mann–Whitney U test. P-values
of less than 0.05 were considered to be statistically significant.
RESULTS
Clinical
characteristics
The clinical characteristics of the treated patients
are shown in Table 1. Tobacco smoking (16/19, 84.2%), and alcohol consumption
(16/19, 84.2%) were prevalent behaviors. According to the tumor location, 14 of
20 lesions (70.0%) were located at the middle third of the esophagus, and 6 lesions (30.0%) were located at the lower third of
esophagus. According to the tumor size, the mean longitudinal diameter of the
lesions was 23.7±7.9 mm (range 8-38 mm). We divided the tumors into
four categories on the basis of their size: ≤10 mm (1 lesions), 11-20 mm (3
lesions), 21-30 mm (10 lesions), and ≥31 mm (6
lesions). The macroscopic types of lesions included the elevated type (types I
and 0-IIa; 3 lesions), the flat type (type 0-IIb; 13 lesion), and the
superficial depressed type (type 0-IIc; 4 lesions). All lesions were squamous
cell carcinoma according to the histological analyses. According to the tumor
depth, eleven (55.0%) tumors were classified as T1a-epithelinm (T1a-EP), five
(25.0%) were classified as T1a-lamina propria mucosae (T1a-LPM), and four (20.0%)
were classified as T1a-muscularis mucosae (T1a-MM) [16].
Screening
performance of ultrathin transnasal endoscopy
All 20 lesions were detected using UT; therefore, no
lesions were classified as undetectable. Twelve of 20 (60.0%) lesions were
accurately assessed for malignancy by UT, and the diagnostic utility was
defined as distinct. Eight of 20 (40.0%) lesions were detected but could not be
accurately assessed for malignancy by UT, and the diagnostic utility was
therefore defined as indistinct. Because CO can perform magnification
endoscopy, all 20 lesions were accurately assessed for malignancy, and the
diagnostic utility was defined as distinct. Using NBI observation, 1 of 8
lesions which were indistinct by UT with white light was diagnosed as a malignancy.
As a result, 13 of 20 (65.0%) lesions were assessed as distinct by UT with
NBI. Concerning the type of
lesions, 3 of 3 (100.0%) cases with the elevated type, 5 of 13 (38.5%) cases
had flat type, and 4 of 4 (100.0%) cases with the superficial depressed type
were defined as distinct by UT. As a result, the flat type was difficult to
diagnose according to the type of lesions (P < 0.05). There was no
obvious correlation between the diagnostic utility and the tumor location.
Concerning the tumor size, 1 of 1 (100.0%) tumor with ≤10 mm, 2 of 3 (66.7%)
tumors with 11-20 mm, 6 of 10 (60.0%) tumors with 21-30 mm, and 3 of 6 (50.0%)
tumors with ≥31 mm in size were defined as distinct by UT. There was no obvious correlation
between the diagnostic utility and the tumor size. Concerning the tumor depth,
5 of 11 (45.5%) T1a-EP tumors, 4 of 5 (80.0%) T1a-LPM tumors, 3 of 4 (75.0%)
T1a-MM tumors were defined as distinct by UT. Although this trend did not reach
statistical significance, T1a-EP tumors were difficult to diagnose in
comparison with T1a-LPM and T1a-MM tumors.
Representative
cases
Figure 3 shows the representative cases of endoscopic
findings by UT and CO. In figure 3A, UT revealed the lesion to a similar extent
as CO. UT revealed the redness, mucosal irregularity, vessel irregularity and
loss of glossy appearance. However, the fur white coat was not revealed by UT.
CO also revealed the same findings as UT. In Figure 3B, UT was inferior to CO
in one category. Although CO could reveal all 5 characteristics, UT did not
reveal the fur white coat. figure 3C shows a representative patient in whom UT
was inferior to CO. CO could reveal all 5 categories. In contrast, UT only
revealed only the redness.
Comparison
of mucosal findings between ultrathin transnasal endoscopy and conventional
transoral endoscopy
The comparisons of the mucosal findings between UT
and CO are shown as figure 4. Redness was observed in 80% (16/20) of the tumors
with UT and 90% (18/20) of the tumors with CO; fur white coat was observed in
60% (12/20) of the tumors with UT and 90% (18/20) of the tumors with CO;
mucosal irregularity, 80% (16/20) by UT and 95% (19/20) by CO; vessel
irregularity, 75% (15/20) by UT and 100% (20/20) by CO; loss of glossy, 55%
(11/20) by UT and 100% (20/20) by CO. UT was significantly inferior for
detecting the fur white coat (P <0.05), vessel irregularity (P
<0.05) and loss of glossy (P <0.01) in comparison with CO. There
was no change in the brownish areas of NBI between UT and CO.
Quantitative
analyses of endoscopic findings
To quantitatively compare the imaging findings, the
densities of cancer lesions or surrounding non-tumor lesions were measured
using the ImageJ software program (Figure 5). The densities of cancer lesions
by UT with white light and CO with white light were 116.9±18.9 and 120.8±17.2,
respectively (not significantly difference). The densities of cancer lesions
were significantly lower than those of the surrounding non-tumor lesions by UT
and CO (P <0.05). The
densities of the cancer lesions were -14.4±9.2% in UT and -14.3±9.6% in CO
compared with the normal lesions (not significantly difference). As a result,
the imaging contrasts were not significantly different between UT and CO,
confirming the results from the same detection rate. The densities of imaging
with NBI by UT and CO revealed significantly better contrast between the tumor
and the surrounding non-tumor lesion in comparison with
those obtained using white light (P <0.05). The densities of the cancer lesions were -36.5±7.6% in UT with NBI and -40.1±10.5% in CO
with NBI compared with the normal lesions. NBI significantly improve the lesion
contrast using UT and CO (P <0.05), and the utility of NBI imaging
was confirmed by the analytical parameters.
DISCUSSION
We demonstrated that UT could be used in conjunction
with NBI for the screening of EEC. The detection of the lesions was achieved
for all lesions by UT in the present study. The quantitative imaging analyses
revealed that UT had similar contrast densities with CO. Although the imaging
quality of UT was inferior to CO, UT could screen for EEC. Furthermore,
combined imaging with NBI yielded a
higher detection rate. As a result, UT can be used
for the screening of EEC. However, it is important to consider the
disadvantages of UT. It may
therefore be useful for the endoscopist to change to CO with magnified
endoscopy when EEC is suggested based on the findings of screening endoscopy
with UT and NBI. A future goal is therefore to be able to make both an accurate
diagnosis or differential diagnosis with UT.
UT has been increasingly carried out in health care institutions in
Japan, particularly in patients anticipating comfortable unsedated upper
gastrointestinal endoscopy. With the recent ultrathin videoscopes, several
studies reported an improved detection rate of gastric cancer in Japan,
suggesting that no differences were noted between UT and CO when it was carried
out by experienced endoscopists [9]. Several studies reported the
diagnostic accuracy and optical quality of UT to be equivalent to those of CO[17-21].
However, those studies targeted lesions other than early gastric cancers, such
as esophagitis, Barrett's esophagus, hiatal hernia, esophageal varices, and
gastric ulcers[17-21]. Catanzaro et al[19]
reported that the overall accuracy for esophageal findings was 98%; the
sensitivity, 91%; and the specificity, 99%. Sorbi et al [20]
reported that 97% of the lesions were correctly detected by UT compared with
CO. However, the use of UT for screening for early gastric cancers still
remains controversial. As a result, it also remains controversial to use UT to
screen for EEC. Because the
inherent shortcomings of UT include its poor resolution, lower light source,
and lack of magnification[7], it may be more difficult to detect EEC
than early gastric cancers.
In the present series, all EEC lesions were accurately detected. Although there was data on the EEC
before the procedure, which was carried out by experienced endoscopists, the
brownish areas of NBI were all accurately detected by UT. Combined imaging with
NBI improved the sensitivity of UT for the screening of EEC. Furthermore, the utility of NBI was
revealed by the mathematical parameters in the present study. Our patient series
showed that UT was inferior to CO in regarding the mucosal findings, including
the fur white coat, vessel irregularity, and loss of glossy appearance. The
explanation is that the lower resolution and lower luminous intensity of the UT
render it difficult to detect these findings. However, mucosal irregularity was
relatively well detected by UT. The light guide of UT was one, although the
light guide of CO was two. The findings of the mucosal irregularity were easily
detected because of only one light guide, which may have resulted in a clearer
light/shadow contrast. The
comparison of the mucosal findings in UT with CO is subjective because it may
vary with the experience of the endoscopists. Therefore, using the ImageJ software
program to compare image quality is a benefit of this study. This study showed
that there was no significant difference in the imaging contrasts between UT
and CO, confirming the results from the same detection rate. The density of
imaging with NBI by UT and CO revealed significantly better contrast between
the tumor and the surrounding non-tumor lesion in comparison to those obtained
using white light. NBI significantly improve the lesion contrast using UT and
CO, and the utility of NBI imaging was confirmed by the analytical parameters.
The time required for endoscopic examination to diagnose EEC is
important. The examination time using UT was compared with the time using CO to
evaluate the usefulness of UT as a screening test for EEC. The time required
for endoscopic examination of the esophagus (excluding the observation of
stomach and duodenum) was 152.0±43.1 sec in UT
and 137.0±47.3 sec in CO (P=0.10). The time from insertion to detecting
EEC was 55.5 ±
51.7 sec in UT and 40.0±25.4 sec in CO in observation time (P=0.08). There were no
significant differences in examination times for EEC between UT and CO in this study.
Lee et al[11, 23] reported that interpretations
based on endoscopy with NBI are much more consistent than those based on
standard endoscopy alone. Moreover, the reliability of interpretation based on
Lugol chromoendoscopy can be improved with information derived from previous
NBI endoscopy[11, 22, 23]. UT might increase the patient tolerance
for longer procedures. The achievement of a higher level of resolution and a
brighter image compared to previous methods is clearly important. Further
innovations, such as the use of high-resolution charge-coupled devices (CCD),
strong-power light sources, and enhanced integration of the imaging system will
improve the image quality of UT.
In conclusion, UT was
found to be useful for the screening of EEC. The imaging qualities and diagnostic
accuracy of UT were lower than those of CO. However, combination with NBI
yielded a higher sensitivity, and UT with NBI could detect EEC.
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Peer reviewers:
Chenghao Guo,
MD, PhD, Professor, Department of
Pathology,
Institute of Pathology and Pathophysiology, School of Medicine, Shandong
University, Wenhuaxi R.d44, Jinan city, 250012, Shandong Province, China; Hoon
Jai Chun, MD, PhD, Professor, Division of Gastroenterology and Hepatology,
Department of Internal Medicine, Institute of Digestive Disease and Nutrition,
Korea University College of Medicine, 126-1, 5-Ga, Anam-Dong, Seongbuk-Gu,
Seoul, 136-705, Korea; Hee Man Kim, Assistant Professor, Department of Internal
Medicine, Kwandong University College of Medicine, 697-24 Hwajung-dong,
Deokyang-gu, Goyang city, 412-270, Republic of Korea.
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