Although serology-based diagnosis of celiac disease (CD) in children recently has
been legitimized [1], small bowel biopsy remains the gold standard for diagnosis of the condition [2]
[3]. Upper endoscopy, therefore, takes on paramount importance in management of CD for
several reasons, including serendipitous discovery of endoscopic markers of CD, assessment
of “patchy” villous atrophy, targeting of biopsy sampling, and evaluation of CD-related
complications.
Macroscopic markers of CD, estimable with white light endoscopy, include the “scalloped”
appearance of duodenal folds, nodular pattern of the mucosa (the so-called “mosaicism”),
evidence of submucosal vessels, and epithelial fissurations [4]. The diagnostic accuracy of these findings is largely variable, according to different
reports [5]
[6], and they are associated with a significant rate of underdiagnosis of CD [7]
[8]. Because standard endoscopy is unreliable, other endoscopic tools have been investigated
for diagnosis opf CD, which fall into two categories based on their working principle:
machine-independent techniques and machine-dependent techniques; the latter include software- and hardware-dependent techniques [9]
[10]. The water-immersion technique (WIT) and dye-staining chromoendoscopy and machine-independent.
Software-dependent techniques include Narrow-Band Imaging (optical dye-less chromoendoscopy),
Fujinon Intelligent Chromo Endoscopy (virtual dye-less chromoendoscopy) and i-SCAN,
which are dyeless chromoendoscopy tools. Hardware-dependent techniques such as optical
coherence tomography, confocal laser endomicroscopy, video capsule endoscopy, and
enteroscopy can be performed only with dedicated tools that are different from regular
gastroscopes, or with the use of probes [9]
[10]. The combination of these techniques has been suggested to improve the detection
of duodenal villous abnormalities [11].
In this issue of Endoscopy International Open, Iacucci et al [12] present a retrospective cohort study of 58 patients with clinical suspicion of CD
and positive serology testings who underwent upper endoscopy and duodenal evaluation
with both white light endoscopy (WLE) and a combination of i-SCAN and WIT (iSCAN-HDWI).
The duodenal view was respectively classified as normal, reduction of folds, mosaic
pattern, scalloping and atrophy with visible vessels with WLE, and as normal, mild,
moderate, patchy or severe villous atrophy with iSCAN-HDWI.
The authors found a significant correlation between the endoscopic grade evaluated
by iSCAN-HDWI and the histology score. Assessment with WLE showed a lower but significant
grade of correlation. In particular, iSCAN-HDWI achieved 96 % sensitivity, 63 % specificity,
and 100 % accuracy for predicting duodenal damage (excluding Marsh I lesions), whereas
WLE showed 78 % sensitivity, 50 % specificity, and 72 % accuracy for the same gold
standard. Respectively, WLE identified no abnormalities in 55.6 % of patients diagnosed
with patchy villous atrophy and in 33.3 % of patients diagnosed with mild villous
atrophy after iSCAN-HDWI evaluation.
WIT is an easy technique that allows real-time enhancement of duodenal villous pattern
during upper endoscopy. After aspiration of air from the duodenal lumen, the operator
injects 100 mL to 150 mL of water to highlight villi [13]. WIT achieved high levels of accuracy in diagnosing total villous atrophy (TVA),
with only slightly less accurate results in identifying partial villous atrophy (PVA)
[14]
[15]
[16]
[17].
i-SCAN is a digital tool developed by Pentax Medical. It enhances images through three
different modalities: contrast enhancement, which highlights mucosal abnormalities,
particularly those of depressed areas; surface enhancement, which increases contrast
between light and dark; and tone enhancement, which groups and recombines blue, red,
and green components of images. i-SCAN produced results similar to WIT in assessment
of TVA and PVA [18].
The combination of iSCAN technology with WIT both highlights vascular and mucosal
pattern and allows direct visualization of villi. Such a “joint-venture” can be of
help in evaluating the duodenal villous pattern, especially in the case of partial
or patchy villous atrophy, and in targeting biopsy sampling; therefore, it is advocated
to decrease the number of CD misdiagnoses and related unnecessary costs. Further studies,
combining other modalities for imaging enhancement, are therefore welcome to improve
our knowledge of the diagnostic potential of endoscopic tools in CD.
