Advanced diagnostic tools: virtual colonoscopy and magnifying chromoendoscopy

Early endoscopic diagnosis of colorectal cancers (CRCs) represents the best tool for the reduction of CRC mortality, but the conventional colonoscopic view seems unable to clarify faint changes of colorectal mucosa. For these reasons, during the last few decades, two new techniques have been developed in order to better define, diagnose and treat colorectal lesions: chromoendoscopy (CE) and magnifying chromoendoscopy (MC). The authors herein highlight the benefits of both and compare the results of conventional endoscopy and CE with 0.2% indigo carmine solution, evaluating 995 consecutive selected patients referred for colonoscopy between January 1999 and March 2003 at the International Health Union of Rome. CE showed new neoplastic patterns not detectable with conventional endoscopy in 102 patients (10.2%). The incidence of high-grade dysplasia and early carcinomas was 9.9% for protruded, 13.1% for flat and 60% for depressed lesions. Our comparative study on 995 consecutive selected patients confirmed the existence of flat and depressed neoplasms in Italy and shows the high accuracy rate of CE over conventional endoscopy for the detection of non-polypoid lesions. CE should be used routinely in order to enhance the early diagnosis of CRCs, while MC in experienced hands represents a significant advance in colonoscopic practice improving the diagnosis of every single lesion, enhancing therapeutic efficacy of colorectal tumours.     

Flat and depressed colorectal tumours in a southern Swedish population: a prospective chromoendoscopic and histopathological study

BACKGROUND: Flat and depressed colorectal tumours are common in Japan but are very rare or non-existent in Western countries. AIMS: To study the occurrence of flat colorectal tumours in a southern Swedish population. METHODS: In this prospective study, 371 consecutive European patients were examined by high resolution video colonoscopy combined with chromoendoscopy. The nature of the lesions was determined by histopathological examination. RESULTS: A total of 973 tumours were found; 907 (93.2%) were protruding and 66 (6.8%) were flat or depressed. Of the flat/depressed tumours, five (7.7%) were early adenocarcinomas infiltrating the submucosa. Eleven carcinomas (1.2%) were found among protruding tumours. High grade dysplasia was observed in 18% (n=11) of flat/depressed adenomas in contrast with 7.3% (n=65) of protruding adenomas, and occurred in smaller flat/depressed tumours compared with protruding ones (mean diameter 8 mm v 23 mm, respectively). Furthermore, high grade dysplasia was significantly more common in flat elevated tumours with central depression or in depressed adenomas (35.7%; 5/14) than in flat elevated adenomas (12.8%; 6/47). CONCLUSION: Flat and depressed tumours exist in a Western population. Future studies should address whether or not chromoendoscopy with video colonoscopy is necessary in the search for flat colorectal neoplasms.     

Chromoendoscopic colonoscopy for detecting preneoplastic lesions in hereditary nonpolyposis colorectal cancer syndrome.

BACKGROUND & AIMS: In hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, flat and small adenomas are particularly prone to malignant transformation but might be missed by standard colonoscopy. We prospectively studied the diagnostic yield of high-resolution colonoscopy coupled with chromoendoscopy for preneoplastic and neoplastic colorectal lesions in patients with HNPCC syndrome. METHODS: Thirty-six consecutive asymptomatic patients (mean age, 42 years) belonging to HNPCC families and receiving genetic counseling were enrolled in this prospective study. Colonoscopy was performed in 2 steps. Conventional colonoscopy was performed first, followed by a second colonoscopy with chromoendoscopy with indigo carmine (.4%) dye sprayed onto the entire proximal colon. RESULTS: Conventional colonoscopy identified 25 lesions (mean size, 4 +/- 3 mm) in 13 patients. Seven lesions, detected in 5 patients, were adenomas, 3 of which were located in the proximal colon. Chromoendoscopy identified additional 45 lesions (mean size, 3 +/- 1 mm) in 20 patients; most of these lesions were flat and hyperplastic. Eleven additional adenomas were detected in the proximal colon of 8 patients, and 8 of these 11 lesions were flat. The use of chromoendoscopy significantly increased the detection rate of adenomas in the proximal colon, from 3 of 33 patients to 10 of 33 patients (P = .045). CONCLUSION: Relative to conventional colonoscopy, high-resolution colonoscopy with chromoendoscopy markedly improves the detection of adenomas in patients with HNPCC syndrome and might help to prevent colorectal carcinoma in these patients with a very high risk of colorectal cancer.     

Endoscopic mucosal resection for colonic non-polypoid neoplasms

BACKGROUND: Colonic neoplastic lesions can be classified morphologically into polypoid and non-polypoid types. Non-polypoid lesions have a higher malignant potential than polypoid lesions. Removing these lesions and obtaining integral specimen for histopathology evaluation during colonoscopy examination is an important task. Endoscopic mucosal resection (EMR) is an alternative to surgery for removing of non-polypoid lesions of the GI tract. This study assessed the safety, efficacy, and clinical outcomes of EMR. PATIENTS AND METHODS: From October 2000 to October 2003 during the routine colonoscopy performed at one medical center, identified 152 non-polypoid colonic neoplasms in 149 patients (92 males, 57 females) were found. The mean patient age was 57.8 +/- 15.5 yr (range 32-80 yr). EMR was performed for lesions suspected of being neoplastic tumors via magnification colonoscopy with the indigo carmine dye spray method. The lesions were removed via EMR with pure cutting current after which hemoclips were applied to the resected wounds. RESULTS: The study identified 40 flat type lesions, 106 lateral spreading tumors, and 6 depressed lesions that were completely resected. The mean size of lesions was 19.4 +/- 10.3 mm (range 6-60 mm). Histological findings were 4 adenocarcinomas, 59 with high-grade adenoma/dysplasia, and 89 with low-grade adenoma/dysplasia. Two patients experienced bleeding immediately following EMR, while adequate hemostasis was achieved using hemoclips. Neither delayed bleeding nor perforation developed following EMR. CONCLUSION: EMR by using pure cutting current and hemoclip is a useful method for obtaining integral specimen for accurate pathologic assessment. This method provides a safe and minimally invasive technique managing of colonic non-polypoid lesions.     

Flat adenoma in colon: Two decades of debate

The existence of flat adenomas in the colon is well recognized. Whether they represent a distinct disease with a pathogenetic pathway different from that of the classical adenoma-carcinoma sequence in colorectal tumorigenesis and have higher malignant potential remains a matter of debate. To review the epidemiology, clinical features, detection and management of flat and depressed (non-polypoid) colonic neoplasm, we performed a thorough literature review on studies focusing on the prevalence, histological features, genetics, detection and treatment of flat and depressed (non-polypoid) colonic neoplasm. A high percentage of severe dysplasia in flat colonic adenomas has not been consistently demonstrated. Their malignant potential appears to be size-dependent. Flat adenomas are found to have a lower incidence of major genetic abnormalities involved in the classical adenoma-carcinoma sequence and that has raised suspicions that they may have a different pathogenesis. The depressed type of colorectal carcinoma is uncommon but shows more aggressive behavior. More advanced colonoscopic techniques, such as chromoendoscopy, may enhance the detection of small and inconspicuous colonic neoplastic lesions that lack a protruding configuration. It is essential for endoscopists to appreciate the existence and clinical significance of flat and depressed colonic lesions as an important variant of colonic neoplasms so that the goal of reducing colorectal carcinoma incidence by polypectomy can be better achieved.     

内镜窄带成像与染色技术诊断大肠肿瘤的对比研究

目的通过窄带成像技术（NBI）和染色放大方法对大肠新生性病变进行观察，比较这两种技术对大肠肿瘤及非肿瘤性病变的鉴别诊断精度差异。方法2006年6月至9月间，共302例年龄在加至80岁之间的患者进行了NBI肠镜检查，其中98例入选。内镜插入至回盲部，退镜时分别采用常规模式、NBI模式观察，发现病变后，分别用NBI模式及染色放大方法进行血管分型及腺管开口分型，然后行病理检查进行评价比较。结果在98例患者发现新生性病变147个，其中常规内镜下发现的病变有90．5％（133／147），采用NBI发现病变有98．6％（145／147），差异有统计学意义（P〈0．01），漏诊的主要为平坦型病变。NBI观察对肿瘤性或非肿瘤的判断符合率为91．8％，染色内镜为82．3％（P〈0.01）。结论NBI技术观察黏膜表面变化，判断肿瘤或非肿瘤病变的符合率比普通内镜和染色内镜高，敏感性强；操作转换简单易行，尤其有利于平坦型病变的发现及诊断。     

Chromoendoscopy or white light endoscopy for neoplasia detection in Lynch syndrome,a meta-analysis

BackgroundLynch syndrome carries an increased risk of colorectal neoplasia, hence annual surveillance colonoscopy is recommended. This study aimed to compare the diagnostic yields of image enhancement modalities for colorectal neoplasia in patients with Lynch syndrome.MethodsMeta-analysis of pooled ratios of lesion detection rates (RRs) and odds ratios (ORs) with 95% confidence intervals (CIS), comparing white light endoscopy (WLE) and chromoendoscopy (ChE).ResultsFour studies comparing WLE to ChE were analyzed. ChE fared better than WLE in overall lesion detection (RR 1.97, 95% CI 1.63–2.38) and detection of adenomas (RR 1.53, 95% CI 1.07–2.17), flat lesions (RR 3.4, 95% CI 2.47–4.67) and proximally-located lesions (RR 2.93, 95% CI 1.91–4.5). The odds of a patient having any lesion found were higher in ChE compared to WLE (OR 2.42, 95% CI 1.56–3.75). The odds of a patient having adenoma(s) found on endoscopy were not significantly higher in chromoendoscopy compared to white light endoscopy (OR 1.81, 95% CI 0.65–5.01).ConclusionUsing standard definition technology, ChE allows detection of more lesions, especially adenomas, flat lesions and proximal lesions in Lynch syndrome patients, compared to WLE. The results show that surveillance colonoscopy of Lynch syndrome patients should be performed using ChE.     

New aspects of modern endoscopy

The prognosis for patients with malignancies of the ga-strointestinal-tract is strictly dependent on early detec-tion of premalignant and malignant lesions. However, small, flat or depressed neoplastic lesions remain dif-ficult to detect with these technologies thereby limiting their value for polyp and cancer screening. At the same time computer and chip technologies have undergone major technological changes which have greatly im-proved endoscopic diagnostic investigation. New imag-ing modalities and techniques are very notable aspects of modern endoscopy. Chromoendoscopy or filter-aided colonoscopy(virtual chromoendoscopy) with high defi-nition endoscopes is able to enhance the detection and characterization of lesions. Finally, confocal laser en-domicroscopy provides histological confirmation of the presence of neoplastic changes. The developing tech-niques around colonoscopy such as the retro-viewing colonoscope, the balloon-colonoscope or the 330-de-grees-viewing colonoscope try to enhance the efficacy by reducing the adenoma miss rate in right-sided, non-polypoid lesions. Colon capsule endoscopy is limited to identifying cancer and not necessarily small adenomas. Preliminary attempts have been made to introduce this technique in clinical routine.     

Computed virtual chromoendoscopy for classification of small colorectal lesions: a prospective comparative study

OBJECTIVES: Standard colonoscopy offers no reliable discrimination between neoplastic and nonneoplastic colorectal lesions. Computed virtual chromoendoscopy with the Fujinon intelligent color enhancement (FICE) system is a new dyeless imaging technique that enhances mucosal and vascular patterns. This prospective trial compared the feasibility of FICE, standard colonoscopy, and conventional chromoendoscopy with indigo carmine in low- and high-magnification modes for determination of colonic lesion histology. METHODS: Sixty-three patients with 150 flat or sessile lesions less than 20 mm in diameter were enrolled. At colonoscopy, each lesion was observed with six different endoscopic modalities: standard colonoscopy, FICE, and conventional chromoendoscopy with indigo carmine (0.2%) dye spraying in both low- and high-magnification modes. Histopathology of all lesions was confirmed by evaluation of endoscopic resection or biopsy specimens. Endoscopic images were stored electronically and randomly allocated to a blinded reader. RESULTS: Of the 150 polyps, 89 were adenomas and 61 were hyperplastic polyps with an average size of 7 mm. For identifying adenomas, the FICE system with low and high magnifications revealed a sensitivity of 89.9% and 96.6%, specificity of 73.8% and 80.3%, and diagnostic accuracy of 83% and 90%, respectively. Compared with standard colonoscopy, the sensitivity and diagnostic accuracy achieved by FICE were significantly better under both low (P < 0.02) and high (P < 0.03) magnification and were comparable to that of conventional chromoendoscopy. CONCLUSIONS: The FICE system identified morphological details that efficiently predict adenomatous histology. For distinguishing neoplastic from nonneoplastic lesions, FICE was superior to standard colonoscopy and equivalent to conventional chromoendoscopy.     

Recognition and characterization of small colonic neoplasia with high-definition colonoscopy using i-Scan is as precise as chromoendoscopy

BackgroundThe EPKi system (Pentax, Japan) enables resolution above HDTV. Aim of the study was to test the efficacy of HD+ alone and with the new post-processing digital filter i-Scan or chromoendoscopy (Methylene blue 0.1%) in screening for colorectal cancer. We focused on lesions less than 5 mm as a surrogate marker for the optical possibilities of the EPKi system.MethodsThe last 30 cm of the colon in a screening population were inspected with HD+ alone, in combination with i-Scan (2:1 randomisation) and subsequently with chromoendoscopy.All lesions were characterized and targeted biopsies were performed.Resultsi-Scan augmented in 69 patients the identification of lesions from 176 to 335 (p < 0.001) and chromoendoscopy to 646 (p < 0.001). The additional lesions were mainly flat (type IIb, 74%), which were only recognized using i-Scan or chromoendoscopy. The amount of neoplasias was not significantly different (HD+: 5, i-Scan: 11, Chromoendoscopy: 11), but all could correctly be predicted using i-Scan or chromoendoscopy.ConclusionsHD+ colonoscopy with and without i-Scan unmask a plethora of small lesions but chromoendoscopy can even advance the number. However, i-Scan was able to predict neoplasia as precisely as chromoendoscopy and might shortly replace chromoendoscopy as a more time efficient tool.     

放大色素内镜在结直肠肿瘤内镜黏膜切除治疗中的应用

目的 评估内镜黏膜切除术(EMR)结合放大色素内镜诊治结直肠肿瘤的有效性和安全性.方法 收集结肠镜检查患者中符合EMR指征的无蒂型或平坦、凹陷型病灶.观察病灶形态学与EMR术后组织学结果 的相关性,评估放大色素内镜判断病灶浸润深度的准确性.结果 81例患者经EMR切除病灶90个(无蒂型25个,平坦、凹陷型65个).组织学显示低级别上皮内瘤变(LGD)58个,高级别上皮内瘤变(HGD)20个,腺癌12个.其中HGD和癌变病灶直径大于LGD病灶[(1.4±0.5)cm和(1.6±0.5)cm比(1.05:0.4)cm],但组间差异无统计学意义(P>0.05).平坦、凹陷型病灶较无蒂型病灶更易出现HGD或癌,但差异亦无统计学意义[41.5%(27/65)比20.0%(5/25),P=0.084].病灶表面有凹陷者出现HGD或癌的比例显著高于无凹陷者[51.0%(25/49)比17.1%(7/41),P<0.01)].放大色素内镜判断病灶浸润深度的准确性为97.8%(88/90).完整的组织学切除占所有病灶的95.6%(86/90).结论 凹陷型和平坦型伴中央凹陷的结直肠病变的恶性倾向高.应用放大色素内镜能准确判断病灶浸润深度,从而使EMR治疗更安全有效.     

结直肠肿瘤样病变内镜活检与黏膜切除术后病理诊断比较

背景：结直肠肿瘤样病变内镜黏膜切除术（EMR）后病理诊断与术前内镜活检病理诊断的差异未明。目的：评估放大色素内镜指导下EMR获得的结直肠肿瘤样病变标本的诊断价值。方法：连续收集接受EMR治疗的直径≤2cm的无蒂型或平坦、凹陷型结直肠肿瘤样病变纳入研究,分析EMR病理诊断与术前活检病理诊断的差异。结果：共纳入EMR切除病灶90个,无蒂型25个,平坦、凹陷型65个,后者为高度异型增生（HGD）或腺癌的可能性略高于前者（41．5％对20．0％,P〉0．05）。术前活检病理诊断的总体准确性为68．9％,28个（31．1％）病灶的诊断于术后发生改变．其中4个增生性病变术后均诊断为低度异型增生（LGD）,14个LGD诊断为HGD,5个LGD诊断为腺癌,5个HGD诊断为腺癌。病灶形态学表现及其浸润深度与病理诊断结果的改变无关。结论：放大色素内镜指导下的EMR病理诊断纠正了本组近1／3结直肠肿瘤样病变的术前活检病理诊断,具有完善诊断和治疗的双重作用。     

窄带成像技术在结直肠肿瘤性与非肿瘤性病变诊断中的临床应用价值

目的探讨内镜窄带成像技术(NBI)在结直肠肿瘤性及非肿瘤性病变诊断中的临床价值.方法选择2010年2月至2011年3月常规结肠镜检查发现的结直肠肿瘤性与非肿瘤性病变75个(60例).发现病变后分别采用常规模式、NBI模式及染色方法对病变轮廓、黏膜表面腺管开口(PIT)及微血管(CP)形态进行观察,与病理检查结果进行对比...     

窄带内镜、染色内镜与常规内镜对远端大肠ACF发现率的对比研究

目的比较常规内镜与窄带内镜（NBI）、染色内镜对远端大肠异常隐窝灶（aberrant cryptfoci,ACF）的发现率。方法选择2011年8月至12月就诊于江西省萍乡市人民医院准备接受结肠镜检查的患者670例,用随机数字表法将患者分为3组：其中常规内镜组228例、NBI组220例、染色内镜组222例。比较三种方法对远端大肠ACF检出率及各组间所用操作时间。结果在三组中,共发现155例ACF病例数。常规内镜、NBI组及染色内镜组发现ACF病例数分别为5例（2.19%）、25例（11.36%）,125例（56.31%）,三组组间比较有显著性统计学差异（P〈0.01）。但是与常规内镜相比,NBI组、染色内镜组操作时间有所延长。结论染色内镜能大幅提高远端大肠ACF发现率。NBI内镜较常规白光内镜能提高远端结肠ACF发现率,但比染色内镜低。常规白光内镜对远端结肠ACF发现率低。     

Flat colorectal neoplasms and the impact of the revised Vienna Classification on their reporting: A case-control study in UK and Japanese patients

Objective. The prevalence and interpretation of flat colorectal neoplasms in the East or West remain highly variable. Several factors may contribute to this variability including differences in reporting techniques between Japanese and Western histopathologists when lesions are classified. The aims of this study were (i) to determine the frequency and characteristics of flat colorectal neoplasms in British and Japanese patients, (ii) to examine whether histopathological discrepancies exist between Western and Japanese-trained pathologists applying conventional classification methods and (iii) to determine the impact of the revised Vienna Classification on any differences observed. Material and methods. One hundred and forty-four patients in the United Kingdom with neoplastic lesions prospectively identified by a colonoscopist, fully-trained in Japan, were age and gender-matched with 144 Japanese patients with neoplastic lesions detected by the same colonoscopist. Two British and two Japanese pathologists were independently asked to assess all neoplasms using both conventional and revised Vienna Classification methods. Results. No significant difference in the frequency of flat neoplasms was found between British and Japanese patients; however, flat neoplasia from Japanese patients tended to contain more advanced pathologies. Discrepancies in histological diagnoses were observed between pathologists but which were reduced with the revised Vienna Classification. Japanese pathologists tended to diagnose higher grades of dysplasia for the same lesion compared to their British counterparts. Conclusions. The frequency of flat neoplasms in British and Japanese patients is similar. However Japanese lesions, especially flat (IIb) and slightly depressed (IIc) neoplasms tend to be more biologically aggressive. The revised Vienna Classification achieves greater consensus.     

Detection of colorectal adenomas by routine chromoendoscopy with indigocarmine

OBJECTIVES: Nonpolypoid adenomas, which can be important precursors of colorectal cancers, are difficult to find during routine colonoscopy. The aim of this study was to evaluate the usefulness of routine chromoendoscopy in Korea, where the incidence of colorectal cancer is low compared with western countries. METHODS: Colonoscopy with chromoendoscopy was performed in 74 consecutive patients (48 men, 26 women; mean age 53.0 yr). After a careful examination of the whole colon, a defined segment of the sigmoid colon and rectum (0-30 cm from the anal verge) was stained with 20 ml of 0.2% indigocarmine solution with a spraying catheter. Nonpolypoid lesions were classified as flat or depressed types. Biopsies were taken from all lesions detected before or after staining with indigocarmine. RESULTS: Indications for colonoscopy included routine check-up (21 patients), diarrhea or loose stool (14 patients), abdominal pain (12 patients), constipation (7 patients), bleeding (6 patients), and others (14 patients). Before staining, 58 lesions were found in 30 patients (43.2%). Histology showed tubular adenoma in 41 lesions, hyperplastic or inflammatory changes in 14 lesions, adenocarcinoma in 2 lesions, and villous adenoma in 1 lesion. After indigocarmine staining for normal-looking distal 30 cm colorectal mucosa, 176 lesions were found in 46 patients (62.2%). Histologically, 158 lesions were hyperplastic or inflammatory in nature, and 17 lesions (from 11 patients) were tubular adenomas. There was one serrated adenoma. Eighteen adenomas seen only after spraying indigocarmine were 2.6 +/- 0.6 mm in diameter, and all of them were classified as flat adenomas. There was no depressed-type adenoma. No adenoma with high grade dysplasia, villous histology, or cancer was found after staining. Presence of macroscopic adenomatous lesions or carcinoma before staining could not predict the existence of adenoma after staining. CONCLUSIONS: In a large proportion of patients, flat or depressed adenomas could be found after spraying indigocarmine for normal-looking colorectal mucosa in Korea. The clinical significance of these diminutive adenomas that can be found only after spraying contrast agent needs to be further investigated.     

Non-polypoid colorectal neoplasms:Classification,therapy and follow-up

In the last years,an increasing interest has been raised on non-polypoid colorectal tumors(NPT) and in particular on large flat neoplastic lesions beyond 10 mm tending to grow laterally,called laterally spreading tumors(LST).LSTs and large sessile polyps have a greater frequency of high-grade dysplasia and local invasiveness as compared to pedunculated lesions of the same size and usually represent a technical challenge for the endoscopist in terms of either diagnosis and resection.According to the Paris classification,NPTs are distinguished in slightly elevated(0-Ⅱa,less than 2.5 mm),flat(0-Ⅱb) or slightly depressed(0-Ⅱc).NPTs are usually flat or slightly elevated and tend to spread laterally while in case of depressed lesions,cell proliferation growth progresses in depth in the colonic wall,thus leading to an increased risk of submucosal invasion(SMI) even for smaller neoplasms.NPTs may be frequently missed by inexperienced endoscopists,thus a careful training and precise assessment of all suspected mucosal areas should be performed.Chromoendoscopy or,if possible,narrow-band imaging technique should be considered for the estimation of SMI risk of NPTs,and the characterization of pit pattern and vascular pattern may be useful to predict the risk of SMI and,therefore,to guide the therapeutic decision.Lesions suitable to endoscopic resection are those confined to the mucosa(or superficial layer of submucosa in selected cases) whereas deeper invasion makes endoscopic therapy infeasible.Endoscopic mucosal resection(EMR,piecemeal for LSTs 20 mm,en bloc for smaller neoplasms) remains the first-line therapy for NPTs,whereas endoscopic submucosal dissection in high-volume centers or surgery should be considered for large LSTs for which en bloc resection is mandatory and cannot be achieved by means of EMR.After piecemeal EMR,follow-up colonoscopy should be performed at 3 mo to assess resection completeness.In case of en bloc resection,surveillance colonoscopy should be scheduled at 3 years for adenomatous lesions ≥ 1 cm,or in presence of villous features or high-grade dysplasia patients(regardless of the size),while less intensive surveillance(colonoscopy at 5-10 years) is needed in case of single(or two) NPT 1 cm presenting tubular features or low-grade dysplasia at histology.     

A prospective comparative study of narrow-band imaging, chromoendoscopy, and conventional colonoscopy in the diagnosis of colorectal neoplasia

BACKGROUND: Discrimination between neoplastic and non-neoplastic lesions is crucial in colorectal cancer screening. Application of narrow-band imaging (NBI) in colonoscopy visualises mucosal vascular networks in neoplastic lesions and may improve diagnostic accuracy. AIM: To compare the diagnostic efficacy of NBI in differentiating neoplastic from non-neoplastic colorectal lesions with diagnostic efficacies of standard modalities, conventional colonoscopy, and chromoendoscopy. METHODS: In this prospective study, 180 colorectal lesions from 133 patients were observed with conventional colonoscopy, and under low-magnification and high-magnification NBI and chromoendoscopy. Lesions were resected for histopathological analysis. Endoscopic images were stored electronically and randomly allocated to two readers for evaluation. Sensitivity, specificity and diagnostic accuracy of each endoscopic modality were assessed by reference to histopathology. RESULTS: NBI and chromoendoscopy scored better under high magnification than under low magnification in comparison with conventional colonoscopy. The diagnostic accuracy of NBI with low or high magnification was significantly higher than that of conventional colonoscopy (low magnification: p = 0.0434 for reader 1 and p = 0.004 for reader 2; high magnification: p<0.001 for both readers) and was comparable to that of chromoendoscopy. CONCLUSION: Both low-magnification and high-magnification NBI were capable of distinguishing neoplastic from non-neoplastic colorectal lesions; the diagnostic accuracy of NBI was better than that of conventional colonoscopy and equivalent to that of chromoendoscopy. The role of NBI in screening colonoscopy needs further evaluation.     

Perspectives of chromo and magnifying endoscopy: how, how much, when, and whom should we stain?

The goal of every routine endoscopy in the gut is the early diagnosis of malignant and premalignant changes of the mucosa. Chromo- and magnifying endoscopes are exciting new tools and offer detailed analysis of the colonic mucosal surface and pit pattern architecture. This review summarizes recent advances in endoscopic characterization of colorectal lesions using magnification endoscopy and chromoendoscopy. Surface analysis of the colon using chromoendoscopy allows a prediction between non-neoplastic and neoplastic lesions with high specificity. The precise delineation of the borders and a more detailed macroscopic analysis of the lesions are further advantages. In particular, flat adenomas and early depressed cancers are now more frequently recognized in western countries suggesting that significant lesions were overlooked by conventional endoscopy in the past. Furthermore, chromoendoscopy can be used in a targeted fashion to screen for sporadic adenomas. Finally, in surveillance colonoscopy, patients with long-standing ulcerative colitis have a valuable benefit if targeted biopsies are performed to detect intraepithelial neoplasias after pan-chromoendoscopy with methylene blue. Although there is a long learning curve, chromoendoscopy should thus belong to every endoscopists armamentarium. However, detailed knowledge about the technique, dyes, and specific staining patterns are mandatory before the yield of screening or surveillance colonoscopy can be increased. The new detailed images seen with magnifying chromoendoscopy are unequivocally the beginning of a new era where new optical developments will allow a unique look on cellular structures.     

Comparative study of conventional colonoscopy, chromoendoscopy, and narrow-band imaging systems in differential diagnosis of neoplastic and nonneoplastic colonic polyps

AIM: To identify the feasibility of the narrow-band imaging (NBI) method compared with that of conventional colonoscopy and chromoendoscopy for distinguishing neoplastic and nonneoplastic colonic polyps. METHOD: This study enrolled consecutive patients who underwent colonoscopy using a conventional colonoscope between January and February 2006 at Chang-Gung Memorial Hospital, Linkou Medical Center, Taiwan. These 78 patients had 110 colorectal polyps. During the procedure, conventional colonoscopy first detected lesions, and then the NBI system was used to examine the capillary networks. Thereafter indigo carmine (0.2%) was sprayed directly on the mucosa surface prior to evaluating the crypts using a conventional colonoscope. The pit patterns were characterized using the classification system proposed by Kudo. Finally, a polypectomy or biopsy was performed for histological diagnosis. RESULTS: Of the 110 colorectal polyps, 65 were adenomas, 40 were hyperplastic polyps, and five were adenocarcinomas. The NBI system and pit patterns for all lesions were analyzed. For differential diagnosis of neoplastic (adenoma and adenocarcinoma) and nonneoplastic (hyperplastic) polyps, the sensitivity of the conventional colonoscope for detecting neoplastic polyps was 82.9%, specificity was 80.0% and diagnostic accuracy was 81.8%, significantly lower than those achieved with the NBI system (sensitivity 95.7%, specificity 87.5%, accuracy 92.7%) and chromoendoscopy (sensitivity 95.7%, specificity 87.5%, accuracy 92.7%). Therefore, no significant difference existed between the NBI system and chromoendoscopy during differential diagnosis of neoplastic and nonneoplastic polyps. CONCLUSION: The NBI system identified morphological details that correlate well with polyp histology by chromoendoscopy.