Narrow-band imaging magnification predicts the histology and invasion depth of colorectal tumors

Endoscopic colorectal imaging and therapy

PURPOSE OF REVIEW

Colorectal cancer screening and prevention is a pivotal element in every gastroenterologist practice. Recent advances in imaging technology and treatment opened the field for endoscopic management of large flat colorectal polyps and early cancer.

RECENT FINDINGS

High-definition white light colonoscopy allowed for better characterization of colon polyps, particularly flat lesions. Chromoendoscopy facilitated the identification of colon polyps as well as better endoscopic polyp characterization, with strong correlation with final pathological diagnosis, opening the field of 'virtual' biopsy. One particular technology, confocal endomicroscopy can magnify an image approximately 1000 times resembling optical microscopy with very good correlation with histology. Endoscopic mucosal resection has gained great acceptance to manage flat colorectal polyps with the two major complications being bleeding and perforation, both now under 5% in experienced hands. Endoscopic submucosal resection was developed to increase en-bloc resection (less residual disease) of a flat colorectal lesion but one has to accept a higher perforation rate around 10%.

SUMMARY

Current technology allows for better polyp identification and characterization, which can be managed endoscopically.

Efficacy of magnifying endoscopy with flexible spectral imaging color enhancement in the diagnosis of colorectal tumors

BACKGROUND

Magnifying endoscopy with flexible spectral imaging color enhancement (FICE) is an image-enhanced endoscopy that captures the surface and vascular patterns of colorectal tumors. We evaluated and compared FICE magnification to narrow-band imaging (NBI) magnification.

METHODS

Flexible spectral imaging color enhancement or NBI magnification was performed to the visualize surface and vascular patterns of colorectal tumors, classified into 4 types: Type A, Type B, Type C1/C2, and Type C3, as previously reported. A total of 235 colorectal tumors were examined. The correlations between classifications found by FICE or NBI magnification and histopathological diagnoses were examined. Image evaluation was validated by assessing inter-observer and intra-observer agreements on examinations.

RESULTS

Twenty-eight hyperplastic polyps (HPs), 115 tubular adenomas (TAs), 72 mucosal and slightly invaded submucosal cancers (M-sSM), and 20 massively invaded submucosal cancers (mSM) were diagnosed. By FICE magnification, HP and TA were observed in 93.3 and 6.7% of Type A (15 lesions), respectively. TA, M-sSM, and HP were observed in 82.6, 15.4, and 2.0% of Type B (52 lesions),respectively. M-sSM, TA, and mSM were observed in 50.0,46.0, and 4.0% of Type C1/2 (50 lesions), respectively.mSMs were observed in all 7 Type C3 lesions. In diagnosing mSM in Type C3, the sensitivity and specificity of FICE magnification were 77.7 and 100%, respectively, compared to those of NBI, at 63.6 and 99.0%, respectively. Imaging evaluation was validated accurately by intra- and intraobserver measurements showing consistent results.

CONCLUSIONS

The classification of colorectal tumors by FICE magnification correlated well with the histopathological diagnoses, similar to findings for NBI magnification. FICE magnification can be evaluated accurately with the same diagnostic classifications as those used for NBI magnification.

Prevention of gastrointestinal cancer by surveillance endoscopy

The classification of the endoscopic appearance of superficial neoplastic lesions of the digestive mucosa aims to evaluate the risk of progression to advanced neoplasia in 3° (low, intermediate, high) and to predict appropriate treatment and corresponding surveillance. The privileged position of endoscopy results from its double impact on prevention of digestive cancer through reduction in incidence after early detection and eradication of precursors; and through reduction of mortality after detection and treatment of cancer at an early and curable stage. However the efficacy of diagnostic endoscopy still requires improvement and quality control on the following points: (1) technology, with a generalized use of the recently introduced high-resolution endoscopes. (2) diagnosis of poorly visible nonpolypoid precursors: this applies to small depressed lesions and large slightly elevated or sessile serrated and non-serrated precursors, particularly in the proximal colon. (3) treatment and training in therapeutic endoscopy, including the most recent techniques of mucosal resection of nonpolypoid lesions.

Characterization of colorectal tumors using narrow-band imaging magnification: combined diagnosis with both pit pattern and microvessel features

OBJECTIVE

We aimed to clarify the clinical usefulness of narrow-band imaging (NBI) magnification for evaluating both pit appearances and microvessel architecture in comparison with evaluation of microvessel architecture alone in invasion depth of colorectal tumors.

MATERIAL AND METHODS

A total of 189 colorectal lesions [37 adenomas, 73 intramucosal to scanty submucosal invasive carcinomas and 79 massive submucosal invasive (SM-m) carcinomas] were analyzed. All lesions showing irregular pit structure were observed by NBI magnifying endoscopy. Based on both pit appearance and microvessel features, lesions were classified into three grades (C1, C2, C3), as described previously. Also, lesions were classified as high or low by microvessel irregularity. Furthermore, the histopathological background and the inter- and intraobserver variability of C subtype were assessed.

RESULTS

The SM-m rate of C1, C2 and C3 was 5.2, 60.5 and 92.7%, respectively. On the other hand, SM-m rate of lesion with mildly and highly irregular vessels was 13.3 and 55.0%, respectively. For the histopathological background, a high percentage of destruction of the glandular orifice, disappearance of the lamina muscularis mucosae and superficial exposure of desmoplastic reaction (DR) were observed in type C3. For C subtype classification of NBI magnification findings, the kappa value for interobserver variability was 0.749, and the kappa value for intraobserver variability was 0.745.

CONCLUSIONS

NBI magnification findings evaluated by both pit appearances and microvessel features (C subtype) showing a good kappa value in variability are more useful in invasion depth diagnosis of colorectal tumor than those evaluated by microvessel features alone.

Colonoscopic polypectomy and associated techniques

Polypectomy of colonic polyps has been shown to reduce the risk of colon cancer development and is considered a fundamental skill for all endoscopists who perform colonoscopy. A variety of polypectomy techniques and devices are available, and their use can vary greatly based on local availability and preferences. In general, cold forceps and cold snare have been the polypectomy methods of choice for smaller polyps, and hot snare has been the method of choice for larger polyps. The use of hot forceps has mostly fallen out of favor. Polypectomy for difficult to remove polyps may require the use of special devices and advanced techniques and has continued to evolve. As a result, the vast majority of polyps today can be removed endoscopically. Since electrocautery is frequently used for polypectomy, endoscopists should be thoroughly familiar with the basic principles of electrosurgery as it pertains to polypectomy. Tattooing of a polypectomy site is an important adjunct to polypectomy and can greatly facilitate future surgery or endoscopic surveillance. The two most common post-polypectomy complications are bleeding and perforation. Their incidence can be decreased with the use of meticulous polypectomy techniques and the application of some prophylactic maneuvers. This review will examine the technique of polypectomy and its complications from the perspective of the practicing gastroenterologist.

Efficacy of computed virtual chromoendoscopy on colorectal cancer screening: a prospective, randomized, back-to-back trial of Fuji Intelligent Color Enhancement versus conventional colonoscopy to compare adenoma miss rates

BACKGROUND

Colonoscopy is the criterion standard for screening of colorectal neoplasms. Nonetheless, a substantial miss rate with conventional, white-light colonoscopy (WL) remains a challenge.

OBJECTIVE

To assess whether Fuji Intelligent Color Enhancement (FICE) can detect more adenomas than WL in screening colonoscopy.

DESIGN

Prospective, randomized trial of tandem colonoscopy adjusted for withdrawal time and lavage effect.

SETTING

Seoul National University Hospital Healthcare System Gangnam Center, Korea.

PATIENTS

This study involved 359 average-risk adults undergoing screening colonoscopy.

INTERVENTION

Patients were randomized to the first withdrawal with either FICE (FICE-WL group) or WL (WL-FICE group).

MAIN OUTCOME MEASUREMENTS

The primary end point measure was the difference in adenoma miss rates, and the secondary outcome measure was the adenoma detection rate.

RESULTS

We enrolled 359 patients (mean age 50.6 years, male 66.9%) and randomly assigned 181 to the WL-FICE group and 178 to the FICE-WL group. The number of adenomas detected by FICE and WL was 123 and 107, respectively. The adenoma miss rate with FICE showed no significant difference compared with that of WL (6.6% vs 8.3%, P = .59). Characteristics of lesions missed by use of FICE were similar to those missed by use of WL; 93% of overall missed polyps were < or =5 mm, and none were > or =1 cm. All missed adenomas were low grade and nonpedunculated. There was no significant difference between FICE and WL in adenoma detection rate (mean 0.64 vs 0.55 per patient, P = .65) nor percentage of patients with > or =1 adenoma (33.7% vs 30.4%, P = .74).

LIMITATIONS

Single-center study.

CONCLUSION

FICE at screening colonoscopy did not improve the adenoma miss rate or detection rate compared with WL.

Diagnostic accuracy of pit pattern and vascular pattern analyses in colorectal lesions

BACKGROUND

The aim of this prospective study is to compare the usefulness of magnifying narrow band imaging (NBI) and magnifying chromoendoscopy in the diagnosis of colorectal lesions.

METHODS

The subjects were 1185 patients who underwent a complete colonoscopic examination and endoscopic or surgical treatment, from January 2006 to February 2008. A total of 1473 lesions were evaluated (53 hyperplastic polyps, 1317 adenomas, 103 submucosally invasive cancers). The digital images with NBI or chromoendoscopy were recorded and diagnosed independently from each other by two endoscopists who were blinded to the final pathological diagnosis.

RESULTS

We could differentiate between neoplastic and non-neoplastic lesions with sensitivity of 88.9%, specificity of 98.5% and accuracy of 98.2% according to the vascular pattern. By recognizing an irregular or sparse pattern with NBI, massively invasive submucosal cancer could be diagnosed with the sensitivity and specificity of 94.9% and 76.0%. Using chromoendoscopy, we could differentiate between neoplastic and non-neoplastic lesions with sensitivity of 86.8% and specificity of 99.2%. We were able to differentiate between massively invasive cancers and slightly invasive cancers using the pit patterns with sensitivity of 89.7% and specificity of 88.0%. The specificity was superior to that of NBI colonoscopy.

CONCLUSION

Both NBI and chromoendoscopy can be useful for distinguishing between neoplastic and non-neoplastic lesions. In the diagnosis of submucosal cancer, pit pattern diagnosis was slightly superior to vascular pattern diagnosis. It is desirable to perform chromoendoscopy in addition to NBI for distinguishing between slightly and massively invasive submucosal cancer lesions and determining the treatment.

Non-polypoid colorectal neoplasms in ulcerative colitis

The incidence of colorectal cancer associated with ulcerative colitis (UC) increases with time. It is imperative to identify dysplasia-associated lesions or masses (DALM) and non-polypoid colorectal neoplasms (NP-CRN) to reduce the morbidity and mortality from colorectal cancer associated with UC. Recent findings suggest most dysplastic lesions in UC can be considered as visible under careful endoscopic observation. To find NP-CRN in UC, the careful examination of well-prepared mucosa and noting subtle differences is necessary. Magnifying chromoendoscopy, therefore, can be useful to endoscopically diagnose these subtle findings. The authors believe that targeted biopsies during chromoendoscopy will increasingly be used and replace random biopsies in the future.

Flat (nonpolypoid) colorectal lesions identified at CT colonography in a U.S. screening population

RATIONALE AND OBJECTIVES

The aim of this study was to investigate the clinical importance and height definition of flat (nonpolypoid) colorectal lesions detected on screening computed tomographic colonography (CTC).

MATERIALS AND METHODS

Results from prospective screening CTC in 5107 consecutive asymptomatic adults (mean age, 56.9 years) at a single center were analyzed. All detected colorectal lesions > or = 6 mm were prospectively categorized as polypoid or flat (nonpolypoid). The maximal height of all flat lesions was measured to assess the suggested 3-mm threshold definition.

RESULTS

Of 954 polyps measuring > or = 6 mm identified on screening CTC, 125 lesions (13.1%) in 106 adults were prospectively categorized as flat, with a mean size of 12.7 mm (range, 6-80 mm), including 73 lesions 6 to 9 mm, 42 lesions 10 to 29 mm, and 10 lesions > or = 3 cm (carpet lesions). For polyps between 6 and 30 mm in size, flat lesions were less likely than polypoid lesions to be neoplastic (25.0% vs 60.3%, P < .001), histologically advanced (5.4% vs 12.1%, P = .07) or malignant (0% vs 0.5%, P = NS). Two of 10 carpet lesions (20%) were malignant, compared to 50% of polypoid masses > or = 3 cm. Of nine flat lesions seen only on colonoscopy (false-negatives on CTC), two were neoplastic (tubular adenomas), and none was histologically advanced. For all flat lesions between 6 and 30 mm, the maximal height averaged 2.2 mm and was < or =3 mm in 86.1%, including 93.2% of small 6-mm to 9-mm flat lesions.

CONCLUSION

In a US screening population, flat colorectal lesions detected on CTC demonstrated less aggressive histologic features compared to polypoid lesions. Excluding carpet lesions, a maximal height of 3 mm appears to be a reasonable definition.