Source of errors in the evaluation of early rectal cancer by endoluminal ultrasonography

Learning curve for endorectal ultrasound in young and elderly: lights and shades

Aim of the study is to highlight difficulties faced by an inexperienced surgeon in approaching endorectal-ultrasound, trying to define when learning curve can be considered complete.

A prospective analysis was conducted on endorectal-ultrasound performed for subperitoneal rectal adenocarcinoma staging in the period from January 2008 to July 2013, reported by a single surgeon of Department of Oncology, Section of General Surgery, “San Luigi Gonzaga” Teaching Hospital, Orbassano (Turin, Italy); the surgeon had no previous experience in endorectal-ultrasound. Fourty-six endorectal-ultrasounds were divided into two groups: early group (composed by 23 endorectal-ultrasounds, made from January 2008 to May 2009) and late group (composed by 23 endorectal-ultrasound, carried out from June 2009 to July 2013).

In our experience, the importance of a learning curve is evident for T staging, but no statystical significance is reached for results deal with N stage.

We can conclude that ultrasound evaluation of anorectal and perirectal tissues is technically challenging and requires a long learning curve. Our learning curve can not be closed down, at least for N parameter.

Management of colorectal T1 carcinoma treated by endoscopic resection from the Western perspective

Detection of early colorectal cancer is expected to rise in light of national colorectal cancer screening programs. This The present review article delineates current endoscopic risk assessments, differentiating invasive from non-invasive neoplasia, for high likelihood of lymph node metastasis in early colorectal cancer, also termed high-risk early colorectal cancer, and endoscopic and surgical resection methods from a Western hemisphere perspective.

Rectal cancer staging: Correlation between the evaluation with radial echoendoscope and rigid linear probe

Background and Objectives:

The National Cancer Institute estimated 40,340 new cases of rectal cancer in the United States in 2013. The correct staging of rectal cancer is fundamental for appropriate treatment of this disease. Transrectal ultrasound is considered one of the best methods for locoregional staging of rectal tumors, both radial echoendoscope and rigid linear probes are used to perform these procedures. The objective of this study is to evaluate the correlation between radial echoendoscopy and rigid linear endosonography for staging rectal cancer.

Patients and Methods:

A prospective analysis of 48 patients who underwent both, radial echoendoscopy and rigid linear endosonography, between April 2009 and May 2011, was done. Patients were staged according to the degree of tumor invasion (T) and lymph node involvement (N), as classified by the American Joint Committee on Cancer. Anatomopathological staging of surgical specimen was the gold standard for discordant evaluations. The analysis of concordance was made using Kappa index.

Results:

The general Kappa index for T staging was 0.827, with general P < 0.001 (confidence interval [CI]: 95% 0.627-1). The general Kappa index for N staging was 0.423, with general P < 0.001 (CI: 95% 0.214-0.632).

Conclusion:

The agreement between methods for T staging was almost perfect, with a worse outcome for T2, but still with substantial agreement. The findings may indicate equivalence in the diagnostic value of both flexible and rigid devices. For lymph node staging, there was moderate agreement between the methods.

Endoanorectal ultrasonography

Endoanorectal ultrasonography (EARUS) may be used for diagnosing various anorectal disorders. EARUS is easy to perform, has a short learning curve, and causes less discomfort than routine digital examination. Anal sphincters can be clearly visualized, and one can easily distinguish between the internal (hypoechoic) and external (hyperechoic) anal sphincters. Other pelvic floor structures, like the puborectalis muscle, can also be visualized. The use of contrast agents can increase the accuracy of EARUS in the assessment of perianal fistulae. In addition, EARUS is an excellent alternative to expensive magnetic resonance imaging. Besides its use in incontinence and perianal sepsis, the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. With 3-dimensional EARUS, it is possible to diagnose the anorectal diseases, in multiplane, with high spatial resolution, adding important information about the therapeutic decision. The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography with complementary techniques such as transvaginal and transperineal ultrasound are reviewed in this article.

Does a learning curve exist in endorectal two-dimensional ultrasound accuracy?

BACKGROUND

Aim of the study was to assess adequacy of Colorectal Surgical Society of Australia and New Zealand (CSSANZ) endorectal ultrasound (ERUS) training and whether a subsequent learning curve exists.

METHODS

A prospective audit of ERUS for staging rectal cancer by a single surgeon from commencement of consultant practice was performed. Data were recorded in a prospectively maintained database. The audit commenced on completion of CSSANZ training. T- and N-stage were assessed clinically, then by ERUS prior to treatment and finally by histology over 8 years.

RESULTS

The results were compared over three time periods: the first a single year, then two three-year periods. Two hundred and seventy-two patients were examined. Two hundred and thirty-three were assessable for T-stage (13 no tumour excision, 26 long course pre-operative radiotherapy) and 142 for N-stage (74 endoanal excision, 17 proximal mesorectum un-assessable). Overall accuracy was 82% for T-stage and 73% for N-stage. Accuracy for T- and N-staging did not change significantly over the three time periods (T: 82.1, 82.3, 81.6%, P = 0.14; N: 83.3, 67.9, 74.2%, P = 0.31). The utility of ERUS was demonstrated by clinical assessment not being possible in 32% of cases and where the two modalities disagreed was correct 82% of the time.

CONCLUSIONS

Endorectal ultrasound rectal cancer staging is accurate for T-stage. Competency in ERUS can be achieved in the CSSANZ fellowship and accuracy does not improve with further experience. An ERUS accreditation scheme should be established for future trainees.

Pretherapy imaging of rectal cancers: ERUS or MRI?

ERUS and MRI should be seen more as complementary rather than competitive techniques. Each has its own strengths and weaknesses. ERUS is better in showing the tumor extent in small superficial tumors, whereas MRI is superior in imaging the more advanced tumors. The choice of imaging technique depends also on the amount of information that is required for choosing certain treatment strategies, like the distance to the mesorectal fascia for a short course of preoperative radiotherapy. For lymph node imaging, both techniques are at present only moderately accurate, although this could change with advances in new MR techniques.

The value of high-resolution three-dimensional endorectal ultrasonography in the management of submucosal invasive rectal tumors

PURPOSE

The aims of this prospective study were 1) to evaluate the accuracy of high-resolution three-dimensional endorectal ultrasonography in distinguishing slight from massive submucosal invasion of early rectal tumors, and 2) to determine the technology's role in treatment selection.

METHODS

A total of 142 consecutive patients with clinically possible pT1 rectal cancers underwent three-dimensional endorectal ultrasonography. Slight or massive irregularity of the hyperechoic submucosal layer was considered to characterize uT1-slight or uT1-massive tumors. Treatment was selected on the basis of ultrasonographic findings: endoscopic resection or full-thickness transanal local excision was selected for uT1-slight lesions, and radical resection was selected for uT1-massive tumors. Ultrasonographic staging was compared with histopathologic staging.

RESULTS

One hundred twenty-six patients were included in the final analyses. Three-dimensional endorectal ultrasonography staged 77 lesions as uT0, 25 as uT1-slight, 20 as uT1-massive, and 4 as uT2. Histologically, adenomas were found in 75 patients and tumor invasion was found in 44 lesions (24 pT1-slight, 16 pT1-massive, 4 pT2). The overall kappa for the concordance between ultrasonographic and histopathologic stagings was 0.81 (95% confidence interval, 0.72-0.89). No invasive carcinomas remained undetected. The depth of invasion was correctly determined in 87.2% of both pT1-slight and pT1-massive lesions. Considering the complete series of 126 patients, the accuracy of this modality in selecting appropriate management was 95.2% (kappa, 0.84; 95% confidence interval, 0.71-0.96). Adequate surgery was performed in 87.5% of pT1 tumors.

CONCLUSION

Three-dimensional endorectal ultrasonography is useful for assessing the depth of submucosal invasion in early rectal cancer and for selecting therapeutic options.

Endosonographic staging of lower intestinal malignancy

The use of EUS in the assessment of rectal pathology is well established. The accurate staging of lower intestinal tumours predicts prognosis and guides the planning of individual patient treatment. Increased experience and the development of high resolution three-dimensional EUS has lead to the greater accuracy of rectal staging with EUS of rectal tumours now considered the gold standard showing T stage accuracy that ranges from 75% to 95%, with N stage accuracy ranging from 65% to 80%. The use of EUS in the staging of colonic pathology, however, is not so well established though advances in miniprobe EUS has improved the assessment of colonic tumours. EUS is also of benefit in the assessment of anal pathology though here, accurate correlation with histology has not been firmly established.

A new rectal ultrasonographic method for the staging of rectal cancer

PURPOSE

Radial transrectal ultrasound is the most frequently used method for preoperative staging of rectal cancer. Accuracy rates of transrectal ultrasound have fallen significantly to 64% and 70% for tumor and node staging, respectively. The use of a frontal probe may overcome the drawbacks of radial transrectal ultrasound. This study was designed to compare the accuracy of frontal transrectal ultrasound performed with a frontal probe with the classic procedure, which uses a radial probe, in the preoperative T and N staging of rectal cancer.

METHODS

Seventy-four patients with rectal adenocarcinoma underwent both techniques. Thirty patients had a neoadjuvant treatment. The staging accuracy of both methods was determined by comparing the results of each with the findings of surgical histopathologic evaluation.

RESULTS

Forty-six men and 28 women were recruited. Frontal transrectal ultrasound was performed in all patients. Staging was amenable in only 58 patients with the radial transrectal ultrasound because the tumors were either stenotic or too proximal. Frontal transrectal ultrasound was accurate in the T staging of 89% of the tumors, whereas radial transrectal ultrasound was accurate in only 69% (P = 0.004). The difference was even more significant when we compared accuracy among the 58 patients in whom both examinations were completed (P = 0.002). Both methods had similar accuracy for lymph node staging. Neoadjuvant treatment had no influence on accuracy. No overstaging of the tumor occurred with the frontal transrectal ultrasound. Understaging was more frequently encountered with radial transrectal ultrasound than with frontal transrectal ultrasound (26% vs. 11%, respectively; P = 0.036).

CONCLUSION

Compared with radial transrectal ultrasound, frontal transrectal ultrasound has a better accuracy for T staging of rectal cancer. Its advantage in overcoming the drawbacks of radial transrectal ultrasound may make this procedure the method of choice for rectal cancer staging.

Accuracy of endoscopic ultrasound to diagnose nodal invasion by rectal cancers: a meta-analysis and systematic review

BACKGROUND

Nodal staging in patients with rectal cancer predicts prognosis and directs therapy. Published data on the accuracy of endoscopic ultrasound (EUS) for diagnosing nodal invasion in patients with rectal cancer has been inconsistent.

AIM

To evaluate the accuracy of EUS in diagnosing nodal metastasis of rectal cancers.

METHOD

Study Selection Criteria: Only EUS studies confirmed by surgical histology were selected. Data Collection and Extraction: Articles were searched in Medline, Pubmed, and CENTRAL.

STATISTICAL METHOD

Pooling was conducted by both fixed-effects model and random-effects model.

RESULTS

The initial search identified 3610 reference articles in which 352 relevant articles were selected and reviewed. Data were extracted from 35 studies (N = 2732) that met the inclusion criteria. Pooled sensitivity of EUS in diagnosing nodal involvement by rectal cancers was 73.2% (95% confidence interval [95% CI] 70.6-75.6). EUS had a pooled specificity of 75.8% (95% CI 73.5-78.0). The positive likelihood ratio of EUS was 2.84 (95% CI 2.16-3.72), and negative likelihood ratio was 0.42 (95% CI 0.33-0.52). All the pooled estimates, calculated by fixed- and random-effect models, were similar. SROC curves showed an area under the curve of 0.79. The P for chi-squared heterogeneity for all the pooled accuracy estimates was >.10.

CONCLUSIONS

EUS is an important and accurate diagnostic tool for evaluating nodal metastasis of rectal cancers. This meta-analysis shows that the sensitivity and specificity of EUS is moderate. Further refinement in EUS technologies and diagnostic criteria are needed to improve the diagnostic accuracy.

How good is endoscopic ultrasound in differentiating various T stages of rectal cancer? Meta-analysis and systematic review

Published data on accuracy of endoscopic ultrasound (EUS) in differentiating T stages of rectal cancers is varied. Study selection criteria were to select only EUS studies confirmed with results of surgical pathology. Articles were searched in Medline and Pubmed. Pooling was conducted by both fixed and random effects models. Initial search identified 3,630 reference articles, of which 42 studies (N = 5,039) met the inclusion criteria and were included in this analysis. The pooled sensitivity and specificity of EUS to determine T1 stage was 87.8% [95% confidence interval (CI) 85.3-90.0%] and 98.3% (95% CI 97.8-98.7%), respectively. For T2 stage, EUS had a pooled sensitivity and specificity of 80.5% (95% CI 77.9-82.9%) and 95.6% (95% CI 94.9-96.3%), respectively. To stage T3 stage, EUS had a pooled sensitivity and specificity of 96.4% (95% CI 95.4-97.2%) and 90.6% (95% CI 89.5-91.7%), respectively. In determining the T4 stage, EUS had a pooled sensitivity of 95.4% (95% CI 92.4-97.5%) and specificity of 98.3% (95% CI 97.8-98.7%). The p value for chi-squared heterogeneity for all the pooled accuracy estimates was > 0.10. We conclude that, as a result of the demonstrated sensitivity and specificity, EUS should be the investigation of choice to T stage rectal cancers. The sensitivity of EUS is higher for advanced disease than for early disease. EUS should be strongly considered for T staging of rectal cancers.

Impact of biopsy on the accuracy of endorectal ultrasound staging of rectal tumors

PURPOSE

Endorectal ultrasound is a well-established method for the preoperative staging of rectal tumors. This prospective study was performed to establish whether obtaining a biopsy before endorectal ultrasound has an influence on staging accuracy.

METHODS

Between 1990 and 2003, a total of 333 rectal tumors were examined preoperatively by using endorectal ultrasound. All patients underwent rectal resection, and the specimens were sent for histologic evaluation. Thirty-three were not biopsied, the remaining at various times before endorectal ultrasound. The chi-squared test or Fisher's exact test were used for statistical analysis to compare the accuracies.

RESULTS

The overall staging accuracy was 71 percent but differed significantly (P = 0.004) between the groups as a function of time elapsed since biopsy. The best results were seen in tumors that were not biopsied before endorectal ultrasound, which were correctly staged in 85 percent of the cases. The least accurate staging (53 percent) was noted when endorectal ultrasound was performed in the third week after biopsy, mostly as a result of overstaging. Biopsy did not have a significant effect on nodal staging.

CONCLUSIONS

Biopsy before endorectal ultrasound significantly affects its accuracy. To achieve the most accurate staging, biopsy should be performed after endorectal ultrasound. Endorectal ultrasound staging performed in the first week after biopsy is the second best option but should be interpreted with caution in the second or third week.

Accuracy of endorectal ultrasonography and computed tomography for restaging rectal cancer after preoperative chemoradiation

BACKGROUND

Preoperative restaging of irradiated rectal cancer is essential for the planning of optimal therapy. The aim of this study was to compare the accuracy of endorectal ultrasonography (ERUS) and CT in restaging rectal cancer after preoperative chemoradiation and to evaluate the factors affecting the accuracy of ERUS.

STUDY DESIGN

Eighty-three patients with initial, locally advanced rectal cancer were prospectively evaluated by ERUS (n=60) and CT (n=80) after preoperative chemoradiation and just before surgery. All patients then underwent subsequent surgical resection and complete pathologic staging.

RESULTS

In restaging the depth of invasion, the overall accuracy was 38.3% (23 of 60) by ERUS and 46.3% (37 of 80) by CT. Overstaging was more common than understaging with both imaging modalities. Accuracy for restaging lymph node metastasis was 72.6% (37 of 51) by ERUS and 70.4% (50 of 71) by CT. The predictive value of node-negative cases by ERUS was somewhat lower than that of CT (81.1% versus 85.4%, respectively). Complete pathology-proved remission was not correctly predicted in any of the 11 patients by any imaging modalities. Pathologic T and N staging correlated with the staging accuracy of ERUS (p=0.028 and p=0.001, respectively).

CONCLUSIONS

ERUS and CT may allow good prediction of node-negative rectal cancers, although they are inaccurate modalities for predicting treatment response on the rectal wall. New methods of interpretation and diagnostic criteria for ERUS and CT are essential for increasing the accuracy of cancer prediction in at-risk patients.

The role of endorectal ultrasound in therapeutic decision-making for local vs. transabdominal resection of rectal tumors

INTRODUCTION

In rectal tumors, preoperative biopsies frequently fail to diagnose an invasive carcinoma. Endorectal ultrasound is considered a useful adjunct in preoperative staging of rectal tumors. However, feasibility of endorectal ultrasound and its role in therapeutic decision-making in presumed rectal adenomas is sparsely studied.

METHODS

Endorectal ultrasound was performed in 268 tumors referred for local excision because biopsies showed tubulovillous adenoma. Feasibility of endorectal ultrasound was studied and ultrasound staging was compared with definite histopathologic findings.

RESULTS

In 231 tumors, endorectal ultrasound was technically feasible (86 percent). Median distance from the dentate line was 11 cm in nonassessable tumors and 7 cm in assessable tumors (P < 0.001). In 21 tumors, endorectal ultrasound was not conclusive, mainly in tumors being recurrent or after recent endoscopic manipulation (P < 0.001). With endorectal ultrasound the rate of preoperative missed carcinomas could be reduced from 21 to 3 percent (P < 0.01). In diagnosing tubulovillous adenomas, sensitivity and specificity of endorectal ultrasound was 89 and 86 percent, respectively.

CONCLUSIONS

Endorectal ultrasound is technically feasible in almost all presumed rectal adenomas, referred for local excision. Proper endorectal ultrasound interpretation is possible in 78 percent of all presumed rectal adenomas. Endorectal ultrasound is very reliable in diagnosing tubulovillous adenomas, and therapeutic decision-making regarding local excision vs. radical surgery based on endorectal ultrasound is valid.

Preoperative staging of rectal carcinoma by endorectal ultrasound: is there a learning curve?

BACKGROUND AND AIMS

Endorectal ultrasound (ERUS) is becoming an essential tool in the management of rectal cancer. However, accuracy in the assessment of disease staging may be dependent on operator experience. The aim of this study was to determine if a learning curve exists.

MATERIALS AND METHODS

From October 1999 to December 2004, all patients with rectal cancer had a pre-operative ERUS performed by a single radiologist. ERUS staging was compared with post-operative pathology findings using the tumour, node, metastases (TNM) classification. The accuracy of ERUS in tumour (T) and node (N) staging after each additional consecutive ten patients was calculated.

RESULTS

One hundred and thirty one patients were investigated by ERUS, of which 36 were excluded, leaving 95 patients in the study (60 men). Overall accuracy for T staging was 71.6%. No improvement with experience was noted (p > 0.05). With regard to T staging, ERUS tended to overstage more frequently than understage (24.2 versus 4.2%). The sensitivity, specificity, positive predictive value and negative predictive value of uT3 staging were 96.6, 33.3, 70.4 and 85.7%, respectively. Overall accuracy of uN staging was 68.8%. ERUS tended to overstage nodal disease more frequently than understage (16.1 versus 15.1%). Sensitivity, specificity, positive predictive value and negative predictive value were calculated for ultrasound-detected nodal disease (73.2, 62.2, 74.5 and 60.5%, respectively). Nodal staging accuracy improved from 50% after assessment of 10 cases to 77% after 30 cases were examined.

CONCLUSIONS

ERUS is an accurate method for staging rectal cancer pre-operatively. Accurate assessment of tumour stage can be achieved immediately by an experienced radiologist without specific training in ERUS. Nodal staging accuracy tends to improve with experience but reaches a plateau after 30 cases.

Local therapy for rectal cancer: still controversial?

PURPOSE

Many considerations, such as morbidity, sexual and urinary dysfunction, or risk of definitive stoma have led to the increased popularity of local therapy in the therapeutic strategy for rectal cancer. However, its role in curative intent is still controversial with oncologic long-term results lower than those obtained by radical surgery.

METHODS

MEDLINE, EMBASE, LILACS, Abstract books, and reference lists from reviews were searched with English language publications to review the current status of evidence for local therapy in rectal cancer, looking especially at the oncologic results and patient selection. We have focused on the new strategies combining neoadjuvant and adjuvant treatment to explain their place in the management of rectal cancer.

RESULTS AND CONCLUSIONS

The key to potentially curative local treatment for rectal cancer is patient selection by identifying the best candidates with preoperative tumor staging and clinical and pathologic assessment of favorable features. Low-risk T1 is suitable for local excision alone. Limited data suggest that adjuvant chemoradiotherapy may be helpful in patients with unfavorable T1 and T2 lesions, achieving a local recurrence rate<20 percent. However, the efficacy of salvage surgery after local excision is uncertain.

The advantages of volume rendering in three-dimensional endosonography of the anorectum

Anorectal diseases require imaging for proper case management. At present, endoanal ultrasonography and endorectal ultrasonography have become important parts of diagnostic workup of patients with fecal incontinence, perianal fistulas, and rectal cancer and provides sufficient information for clinical decision-making in many cases. However, with the currently available ultrasonographic equipment and techniques, a good deal of relevant information may remain hidden. The advent of high-resolution three-dimensional endoluminal ultrasound, constructed from a synthesis of standard two-dimensional cross-sectional images, and of "Volume Render Mode," a technique to analyze information inside a three-dimensional volume by digitally enhancing individual voxels, promises to revolutionize diagnosis of pelvic floor disorders. By use of the different postprocessing display parameters, the volume-rendered image provides better visualization performance when there are not large differences in the signal levels of pathologic structures compared with surrounding tissues. The anatomic structures in the pelvis, the axial and longitudinal extension of anal sphincter defects, the anatomy of the fistulous tract in complex perianal sepsis, and the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. This additional information will bring an improvement for both planning and conduct of surgical procedures.

Efficacy of 3-dimensional endorectal ultrasonography compared with conventional ultrasonography and computed tomography in preoperative rectal cancer staging

BACKGROUND

This study was performed to verify reports of the decreased accuracy of endorectal ultrasonography (EUS) in preoperative staging of rectal cancer, and to compare the efficacy of 3-dimensional (3D) EUS with that of 2-dimensional (2D) EUS and computed tomography (CT).

METHODS

Eighty-six consecutive rectal cancer patients undergoing curative surgery were evaluated by 2D EUS, 3D EUS, and CT scan.

RESULTS

The accuracy in T-staging was 78% for 3D EUS, 69% for 2D EUS, and 57% for CT (P < .001-.002), whereas the accuracy in evaluating lymph node metastases was 65%, 56%, and 53%, respectively (P < .001-.006). Examiner errors were the most frequent cause of misinterpretation, occurring in 47% of 2D EUS examinations and in 65% of 3D EUS examinations. By eliminating examiner errors, the accuracy rates in T-staging and lymph node evaluation could be improved to 88% and 76%, respectively, for 2D EUS, and to 91% and 90%, respectively, for 3D EUS. Conical protrusions along the deep tumor border on 3D images were correlated closely with infiltration grade, advanced T-stage, and lymph node metastasis.

CONCLUSIONS

We found that 3D EUS showed greater accuracy than 2D EUS or CT in rectal cancer staging and lymph node metastases. Concrete 3D images based on tumor biology appear to provide more accurate information on tumor progression.

Endoscopic ultrasound staging of rectal cancer: diagnostic value before and following chemoradiation

BACKGROUND

Endoscopic ultrasound (EUS) has been shown to be a reliable tool for staging rectal cancer. Nevertheless, the accuracy of EUS after chemoradiation remains unclear; therefore the purpose of the present paper was to compare the accuracy of EUS staging for rectal cancer before and following chemoradiation.

METHODS

Patients with rectal cancer undergoing EUS staging were stratified into two groups. Group I consisted of 66 patients who underwent surgery following EUS staging without preoperative chemoradiation. Group II consisted of 25 patients who had EUS evaluation following chemoradiation. The EUS staging was compared to surgical/pathological staging.

RESULTS

The accuracy of the T staging for group I was 86% (57/66). Inaccurate staging was mainly associated with overstaging EUS T2 tumors. The accuracy of the N staging for group I was 71% (47/66). The accuracy of EUS for a composite T and N staging relevant to treatment decisions in group I was 91%. In group II, the accuracy of T and N staging was 72% (18/25) and 80% (20/25), respectively. Overstaging EUS T3 tumors accounted for most inaccurate staging. The EUS staging predicted post-chemoradiation T0N0 stage correctly in only 50% of cases.

CONCLUSIONS

Preoperative staging of rectal cancer by EUS is a useful modality in determining the need for preoperative chemoradiation. The EUS T staging following chemoradiation appears to be less accurate. Detection of complete response may be insufficient for selecting patients for limited surgical intervention.

Endosonography in anorectal disease: an overview

Anorectal endosonography (AE), which was introduced 20 years ago, derives from the study of urology. It was first used to evaluate rectal tumours and later also to investigate benign disorders of the anal sphincters and pelvic floor. The technique is easy to perform, it has a short learning curve and causes no more discomfort than a routine digital examination. A rotating probe with a 360 degrees radius and a frequency between 5 and 16 MHz is introduced to the rectum and then slowly withdrawn so that the pelvic floor and subsequently the sphincter complex are seen. Recently, it has become possible to reconstruct three-dimensional images. AE has been used for almost every possible disorder in the anal region and has increased our insight into anal pathology. The clinical indications for AE are: 1. Faecal incontinence in patients when surgery is an option. AE can show sphincter defects with excellent precision. There is a perfect correlation with surgical findings. Studies comparing AE with endoanal magnetic resonance imaging (MRI) have shown that both methods are equally good for demonstrating defects in the external anal sphincter; the internal anal sphincter is better visualized with AE. After sphincter repair, the effect is directly related to the decrease in the sphincter defect. 2. Perianal fistulae. AE has been shown to be accurate in staging perianal cryptoglandular fistulae and fistulae in Crohn's disease. When there is an external fistula opening, H2O2 can be introduced with a plastic infusion catheter. The tract then becomes visible as a hyperechoic lesion ("white"). It has been shown that this corresponds well with surgical findings. It is equally sensitive as endoanal MRI. Since recurrent cryptoglandular fistulae are complex in 50% and Crohn's fistula in 75%, it is mandatory to perform AE preoperatively in these patients to avoid missed tracts during surgery and subsequent recurrences. 3. Rectal tumors. In low tubulovillous adenomas or malignant polyps considered removable locally, confirming the local resectability (T0 or T1) is mandatory. Although larger rectal and more advanced tumours can be evaluated with AE, MRI is more sensitive in staging nodal involvement. 4. Anal carcinoma for staging. AE has been shown to stage better than the classical TNM classification for both local extension and prognosis. In conclusion, AE images the internal and external anal sphincter with high accuracy. It is easy to perform and is of particular value in the diagnosis of anal incontinence and perianal fistulae. It is excellent in staging anal carcinoma and can also be used in staging rectal carcinoma, especially very low large malignant polyps.

Development of a cost-effective system for digital off-line analysis of transrectal ultrasound

BACKGROUND

Transrectal ultrasound (TRUS) is the most sensitive and accurate technique for preoperative staging and follow-up of rectal cancer. One of the most relevant problems of this technique is that the assessment of TRUS is possible only during real-time examination. Furthermore, interpretation of the ultrasound findings is difficult and requires long experience. We show the development of a new, cost-effective software solution for off-line examination and documentation of transrectal ultrasound.

METHODS

The ultrasound device is connected to a frame-grabber card in a standard PC. Video capturing is done using a freeware software solution and various video codecs. The whole examination course is recorded. The examiner only has to concentrate on producing an artifact-free realization of the examination.

RESULTS

The software solution offers a flexible review of each individual "frame" of the investigation on the personal computer, very similar to CT and MRI scans. Infiltration depth and lymph node status can be assessed at any time, independently of the investigation and the investigator. The picture quality is excellent even if a lossy codec is used. It is not necessary to do definitive assessment of the TRUS during the examination.

CONCLUSIONS

This new technique gives a cost-effective possibility for high-quality off-line staging, re-examination, re-evaluation, and documentation of rectal cancer. TRUS becomes an examiner-independent objective examination technique for staging and follow-up of rectal cancer.

A technically difficult endorectal ultrasound is more likely to be inaccurate

OBJECTIVE

Endorectal ultrasound (ERUS) is well established as an accurate modality for local staging of rectal tumours. The aim of this study was to identify reasons for inaccurate staging of tumours, and to assess whether difficulties encountered during scanning are likely to influence accuracy.

PATIENTS AND METHODS

ERUS was performed by a single operator using a 10 MHz rigid instrument. One hundred and seventeen patients that had both ERUS and surgery are included in this study (patients that had pre-operative radiotherapy were excluded). During ERUS, procedural conditions and limiting factors were recorded. Data was collected prospectively.

RESULTS

In 78 (66.7%) patients no technical difficulty was encountered during ERUS. In this group accuracy was 80% for T-stage and 77% for N-stage. Specific reasons for inaccuracy identified in this group were: inflammatory lymph nodes (from a tumour associated abscess and a colovesical fistula) and deep biopsy causing a submucosal defect with intramural haemorrhage in benign lesions (2 cases). In the remaining 39 (33.3%), the following problems were encountered: stenotic lesions (23), patient discomfort (8), poor bowel preparation (6), and scarring from previous surgery (2). In 11 patients from this group, the scan was considered inconclusive and no stage could be determined. For the other 28, the accuracy for T-stage was 68% and for N-stage 67%.

CONCLUSION

A technically difficult ERUS is likely to give an inconclusive or inaccurate result for both T-stage (P = 0.001) and N-stage (P = 0.003). In this situation a repeat scan may be considered (where appropriate). Alternatively, further assessment by MRI or flexible endoscopic ultrasound may be considered.

Development of a three-dimensional freehand endorectal ultrasound system for use in rectal cancer imaging

The initial study reporting the accuracy of an optically tracked endorectal ultrasound (TERUS) probe for the purpose of improving the staging of rectal cancer is presented here. In this work we describe the need for a more accurate ERUS system and why the incorporation of image guidance makes this goal feasible. A rectal phantom was constructed with five targets placed in positions where tumors normally occur. The locations of these targets were found using two different imaging modalities, CT and ultrasound, and the target registration error (TRE) between these two image sets was calculated. The average TRE of 33 image captures of the five targets using TERUS was 2.1 mm. This is a promising outcome because the desired tumor margins for rectal cancer are on the order of centimeters. These preliminary results support the proof of concept for a TERUS system that should improve ultrasound imaging in rectal cancer.

Assessment of publication bias in the reporting of EUS performance in staging rectal cancer

INTRODUCTION

Endoscopic ultrasound (EUS) has emerged as a promising diagnostic modality for locoregional staging of rectal cancer. However, as with any new technology, publication bias, the selective reporting of studies featuring positive results, may result in overestimation of the capability of EUS. The aim of this study was to systematically assess for publication bias in the reporting of the accuracy of EUS in staging rectal cancer.

METHODS

A MEDLINE search for all published estimates of EUS accuracy in staging rectal cancer between 1985 and 2003 was performed. All retrieved studies were fully published in the English literature. Published studies were analyzed and the following information was abstracted: accuracy of EUS, year of publication, number of subjects studied, impact factor of journal, and type of journal (gastroenterology, surgery, radiology, other).

RESULTS

Two hundred and two abstracts were reviewed; 41 publications met the stated criteria for inclusion. EUS T-staging accuracy was reported in 40 studies while EUS N-staging accuracy was reported in 27 studies. The experience of 4, 118 subjects was reported with an overall mean T-staging accuracy of 85.2% (median, 87.5%) and N-staging accuracy of 75.0% (median, 76.0%). There was a paucity of smaller studies expressing low EUS accuracy rates. Both T-staging and N-staging accuracy rates also declined over time with the lowest rates reported in more recent literature.

CONCLUSION

The performance of EUS in staging rectal cancer may be overestimated in the literature due to publication bias. This inflated estimate of the capability of EUS may lead to unrealistic expectations of this technology.

Depiction and Local Staging of Rectal Tumors: Comparison of Transrectal US before and after Water Instillation

PURPOSE

To determine whether transrectal ultrasonography (US) with intrarectal water instillation can improve the depiction and accuracy of US in local staging of rectal tumors.

MATERIALS AND METHODS

Between October 1999 and February 2002, 63 patients (mean age, 56 years; age range, 23-91 years) with 63 rectal tumors were evaluated with transrectal US before and after intrarectal water instillation. Transrectal US examinations were performed with a 7-10-MHz radial transducer. Immediately after the first transrectal US examination, the rectal lumen was filled with 50-150 mL of degassed water, and a second US examination was performed. All patients underwent surgery within 1 month after transrectal US. Depiction of the tumor was compared between the two methods. The McNemar test was used to compare the accuracy between the two techniques in local staging of the tumor by using pathologic findings in the resected specimen as the standard.

RESULTS

The tumors ranged from 0.5 to 8.0 cm (mean, 2.8 cm) as measured at pathologic evaluation. All 63 tumors were clearly depicted at transrectal US after water instillation, while only 42 (67%) of the tumors were depicted at transrectal US before water instillation. In the 42 tumors clearly depicted at transrectal US examinations both before and after water instillation, the accuracy of transrectal US in local tumor staging was significantly higher after water instillation (85.7% [36 of 42]) than before water instillation (57.1% [24 of 42]; P <.001).

CONCLUSION

Water instillation during transrectal US examination of rectal tumors improves the depiction and local staging of the tumors.

Assessment of the accuracy of transrectal ultrasonography in anorectal neoplasia

BACKGROUND

Accurate preoperative staging of anorectal neoplasia is required to identify patients for whom local excision or adjuvant therapy may be appropriate. The objectives of this study were to review the accuracy of endoluminal transrectal ultrasonography (TRUS) in the staging of rectal cancers and to determine the learning curve before optimal staging accuracy can be achieved.

METHODS

The results of all TRUS examinations for the assessment of anorectal neoplasia performed by two colorectal surgeons at two teaching hospitals of the University of Sydney from 1991 to 2001 were collected prospectively.

RESULTS

Of the 433 patients examined by TRUS, 356 were included, of whom 263 (73.9 per cent) had nodal status assessed histologically. Of the 77 patients excluded, 50 had undergone radiotherapy before operation. TRUS achieved excellent accuracy when compared with histopathology reports using kappa statistics for standard Union Internacional Contra la Cancrum (UICC) staging (kappa = 0.89), tumour wall penetration (kappa = 0.70), lymph node detection (kappa = 0.66) and a proposed new staging system (kappa = 0.94). In addition, the increase in TRUS accuracy with operator experience demonstrates the need to perform 50 or more procedures before optimal accuracy is achieved.

CONCLUSION

TRUS provides an appropriate investigation with which to select patients with T1 tumours for local excision, and patients with T3 or T4 tumours for preoperative radiotherapy. The relative inaccuracy of staging T2 tumours by TRUS has led to a proposed alternative ultrasonographic staging system.

Comparative study of three-dimensional and conventional endorectal ultrasonography used in rectal cancer staging

BACKGROUND

Three-dimensional (3D) imaging offers improved knowledge of various anatomic structures and tumors by providing 3D images. This prospective study was performed to verify whether 3D endorectal ultrasonography (EUS) enhances the accuracy of rectal cancer staging, as compared with conventional EUS.

METHODS

Using both 3D and conventional EUS, 33 consecutive patients with operable rectal cancer were preoperatively staged. A rigid 3D probe with a scanner was used for 3D EUS, and a rigid endorectal probe with a scanner was used for conventional EUS.

RESULTS

The accuracy of 3D EUS was 90.9% for pT2 and 84.8% for pT3, whereas that of conventional EUS was 84.8% and 75.8%, respectively, thereby showing no difference between these two methods. The lymph node metastasis was accurately predicted by 3D EUS in 28 patients (84.8%), whereas conventional EUS predicted the disorder in 22 patients (66.7%). The difference was not statistically significant. The average infiltration grade of the circumference on transverse 3D EUS scans was associated closely with advancement of the TNM stage (p <0.001-0.006) and lymph node metastasis (p = 0.003). The presence of a cone-shaped surface on the deep tumor border correlated with the infiltration grade shown on all of the sectional displays (p <0.001-0.042) and with advancement of the TNM stage (p = 0.018).

CONCLUSIONS

Although the findings did not show 3D EUS to have a significant advantage over conventional EUS for the accurate evaluation of rectal cancer, a numeric advantage may possibly be statistically significant in a further study with larger cases. Furthermore, stereoscopic visualization provided easier and complete understanding of both focal lesions and lymph nodes.