Pitfalls and sources of error in staging rectal cancer with endorectal us

3D imaging for driving cancer discovery

Our understanding of the cellular composition and architecture of cancer has primarily advanced using 2D models and thin slice samples. This has granted spatial information on fundamental cancer biology and treatment response. However, tissues contain a variety of interconnected cells with different functional states and shapes, and this complex organization is impossible to capture in a single plane. Furthermore, tumours have been shown to be highly heterogenous, requiring large-scale spatial analysis to reliably profile their cellular and structural composition. Volumetric imaging permits the visualization of intact biological samples, thereby revealing the spatio-phenotypic and dynamic traits of cancer. This review focuses on new insights into cancer biology uniquely brought to light by 3D imaging and concomitant progress in cancer modelling and quantitative analysis. 3D imaging has the potential to generate broad knowledge advance from major mechanisms of tumour progression to new strategies for cancer treatment and patient diagnosis. We discuss the expected future contributions of the newest imaging trends towards these goals and the challenges faced for reaching their full application in cancer research.

Tissue clearing to examine tumour complexity in three dimensions

The visualization of whole organs and organisms through tissue clearing and fluorescence volumetric imaging has revolutionized the way we look at biological samples. Its application to solid tumours is changing our perception of tumour architecture, revealing signalling networks and cell interactions critical in tumour progression, and provides a powerful new strategy for cancer diagnostics. This Review introduces the latest advances in tissue clearing and three-dimensional imaging, examines the challenges in clearing epithelia - the tissue of origin of most malignancies - and discusses the insights that tissue clearing has brought to cancer research, as well as the prospective applications to experimental and clinical oncology.

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.

Learning curve of endorectal ultrasonography in preoperative staging of rectal carcinoma

Accurate preoperative staging of rectal carcinoma is essential for optimal treatment. This study was designed to evaluate the accuracy and learning curve of endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma. We retrospectively analyzed the records of patients with rectal carcinoma who underwent preoperative ERUS followed by curative surgery at the Shanxi Province Tumor Hospital between January, 2007 and March, 2010. The patients were divided into three groups, namely A, B and C, depending on whether the examination was performed between January and December, 2007, between January and December, 2008 or between January, 2009 and March, 2010, respectively. Five physicians with no prior experience in ERUS performed the examinations. We compared the ERUS staging with the pathological findings using the tumor-node-metastasis (TNM) classification. The accuracy of ERUS in T and N staging after each additional consecutive 20 patients was calculated for physicians D, E and F. A total of 319 patients underwent ERUS prior to surgery. There were 38 patients in group A, 135 in group B and 146 in group C. Two of the five physicians performed only 47 of the 319 examinations, whereas the remaining 272 patients were examined by physicians D (n=162), E (n=64) and F (n=46). The overall accuracy in assessing the extent of rectal wall invasion (T) was 67%, with 16% of the cases overstaged and 17% understaged and the accuracy in assessing nodal involvement (N) was 66%, with 11% of the cases overstaged and 23% understaged. The total T and N staging accuracy of physicians D, E and F was 75 and 72%; 59 and 59%; and 50 and 52%, respectively. For physicians D, E and F, the accuracy of T and N staging after each additional 20 patients was calculated and the curve of the accuracy reached a plateau after physician D completed 80 cases. Therefore, ERUS is a valuable tool for assessing the depth of tumor invasion and it appears that after ~80 cases a physician may be considered able to apply it efficiently.

ACR Appropriateness Criteria pretreatment staging of colorectal cancer

Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

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.

Pelvic colorectal recurrence: crucial role of radiologists in oncologic and surgical treatment options

Radical resection is the only potential cure for patients with locally advanced primary and recurrent rectal cancer and is considered curative only when the histologic margins are clear of tumour. Early diagnosis of the disease is essential as it increases the likelihood of a potentially curative resection and prevention of dissemination. Clinical examination, tumour markers and radiologic modalities such as ultrasonography, computed tomography, magnetic resonance imaging and positron emission tomography are routinely used in an effort to accurately stage these patients and provide useful information for the selection of patients for further treatment/management. This review describes the methods of staging patients with locally advanced primary and recurrent rectal cancer prior to surgery emphasizing the role that radiologists have in this process.

Prognostic heterogeneity of endosonographic T3 rectal cancer

PURPOSE

This study aimed to assess the prognostic implications of uT3 rectal carcinomas according to the tumor thickness and to analyze the correlation between this ultrasound-based parameter and other prognostic factors.

METHODS

Seventy-four patients with uT3(pM0) rectal tumors underwent primary surgery from 1996 to 2003. Preoperative endorectal ultrasound was used to assess uN stage, maximum tumor perimeter, and maximum tumor thickness. An ultrasound maximum tumor thickness cutoff point for local recurrence subdividing T3 tumors into uT3a and uT3b was established.

RESULTS

Median follow-up was 41 months (range, 24-59). The 5-year actuarial local and overall recurrence rates were 9.82 percent (n = 7) and 42.46 percent (n = 23), respectively. uN stage(P = 0.05), circumferential resection margin involvement (P = 0.002), an ultrasound maximum tumor thickness (P = 0.01), and locally advanced tumors (P = 0.001) were related to a significantly increased risk of local recurrence. An ultrasound maximum tumor thickness (hazard ratio, 1.15; 95 percent confidence interval, 1.0-1.2) and locally advanced tumor (hazard ratio, 17.21; 95 percent confidence interval, 2.99-98.84) were preoperative independent variables for predicting local recurrence. Locally advanced tumor was the only preoperative independent prognostic factor for overall recurrence (P = 0.004; hazard ratio, 1.09; 95 percent confidence interval, 1.0-1.1). An ultrasound maximum tumor thickness with a 19-mm cutoff point, subdividing the T3 tumors into uT3a and uT3b, can be used to predict local recurrence. Locally advanced tumors (P = 0.02) and circumferential resection margin involvement (P = 0.005) showed a significant association with an ultrasound maximum tumor thickness >19 mm.

CONCLUSIONS

A maximum tumor thickness measured by endorectal ultrasound in pT3 rectal cancer is an independent prognostic factor for local and overall recurrence. An ultrasound maximum tumor thickness cutoff point of 19 mm may be useful to classify patients preoperatively and to select them for primary surgery or neoadjuvant therapy.

Ultrasound staging of rectal cancer

Endorectal ultrasound (ERUS) is a primary imaging technique in the preoperative evaluation of patients with rectal adenocarcinoma. The purpose of this report is to review ultrasound staging with emphasis on technique and potential pitfalls. The role of ultrasound in multimodality staging and surveillance is also explored. An awareness of inherent imaging challenges and implications may optimize staging accuracy and resultant management of rectal cancer patients.

Accuracy of endorectal ultrasonography in staging locally advanced rectal cancer after preoperative chemoradiation

AIM

The aim of our study was to determine the accuracy of endorectal ultrasonography (ERUS) in staging locally advanced rectal cancer after preoperative neoadjuvant chemoradiation and to point out the most common reasons for false interpretation.

METHODS

Forty-four patients with locally advanced rectal cancer received neoadjuvant chemoradiation followed by radical surgery. Restaging was done 1-2 weeks before surgery and the results of ERUS staging were compared with histopathology findings of the resected specimen.

RESULTS

The accuracy of ERUS for T stage after chemoradiation was 75% (33/44). Overstaging occurred in 18% (8/44) of patients, and 7% (3/44) were understaged. The majority of overstaging occurred in patients with ERUS T3 tumors, eventually found to have pathological pT0-pT2 staging. Five patients (11.4%) had complete histology regression and only one of these patients was staged correctly while others were overstaged. In the detection of perirectal lymph node metastases, ERUS was accurate in 68% of patients (30/44). Twenty percent (9/44) of patients were overstaged and 11% were (5/44) understaged.

CONCLUSIONS

ERUS provides a good accuracy rate for staging rectal cancer after neoadjuvant chemoradiation. However, it is insufficient in detection of complete pathological response.

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.

Preoperative staging of rectal tumors: comparison of endorectal ultrasound, hydro-CT, and high-resolution endorectal MRI

AIM

The aim of this study was to compare transrectal ultra-sound (TRUS), hydro-computed tomography (hydro-CT), and endorectal magnetic resonance imaging (MRI) in the preoperative staging of rectal cancer.

PATIENTS AND METHODS

23 patients with rectal adenocarcinoma underwent TRUS, hydro-CT, and MRI (1 Tesla) with endorectal coil. The results were correlated with the histopathological findings based on the TNM classification.

RESULTS

T staging with TRUS, hydro-CT, and endorectal MRI correlated with the histopa-thological findings in 83% of patients (19/23). Tumors were overestimated by TRUS in 2/23 patients, by CT in 3/23, and by MRI in 3/23 patients. Tumor size was underestimated by TRUS in 2 patients, by CT and MRI in 1 case each. Local lymphatic node involvement was correctly diagnosed with CT and MRI in 87% and 83%, respectively. Using TRUS, false-negative results in the staging of lymph node involvement were seen in 3/23 patients, whereas 1 patient was over-staged. Using hydro-CT as well as endorectal MRI, overstaging of the local lymph nodes took place in 2/23 patients.

CONCLUSION

All methods are limited because peritumoral inflammation cannot be precisely distinguished from infiltration by the tumor. Correct lymph node staging is hampered in advanced disease using TRUS. In these patients, further cross-sectional imaging may be required.

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.

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.

Transvaginal Sonography as an Adjunct to Endorectal Sonography in the Staging of Rectal Cancer in Women

OBJECTIVE

The purpose of this study was to evaluate the contribution of transvaginal sonography (TVS) in the staging of rectal cancer in women.

MATERIALS AND METHODS

Sixty women with rectal tumors underwent TVS. Forty-five of the 60 women also underwent endorectal sonography. Forty-nine of the women had rectal carcinoma; nine, tubulovillous adenoma; and two, gastrointestinal stromal tumor confirmed at surgical pathologic examination (n = 41) and biopsy before chemoradiation therapy (n = 19). Four of the 49 rectal carcinomas were T1; seven, T2; 35, T3; and three, T4. Images from TVS and endorectal sonography were shown independently to two blinded reviewers, who staged the tumors and assessed examination adequacy for tumor presence, size, and depth and nodal status. Staging results with TVS were compared with those obtained with endorectal sonography and histopathologic examination.

RESULTS

All tumors were seen with TVS. In 30 of the 49 rectal carcinomas confirmed at surgical pathologic examination TVS tumor staging was accurate in 25 (83.3%) of the cases. Two (6.7%) of the 30 tumors were understaged, and 3 (10%) were overstaged. All tumors selected for chemoradiation (n = 19) were correctly staged T3. Endorectal sonography was suboptimal for tumors that were stenotic (n = 3), large (n = 2), high at the rectosigmoid junction (n = 4), or low at the anal canal (n = 3). In these 12 cases, TVS successfully depicted the lesion, and the images gave enough information for prediction of stage. In interpretation of the images of 45 patients who underwent both TVS and endorectal sonography, the blinded reviewers had good agreement and comparable accuracy for staging in adequate examinations with each technique. Four of the nine villous adenomas were overstaged as T1 on TVS. Gastrointestinal stromal tumors manifested as intramural vascular masses.

CONCLUSION

TVS is an excellent adjunct to endorectal sonography in the staging of rectal cancer in women. It helps resolve the findings after endorectal sonography has been unsuccessful because the tumors are stenotic or in a high or low position.

Neoadjuvant radiochemotherapy in the treatment of fixed and semi-fixed rectal tumors. Analysis of results and prognostic factors

PURPOSE

To report the retrospective analysis of patients with locally advanced rectal cancer treated with neodjuvant radiochemotherapy.

METHODS AND MATERIALS

From January 1994 to December 2003, 101 patients with fixed (25%) or semi-fixed (75%) rectal adenocarcinoma were treated by preoperative radiotherapy with a dose of 45 Gy at the whole pelvis and 50.4 Gy at primary tumor, concomitant to four weekly chemotherapies with 5-Fluorouracil (425 mg/m2) and Leucovorin (20 mg/m2). In 71 patients (70.3%) the primary tumor was located up to 6 cm from the anal verge and in 30 (29.7%) from 6.5 cm to 10 cm. Age, gender, tumor fixation, tumor distance from the anal verge, clinical response, surgical technique, and postoperative TNM stage were the prognostic factors analyzed for overall survival (OS), disease-free survival (DFS), and local control (LC) at five years.

RESULTS

Median follow-up time was 38 months (range, 2-141). Complete response was observed in eight patients (7.9%), partial in 54 (53.4%) and absence in 39 (38.7%). OS, DFS and LC were 52.6%, 53.8%, and 75.9%, respectively. Distant metastasis occurred in 40 (39.6%) patients, local recurrence in 20 (19.8%) and both in 16 (15.8%). Patients with fixed tumors had lower OS (17% Vs 65.6%; p < 0.001), DFS (31.2% Vs 60.9%; p = 0.005), and LC (58% Vs 82%; p = 0.004). Patients with tumors more than 6 cm above the anal verge had better LC (93% Vs 69%; p = 0.04). The postoperative TNM stage was a significant factor for DFS (I:64.1%, II:69.6%, III:35.2%, IV:11.1%; p < 0.001) and for LC (I:75.7%, II: 92.9%, III:54.1%, IV:100%; p = 0.005). Patients with positive lymph nodes had worse OS (37.9% Vs 70.4%, p = 0.006), DFS (32% Vs 72.7%, p < 0.001) and LC (56.2% Vs 93.4%; p < 0.001).

CONCLUSION

This study suggests that the neoadjuvant treatment employed was effective for local control. Fixation of the lesion and lymph nodes metastasis were the main adverse prognostic factors. Distant failures were frequent, supporting the need of new drugs for adjuvant chemotherapy.

Endosonographic imaging of anorectal diseases

OBJECTIVE

The normal sonographic anatomy of the anorectum, sonographic findings of anorectal diseases, and indications and limitations of endosonography compared with magnetic resonance imaging are reviewed. Methods. Endosonographic imaging was performed with a Siemens (Erlangen, Germany) FI 400 ultrasound scanner with an end-fire 7.5-MHz biplane endorectal probe and a B-K Medical (Sandhoften, Denmark) scanner with an 1850 axial-type side-fire 5.0- to 10.0-MHz rotating endoscopic probe.

RESULTS

Rectal carcinoma appears on endorectal sonography as a low-echogenicity lesion that abruptly interrupts the normal sequence of layers. The internal anal sphincter is seen very clearly on endoanal sonography, and it is easy to appreciate atrophy and small tears of this sphincter. Endoanal sonography cannot accurately show thinning of the external anal sphincter. Peroxide-enhanced endoanal sonography is especially useful for patients with recurrent perianal fistulas in whom scarring should be distinguished from recurrent fistulas and detection of the internal opening. However, sonography does not provide an adequate deep and global display of all adjacent pelvic and perineal spaces.

CONCLUSIONS

Endosonography can accurately stage primary rectal tumors and assess the internal anal sphincter. Peroxide-enhanced 3-dimensional imaging can increase the utility of endoanal sonography in detection and characterization of perianal fistulas and planning of optimal therapy. However, magnetic resonance imaging can be used a complementary modality to endosonography, especially for evaluation of external anal sphincter atrophy and deep pelvic inflammation.

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.

Endoanal and endorectal ultrasound: applications in colorectal surgery

Endoanal and endorectal ultrasound have an important role in colorectal surgery. They can be applied in the management of faecal incontinence, rectal tumours and inflammatory perianal conditions. In faecal incontinence, anal ultrasound will confirm the presence or absence of sphincter defects. This will direct any operative intervention such as direct sphincter repair. Ultrasound in rectal cancer allows staging of the tumour by assessing the depth of invasion through the bowel wall and involvement of mesenteric nodes. Such staging might influence the choice of operation and determine which patients might benefit from preoperative chemotherapy and radiotherapy. Ultrasound has a particular role in recurrent and complex anal fistula and perianal sepsis. Preoperative and perioperative planning with accurate delineation of fistula tracts, extensions and sphincter involvement might help prevent recurrence and impaired continence from sphincter damage after surgery. Correct interpretation of ultrasound images requires training and experience so that the results can be properly correlated with the clinical situation.

Controversies in the surgical management of rectal cancer

At the present time, standard therapy for potentially curable rectal cancer consists of transabdominal surgical resection and adjuvant chemoradiation for American Joint Committee on Cancer stage II/III disease. Controversial issues include the use of local excision as opposed to formal resection and total mesorectal excision (TME) alone without adjuvant therapy. Although early stage tumors are the ideal potential candidates for local excision, clinical staging with endoscopic ultrasound is extremely variable in accurately predicting T and N stage. In addition, even low-grade or T1 tumors are associated with a 7% to 14% chance of nodal metastatic disease. Overall, the risk for local recurrence is higher after local excision but may be reduced by adjuvant therapy. Salvage rates for recurrent disease range from 21% to 91%. In regard to TME, local recurrence rates are an impressive 0% to 12% without adjuvant radiation. However, the addition of radiation therapy may further reduce these already low rates, especially in higher-risk groups. The results of 2 large European studies show acceptable complication rates and the applicability of this technique to a diverse patient population.

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.

Flexible endorectal ultrasound for predicting pathologic stage of rectal cancers

BACKGROUND

Endorectal ultrasound (ERUS) is an accurate method for preoperative staging of rectal cancers. Most often, a rigid 360-degree rotating probe is used. We studied whether flexible probes could attain equivalent accuracy for bowel wall penetration.

METHODS

Forty-five patients were prospectively evaluated with flexible devices. Results were compared with 20 rigid and 10 flexible probe studies. To assess learning curves, we used logistic regression analysis and coefficients of correlation on accuracy data to compare ERUS accuracy with the number of examinations.

RESULTS

Level of invasion was correct in 49%. Nodal examinations were correct in 78%. Learning curves leveled out at 100 examinations with 87% accuracy for the rigid probe (R = 0.46) and 77% for the flexible devices (R = 0.31).

CONCLUSIONS

The coefficient of correlation for each method portends a more reliable learning curve for the rigid devices. Flexible devices were less accurate for level of invasion than the literature reported for rigid devices.

MR imaging and computed tomography in patients with rectal tumours clinically judged as locally advanced

AIM

To compare magnetic resonance (MR) imaging and computed tomography (CT) in the local staging of locally advanced rectal tumours.

MATERIALS AND METHODS

Sixteen consecutive patients who, after pre-operative radio-chemotherapy (RCT), had surgery for rectal tumours clinically judged as extending into neighbouring tissues in the pelvis, were examined using MR and CT before and after treatment. The examinations were reviewed by four radiologists. The relation of the tumours to 14 different anatomic structures in the pelvis in a total of 50 examinations was studied. The results were compared to surgical and histopathological findings.

RESULTS

Seven patients had tumour infiltration of adjacent organs in the pelvis at surgery, the most common being the urinary bladder, prostate, uterus and small bowel. MR predicted involvement of the urinary bladder and the uterus better than CT. However, there were more false positive findings on MR than on CT compared to surgical and histopathological findings.

CONCLUSION

For staging of advanced rectal cancers, the overall results were not significantly better for MR than CT. If involvement of the urinary bladder and the uterus cannot be ruled out using CT, MR is advocated due to its higher soft tissue contrast resolution and multi-planar capability.

Detection of lymph node metastases in colorectal carcinoma

The detection of lymph node metastases is the single most important prognostic factor for patients with colorectal cancer. This review outlines the difficulties and methods of detecting positive lymph node metastases in this disease. An outline of traditional diagnostic methods including preoperative ultrasound and cross sectional imaging techniques are evaluated alongside newer modalities including immunoscintography and PET scanning and intraoperative radioguided imaging. Pathological methods of detecting positive nodal disease using standard histopathological staging, enhanced lymph node harvesting and determination of micrometastases are also discussed.

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

PURPOSE

Although preoperative evaluation of early rectal cancers can be done by endoluminal sonography and by means of colonoscopic findings, it is still controversial whether endoluminal sonography can effectively discriminate mucosal from submucosal lesions. This study was performed to verify objective causes of errors in the evaluation of early rectal cancer (T0/1) using a review of videotaped endoluminal sonography images.

METHODS

Eighty-nine patients with suspected early rectal cancer on endoluminal sonography were included. Two different scanners with appropriate probes were used according to tumor location, i.e., transrectal ultrasonography was used to scan up to 8 cm of the rectum above the anal verge, whereas endoscopic ultrasonography was used to assess higher lesions. Endoluminal sonography images were correlated with histologic infiltration and were reevaluated carefully to identify sources of errors.

RESULTS

Sensitivity and specificity were 83.1 and 96.5 percent, respectively, for tumor staging, whereas sensitivity was very low compared with specificity (16.7 vs. 90.2 percent) for metastatic lymph nodes. Endoluminal sonography images showed irregularity of the underlying tumor border (P < 0.01) and hypoechoic blurring or cutoff of the inner and outer hypoechoic layers (P < 0.001), all of which closely correlated with histologic infiltration of tumor cells. Overstaging occurred more than twice as often as understaging in tumor reevaluation (14 vs. 5 occurrences). In contrast to tumors, lymph nodes showed a similar amount of both overstaging (four cases) and understaging (five cases). The sources of errors were summarized as five types: false instrumentation, interpretive errors, anatomic defects, imaging failure, and inevitable errors.

CONCLUSIONS

Because false instrumentation, interpretive errors, and anatomic defects were considered preventable, 23 (82.1 percent) of the 28 errors might have been avoided. Therefore, a clear image by endoluminal sonography can effectively distinguish mucosal from submucosal lesions in early rectal cancer.

Transrectal sonography of anal sphincter infiltration in lower rectal carcinoma

OBJECTIVE

The purpose of the study was to assess the accuracy of transrectal sonography in determining invasion by lower rectal cancer into the anal canal.

SUBJECTS AND METHODS

Thirty-eight patients (14 women, 24 men; mean age, 65 years) with lower rectal cancer underwent transrectal sonography before surgery. Both depth of infiltration and tumor invasion into the anal canal were assessed, and results were compared with histopathology of the resected specimens.

RESULTS

Infiltration into the anal canal was found histopathologically in 12 (32%) of 38 patients. Transrectal sonography revealed a true-positive diagnosis in 11 of these 12 patients. A false-positive diagnosis of anal canal infiltration was made in two patients for a sensitivity of 91%, a specificity of 85%, and an accuracy of 92%. In the 11 patients diagnosed correctly on transrectal sonography, the depth of tumor infiltration into the anal canal corresponded with histopathology.

CONCLUSION

This study shows that transrectal sonography is an accurate method for assessment of anal canal infiltration in lower rectal cancer.

Endorectal magnetic resonance imaging of a rectal duplication cyst

A case of a duplication cyst of the rectum is presented. This case highlights the potential role of endoluminal magnetic resonance imaging in the diagnosis of this uncommon condition. Alternative imaging modalities and differential diagnoses are discussed.

Staging of rectal cancer after polypectomy: usefulness of endorectal US

PURPOSE

To determine the usefulness of endorectal ultrasonography (US) in staging rectal cancer discovered at polypectomy.

MATERIALS AND METHODS

Before surgical resection, endorectal US was performed in 18 consecutive patients with adenocarcinoma discovered in polypectomy specimens. A rotating 7-10-MHz endoprobe with an inflatable balloon was used in all cases. The precise depth of penetration (T stage) was determined with endorectal US and correlated with the histopathologic findings.

RESULTS

For detection of residual tumor after polypectomy, endorectal US had a sensitivity of 100%, specificity of 44%, positive predictive value of 64%, and negative predictive value of 100%. Although the precise T stage was correctly predicted with endorectal US in only eight patients (44%), endorectal US was able to demonstrate whether the tumor was limited to the bowel wall in 16 patients (89%).

CONCLUSION

Endorectal US is an accurate technique for localizing tumors to or beyond the rectal wall in patients who have undergone diagnostic polypectomy. Although inaccuracies in determining the specific T stage may occur, endorectal US facilitates surgical planning in the vast majority of patients and should therefore remain the local staging technique of choice in this specific patient population.