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

Comparing three-dimensional endorectal ultrasound and magnification chromoendoscopy for early rectal neoplasia invasion depth assessment

INTRODUCTION

Accurate assessment of invasion depth of early rectal neoplasms is essential for optimal therapy. We aimed to compare three-dimensional endorectal ultrasound (3D-ERUS) with magnification chromoendoscopy (MCE) regarding their accuracy in assessing parietal invasion depth (T).

METHODS

Patients with middle and distal rectum neoplasms were prospectively included. Two providers blinded to each other's assessment performed 3D-ERUS and MCE, respectively. The T stage assessed through ERUS was compared to the MCE evaluation. The results were compared to the surgical specimen anatomopathological report. Sensitivity, specificity, accuracy, positive (PPV), and negative (NPV) predictive values were calculated for the T stage and for the final therapy (local excision or radical surgery).

RESULTS

In 8 years, 70 patients were enrolled, and all underwent both exams. MCE and ERUS showed an accuracy of 94.3% and 85.7%, sensitivity of 83.7 and 93.3%, specificity of 96.4 and 83.6%, PPV of 86.7 and 60.9%, and NPV of 96.4 and 97.9%, respectively. Kappa for T stage assessed through ERUS was 0.64 and 0.83 for MCE.

CONCLUSION

MCE and 3D-ERUS had good diagnostic performance, but the endoscopic method had higher accuracy. Both methods reliably assessed lesion extension, circumferential involvement, and distance from the anal verge.

Association Between Three-Dimensional Transrectal Ultrasound Findings and Tumor Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer: An Observational Study

Background

There is a significant demand for the development of non-surgical methods for the evaluation of complete response to tumor therapy. Predicting ability and image quality of routine imaging has not been satisfactory. To avoid the deficiencies, we assessed the capability of three-dimensional transrectal ultrasound in predicting the response to neoadjuvant chemoradiotherapy in rectal cancer patients.

Methods

The inclusion criteria were patients with locally advanced rectal adenocarcinoma, receiving capecitabine-based neoadjuvant chemoradiotherapy, distance from anal verge (≤6 cm), clinical stage T3-4 and/or N+ without evidence of distant metastasis, and restaging ycT0-3a (T3a <5 mm) after the end of neoadjuvant chemoradiotherapy. Three-dimensional transrectal ultrasound was performed 7 weeks after neoadjuvant chemoradiotherapy to discern the patients with complete response from the others. Eight main parameters were obtained from three-dimensional transrectal ultrasound: thickness of muscularis on the residual side, thickness of contralateral muscularis, angle of residual arc, regularity of the shape, integrity of the mucosal layer, blurring of the margin, internal echo, and posterior echo. The association between tumor response and three-dimensional transrectal ultrasound parameters was analyzed, and a model was developed by logistic regression.

Results

Between 2014 and 2019, 101 patients were recruited; 72 cases received total mesorectal excision, and 29 cases underwent watch-and-wait. Among the three-dimensional transrectal ultrasound parameters, the adjusted-thickness of the muscularis (P<0.01), angle of the residual arc (P<0.01), and regularity of the residual shape (P<0.01) were strongly associated with tumor response. In the dataset with total mesorectal excision cases (TME dataset), the residual adjusted-thickness (odds ratio [OR]=4.88, 95% confidence interval [CI]=1.44–16.6, P=0.01) and regularity of the residual shape (OR=5.00, 95% CI=1.13–22.2, P=0.03) were kept in the final logistic model. The area under the curve of the logistic model was 0.84. Among these parameters, residual adjusted-thickness correlated significantly with tumor response. Additionally, we observed similar results in the whole population of 101 cases (whole dataset) and in the cross-validation.

Conclusion

Three-dimensional transrectal ultrasound model is a valuable method for predicting tumor response in rectal cancer patients undergoing neoadjuvant chemoradiotherapy, which should be included as a factor for evaluating clinical complete response.

Trial Registration

This trial was registered with ClinicalTrials.gov, number NCT02605265. Registered 9 November 2015 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT02605265

Endoscopic ultrasound in oncology: An update of clinical applications in the gastrointestinal tract

An accurate staging is necessary to select the best treatment and evaluate prognosis in oncology. Staging usually begins with noninvasive imaging such as computed tomography, magnetic resonance imaging or positron emission tomography. In the absence of distant metastases, endoscopic ultrasound plays an important role in the diagnosis and staging of gastrointestinal tumors, being the most accurate modality for local-regional staging. Its use for tumor and nodal involvement in pre-surgical evaluation has proven to reduce unnecessary surgeries. The aim of this article is to review the current role of endoscopic ultrasound in the diagnosis and staging of esophageal, gastric and colorectal cancer.

Efficacy of 3-Dimensional Endorectal Ultrasound for Staging Early Extraperitoneal Rectal Neoplasms

BACKGROUND

Adequate oncologic staging of rectal neoplasia is important for treatment and prognostic evaluation of the disease. Diagnostic methods such as endorectal ultrasound can assess rectal wall invasion and lymph node involvement.

OBJECTIVE

The purpose of this study was to correlate findings of 3-dimensional endorectal ultrasound and pathologic diagnosis of extraperitoneal rectal tumors with regard to depth of rectal wall invasion, lymph node involvement, percentage of rectal circumference involvement, and tumor extension.

DESIGN

Consecutive patients with extraperitoneal rectal tumors were prospectively assessed by 3-dimensional endorectal ultrasound blind to other staging methods and pathologic diagnosis.

PATIENTS

Patients who underwent endorectal ultrasound followed by surgery were included in the study.

SETTINGS

The study was conducted at a single academic institution.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive and negative predictive values, area under curve, and κ coefficient between 3-dimensional endorectal ultrasound and pathologic diagnosis were determined. Intraclass correlation coefficient was calculated for tumor extension and percentage of rectal wall involvement.

RESULTS

Forty-four patients (27 women; mean age = 63.5 years) were evaluated between September 2010 and June 2014. Most lesions were malignant (72.7%). For depth of submucosal invasion, 3-dimensional endorectal ultrasound showed sensitivity of 77.3%, specificity of 86.4%, positive predictive value of 85.0%, a negative predictive value of 79.2%, and an area under curve of 0.82. The weighted κ coefficient for depth of rectal wall invasion staging was 0.67, and there was no agreement between 3-dimensional endorectal ultrasound and pathologic diagnosis for lymph node involvement (κ = -0.164). Intraclass correlation coefficient for lesion extension and percentage of rectal circumference involvement were 0.45 and 0.66. A better correlation between 3-dimensional endorectal ultrasound and pathologic diagnosis was observed in tumors <5 cm and with <50% of rectal wall involvement.

LIMITATIONS

The relatively small sample size of patients with early rectal lesions referred directly for surgery could represent a potential selection bias.

CONCLUSIONS

Three-dimensional endorectal ultrasound was effective for determining rectal wall invasion and lesion extension in tumors <5 cm and with <50% of rectal wall invasion but was limited for detecting lymph node involvement in early rectal lesions.

Usefulness of anorectal and endovaginal 3D ultrasound in the evaluation of sphincter and pubovisceral muscle defects using a new scoring system in women with fecal incontinence after vaginal delivery

PURPOSE

This study aims to evaluate pubovisceral muscle and anal sphincter defects in women with previous vaginal delivery and fecal incontinence and to correlate the findings with the severity of symptoms using the combined anorectal and endovaginal 3D ultrasonography with a new ultrasound scoring system.

METHODS

Consecutive female patients with previous vaginal delivery and fecal incontinence symptoms were screened. Fecal incontinence was assessed with the Cleveland Clinic Florida fecal incontinence scale, and the extent of defects was assessed by an ultrasound score based on results of anorectal and endovaginal 3D ultrasound. Fecal incontinence was assessed with the Cleveland Clinic Florida fecal incontinence scale.

RESULTS

Of 84 women with previous vaginal delivery and fecal incontinence, 21 (25%) had intact pubovisceral muscles and anal sphincters; 63 (75%) had a pubovisceral muscle or anal sphincter defect, or both. Twenty-eight (33%) had a pubovisceral muscle defect [23% with an external anal sphincter (EAS) defect or combined EAS/internal anal sphincter defects; 11% with intact anal sphincters]. Thirty-five (42%) had intact pubovisceral muscles and an anal sphincter defect. Compared with women with intact pubovisceral muscles/anal sphincter defects, patients with pubovisceral muscle defects had significantly higher incontinence scores and significantly higher ultrasound scores indicating more extensive defects. Incontinence symptoms correlated positively with the ultrasound score, measurements of sphincter defects, and area of the levator hiatus.

CONCLUSIONS

Evaluation of both pubovisceral muscles and anal sphincters is important to identify defects and determine treatment for women with fecal incontinence after vaginal delivery. The severity of fecal incontinence symptoms is significantly related to the extent of defects of the pubovisceral muscles and anal sphincters.

Practice parameters for early rectal cancer management: Italian Society of Colorectal Surgery (Società Italiana di Chirurgia Colo-Rettale; SICCR) guidelines

The introduction of new technologies for diagnosis and screening programs led to an increasing rate of early detection of colorectal cancer. This, associated with the evolution of endoscopic techniques of local excision, led to the assessment of new strategies to reduce morbidity related to treatment, especially for early rectal cancer (ERC). Nevertheless, the definition of ERC and its staging and treatment algorithm are still under debate. The Italian Society of Colorectal Surgery developed practice guidelines to provide recommendations on the diagnosis, staging and treatment of ERC. A systematic review on the topic was performed by a multidisciplinary group of experts selected based on their clinical and scientific expertise in endoscopy, endoscopic ultrasound, magnetic resonance and surgery, with the aid of an external international audit.

The role of 3-D endorectal ultrasound in rectal cancer: our experience

In the last 20 years, endorectal ultrasound (ERUS) has been one of the main diagnostic methods for locoregional staging of rectal cancer. ERUS is accurate modality for evaluating local invasion of rectal carcinoma into the rectal wall layers (T category). Adding the three-dimensional modality (3-D) increases the capabilities of this diagnostic tool in rectal cancer patients. We review the literature and report our experience in preoperative 3-D ERUS in rectal cancer staging. In the group of 71 patients, the staging of preoperative 3-D endorectal ultrasonography was compared with the postoperative morphologic examination. Three-dimensional ERUS preoperative staging was confirmed with morphologic evaluation in 66 out of 71 cases (92.9%). The detection sensitivities of rectal cancer with 3-D ERUS were as follows: T1, 92.8%; T2, 93.1%; T3, 91.6%; and T4, 100.0%; with specificity values of T1, 98.2%; T2, 95.4%; T3, 97.8%; and T4, 98.5%. Three-dimensional ERUS correctly categorized patients with T1, 97.1%; T2, 94.3%; T3, 95.7%; and T4, 98.5%. The percentage of total overstaged cases was 2.75% and that of understaged cases was 6.87%. The metastatic status of the lymph nodes was determined with a sensitivity of 79.1% (19 of 24), specificity of 91.4% (43 of 47), and diagnostic accuracy of 87.3% (62 of 71). In our experience, 3-D ERUS has the potential to become the diagnostic modality of choice for the preoperative staging of rectal cancer.

Imaging in rectal cancer: magnetic resonance imaging versus endorectal ultrasonography

Over the past several decades there have been tremendous improvements in the outcomes of patients with rectal cancer. Imaging modalities such as endorectal ultrasonography (ERUS), magnetic resonance imaging (MRI), and computed tomography scanning play a pivotal role in evaluating rectal cancer preoperatively, planning surgical procedures, and selecting patients for neoadjuvant therapy. This article provides an overview of rectal anatomy and pelvic structures relevant to preoperative assessment and surgical treatment. The technical aspects, applications, and limitations of the imaging tools currently in use are examined, focusing on MRI and ERUS.

Advanced EUS imaging for early detection of pancreatic cancer

Endoscopic ultrasound (EUS)-fine needle aspiration remains the gold standard for diagnosing pancreatic malignancy. However, in a subset of patients, limitations remain in regards to image quality and diagnostic yield of biopsies. Several new devices and processors have been developed that allow for enhancement of the EUS image. Initial studies of these modalities do show promise. However, cost, availability, and overall incremental benefit to EUS-fine needle aspiration have yet to be determined.

A novel three-dimensional endoscopic ultrasound technique for the freehand examination of the oesophagus

This study details the development and evaluation of a freehand radial three-dimensional endoscopic ultrasound (3D-EUS) technique for use in the upper gastro-intestinal tract. It comprised of a commercial EUS system, a custom acquisition system to simultaneous acquire radial B-mode images and corresponding incremental changes in position of the scope as it was withdrawn and a custom 3D-EUS package written in Matlab™, to reconstruct and analyse the volume. This technique was evaluated using an EUS phantom with embedded objects of known dimensions and volumes and with clinical images acquired during routine cancer staging. For the phantom measurements, average Z-dimensional error was <1% and volume errors were 1.4% (volume(1) = 48930 mm(3)) and 4.5% (volume(2) = 5100 mm(3)). Application of this technique to EUS acquired clinical images produced excellent characterisation of oesophageal structures and accurate dimension and volume measurements. It also enabled the endoscopist to review "off-line" the EUS examination in case important information was missed.

Anatomic characteristics of anal fistula on three-dimensional anorectal ultrasonography

BACKGROUND

Surgery for anal fistula is often associated with continence disorders due to the transection of sphincter muscles. Extensive knowledge of anal canal anatomy and anal fistula can help prevent this outcome.

OBJECTIVE

This study aimed to correlate the anatomical conformation of the anal canal, the fistula track, and the internal opening according to sex and hemicircumference (anterior vs posterior) by use of 3-dimensional ultrasonography.

METHODS

One hundred sixty-five patients with fistula were evaluated with 3-dimensional ultrasound and grouped according to sex, fistula type, internal opening, and track position. Fistulas were transsphincteric in 128 subjects and intersphincteric in 37 subjects. The study measured the external and internal anal sphincter, the puborectalis, the distance from the internal opening to the distal edge of the external and internal sphincter, the length of the internal and external sphincter compromised by the track, and the percentage of compromised muscle.

RESULTS

The anal canal muscles were longer in males. The distance from the internal opening to the internal sphincter was greater for the posterior hemicircumference. The point where the fistulous track crossed the anterior external sphincter was similar for the 2 sexes, but the percentage of compromised muscle was greater in females. The point where the fistulous track crossed the internal sphincter was similar for the 2 sexes, but the percentage of compromised internal sphincter was greater in males for the posterior hemicircumference. The study was limited by the absence of testing for interobserver and intraobserver agreement.

CONCLUSION

The anal canal muscles are longer in males and the pectinate line is asymmetrical. In females, the percentage of compromised external sphincter was greater in the anterior hemicircumference because of the shorter external sphincter, whereas in males the percentage of compromised internal sphincter was greater in the posterior hemicircumference.

Endorectal ultrasound: its role in the diagnosis and treatment of rectal cancer

With development over the past 25 years of new surgical techniques and neoadjuvant therapy regimens for rectal cancer, physicians now have a range of treatment options that minimize morbidity and maximize the potential for cure. Accurate pretreatment staging is critical, ensuring adequate therapy and preventing overtreatment. Many options exist for staging primary rectal cancer. However, endorectal ultrasound (ERUS) remains the most attractive modality. It is an extension of the physical examination, and can be performed easily in the office. It is cost effective and is generally well tolerated by the patient, without need for general anesthesia. The authors discuss the data currently available on ERUS, including its accuracy and limitations, as well as the technical aspects of performing ERUS and interpreting the results. They also discuss new ultrasound technologies, which may improve rectal cancer staging in the future.

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.

The role of three-dimensional endoluminal ultrasound imaging in the evaluation of anorectal diseases: a review

BACKGROUND

The authors conducted a review of the available English literature to evaluate the advantages of three-dimensional ultrasound for assessing anorectal pathology, to provide a state-of-the-art approach, and to compare this technique with conventional endoluminal ultrasound and other imaging methods.

METHODS

All studies describing results obtained with three-dimensional ultrasound in the evaluation of anorectal pathologies, both alone and compared with other techniques, were selected.

RESULTS

Since 1996, 32 articles have been published. In tumor staging, specific data derived by three-dimensional reconstruction for the assessment of T invasion and nodal involvement were more accurate than endoluminal ultrasound and computed tomography. For evaluating perianal sepsis, the detection of secondary fistula tracts and fluid collections and the location of internal openings were superior to endoanal magnetic resonance imaging. In the evaluation of anal incontinence, the results for sphincter defects were similar to those obtained with endoanal magnetic resonance imaging.

CONCLUSION

Analysis of the literature confirmed that three-dimensional ultrasound is a valuable technique for assessing anorectal disorders, facilitating the interpretation of the images obtained, and providing additional data that in many cases have changed the operative approach.

Endoscopic ultrasound in the diagnosis, staging and management of colorectal tumors

Endoscopic ultrasound (EUS) has evolved as a useful technique for imaging and intervention in the colon and rectum. This article reviews the clinical applications of EUS for imaging and intervention in colorectal cancer, with an emphasis on the most recent clinical studies.

cT3N0 rectal cancer: potential overtreatment with preoperative chemoradiotherapy is warranted

PURPOSE

Although combined-modality therapy (CMT) is the preferred treatment for T3 and/or lymph node (LN)-positive rectal cancer, the German rectal cancer study published in 2004 demonstrated that 18% of patients deemed suitable for preoperative CMT by endorectal ultrasound (ERUS) may be overstaged. Because data also suggest that LN-negative rectal cancer after total mesorectal excision may not require radiotherapy, it is reasonable to consider omitting radiotherapy for the cT3N0 subset. We therefore determined the accuracy of pre-CMT ERUS or magnetic resonance imaging (MRI) staging, to explore the validity of a nonpreoperative CMT approach for cT3N0 disease.

PATIENTS AND METHODS

One hundred eighty-eight ERUS-/MRI-staged T3N0 rectal cancer patients received preoperative CMT (fluorouracil based and 45-50.4 Gy) followed by radical resection. Rates of pathologic complete response (pCR) and mesorectal LN involvement were determined.

RESULTS

Tumors were located a median of 5 cm from the anal verge. Sphincter-preserving surgery was performed in 143 patients (76%). Overall pCR was 20%, and 41 patients (22%) had pathologically positive mesorectal LNs. The incidence of positive LNs significantly increased with T stage: ypT0, 3%; ypT1, 7%; ypT2, 20%; ypT3-4, 36% (P = .001).

CONCLUSION

The accuracy of preoperative ERUS/MRI for staging mid to distal cT3N0 rectal cancer is limited because 22% of patients have undetected mesorectal LN involvement despite CMT. Therefore, ERUS-/MRI-staged T3N0 rectal cancer patients should continue to receive preoperative CMT. Although 18% may be overstaged and therefore overtreated, our data suggest that an even larger number would be understaged and require postoperative CMT, which is associated with significantly inferior local control, higher toxicity, and worse functional outcome.

Anal canal anatomy showed by three-dimensional anorectal ultrasonography

BACKGROUND

Demonstrate precisely the anatomic configuration of the anal canal and the length and thickness of the anal sphincters using three-dimensional (3-D) anorectal ultra-sonography in both genders.

METHODS

Twelve normal volunteer males and 14 females, with a mean age of 52.4 and 50.3 years, respectively, were prospectively enrolled in this study. All individuals from both groups were submitted to anorectal ultra-sonography. The anal canal was analyzed, measuring the length and thickness of the external anal sphincter (EAE), internal anal sphincter (IAS), puborectalis muscle (PR) and the gap (distance from the anterior EAS to the anorectal junction) in the midline longitudinal (ML) and transverse (MT) planes, and the results were compared between quadrants and genders.

RESULTS

The distribution of sphincter muscles is asymmetric in both genders. The anterior upper anal canal is an extension of the rectal wall with all layers clearly identified. The anterior IAS is formed in the distal upper anal canal and is significantly shorter in female than in male in all quadrants. The anterior IAS length is shorter than the posterior and lateral in both genders. The anterior EAS length is significantly shorter (2.2 cm) and the gap is longer (1.2 cm) in female than in male (3.4 cm) (0.7 cm) (p < 0.05), respectively. The posterior and lateral EAS-PR is significant longer in males (3.6 cm) (3.9 cm) than in females (3.2 cm) (3.5 cm) (p < 0.05), respectively. The lateral EAS-PR is significant longer than the posterior part in both genders. The anterior IAS is significantly thicker in males (0.19 cm) than in females (0.12 cm) (p = 0.04).

CONCLUSION

3-D anal endosonography enabled measurement of the different anatomical structures of the anal canal and demonstrated its asymmetrical configuration. The shorter anterior EAS and IAS associated with a longer gap could justify the higher incidence of pelvic floor dysfunction in females, especially fecal incontinence and anorectocele with rectal intussusception.

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.

Preoperative loco-regional imaging in rectal cancer

Preoperative staging of rectal cancer can influence the choice of surgery and the use of neoadjuvant therapy. This review evaluates the use of endorectal ultrasound (ERUS) and magnetic resonance imaging (MRI) in the local staging of rectal cancer. Staging for distant metastases is beyond the scope of this review. A MEDLINE search for published work in English between 1984-2004 was carried out by entering the key words of ERUS, MRI and preoperative imaging and rectal cancer. Initially, 867 articles were retrieved. Abstracts were reviewed and papers selected according to the inclusion criteria of a minimum of 50 patients and papers published in English. Papers focusing on preoperative chemoradiotherapy and distal metastases were excluded. Thirty-one papers were included in the systematic review. The examination techniques and images obtained are discussed and the respective accuracy is reviewed. ERUS and MRI have complementary roles in the assessment of tumour depth. Ultrasound has an overall accuracy of 82% (T1, 2, 40-100%; T3, 4, 25-100%) and is particularly useful for early localized rectal cancers. MRI has an accuracy of 76% (T1, 2, 29-80%; T3, 4, 0-100%) and is useful in more advanced disease by providing clearer definition of the mesorectum and mesorectal fascia. Both methods have similar accuracy in the assessment of nodal metastases. Ultrasound is more operator dependent and accuracies improve with experience, but it is more portable and accessible than MRI. Improvements in technology and increased operator experience have led to more accurate preoperative staging. ERUS and MRI are complementary and are most accurate for early localized cancers and more advanced cancers, respectively.

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.

The status of ultrasonography training and use in general surgery residency programs

BACKGROUND

Effective use of ultrasonography (US) by surgeons was demonstrated a decade ago. Major surgical organizations now require its incorporation into surgical training and practice. But little information about the teaching of US to surgical residents exists. This study assesses the current status of US training in general surgery residency programs.

STUDY DESIGN

A survey was mailed to the directors of 255 Accreditation Council for Graduate Medical Education-accredited general surgery residency programs. It questioned whether and how US was taught, who performed the examinations, and the types of US performed. Data were analyzed using chi-square tests comparing university versus community programs and training and practice in trauma US versus training in other US modalities.

RESULTS

The response rate was 51% (130 of 255). Ninety-six percent of the programs responding taught US, with no differences between university- and community-based training programs in presence of training. Focused Assessment for the Sonography of Trauma (FAST) instruction was done by 79% (hands-on) and 68% (didactic) of programs that responded. Abdominal, laparoscopic, breast, endocrine, and vascular US were each taught less frequently (22% to 55%). Program directors at university programs reported that their attending surgeons performed FAST and abdominal US more often than their community counterparts (71% and 31% versus 47% and 14%). Program directors reported that university trainees performed laparoscopic, endocrine, and vascular US more often than community surgery residents (47%, 17%, 35% versus 29%, 3%, 19%). Program directors reported that surgery attendings or residents performed trauma and laparoscopic US more often than their radiology counterparts, and radiology attendings or residents performed more abdominal, breast, endocrine, and vascular US.

CONCLUSIONS

The majority of general surgery residency programs whose directors responded to this survey are teaching US, but most of the training is in FAST. There is no difference in the reported presence of overall US training between university and community programs. But university programs report that their surgeons or residents performed more US in all areas (other than breast) than their community counterparts reported.

Importância do ultra-som tridimensional na avaliação anorretal

RACIONAL: A endosonografia anorretal constitui-se atualmente no principal exame de imagem para avaliar algumas das afecções anorretais. OBJETIVO: Demonstrar a importância do ultra-som tridimensional na avaliação anatômica do canal anal e no diagnóstico de afecções anorretais. MÉTODO: Foram realizados 74 exames, sendo 23 pacientes normais (13 mulheres) e 51 com afecções benignas e malignas (33 mulheres). Foi utilizado um aparelho de ultra-som com transdutor tridimensional 360°. Os indivíduos normais foram avaliados em plano sagital mediano, com relação ao comprimento do canal anal, do esfíncter anal interno, do esfíncter anal externo e do defeito anatômico, no quadrante anterior. RESULTADOS: Comparando homens normais com as mulheres, não houve diferenças no comprimento médio do canal anal e do esfíncter anal interno. Já o comprimento médio do esfíncter anal externo é maior no homem e o defeito anatômico anterior é maior na mulher. Nos doentes com afecções anorretais, foram diagnosticadas 11 lesões esfincterianas, 8 fístulas anais, 7 abscessos, 1 endometriose perirretal, 1 cisto pré-sacral, 3 tumores no canal anal e 10 no reto. Houve coincidência entre os achados cirúrgicos e ultra-sonográficos em todos os pacientes operados. CONCLUSÃO: A avaliação ultra-sonográfica tridimensional evidenciou as diferenças anatômicas entre os sexos, justificando a maior freqüência de distúrbios do assoalho pélvico no sexo feminino. Diagnosticou as afecções anorretais em múltiplos planos com elevada resolução espacial, adicionando informações importantes para a decisão terapêutica, assemelhando-se à ressonância nuclear magnética com bobina intra-retal, com a vantagem de ser mais fácil, mais rápido, de baixo custo e com melhor tolerância.

Diagnostics of rectal cancer: endorectal ultrasound

In rectal cancer, accurate preoperative staging is essential to adequately select patients for different therapeutic regimes. Endosonography has been proven to be an accurate staging modality in multiple prospective studies. A recent large retrospective study, however, has cast doubt on the actual accuracy of endorectal ultrasound for staging rectal cancer in everyday clinical routines. The results of endosonographic staging of rectal tumours over a period of 10 years at the Department of Surgery of the University of Heidelberg are presented. In a first time period, 424 patients with rectal cancer were staged by endosonography and the data recorded prospectively. The examinations were exclusively done by four surgeons with high experience and scientific interest in endosonography. The second time period comprises 332 patients with rectal tumours (including adenomas) having undergone endosonography by six different examiners after introduction of this staging method into the clinical routine. The data here were analysed retrospectively. Accuracy, sensitivity, specificity, and positive and negative predictive values were calculated for the T and N classifications for both series. In the second series, eight factors which have been postulated to influence staging accuracy in the literature were included in a regression analysis in order to identify relevant factors for staging inaccuracies. Accuracy for staging of the T classification was 81% in the first series versus 71.7% in the second series. In the regression analysis of the second series, status post-chemoradiation proved to be the most significant factor for staging inaccuracy (p < 0.0002). When excluding all patients having undergone chemoradiation, the accuracy for staging of the T classification rose to 76%. A major problem of endosonography in this second series was overstaging; the T category was overestimated in 76 cases (22.9% of patients). The main error here was overstaging of adenomas as cancerous lesions (45.5% of all adenomas) and T2-cancers as more advanced cancers (42.2% of all T2-cancers). When excluding the adenomas from this analysis, the accuracy increased to 73.5%. Accuracy for staging of the N classification was 76% in the first series versus 71% in the second series. Status post-chemoradiation again was a relevant factor (p < 0.0003); when excluding these patients the accuracy increased to 73%. The accuracy of endosonography for rectal tumours decreases after introduction of the method into the everyday clinical routine. Nonetheless, apart from magnetic resonance imaging with an endorectal coil, rectal endosonography is still the most accurate staging modality for rectal tumours and allows adequate selection of patients for different therapeutic regimes. As the major problem of rectal endosonography is overstaging, more patients are likely to undergo overtreatment rather than undertreatment. Endosonography is inaccurate in staging patients having undergone chemoradiation.

Imaging for Predicting the Risk Factors—the Circumferential Resection Margin and Nodal Disease—of Local Recurrence in Rectal Cancer: A Meta-Analysis

The aim of the present study was to conduct a meta-analysis of English literature on the accuracy of preoperative imaging in predicting the two most important risk factors for local recurrence in rectal cancer, the circumferential resection margin (CRM) and the nodal status (N-status). Articles published between 1985 and August 2004 that report on the diagnostic accuracy of endoluminal ultrasound (EUS), computed tomography (CT), or magnetic resonance imaging (MRI) in the evaluation of lymph node involvement were included. A similar search was done for the assessment of the circumferential resection margin in rectal cancer in the period from January 1985 till January 2005. The inclusion criteria were as follows: (1) more than 20 patients with histologically proven rectal cancer were included, (2) histology was used as the gold standard, and (3) results were given in a 2 x 2 contingency table or this table could otherwise be extracted from the article by two independent readers. Based on the results summary receiver operating characteristic (ROC) curves were constructed. Only 7 articles matching inclusion criteria were found concerning the CRM. The meta-analysis shows that MRI is rather accurate in diagnosing a close or involved CRM. For nodal status 84 articles could be included. The diagnostic odds ratio of EUS is estimated at 8.83. For MRI and CT, the diagnostic odds ratio are 6.53 and 5.86, respectively. The results show that EUS is slightly, but not significantly, better than MRI or CT for identification of nodal disease. There is no significant difference between the different modalities with respect to staging nodal status. At present, MRI is the only modality that predicts the circumferential resection margin with good accuracy, making it a good tool to identify high and low risk patients. Predicting the N-status remains a problem for the radiologist for every modality, although considering the new developments in MR imaging, this may change in the near future.

Three-dimensional linear endoscopic ultrasound-feasibility of a novel technique applied for the detection of vessel involvement of pancreatic masses

BACKGROUND

Endoscopic ultrasound (EUS) can reliably diagnose and stage pancreatic cancer but is less competent for the differentiation between vascular compression (VC) and invasion (VI).

AIM

Prospective comparison of linear EUS with/without three-dimensional (3D) EUS for vessel involvement in pancreatic cancer to evaluate the feasibility of linear 3D ultrasound.

MATERIAL AND METHODS

Linear echoendoscopy was used to identify the pancreatic tumor, the tumor-vessel relation and for EUS-FNA to obtain tissue diagnosis. Immediately afterwards, 3D image acquisition was performed using a magnetic tracked 3D sensor. The acquisition time was 10-20 s.

RESULTS

EUS results of 22 patients with solid pancreatic lesions were compared to surgical histology. This proved adenocarcinoma in 17 patients and chronic pancreatitis in 5. EUS showed VI in 10 patients, VC in 6, and no vascular involvement (NVI) in 6. Additional 3D evaluation showed VI in 6 patients, VC in 10, and NVI in 6. Surgery proved VI in 7 patients, VC in 9, and NVI in 6. EUS showed VI in 3/5 patients with chronic pancreatitis, 3D showed VC only, while surgery found two patients to have VC and with NVI. In two patients with pancreatic cancer, VI was diagnosed on two dimensional (2D), but VC on 3D evaluation. Surgery showed VC and VI in one each. In the 2D, one patient with NVI had VI on surgery; and on 3D one VC proved to have NVI at surgery. In 1/22 patients the result of 3D was false negative, while 4/22 were false positives and one false negative in conventional EUS.

CONCLUSION

Linear 3D EUS seems feasible for pancreatic evaluation. In addition, linear EUS enhanced the evaluation of vascular involvement of pancreatic lesions, especially in chronic pancreatitis.

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.

Present and future of endoscopic ultrasonography

Endoscopic ultrasonography and endoscopic ultrasonography-guided fine needle aspiration are well-established techniques, encompassing a variety of diagnostic and therapeutic applications. Along with traditional indications that constitute everyday clinical practice in all endoscopic ultrasonography centres, new indications are emerging that resemble the continuing research carried on in this field. Some of these are innovative applications, developed by highly experienced endosonographers and with a putative role for clinical practice in the near future. Others are merely experimental applications, carried out on in animal models or in highly selected groups of patients, opening up new fascinating areas of research but not for imminent introduction in clinical practice. The purpose of this review, after summarising the present indications of endoscopic ultrasonography, is to focus on the future applications and try to establish their possible advent, either in the near or in the far future.

A new method for three-dimensional laparoscopic ultrasound model reconstruction

BACKGROUND

Laparoscopic ultrasound is an important modality in the staging of gastrointestinal tumors. Correct staging depends on good spatial understanding of the regional tumor infiltration. Three-dimensional (3D) models may facilitate the evaluation of tumor infiltration. The aim of the study was to perform a volumetric test and a clinical feasibility test of a new 3D method using standard laparoscopic ultrasound equipment.

METHODS

Three-dimensional models were reconstructed from a series of two-dimensional ultrasound images using either electromagnetic tracking or a new 3D method. The volumetric accuracy of the new method was tested ex vivo, and the clinical feasibility was tested on a small series of patients.

RESULTS

Both electromagnetic tracked reconstructions and the new 3D method gave good volumetric information with no significant difference. Clinical use of the new 3D method showed accurate models comparable to findings at surgery and pathology.

CONCLUSIONS

The use of the new 3D method is technically feasible, and its volumetrically, accurate compared to 3D with electromagnetic tracking.

Surgeon-performed ultrasound: endorectal ultrasound

Endorectal (ERUS) and endoanal (EAUS) ultrasound imaging is increasingly being performed by surgeons in the office and outpatient setting for the assessment of both benign and malignant disease. Multiple studies have demonstrated the accuracy of these modalities in identifying pertinent anatomy and anatomic abnormalities. The ultrasound is easily tolerated by most patients, and is easily performed with minimal preparation on the patient's part. The ability of the surgeon to perform and interpret this straight forward diagnostic procedure allows for the simplification of the diagnostic process and a more rapid determination of treatment options for the patient.

Rectal cancer: local staging and assessment of lymph node involvement with endoluminal US, CT, and MR imaging--a meta-analysis

PURPOSE

To perform a meta-analysis to compare endoluminal ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging in rectal cancer staging.

MATERIALS AND METHODS

Relevant articles published between 1985 and 2002 were included if more than 20 patients were studied, histopathologic findings were the reference standard, and data were presented for 2 x 2 tables; articles were excluded if data were reported elsewhere in more detail. Two reviewers independently extracted data on study characteristics and results. Bivariate random-effects approach was used to obtain summary estimates of sensitivity and specificity for invasion of muscularis propria, perirectal tissue, and adjacent organs and for lymph node involvement. Summary receiver operating characteristic (ROC) curves were fitted for perirectal tissue invasion and lymph node involvement.

RESULTS

Ninety articles fulfilled all inclusion criteria. For muscularis propria invasion, US and MR imaging had similar sensitivities; specificity of US (86% [95% confidence interval [CI]: 80, 90]) was significantly higher than that of MR imaging (69% [95% CI: 52, 82]) (P =.02). For perirectal tissue invasion, sensitivity of US (90% [95% CI: 88, 92]) was significantly higher than that of CT (79% [95% CI: 74, 84]) (P <.001) and MR imaging (82% [95% CI: 74, 87]) (P =.003); specificities were comparable. For adjacent organ invasion and lymph node involvement, estimates for US, CT, and MR imaging were comparable. Summary ROC curve for US of perirectal tissue invasion showed better diagnostic accuracy than that of CT and MR imaging. Summary ROC curves for lymph node involvement showed no differences in accuracy.

CONCLUSION

For local invasion, endoluminal US was most accurate and can be helpful in screening patients for available therapeutic strategies.