Transrectal sonography of anal sphincter infiltration in lower rectal carcinoma

Imaging of unusual perineal masses

OBJECTIVE

The purpose of this article is to describe the radiologic features of unusual tumors that occur in the perineum.

CONCLUSION

The perineal space is often overlooked because of the infrequency of abnormalities. Accurate image interpretation and visualization of extent of pathology is important for proper management. Trauma and infectious diseases occur in the acute setting, whereas tumors are common in the chronic setting. Cross-sectional imaging plays a crucial role in depicting perineal anatomy and evaluating the extent of disease.

Magnetic resonance imaging in locoregional staging of rectal adenocarcinoma

A comprehensive overview of the current status of magnetic resonance imaging (MRI) in the locoregional assessment and management of rectal adenocarcinoma is presented. Staging systems for rectal cancer and treatment strategies in its management are discussed to give the reader the context that shapes MRI acquisition techniques and interpretation. Findings on MRI are detailed and their accuracy reviewed based on currently available evidence. Optimization of MRI acquisition and relevant pelvic anatomy are reviewed. A detailed description of our approach in interpreting MRI for locoregional staging of rectal cancer is given and future directions are also introduced.

Preoperative therapy for lower rectal cancer and modifications in distance from anal sphincter

PURPOSE

To assess the frequency and magnitude of changes in lower rectal cancer resulting from preoperative therapy and its impact on sphincter-saving surgery. Preoperative therapy can increase the rate of preserving surgery by shrinking the tumor and enhancing its distance from the anal sphincter. However, reliable data concerning these modifications are not yet available in published reports.

METHODS AND MATERIALS

A total of 98 cases of locally advanced cancer of the lower rectum (90 Stage uT3-T4N0-N+ and 8 uT2N+M0) that had undergone preoperative therapy were studied by endorectal ultrasonography. The maximal size of the tumor and its distance from the anal sphincter were measured in millimeters before and after preoperative therapy. Surgery was performed 6-8 weeks after therapy, and the histopathologic margins were compared with the endorectal ultrasound data.

RESULTS

Of the 90 cases, 82.5% showed tumor downsizing, varying from one-third to two-thirds or more of the original tumor mass. The distance between the tumor and the anal sphincter increased in 60.2% of cases. The median increase was 0.73 cm (range, 0.2-2.5). Downsizing was not always associated with an increase in distance. Preserving surgery was performed in 60.6% of cases. It was possible in nearly 30% of patients in whom the cancer had reached the anal sphincter before the preoperative therapy. The distal margin was tumor free in these cases.

CONCLUSION

The results of our study have shown that in very low rectal cancer, preoperative therapy causes tumor downsizing in >80% of cases and in more than one-half enhances the distance between the tumor and anal sphincter. These modifications affect the primary surgical options, facilitating or making sphincter-saving surgery possible.

Endoanal ultrasound evaluation of anorectal diseases and disorders: technique, indications, results and limitations

Imaging of the rectum, anorectal junction and surrounding tissues is both difficult and technically challenging. CT and conventional barium studies offer limited information in local staging of rectal and perirectal neoplasms, anal carcinomas and extension perianal fistulas in patients with inflamamatory bowel disease, or in evaluating patients with fecal incontinence. During past decade, sonography and MR imaging have resulted in significant improvement in the imaging of rectal and perirectal and anal and perianal disease. The aim of this article is to review possibility of the EAUS in the evaluation both normal anal anatomy and anorectal disease and disorders (anal carcinoma, sphincter defects, anal fistulas, perianal abscesses and other pathological conditions).

Preoperative radiotherapy for rectal adenocarcinoma: Which are strong prognostic factors?

PURPOSE

This retrospective 12-year study evaluated the prognostic value of initial and postoperative staging of rectal tumors.

METHODS AND MATERIALS

Between 1985 and 1996, 297 patients were treated with preoperative radiotherapy (39 Gy in 13 fractions) and surgery for Stage T2-T4N0-N1M0 rectal adenocarcinoma. Pretreatment staging included a clinical examination and endorectal ultrasonography (EUS) since 1988. Clinical staging was performed by digital rectal examination and rigid proctoscopy. EUS was performed in 236 patients. Postoperative staging was performed by examination of the pathologic specimen.

RESULTS

The median follow-up was 49 months. The overall 5-year survival rate was 67%, with a local failure rate of 9%. The rate of sphincter preservation was 65%. The clinical examination findings were strong prognostic factor for both cT stage (p < 0.001) and cN stage (p < 0.006) but had poor specificity for cN stage (only 25 lymph nodes detected). In both univariate and multivariate analyses, EUS had a statistically significant prognostic value for uT (p < 0.014) but not for uN (p < 0.47) stage. In contrast, pT and pN stages were strong prognostic factors (p < 0.001 and p < 0.001, respectively).

CONCLUSION

Pretreatment staging, including clinical examination and EUS, seemed accurate enough to present a high prognostic value for the T stage. EUS was insufficient to stage lymph node involvement. Owing to its lack of specificity, uN stage was not a reliable prognostic factor. An improvement in N staging is necessary and essential. Despite downstaging, postoperative staging remained a very strong prognostic factor for both T and N stages.

Management of colorectal cancers

The management of colorectal cancers, published in a recent issue of Effective Health Care, is reviewed.

Preoperative MRI of rectal cancer with and without rectal water filling: an intraindividual comparison

OBJECTIVE

The purpose of our study was to determine if a rectal distention using warm water may improve the accuracy of MRI for the preoperative staging of rectal carcinoma. SUBJECTS AND METHODS. Sixty-two patients with surgically proven rectal carcinomas underwent pelvic MRI before and after a rectal distention by warm water. Four radiologists, who were blinded to the study, reviewed each set of T1- and T2-weighted axial images obtained before and after the rectal distention and scored the image of the tumor. The accuracies for determining the tumor penetration of the outer wall of the rectum and the regional lymph node involvement were compared by analyzing the area under the receiver operating characteristic curve (A(z)).

RESULTS

For all reviewers, the tumor depiction scores were significantly higher in the distended images (3.8-3.9 for reviewers 1-4) than in the nondistended images (3.0-3.2) (p < 0.01). For determining the outer wall penetration, the accuracy of the three reviewers was significantly higher with the rectal distention images than with the nondistended images (p < 0.05). The mean accuracy of the all reviewers was significantly better with the distended images (A(z) = 0.922) than with the nondistended images (A(z) = 0.841) (p < 0.05). For determining the presence of regional lymph node involvement, all the reviewers came to similar conclusions in analyzing the two image sets.

CONCLUSION

Rectal distention by water filling may improve the depiction of a primary rectal tumor and the assessment accuracy of a perirectal tumor extension, but it does not improve the accuracy for determining the presence of regional lymph node involvement.

Preoperative staging of rectal cancer

Rectal cancer is one of the most frequent neoplasias, with an incidence of 40 in 100,000. For the effective use of new, differentiated treatment options, exact preoperative tumour staging is essential. The tumour stage determines whether radiation or chemotherapy should be used in addition to surgery. Endosonography allows exact differentiation of the rectal wall layers and thus of tumour stages 1-3 with median accuracy of 89%. Magnetic resonance imaging (MRI) can be employed in high and stenosing tumours and leads to an average accuracy of 85%. In recent studies, it has been shown that MRI is a valuable tool to identify the mesorectal fascia. This is a very important feature concerning the resectability and the risk of recurrence. Both, Endosonograpy and MRI plays an important and complimentary role in staging rectal cancer.

Pelvic radiological imaging: a surgeon's perspective

Radiological imaging of the pelvis adds an important dimension to our understanding of rectal and perianal disease. By integrating relevant information obtained from these investigations into planning and conduct of surgical procedures, outcomes for patients may be optimised. This review focuses on three areas from a clinical viewpoint. (1) With the increased use of neoadjuvant treatments pretherapeutic staging strategies become central to the management of rectal cancer patients. At present, transrectal ultrasound (TRUS), computerised tomography and magnetic resonance imaging (MRI) serve in combination to provide the essential informations. (2) The advent of endoanal ultrasound and MRI in the diagnostic workup of patients with faecal incontinence has caused a paradigm shift both conceptionally and in the way treatments are tailored to individual patients. (3) Concerning primary perianal fistulas there is little place for endoanal ultrasound or MRI. However, when a recurrent or Crohn's fistula is present, a combination of surgical exploration with either endoanal ultrasound or MRI depending on local expertise and availability may be the optimal approach to maximise benefit for these patients.