Small spot sign of rectal carcinoma by endorectal ultrasonography: histologic relation and clinical impact on postoperative recurrence

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.

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.