New diagnostic imaging in rectal cancer: endosonography and immunoscintigraphy

Role of Transrectal Ultrasound in Preoperative Local Staging of Carcinoma Rectum and It's Histopathological Correlation

A precise knowledge of depth of invasion of tumor is essential for the planning of treatment of rectal cancer. TRUS is a new diagnostic modality that has become useful in determining depth of invasion preoperatively and the presence or absence of metastatic lymph nodes. Our aim was to determine Role of Transrectal Ultrasound in Preoperative Local Staging of Carcinoma Rectum and it's Histopathological Correlation. TRUS was used in preoperative local staging of 30 patients with carcinoma rectum. 25patients underwent APR (abdomino-perineal resection) & 5 underwent AR. (anterior resection). Preoperative TRUS staging was compared with pathological staging obtained from biopsy of resected specimen. In staging depth of invasion of rectal wall (T stage) overall accuracy was 83.3 %, over staged 10 %, under staged in 6.67 % sensitivity was 92.5 %, and specificity was 62.5 %. In staging lymph nodes (N stage) overall accuracy was 76.67 %, sensitivity was 79.31 %, specificity was 87.5 %. TRUS is a safe and accurate preoperative local staging method for assessment of both depth of invasion of rectal wall and presence or absence of metastatic lymph nodes.

Anorectal ultrasound for neoplastic and inflammatory lesions

Accurate staging of rectal and anal carcinoma is crucial for planning surgery and indicating adjuvant therapy. Although, computed tomography and magnetic resonance imaging are very sensitive in detecting metastatic disease, the local staging of rectal cancer with these techniques has been disappointing. Endorectal ultrasound (ERUS) and anal endosonography (AE) remain the most accurate methods for staging rectal and anal cancer. Anal endosonography is also of value in evaluating perianal sepsis: it can assist the surgeon in planning the surgical strategy by delineating the anatomy of fistula tracts, and can aid in puncturing abscesses in the operating room. Continued research and development has made the instrumentation for ERUS and AE more accurate and user-friendly. New techniques that have contributed significantly to the evolution of ERUS include three-dimensional ERUS, high-frequency miniprobes, transrectal ultrasound-guided biopsy techniques and hydrogen peroxide-enhanced endosonography. Further improvements can be expected from contrast enhancement with microbubbles and colour Doppler imaging. In this new millennium, new developments in ERUS and anal endosonography, such as tri-dimensional ERUS and anal endosonography and radial electronic probing, widen the role of ERUS in the staging of rectal and anal carcinoma, as well as for perianal inflammatory conditions.

Staging of rectal carcinoma with transrectal ultrasonography

BACKGROUND AND AIMS

Transrectal ultrasonography (TRUS) has proven useful for loco-regional staging of rectal carcinoma in specialised centres, but the investigation is not widely used. The aim of this study was to audit the introduction of TRUS performed by surgeons without previous experience with ultrasonography.

MATERIAL AND METHODS

All patients admitted with rectal carcinoma in the period 1996-2002 entered this prospective, comparative study. TRUS with a stiff endorectal probe was performed preoperatively in 118 consecutive patients, 91 of whom subsequently had rectal resection without preoperative radiotherapy (PRT), and seven who had rectal resection after PRT. Twenty patients did not have resection. The main outcome measures was the feasibility of TRUS in staging of rectal cancer, and the accuracy of T- and N-staging, comparing TRUS with the histopathological examination of resected specimens.

RESULTS

TRUS was successful in 81/91 patients who underwent rectal resection without PRT. The accuracy of T-staging was 74% overall; 40% in five pT1 tumours, 81% in 26 pT2 tumours, 80% in 45 pT3 tumours and 25% in four pT4-tumours. With regard to perirectal tissue invasion, the sensitivity and specificity of TRUS was 82% and 84%, respectively, and the positive and negative predictive values were 89% and 71%, respectively. The accuracy of TRUS for N-staging was 65%. The sensitivity for detection of lymph node metastases was 41% and the specificity 68%. TRUS was unsuccessful in 21/118 patients, in 12/98 who had rectal resection, and in 9/ 20 who did not have resection, because of stenosis or high location of the tumour precluding correct placing of the probe.

CONCLUSIONS

TRUS is often unsuccessful in patients with advanced tumours, especially when the tumour is located in the upper rectum. The predictive values for perirectal tumour invasion were acceptable, but the sensitivity for detection of lymph node metastases was low. These results were obtained by surgeons without previous experience with ultrasonographic examinations.

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.

Endoscopic ultrasound and endoscopic mucosal resection for rectal cancers and villous adenomas

EUS is the most accurate tool for local staging of rectal carcinoma. In addition to providing accurate T- and N-stages, EUS allows assessment of the internal and external anal sphincters. Accurate endosonographic staging directs the optimal method of management of rectal carcinoma, type of resection, and candidacy for neoadjuvant therapy. EMR may be applied to large rectal adenomas as an alternative to surgical resection in selected patients. EUS is important in discriminating lesions suitable for EMR.

The role of transrectal ultrasound-guided biopsy in the postoperative follow-up of patients with rectal cancer

BACKGROUND

The value of endorectal ultrasound (EUS) in the diagnosis of recurrent rectal cancer is limited by the inability to differentiate between malignant and benign lesions. We have prospectively investigated the role of EUS with transrectal ultrasound-guided biopsy in the postoperative follow-up of rectal cancer.

METHODS

Since 1995, patients who had undergone a sphincter-saving operation for rectal cancer (n = 312) were followed-up by a standard program including rectal palpation, carcinoembryonic antigen monitoring, computed tomography, and EUS. Transrectal EUS-guided biopsy of perirectal lesions was performed in 68 patients with perirectal lesions by using a rigid endoprobe with a 10 MHZ multiplane transducer and special targeting device.

RESULTS

Overall local recurrence was observed in 36 patients. Intraluminal recurrence was diagnosed by proctoscopy in 12 patients. Transrectal EUS-guided biopsy showed pelvic recurrence in 22 of 68 patients with perirectal lesions. Biopsy specimens with benign histology were obtained from 41 patients, and the procedure failed in 5 cases (accuracy, 92%). There was a strong agreement between transrectal biopsy results and the final diagnosis (kappa = 0.84), the sensitivity and specificity being 91% and 93%, respectively. In contrast, clinical examination (kappa = 0.27), computed tomography (kappa = 0.47), or EUS (kappa = 0.42) showed only a moderate level of agreement with the histopathologic diagnosis, mainly because of the limited specificity of all 3 methods (65% vs 46% vs 57%). EUS-guided biopsy was significantly more accurate than computed tomography and EUS (P <.01). The biopsy results had a considerable impact on the management in 18 of 68 patients (26%).

CONCLUSIONS

Transrectal EUS-guided biopsy is a safe and efficient method for tissue sampling of perirectal lesions. This minimally invasive and inexpensive technique improves the accuracy of endorectal ultrasound in the diagnosis of recurrent 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.

Effectiveness of endoluminal sonography in the identification of occult local rectal cancer recurrences

PURPOSE

Local recurrence of rectal cancer after curative surgery appears in 5 to 30 percent of all cases. It is necessary to detect local recurrence in a resectable stage to have an opportunity for curative reintervention or palliative prevention of those symptoms. Because most local recurrences occur extraluminally, conventional follow-up fails to detect them at an early stage. Therefore, a prospective study was performed to assess the diagnostic potential of endorectal and endovaginal ultrasound to detect asymptomatic resectable local recurrence.

METHODS

In 338 patients 721 endoluminal ultrasound examinations were added to routine follow-up of rectal and left colonic cancer, with a mean of 2.1 (range, 1-10) endoluminal ultrasound examinations for each patient.

RESULTS

A total of 116 patients (34.3 percent) were shown to have local recurrence, which was suggested by endoluminal ultrasound and proven by endoluminal ultrasound-guided needle biopsy in all cases of unclear pararectal structures that could not be verified by endoscopic biopsy. Digital examination failed to detect local recurrence in 91 patients, endoscopy failed to detect local recurrence in 80 patients, and the levels of tumor markers were normal in 25 patients with confirmed local recurrence. In 33 cases of local recurrence, both digital examination and endoscopy results were normal. Twenty-five patients, in whom carcinoembryonic antigen levels, digital examination, and endoscopy results were normal, underwent potential curative reoperation, with total resection of the local recurrence. All 25 patients were still alive at the end of the study period, and 21 were free from disease. On the other hand, only 6 of 67 patients with local recurrence detectable by conventional follow-up could be operated on with curative intention.

CONCLUSION

Postoperative endoluminal ultrasound is able to detect local recurrence at an earlier and asymptomatic stage and can be verified by endosonography-guided needle biopsy. Routine use in follow-up may raise the ratio of curative retreatment by early detection of extramural local recurrence.

Value and limits of endorectal ultrasonography for preoperative staging of rectal carcinoma

In rectal cancer, the depth of tumor infiltration and metastatic involvement of lymph nodes are important prognostic factors. Endosonography of the rectum, combining the advantages of both endoscopy and sonography, provides information not available from other imaging diagnostic techniques. From January 1989 to December 1997, 85 patients affected by rectal carcinoma were submitted to preoperative evaluation with endorectal ultrasonography. In 75 cases the results obtained with the endosonography were compared to the histology of the resected specimens. Overall accuracy in staging depth of infiltration was 90.7%. Overstaging occurred in 4% of patients, whereas understaging occurred in 5.3%. In staging lymph nodal involvement, overall accuracy was 76%, sensitivity was 69.8%, specificity was 84.4%, positive predictive value was 85.7%, and negative predictive value was 67.5%. Endorectal ultrasound is a safe and accurate diagnostic method for staging both tumor invasion and lymph node metastatic involvement, and for selecting an appropriate surgical strategy in patients affected by rectal cancer.

Multidisciplinary management of recurrent colorectal cancer

Isolated pelvic recurrence of rectal carcinoma may occur in up to one third of patients following definitive resection of primary disease. The means by which recurrence is diagnosed, methods by which it may be treated, and reported outcomes are all evolving and improving. Current data indicate that a substantial proportion of patients treated by aggressive multi-modality salvage therapy may be provided with durable survival. This review highlights current concepts in the diagnosis and management of locally recurrent rectal carcinoma.

Early detection of locally recurrent rectal cancer by endosonography

After curative surgery for rectal cancer, the goal of an aggressive surveillance programme is the detection of local recurrence (LR) at an early and potentially curable stage 62 patients (mean age 66.2 years) operated on for rectal cancer were prospectively enrolled in a follow-up study including endorectal ultrasound (EUS), serial CEA levels, digital examination, colonoscopy and pelvic CT. A total of 192 sonographic scans were performed, with a mean of three (range 2-7) for each patient. LR occurred in 11 patients; in all cases this was suggested by EUS. In two patients (18%) other techniques had failed to detect recurrent disease, which was identified solely by EUS. These two were treated radically and the remainder received radiotherapy or other palliative management. Five patients are alive at, on average, 18 months after LR (range 4-26 months). These include both cases treated with salvage surgery and who remain disease free. EUS is a valuable tool in the detection of locally recurrent rectal cancer.

Evaluation and biopsy of recurrent rectal cancer using three-dimensional endosonography

PURPOSE

The value of endorectal ultrasonography for postoperative follow-up of rectal cancer is limited by the inability to distinguish recurrent malignancy from benign lesions, e.g., fibrotic tissue. This study was conducted to investigate the role of three-dimensional (3D) endosonography for evaluation and biopsy of recurrent rectal cancer.

METHODS

Endorectal ultrasonography was performed in routine follow-up program after resection of rectal cancer. 3D volume scans were recorded using a bifocal multiplane 3D transducer (7.5/10 MHz) with a 100 degrees longitudinal and a 360 degrees transversal scan angle. For transrectal ultrasound-guided biopsy of pararectal lesions, a specially designed targeting device was attached to the endoprobe.

RESULTS

Overall pararectal lesions were detected in 28 of 163 patients (17 percent) who were undergoing endorectal ultrasonography for follow-up after resection of rectal cancer. 3D image analysis facilitated assessment of suspicious pararectal lesions by contemporary display of three perpendicular scan planes or volume reconstructions of the scanned area. Ultrasound-guided biopsy was performed in all 28 patients with pararectal lesions identified by endorectal ultrasonography. Biopsy revealed recurrent disease or lymph node metastases in seven and two patients, respectively. Benign lesions explained the endosonographic findings in 17 patients. All patients with benign histology still have no evidence of recurrent disease after a median follow-up of seven months. Nonrepresentative material was obtained in only 2 of 28 patients (accuracy, 93 percent). Histology changed the endosonographic diagnosis in 28 percent of cases.

CONCLUSIONS

3D endosonography with ultrasound-guided biopsy improves the diagnosis of extramural recurrence after curative resection of rectal cancer. 3D image display allows precise control of the position of the biopsy needle within the target.

Transanal local resection for benign and malignant rectal tumours

Local therapy has been widely reported and accepted for benign tumours and carefully selected cancers of the rectum. Thirty-three patients with benign or malignant low rectal tumors have undergone a prospective evaluation after local resection with transanal electroresection as described by Faivre. Patients were divided in three groups: 1) local excision of benign tumours (12 patients), 2) curative resection for localised malignant tumours (7 patients) and 3) palliative local resection for malignant tumours (14 patients). The complications included transient incontinence and rectal bleeding. Patients have been followed for a mean period of 18 months (1-54). In group 3 there were four (28%) recurrences. The remainder of the patients with malignant tumours have been free of disease on follow-up. Although it is ideal for benign neoplasms, further follow-up is needed to determine its true indication in malignant lesions.