Role of three-dimensional anorectal ultrasonography in the assessment of rectal cancer after neoadjuvant radiochemotherapy: preliminary results

Establishing the normal ranges of female and male anal canal and rectal wall vascularity with color Doppler anorectal ultrasonography

Study objectives To evaluate blood supply in the anal canal, rectal wall and mesorectal fat of men and women, using color Doppler endorectal sonography to establish normal ranges for vascular parameters.

Methods A prospective cross-sectional study conducted at a tertiary-care hospital recruited asymptomatic volunteers (≤50 years). Vascularity percentage and index were calculated for defined regions.

Results Vascularity percentage and index were significantly higher in the puborectalis, mid-level external and upper internal anal sphincter compared to the low anal canal; these parameters were higher in men than in women at upper and middle levels of the inner anal canal structures. At mid-level, vascularity was greater in the external compared to the internal anal sphincter in both sexes; however, at the upper level it was greater in the puborectalis compared to the internal anal sphincter in women. Vascularity was greater in the rectal wall compared to the mesorectal fat, with no difference between middle and lower levels.

Conclusions Blood supply is highest at upper levels of the anal canal; however, inner structures are better irrigated in men. Moreover, the rectal wall is better irrigated than the mesorectal fat. Establishing normal ranges may permit future comparisons of the studied structures in disease states as well as the hormonal and age related changes.

Neoadjuvant chemoradiotherapy of the rectal carcinoma - The correlation between the findings on the restaging multiparametric 3T MRI scanning and the surgical findings

AIM

To figure out how to correlate the findings on functional MRI and carried out after neoadjuvant CRT of rectal carcinoma with final histology after surgery.

BACKGROUND

Neoadjuvant CRT is the standard treatment of locally advanced rectal carcinoma. Its use leads to the downstaging of the disease and in 15-42% of patients even to the detection of pCR after TME. The use of functional MRI improves the sensitivity and specificity of pCR detection up to 52-64% and 89-98%, respectively.

MATERIALS AND METHODS

Between January 2013 and June 2016, 67 patients suffering from histologically proven locally advanced rectal cancer underwent neoadjuvant RT or CRT. We selected for further investigation only patients (33 patients) who underwent pelvic staging and restaging using multiparametric imaging on 3T MRI scanner. We compared the findings on functional MRI after neoadjuvant CRT with final histology after surgery.

RESULTS

In 15 patients pathologic staging of primary tumor differed from expected staging assessed according to preoperative MRI. In 5 patients pathologic complete remission was achieved. In none of these 5 patients pCR was predicted using preoperative MRI. Sensitivity and specificity of MRI in predicting pCR were 0% and 96%. Accuracy of MRI in predicting pT and pN was 79% and 74%.

CONCLUSIONS

We have verified that the use of neoadjuvant CRT in the treatment of locally advanced rectal carcinoma leads to a possible achievement of pCR. But in our group of patients this was not predictable nor was it with the use of multiparametric 3T MRI.

Neoadjuvant chemoradiation therapy and pathological complete response in rectal cancer

The management of rectal cancer has evolved significantly in the last few decades. Significant improvements in local disease control were achieved in the 1990s, with the introduction of total mesorectal excision and neoadjuvant radiotherapy. Level 1 evidence has shown that, with neoadjuvant chemoradiation therapy (CRT) the rates of local recurrence can be lower than 6% and, as a result, neoadjuvant CRT currently represents the accepted standard of care. This approach has led to reliable tumor down-staging, with 15-27% patients with a pathological complete response (pCR)-defined as no residual cancer found on histological examination of the specimen. Patients who achieve pCR after CRT have better long-term outcomes, less risk of developing local or distal recurrence and improved survival. For all these reasons, sphincter-preserving procedures or organ-preserving options have been suggested, such as local excision of residual tumor or the omission of surgery altogether. Although local recurrence rate has been stable at 5-6% with this multidisciplinary management method, distal recurrence rates for locally-advanced rectal cancers remain in excess of 25% and represent the main cause of death in these patients. For this reason, more recent trials have been looking at the administration of full-dose systemic chemotherapy in the neoadjuvant setting (in order to offer early treatment of disseminated micrometastases, thus improving control of systemic disease) and selective use of radiotherapy only in non-responders or for low rectal tumors smaller than 5 cm.

Criteria for three-dimensional anorectal ultrasound assessment of response to chemoradiotherapy in rectal cancer patients

AIM

The aim of this study was to identify criteria for three-dimensional anorectal ultrasonography (3D-AUS) to assess the response of rectal cancer to chemoradiotherapy; the 3D-AUS results were compared with the histopathological findings of the resected specimen.

METHOD

Thirty-five patients underwent 3D-AUS and were grouped according to the presence (GI; n = 19) or absence (GII; n = 16) of anal canal invasion. All patients received chemoradiotherapy, then underwent a second 3D-AUS. The response (complete, partial or insignificant and lymph node metastasis) was evaluated. Tumour length (cm) and volume (cm(3) ), length and volume regression percentage (%), distal length regression, and distance between the distal tumour edge and the proximal border of the internal anal sphincter were measured before and after chemoradiotherapy. All patients underwent surgery, and the 3D-AUS image was compared with the histopathological findings.

RESULTS

Before chemoradiotherapy, the average tumour length was similar in G1 and GII, but the volume differed significantly (P = 0.0408). The response was insignificant in seven (37%) patients, partial in 10 (53%) patients and complete in two (10%) patients in GI. The corresponding figures for GII were one (6%) patient, 12 (75%) patients and three (19%) patients (P = 0.0318). The agreement between pathological and post-chemoratherapy 3D-AUS findings was almost identical for the identification of residual tumour or complete response (κ = 1.0) and substantial for lymph node metastases (κ = 0.74). The mean distance to the internal anal sphincter was greater in GII. A sphincter-saving resection was performed in 2/19 patients in GI and in 14/16 patients in GII (P < 0.0001). The histopathological examination revealed a free distal margin.

CONCLUSION

3D-AUS was shown to evaluate accurately the response to chemoradiotherapy, helping in the selection of patients for a sphincter-saving resection. The distance between the tumour and the internal anal sphincter was the most important parameter in this respect.

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.