MRI in staging of rectal carcinoma Poster No.: C-0152 Congress: ECR 2015 Type: Scientific Exhibit Authors: J. R. Ramos Rodriguez, M. Atencia Ballesteros, M. D. M. Muñoz Ruiz, A. J. Márquez Moreno, M. D. Domínguez Pinos; Málaga/ES Keywords: Neoplasia, Multidisciplinary cancer care, Cancer, Surgery, Diagnostic procedure, Decision analysis, MR-Diffusion/Perfusion, MR, Oncology, Abdomen DOI: 10.1594/ecr2015/C-0152 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 14
Aims and objectives Rectal MRI is increasingly used in the context of multidisciplinary approach of rectal cancer for preoperative evaluation in order to select the most appropriate treatment for each patient. The aim of this study is to determine the diagnostic performance of preoperative rectal MRI in the study of rectal carcinoma regarding depth of infiltration in rectal wall and adjacent structures (T), local lymph node involvement (N), implication of mesorectal fascia and distance of lesion relative to anal margin. Page 2 of 14
Methods and materials Patients were prospectively followed after pelvic MRI for rectal cancer preoperative staging was performed with the following MRI sequences: AXIAL OBLIQUE T2 (TSE): Thin slices (3 mm maximum) perpendicular to tumor, to accurately assess the tumor and its relationship to the rectal wall, mesorectal fascia and pelvic organs. CORONAL T2 (TSE): Especially useful for patients with low rectal cancer to evaluate elevator muscles, sphincter complex, intersphincteric plane and relationship with rectal wall. SAGITAL T2 (TSE): Mainly to calculate the distance to the top edge of the anal sphincter complex and anal verge. AXIAL DWI (Difussion): Very useful to locate the tumor without use of cleansing enemas or gel. May be useful for detection of extramural venous invasion, location of lymph nodes and evaluation of the response after chemotherapy and radiotherapy. ADDITIONAL SEQUENCES (T1 and STIR): Primarily for assessment of regional or distant involvement (lymph nodes, bone metastases, etc) MRI was performed avoiding administration of rectal gel or cleansing enemas in order to prevent discomfort or injury to patients and avoid overdistension of rectal walls that can distort the assessment of tumor depth. MRI Scan was assessed by a radiologist with more than 5 years of experience, studying depth of tumor Infiltration (T stage) [1,2,3], involvement of the mesorectal fascia (fascia is preserved when tumor is farther than 2 mm) [4], distance to anal verge (considering a margin of error of + / - 1 cm) and nodal involvement (N stage) [2] using TNM classification (American Joint Committee on Cancer/International Union Against Cancer) These results were compared with histological analysis of the tumor after resection. Page 3 of 14
Images for this section: Fig. 1: Case 1: Procedure to estimate distance to anal sphincter complex and anal verge in sagital T2 sequence. Page 4 of 14
Fig. 2: Case 1: Assesment depth of infiltration T2: Tumor does not exceed the muscular. Page 5 of 14
Fig. 3: Case 1: Location of tumor by DWI. Page 6 of 14
Results 29 patients have been studied, excluding 10 due to not meeting the conditions of the study. In the remaining 19 patients, rectal MRI has correctly calculated the distance to anal margin in 89.47% of cases. Involvement of mesorectal fascia was successfully set at 100%. As for nodal staging, was performed correctly in 73.68%. Regarding degree of depth infiltration in rectal wall and mesorectal adipose tissue T staging was successful in 52.63%. In our study diagnostic performance of MRI scanning in the preoperative assessment of rectal cancer, especially determining distance to anal margin or anal sphincter complex and possible involvement of the mesorectal fascia is confirmed. In the first case it must be stressed that the two cases in which MRI underestimated distance to anal verge these tumors were located in the rectosigmoid junction, more than 14 cm from the anal margin. Estimation of nodal involvement was satisfactory, however valuation of infiltration in rectal wall had worse results, especially in determining whether the lesion is confined to the muscular layer or infiltrates mesorectal fat minimally (T2/T3a) However, from a practical point of view, the most important implication for patients in terms of prognosis and therapeutic approach is to determine if tumor infiltrates mesorectal fat beyond 5 mm. [2,5]. Taking this as the cutoff to determine whether or not the tumor extends beyond this distance (T3b or less/t3c or more) MRI correctly classifies 94.74 % of the injuries. In all cases it was possible to locate tumor by DWI sequence without rectal gel or cleansing enema. Page 7 of 14
Images for this section: Fig. 4: Case 2: Stage T3b. infiltration outside muscular layer towards mesorectal fat less than 5 mm. Note the presence of two local lymphadenopathies. Page 8 of 14
Fig. 6: Case 2: DWI shows tumor an pathological local nodes. Page 9 of 14
Fig. 5: Case 2: DWI 3D reconstruction movie: tumor is clearly identified. Page 10 of 14
Conclusion Rectal MRI is an excellent diagnostic tool for preoperative evaluation of rectal carcinoma, allowing the correct identification of tumor location, assessing surgical resection margins regarding involvement of mesorectal fascia and estimating properly nodal involvement. In our study, staging depth of infiltration was particularly successful in determining if the tumor infiltrates 5 mm beyond the mesorectal fat, crucial point for the prognosis and tumor treatment planning. Page 11 of 14
Images for this section: Fig. 7: Case 3: Involvement of anterior mesorectal fascia. Page 12 of 14
Fig. 8: Case 3: Distance to anal verge. Page 13 of 14
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