Mesorectal Fascia Status Research Articles

MR staging of rectal cancer: Comparison between the 2012 and 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) Guidelines

PurposeTo compare the adherence of the interpretation and reporting staging system, respectively proposed in the 2012 and 2016 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) Guidelines for Magnetic Resonance Imaging (MRI) staging of rectal cancer, focusing on the improvement offered by the criteria introduced by 2016 ESGAR guidelines. MethodFifty-six patients affected by rectal cancer were included; 25/56 patients underwent upfront surgery; 31 underwent to neo-adjuvant chemo-radiotherapy before surgery. All patients underwent 3 T MRI examination for local staging. All MR exams were evaluated by two radiologists with 20- and 4-years’ experience, who were blinded to each other; the T and N stages, the Mesorectal Fascia (MRF) status and the Extramural Vascular Invasion (EMVI) were assessed according to both 2012 and 2016 ESGAR guidelines. The correlation between radiological and pathological findings, as well as the MRI staging were evaluated. ResultsAs to the expert reviewer, no significant differences were found by comparing the MR T and N stages, T and N restaging, MRF status and EMVI according to 2012 and 2016 ESGAR guidelines. As to the 4-years’ experience radiologist the MR staging agreement between 2012 and 2016 guidelines was “moderate” in N-stage evaluation and “fair” in T-restaging evaluation. No significant discrepancies were found for other parameters. ConclusionsMRI is a reliable method in rectal cancer staging/restaging. The assessment of T-restaging is improved by adopting the 2016 ESGAR guidelines, especially for non-expert readers; this result could be justified by the introduction of diffusion-weighted imaging. On the contrary, the newest guidelines do not improve the diagnostic performance in assessing nodal staging and restaging.

Preoperative chemoradiotherapy in older patients with rectal cancer guided by comprehensive geriatric assessment within a multidisciplinary team—a multicenter phase II trial

BackgroundThe purpose of this study was to evaluate the safety and efficacy of preoperative concurrent chemoradiotherapy (preCRT) for locally advanced rectal cancer in older people who were classified as “fit” by comprehensive geriatric assessment (CGA).MethodsA single-arm, multicenter, phase II trial was designed. Patients were eligible for this study if they were aged 70 years or above and met the standards of “fit” (SIOG1) as evaluated by CGA and of the locally advanced risk category. The primary endpoint was 2-year disease-free survival (DFS). Patients were scheduled to receive preCRT (50 Gy) with raltitrexed (3 mg/m2 on days 1 and 22).ResultsOne hundred and nine patients were evaluated by CGA, of whom eighty-six, eleven and twelve were classified into the fit, intermediate and frail category. Sixty-eight fit patients with a median age of 74 years were enrolled. Sixty-four patients (94.1%) finished radiotherapy without dose reduction. Fifty-four (79.3%) patients finished the prescribed raltitrexed therapy as planned. Serious toxicity (grade 3 or above) was observed in twenty-four patients (35.3%), and fourteen patients (20.6%) experienced non-hematological side effects. Within a median follow-up time of 36.0 months (range: 5.9-63.1 months), the 2-year overall survival (OS), cancer-specific survival (CSS) and disease-free survival (DFS) rates were 89.6% (95% CI: 82.3-96.9), 92.4% (95% CI: 85.9-98.9) and 75.6% (95% CI: 65.2-86.0), respectively. Forty-eight patients (70.6%) underwent surgery (R0 resection 95.8%, R1 resection 4.2%), the corresponding R0 resection rate among the patients with positive mesorectal fascia status was 76.6% (36/47).ConclusionThis phase II trial suggests that preCRT is efficient with tolerable toxicities in older rectal cancer patients who were evaluated as fit based on CGA.Trial registrationThe registration number on ClinicalTrials.gov was NCT02992886 (14/12/2016).

Total neoadjuvant therapy for locally advanced rectal cancer: a three-group propensity score matched study

PurposeTotal neoadjuvant therapy (TNT) has emerged as a therapeutic approach for locally advanced rectal cancer (LARC). However, the optimal chemotherapy cycles within TNT remain uncertain. This study aimed to evaluate and compare the prognostic efficacy of varying cycles of chemotherapy during TNT for LARC.MethodsPatients diagnosed with LARC (T3-4N0M0/T1-4N1-2M0), who underwent TNT or chemoradiotherapy followed by total mesorectal excision (TME) between 2015 and 2020, were retrospective included. Patients were categorized into three groups based on their neoadjuvant strategy: CRT (long-course chemoradiotherapy), STNT (long-course CRT with one to three cycles of chemotherapy), and LTNT (long-course CRT with four or more cycles of chemotherapy). Propensity score matching (PSM) based on gender, age, body mass index, tumor distance from the anal verge, clinical T stage, clinical N stage, and mesorectal fascia status was employed to reduce confounding bias. Primary endpoints were disease-free survival (DFS) and metastasis-free survival (MFS).ResultsThe study comprised 372 patients, with 73 patients in each group after PSM. Compared with CRT, both STNT and LTNT demonstrated improved DFS (5-year rate: 59.7% vs. 77.8% vs. 76.5%, p = 0.027) and MFS (5-year rate: 65.1% vs. 81.3% vs. 81.4%, p = 0.030). There was no difference in DFS or MFS between STNT and LTNT. These favorable outcomes were consistent among subgroups defined by tumor distance from the anal verge ≥ 5 cm, clinical T3 stage, clinical N positive status, or involved mesorectal fascia.ConclusionCompared to CRT, both STNT and LTNT demonstrated improved DFS and MFS outcomes. Notably, survival outcomes were similar between STNT and LTNT, suggesting that chemotherapy cycles in TNT may not significantly impact survival.

Low Rectal Cancers at Initial Staging MRI.

Low rectal cancers, which are associated with increased risk of local recurrent disease and poorer prognosis, have unique anatomic considerations and issues for staging and treatment that do not apply to mid and high rectal cancers. Although tumor histology help drive the staging and treatment of all rectal cancers, it is of particular importance in low rectal cancers, which may involve the anal canal, to help establish whether a low rectal mass should be staged and treated as a rectal cancer (ie, adenocarcinoma) or an anal cancer (ie, squamous cell carcinoma). Optimal staging and treatment of rectal cancer are contingent on tumor location and local extent, which help guide management decisions including neoadjuvant therapy and curative surgical treatment strategies. Tumor location in the low rectum and local involvement of the anal canal, sphincter, and pelvic floor help determine whether a patient can undergo sphincter-preserving resection such as a low anterior resection versus abdominoperineal resection to achieve negative surgical margins. Issues exist related to the anatomy and patterns of disease spread that are unique to the low rectum and include how to determine and stage anal sphincter involvement, mesorectal fascia status at the pelvic floor, and nodal status of extramesorectal nodes such as the external iliac and inguinal lymph nodes. For these reasons, it is imperative that radiologists who interpret rectal cancer staging MRI examinations feel comfortable with the unique anatomy of the low rectum and anal canal, nuances of low rectal cancer local disease spread, and treatment paradigms for low rectal cancer. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Gollub in this issue.

Treatment pattern and outcome of locally advanced rectal cancer in Tikur Anbessa Specialized Hospital (TASH), Addis Ababa, Ethiopia: An institution-based cross-sectional study.

e15640 Background: The standard management of locally advanced rectal cancer (LARC) is neo-adjuvant concurrent chemo radiation (CCRT) followed by total meso-rectal excision. Recently there is an increased interest in total neo-adjuvant treatment (TNT). Most patients with rectal cancer in developing countries present in advanced stage for several reasons including lack of resources and delayed health seeking behavior. Most patients are not able to get standard management. This study tries to assess treatment patterns and outcomes in LARC. Methods: A cross-sectional study was conducted in patients with LARC that are treated at TASH from Jan 1, 2020 up to Sept. 2022. The data was collected from Patient’s cards using a pre-structured format that included demographic data, laboratory, pathological and imaging information. Data analysis was conducted by using IBM SPSS version 25. Results: 100 patients were included in the study, 51% were male. The median (range) age at diagnosis was 45.5 (20-86) years. 81% of patients came to our center without getting any oncologic treatment and 75.3% of them were presented on a multi-disciplinary tumor board for their treatment decision. Upfront surgery was decided in 48.1% (39/81) of patients. Standard neo-adjuvant treatment of either TNT or CCRT was decided in 23.4% (19/81) and 8.6% (7/81) of patients respectively. There is no significant association between tumor location, TNM stage, mesorectal fascia status and first treatment decision. Only 12 (14.8%) patients were able to finish their whole treatment plan. The most common reason for not finishing all treatment was prolonged radiation waiting time, with the median (range) waiting time of 10 ± 7.1 (1-26) months. From 81 treatment naive patients, 79 were decided to have surgery; and 59.5% (47/79) underwent the planned surgery with 89.9% R0 resection rate. R0 resection rate in patients who undergo upfront surgery was 91.2% (31/34). Neo-adjuvant chemotherapy was given to 34.6% (28/81); and only 18% (5/28) underwent subsequent surgery. The most common reason for not undergoing subsequent surgery was disease progression 43.5% (10/23) during or after finishing the neo-adjuvant chemotherapy. Only 24% of the study participants received radiotherapy. From the patients who took radiotherapy, only two patients received short course radiotherapy. Conclusions: Treatment decisions for rectal cancer in our study did not conform to standard treatment recommendations. Upfront surgery maybe a better option than neoadjuvant chemotherapy, since timely administration of standard neoadjuvant treatment is not possible. Alternative radiotherapy treatment options like short course radiotherapy may be better in resource limited setting to alleviate the longer radiotherapy waiting time.

Comparison of compressed sensing-sensitivity encoding (CS-SENSE) accelerated 3D T2W TSE sequence versus conventional 3D and 2D T2W TSE sequences in rectal cancer: a prospective study

PurposeThis study aimed to evaluate the image quality and diagnostic value of compressed sensing-sensitivity encoding (CS-SENSE) accelerated 3-dimensional (3D) T2-weighted turbo spin-echo (T2W TSE) sequence in patients with rectal cancer compared with conventional 3D and 2-dimensional (2D) sequences.MethodsA total of 54 patients who underwent the above three sequences were enrolled. Two radiologists independently reviewed the image quality using an ordinal 5-point Likert scale. The quantitative measurement was performed to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The diagnostic value was assessed using TN staging, extramural vascular invasion and mesorectal fascia status. Friedman and McNemar’s tests were applied for comparative analysis.ResultsForty-two patients were successfully included. Compared with 3D and 2D sequences, the CS-SENSE 3D sequence speeded up by 39% and 23%, respectively. The edge sharpness of CS-SENSE 3D images was similar to that of 3D and 2D images. The noise of CS-SENSE 3D images was comparable to that of 3D images but higher than that of 2D images. The SNRtumor and SNRrectal wall of CS-SENSE 3D images were considerably lower than those of 3D and 2D images. The CNR of CS-SENSE 3D images was similar to that of 3D images but lower than that of 2D images. However, no considerable differences were noted in diagnostic value among the three sequences.ConclusionsCS-SENSE 3D T2 sequence provided comparable diagnostic performance, with substantially reduced imaging time and no significant sacrifices in image quality. This technique may serve as a reliable tool for evaluating rectal cancer.Graphical abstract

Assessment of mesorectal fascia status in MRI compared with circumferential resection margin after total mesorectal excision and predictors of involved margins

BackgroundCircumferential resection margin is an important prognosticator for total mesorectal excision outcome. We investigated the status of mesorectal fascia on magnetic resonance imaging compared with circumferential resection margin on pathology and factors associated with status change. MethodsThis was a retrospective analysis of a prospective database of rectal cancer patients who underwent surgery. Mesorectal fascia status on magnetic resonance imaging done before neoadjuvant therapy and circumferential resection margin status on pathology were compared. The study outcomes were factors associated with a margin status conversion between magnetic resonance imaging and pathology, and predictors of involved circumferential resection margin. ResultsIn total, 244 patients (average follow-up of 25.4 months) were included. Eighty-one (33.2%) patients had potentially involved mesorectal fascia in magnetic resonance imaging and 12 (4.9%) had involved circumferential resection margin in pathology. A total of 2.8% of patients had a conversion of clear mesorectal fascia in magnetic resonance imaging to involved circumferential resection margin. Abdominoperineal resection was significantly associated with this status change (odds ratio: 25, 95% confidence interval: 2.4–255.8, P = .007). In total, 7.4% of patients with potentially involved mesorectal fascia had persistently involved circumferential resection margin. Lack of total neoadjuvant therapy was associated with higher, yet statistically insignificant, odds of persistently involved circumferential resection margin (odds ratio: 12, 95% confidence interval: 0.65–220.8, P = .09). The significant independent predictors of involved circumferential resection margin were body mass index (odds ratio: 1.2, P = .016) and abdominoperineal resection (odds ratio: 4.22, P = .04). ConclusionChange of clear mesorectal fascia in magnetic resonance imaging to an involved circumferential resection margin in pathology was recorded in 2.8% of patients; abdominoperineal resection might be associated with this change. Approximately 7% of patients had persistent involvement of circumferential resection margin as determined by pathology. Omission of total neoadjuvant therapy might be associated with persistent margin involvement.

Accuracy of magnetic resonance imaging staging of tumour and nodal stage in rectal cancer treated by primary surgery: a population-based study.

The preoperative stage of rectal cancer is an important prognostic factor affecting treatment recommendations. Currently, magnetic resonance imaging (MRI) is used for clinical staging to identify patients who should be recommended for neoadjuvant oncological treatment. The aim of this work was to investigate the accuracy of the preoperative T- and N-stage and also involvement of the mesorectal fascia (MRF) as determined by MRI in a Swedish national cohort. Patients who had undergone resectional surgery for rectal cancer without neoadjuvant treatment in Sweden in the period 2013-2017 were identified through the Swedish Colorectal Cancer Registry (n=2062). The T- and N-stage determined by preoperative MRI were compared with the histopathological results. The MRI-assessed MRF status was compared with the circumferential resection margin. Sensitivity for differentiating T1-2 from T3-4 was 69% and specificity 77%. Sensitivity to detect N1-2 was 42% and specificity 81%. Sensitivity for MRF positivity was 50% and specificity 92%. Agreement analysed by weighted kappa analysis was 0.47 for T-stage [confidence interval (CI) 0.44-0.51], 0.24 for N-stage (CI 0.19-0.24) and 0.20 for MRF status (CI 0.12-0.29). In this study, accuracy of the preoperative MRI was lower than expected for rectal cancers. Overstaging might lead to potentially harmful neoadjuvant treatment and understaging can lead to a higher risk of tumour recurrence. The results of this study show that efforts should be made to increase the accuracy of the preoperative evaluation in order to optimize treatment recommendations.

Nomograms for predicting pathological response to neoadjuvant treatments in patients with rectal cancer.

BACKGROUNDIn recent decades, neoadjuvant therapy (NT) has been the standardized treatment for locally advanced rectal cancer (LARC). Approximately 8%-35% of patients with LARC who received NT were reported to have achieved a complete pathological response (pCR). If the pathological response (PR) can be accurately predicted, these patients may not need surgery. In addition, no response after NT implies that the tumor is destructive, resistant to both chemotherapy and radiotherapy, and prone to having a high metastatic potential. Therefore, developing accurate models to predict PR has great clinical significance and can help achieve individualized treatment in LARC patients.AIMTo establish nomograms for predicting PR to different NT regimens based on pretreatment parameters for patients with LARC.METHODSRectal cancer patients were identified from the database of The Sixth Affiliated Hospital, Sun Yat-sen University from January 2012 to December 2016. Logistic regression and nomograms were developed to predict the probability of pCR and good downstaging to ypT0-2N0M0 (ypTNM 0-I), respectively, based on pretreatment parameters for all LARC patients. Nomograms were also developed for three NT regimens (capecitabine/deGramont-RT, mFOLFOX6, and mFOLFOX6-RT) to predict pCR probability.RESULTSFour hundred and three patients were included in this study; 72 (17.9%) had pCR at the final pathology report, and 177 (43.9%) achieved good downstaging to ypT0-2N0M0 (ypTNM 0-I). The nomogram for predicting pCR probability showed that NT regimens, tumor differentiation, mesorectal fascia (MRF) status, and tumor length significantly influenced pCR probability. When predicting the probability of good downstaging, tumor differentiation, MRF status, and clinical T stage were the significant factors. Nomograms were developed based on NT regimens. For the capecitabine/de Gramont-RT group, the multivariate analysis showed that the neutrophil-lymphocyte ratio (NLR) was the only significant factor, thus we could not develop a nomogram for this regimen. For the mFOLFOX6-RT group, the analysis showed that the significant factors were tumor length and MRF status; and for the mFOLFOX6 group, the significant factors were tumor length and tumor differentiation.CONCLUSIONWe established accurate nomograms for predicting the PR to preoperative NT regimens based on pretreatment parameters for LARC patients.

Quality of preoperative pelvic computed tomography (CT) and magnetic resonance imaging (MRI) for rectal cancer in a region in Ontario: A retrospective population-based study.

Treatment decisions for rectal cancer rely on preoperative staging with CT and MRI scans. We assessed the quality of such scans in a region of Ontario. We retrospectively collected data for patients undergoing rectal cancer surgery between July 2011 and December 2014. We measured three aspects of quality: use; comprehensiveness of reporting T-category, N-category, mesorectal fascia (MRF) status; and in non-radiated patients sensitivity and specificity of reports for relevant elements. A total of 559 patients underwent major rectal cancer surgery. Preoperative staging with CT and MRI was performed in 93% and 50% of patients. CT scan reports provided information on T-category, N-category, and MRF status in 41%, 92%, and 16% of cases. These same elements were reported on MRI in 88%, 93%, and 62% of cases. CT scan sensitivity and specificity was 80% and 80% for T-category, and 85% and 39% for N-category. MRI sensitivity and specificity was 75% and 81% for T-category, 79% and 37% for N-category, and 33% and 89% for MRF status. In this region of Ontario, pre-operative MRI was underutilized, CT reporting of MRF status was low, and when reported sensitivity and specificity of T- and N-category were similar for CT and MRI.

Magnetic resonance imaging following neoadjuvant chemoradiation and transanal endoscopic microsurgery for rectal cancer.

Full-thickness local excision after neoadjuvant chemoradiotherapy (CRT) for patients with rectal cancer and incomplete clinical response has been a treatment strategy for organ preservation. Follow-up of these patients is challenging since anatomic distortion and postoperative changes may be clinically indistinguishable from tumour recurrence. MRI may have a role in detecting recurrence. The aim of this study was to describe the MRI findings during follow-up in patients having local excision following CRT with and without local recurrence. The data were collected retrospectively from a single centre. Fifty-three patients with rectal cancer who had full-thickness local excision after neoadjuvant CRT and near-complete response were eligible for the study. Patients with local recurrence were treated by radical salvage surgery. The main outcome was local MRI assessment findings during follow-up. Fifteen patients (five who developed local recurrence and 10 with no evidence of local recurrence) had MR images available for review and were included in the study. High signal intensity and thickening of the rectal wall were present in all patients with recurrent disease within the rectal wall. Overall, 80% of the patients with recurrence showed diffusion restriction. MRI mesorectal fascia status and circumferential resection margin showed agreement in all cases. A low signal intensity scar was seen in all patients without recurrent disease. MRI shows high signal intensity and thickening of the rectal wall in recurrent disease in comparison to a low signal intensity fibrotic scar in non-recurrent disease. These findings may be useful in surveillance of these patients.

Rectal Mucinous Adenocarcinoma: MR Imaging Assessment of Response to Concurrent Chemotherapy and Radiation Therapy-A Hypothesis-generating Study.

Purpose To develop a system for assessment of tumor regression grade (TRG) with magnetic resonance (MR) imaging that is applicable to rectal mucinous adenocarcinoma (RMAC) and to obtain a preliminary evaluation of the association of MR imaging assessment of TRG with response to preoperative concurrent chemotherapy and radiation therapy (CCRT). Materials and Methods This retrospective study was approved by the institutional review board, and informed consent was waived. Pre- and post-CCRT MR images of 59 patients with RMAC (median age, 59 years; range, 29-80 years; 42 men [median age, 59 years; range, 36-80 years] and 17 women [median age, 57 years; range, 29-79 years]) who underwent CCRT and subsequent elective resection from July 2005 to June 2015 were analyzed. Two experienced gastrointestinal radiologists independently analyzed imaging parameters such as T stage, mesorectal fascia status, extramural vascular invasion status, and TRG by using modified criteria developed for assessment of RMAC. Interobserver variability was calculated with weighted κ analysis, and disagreement was settled in consensus. MR imaging TRG results were compared with those from pathologic TRG analysis (Mandard grade). Logistic regression analyses were performed to evaluate associations between imaging parameters and pathologic TRG. Results There was moderate to substantial agreement for imaging parameters (post-CCRT T stage-weighted κ, 0.7134; post-CCRT mesorectal fascia status, 0.618; TRG, 0.5023). Modified MR imaging TRG results were significantly associated with pathologic responsiveness (responsive group, Mandard grade 1 or 2; nonresponsive group, Mandard grades 3-5; P = .023). Results of univariate and multivariate logistic regression analyses indicated that MR imaging TRG was the only factor significantly associated with CCRT responsiveness (univariate analysis, P = .023; multivariate analysis, P = .0261). Conclusion The modified MR imaging assessment of TRG was associated with treatment response to CCRT in patients with RMAC. © RSNA, 2017 Online supplemental material is available for this article.

Diagnostic Accuracy of MRI for Assessment of T Category and Circumferential Resection Margin Involvement in Patients With Rectal Cancer

The prognosis of rectal cancer is directly related to the stage of the tumor at diagnosis. Accurate preoperative staging is essential for selecting patients to receive optimal treatment. The purpose of this study was to evaluate the diagnostic performance of MRI in tumor staging and circumferential resection margin involvement in rectal cancer. A systematic literature search was performed in MEDLINE, EMBASE, PubMed, Cochrane Database of Systematic Reviews, and Web of Science database. Original articles from 2000 to 2016 on the diagnostic performance of MRI in the staging of rectal cancer and/or assessment of mesorectal fascia status were eligible. Pooled diagnostic statistics including sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated for invasion of muscularis propria, perirectal tissue, and adjacent organs and for circumferential resection margin involvement through bivariate random-effects modeling. Summary receiver operating characteristic curves were fitted, and areas under summary receiver operating characteristic curves were counted to evaluate the diagnostic performance of MRI for each outcome. Thirty-five studies were eligible for this meta-analysis. Preoperative MRI revealed the highest sensitivity of 0.97 (95% CI, 0.96-0.98) and specificity of 0.97 (95% CI, 0.96-0.98) for muscularis propria invasion and adjacent organ invasion. Areas under summary receiver operating characteristic curves indicated good diagnostic accuracy for each outcome, with the highest of 0.9515 for the assessment of adjacent organ invasion. Significant heterogeneity existed among studies. There was no notable publication bias for each outcome. This meta-analysis revealed relatively high diagnostic accuracy for preoperative MRI, although significant heterogeneity existed. Therefore, exploration should be focused on standardized interpretation criteria and optimal MRI protocols for future studies. MRI showed relatively high diagnostic accuracy for preoperative T staging and circumferential resection margin assessment and should be reliable for clinical decision making.

Profiling of rectal cancers MRI in pathological complete remission states after neoadjuvant concurrent chemoradiation therapy

To fully characterise the magnetic resonance imaging (MRI) traits of rectal cancers in a large sample of patients, each experiencing pathological complete remission (pCR) after neoadjuvant concurrent chemoradiation therapy (CCRT). A total of 120 patients (77 male, 43 female; median age, 59.5 years; range, 32-81 years) with rectal cancers in CCRT-induced pCR states who underwent pre- and post-CCRT MRI and eventual surgery between July, 2005 and September, 2014 were retrospectively reviewed. In most (n=100), diffusion-weighted imaging was also performed. Tumour volume, tumour regression grade (TRG), T-stage, mesorectal fascia (MRF) status, and T2 signal intensity (T2-SI) were analysed. Paired t-test and McNemar's test were applied for statistical comparisons. Tumour volume declined sharply after CCRT (pre-CCRT, 21.5 ± 22.4 cm(3); post-CCRT, 6.6 ± 8.4 cm(3); p<0.001). TRG distribution was as follows: G1 (clinical CR), 3; G2, 38; G3, 78; G4, 1; and G5 (marked progression), 0. Downstaging of T-stage (34%,16/47) and MRF status (19.7%,13/66) did occur; but on post-CCRT MRI, 25.8% (31/120) remained at T3 ≥ 5 mm or T4 stage, and 44.2% (53/120) were MRF-positive. A majority (88.3%, 106/120) of patients displayed intermediate T2-SI prior to CCRT. Most converted to dark T2-SI after CCRT, with 12.5% (15/120) unchanged. On post-CCRT MRI, 11% (11/100) of patients showed diffusion restriction. MRI findings in CCRT-induced pCR-status rectal cancers were highly variable. Tumour volume and T2-SI mostly decreased; however, such lesions occasionally presented with unexpected atypical features, such as large residual volume and/or intermediate T2-SI.

Prediction of efficacy of neoadjuvant radiochemotherapy based on depth of invasion in T3 rectal cancer

To investigate the association of mesorectal invasion depth before neoadjuvant radiochemotherapy with pathological outcome and to provide evidence for individualized treatment in T3 rectal cancer. Retrospective analysis was performed on the clinical records of 73 consecutive rectal cancer patients treated with neoadjuvant radiochemotherapy and radical surgery in the Shanghai Cancer Center from January 2010 to December 2012. All the patients underwent high-resolution MRI and the depth of mesorectal invasion, lymph node status, tumor length, and mesorectal fascia status were evaluated. The category T3 was subdivided according to the measurement of the maximal tumor invasion beyond the outer border of the muscularis propria: T3a(<5 mm), T3b(5-10 mm) and T3c(>10 mm). The association of mesorectal invasion depth,other MRI and clinical features with short-term efficacy was analyzed,especially with pathological complete response(pCR). T3a, T3b and T3c accounted for 19.2%, 64.4% and 16.4% in 73 rectal cancer patients who underwent high resolution MRI, respectively. There were 42.9% of T3a patients achieved pathological complete response,significantly higher than those of T3b(14.9%)and T3c(0%) (P=0.017). T3a rectal cancer patients are more likely to achieve pCR than those of T3b and T3c after neoadjuvant radiochemotherapy. The maximal tumor invasion beyond the outer border of the muscularis propria less than 5 mm may act as a predictive factor and guide the follow-up treatment of T3 rectal cancer.

Assessment of T staging and mesorectal fascia status using high-resolution MRI in rectal cancer with rectal distention

To determine the accuracy of high-resolution magnetic resonance imaging (MRI) using phased-array coil for preoperative assessment of T staging and mesorectal fascia infiltration in rectal cancer with rectal distention. In a prospective study of 67 patients with primary rectal cancer, high-resolution magnetic resonance imaging (in-plane resolution, 0.66 multiply 0.56) with phased-array coil were performed for T-staging and measurement of distance between the tumor and the mesorectal fascia. The assessment of MRI was compared with postoperative histopathologic findings. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were evaluated. The overall magnetic resonance accuracy was 85.1% for T staging and 88% for predicting mesorectal fascia involvement. Magnetic resonance sensitivity, specificity, accuracy, positive predictive value, and negative predictive value was 70%, 97.9%, 89.6%, 93.3% and 88.5% for <or= T2 tumors, 90.5%, 76%, 85.1%, 86.4% and 82.6% for T3 tumors, 100%, 95.2%, 95.5%, 62.5% and 100% for T4 tumors, and 80%, 90.4%, 88%, 70.6% and 94% for predicting mesorectal fascia involvement, respectively. High-resolution MRI enables accurate preoperative assessment for T staging and mesorectal fascia infiltration in rectal cancer with rectal distention.