Rectal carcinoma: thin-section MR imaging for staging in 28 patients

Diffusion-weighted imaging of the rectosigmoid colon: preliminary findings

OBJECTIVES

The aims of this study were to determine and evaluate the apparent diffusion coefficient (ADC) values of the rectal wall for identifying inflammatory bowel disease (IBD) and rectosigmoid (rectum and sigmoid colon) malignancies.

METHODS

Diffusion-weighted magnetic resonance imaging (DWI) findings of 23 patients (mean age, 57 years) consisting of 14 patients with rectosigmoid adenocarcinomas and 9 patients with IBD (6 with ulcerative colitis and 3 with Crohn disease) were retrospectively reviewed. In addition, 30 healthy controls (mean age, 45 years) were enrolled in the study. Diffusion-weighted imaging was performed with b factors of 0, 500, and 1000 s/mm2.

RESULTS

The mean (SD) ADC values of the control, IBD, and rectosigmoid adenocarcinoma groups were 1.47 (0.19) x 10(-3) mm2/s, 1.37 (0.12) x 10(-3) mm2/s, and 0.97 (0.14) x 10(-3) mm2/s, respectively. Among the patients with IBD, 2 were in the active, and the rest were in the inactive period, with mean (SD) ADC values of 1.21 (0.08) x 10(-3) and 1.42 (0.09) x 10(-3), respectively. The ADC values of the normal rectum and rectosigmoid malignancy group and rectosigmoid carcinoma and IBD groups were significantly different (P < 0.01). A cutoff value for carcinomas of 1.14 x 10(-3) mm2/s yielded a sensitivity and specificity of 93.3% and 93.3%, respectively.

CONCLUSIONS

Our preliminary findings show that quantitative DWI may be able to differentiate the normal rectum from neoplastic involvement, in addition to distinguishing between inflammatory and neoplastic involvements. However, radiologists should be aware of possible overlaps that may lead to misdiagnoses when DWI is used alone.

Factors related to preoperative assessment of the circumferential resection margin and the extent of mesorectal invasion by magnetic resonance imaging in rectal cancer: a prospective comparison study

BACKGROUND

This study was designed to identify factors related to inaccurate prediction of circumferential resection margin (CRM) and the extent of mesorectal invasion (EMI) in T3 tumors by preoperative magnetic resonance imaging (MRI) in rectal cancer.

METHODS

A total of 66 patients with rectal cancer were enrolled prospectively in this study. CRM was defined as the distance from the outer tumor margin to the mesorectal fascia, and EMI was defined as the distance from the outer surface of the muscularis propria to the outermost tumor margin. CRM and EMI measurements on MRI were compared with corresponding measurements from whole-mount sections using 1-mm and 5-mm reference values, respectively, as prognostic indicators. The following variables were analyzed for relevance to preoperative staging: tumor distance from the anal verge (lower and middle), tumor location (anterior and posterior), tumor (T) and nodal (N) stage, and the thickness of the perirectal fat (anterior, left, right, and posterior positions).

RESULTS

MRI correctly predicted CRM status in 57 of the 66 tumors and EMI status in 51 of the 58 tumors (eight T1 tumors were excluded from EMI analysis). Univariate analysis showed that T3 stage, lymph node involvement, anterior tumor location, and thin perirectal fat thickness at the anterior portion were related to incorrect prediction of CRM. Anterior tumor location and thin perirectal fat thickness at the anterior portion were related to incorrect prediction of EMI.

CONCLUSIONS

Preoperative chemoradiation can be accurately guided by preoperative MRI staging, but CRM and EMI in anterior rectal tumor should be interpreted with caution.

Multidisciplinary Rectal Cancer Management: 2nd European Rectal Cancer Consensus Conference (EURECA-CC2)

BACKGROUND AND PURPOSE

During the first decade of the 21st century a number of important European randomized studies were published. In order to help shape clinical practice based on best scientific evidence from the literature, the International Conference on 'Multidisciplinary Rectal Cancer Treatment: Looking for an European Consensus' (EURECA-CC2) was organized in Italy under the endorsement of European Society of Medical Oncology (ESMO), European Society of Surgical Oncology (ESSO), and European Society of Therapeutic Radiation Oncology (ESTRO).

METHODS

Consensus was achieved using the Delphi method. The document was available to all Committee members as a web-based document customized for the consensus process. Eight chapters were identified: epidemiology, diagnostics, pathology, surgery, radiotherapy and chemotherapy, treatment toxicity and quality of life, follow-up, and research questions. Each chapter was subdivided by a topic, and a series of statements were developed. Each member commented and voted, sentence by sentence thrice. Sentences upon which an agreement was not reached after voting round # 2 were openly debated during a Consensus Conference in Perugia (Italy) from 11 December to 13 December 2008. A hand-held televoting system collected the opinions of both the Committee members and the audience after each debate. The Executive Committee scored percentage consensus based on three categories: "large consensus", "moderate consensus", and "minimum consensus".

RESULTS

The total number of the voted sentences was 207. Of the 207, 86% achieved large consensus, 13% achieved moderate consensus, and only 3 (1%) resulted in minimum consensus. No statement was disagreed by more than 50% of the members. All chapters were voted on by at least 75% of the members, and the majority was voted on by >85%.

CONCLUSIONS

This Consensus Conference represents an expertise opinion process that may help shape future programs, investigational protocols, and guidelines for staging and treatment of rectal cancer throughout Europe.

Accuracy of high-resolution magnetic resonance imaging in preoperative staging of rectal cancer

BACKGROUND

To achieve better prognosis and quality of life for patients with rectal cancer, extent of surgery and neoadjuvant chemoradiotherapy should accurately reflect disease extent. The aim of this study was to evaluate accuracy of high-resolution magnetic resonance imaging (HRMRI) for preoperative staging of rectal cancer.

METHODS

Between 2001 and 2003, 104 patients with primary rectal cancer were examined with HRMRI and underwent radical surgery. Transmural invasion depth and lymph node metastasis were assessed prospectively and classified according to the American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) system by both HRMRI and histopathology, and results were compared. Criteria for mesorectal and lateral pelvic lymph node involvement were short-axis diameters of > or =5 mm and > or =4 mm, respectively.

RESULTS

There were 15 pT1, 25 pT2, 50 pT3, and 14 pT4 tumors. Overall accuracy rate for transmural invasion depth was 84%. The mesorectal fascia could be visualized in 98% of patients. Twenty-three patients had mesorectal fascia involvement and the overall accuracy rate was 96% (sensitivity, 96%; specificity, 96%). Fifty-three patients had mesorectal lymph node metastasis and the overall accuracy rate was 74% (sensitivity, 83%; specificity, 64%). Lateral pelvic lymph node metastasis was observed in 15 patients and the overall accuracy rate was 87% (sensitivity, 87%; specificity, 87%).

CONCLUSIONS

HRMRI was moderately accurate for prediction of mesorectal lymph node metastasis and highly accurate regarding transmural invasion depth, and mesorectal fascia and lateral pelvic node involvement. Therefore, HRMRI appears useful for preoperative decision-making in rectal cancer treatment.

A simple scoring system based on clinical features to predict locally advanced rectal cancers

PURPOSE

The purpose of this study was to identify clinical risk factors and establish a prediction scoring system for locally advanced rectal cancer.

MATERIALS AND METHODS

Retrospective univariate and multivariate logistic analyses were conducted for 413 curable rectal cancer patients. Clinical factors found to be significantly related with tumor stages were incorporated into a scoring system to predict locally advanced stages, which was validated in an independent cohort of 279 rectal cancer patients.

RESULTS

In the training set, tumor size, differentiation, and serum carcinoembryonic antigen (CEA) level (P < 0.01) were significant predictors of locally advanced rectal cancer in both univariate and multivariate analyses, which were incorporated into a proposed scoring system to predict locally advanced stages. The area under the receiver operating characteristic curve (AUROC) of this scoring system was 0.751 and the prediction accuracy was 78.2%. Patients were categorized into three subsets according to the total score. The low-risk group (score 0) had a smaller chance (18.2%) to have locally advanced rectal cancer, compared to mean 49.2% for the intermediate-risk group (score 1) and mean 83.0% for the high-risk group (score of 2-4; P < 0.05). In the validation set, the AUROC of the scoring system was 0.756 and the prediction accuracy was 75.3%.

CONCLUSIONS

Tumor size more than 2 cm, poor differentiation, and elevated serum CEA level are high-risk factors of locally advanced rectal cancer. A simple scoring system based on these three factors may be valuable to predict locally advanced rectal cancer.

Morphology of the mesorectum in patients with primary rectal cancer

PURPOSE

The size and contents of the pelvis differ between the genders, and this may affect mesorectal size and shape. The aim of this prospective pilot study was to examine radiologically the applied anatomy of the mesorectum.

METHODS

Fifty-eight patients (35 male, 23 female) with primary rectal cancer who had suitable high-resolution staging pelvic magnetic resonance images between November 2002 and July 2004 were studied. Ten variables of mesorectal morphology were measured on axial images at the ischial spines. The associations between morphologic variables and gender and body mass index were examined.

RESULTS

Compared with female patients, male patients had a larger area of overall mesorectal package (3,776 mm2 vs. 2,772 mm2, P = 0.001), larger area of mesorectal fat (2,562 mm2 vs. 1,842 mm2, P = 0.001), and higher ratio of anteroposterior to transverse diameter of the mesorectal package (0.82 vs. 0.56, P < 0.001). The anterior mesorectal fat buffer was significantly thinner in females than in males (2.9 mm vs. 7.8 mm, P < 0.001). Mesorectal fat area was greater in males with a body mass index >25 than with a body mass index <25.

CONCLUSIONS

Males have a larger overall mesorectal package compared with females, mainly caused by mesorectal fat. The anterior mesorectal fat is significantly thinner in females than in males. Such morphologic differences may affect resection margin status.

Prognostic heterogeneity of endosonographic T3 rectal cancer

PURPOSE

This study aimed to assess the prognostic implications of uT3 rectal carcinomas according to the tumor thickness and to analyze the correlation between this ultrasound-based parameter and other prognostic factors.

METHODS

Seventy-four patients with uT3(pM0) rectal tumors underwent primary surgery from 1996 to 2003. Preoperative endorectal ultrasound was used to assess uN stage, maximum tumor perimeter, and maximum tumor thickness. An ultrasound maximum tumor thickness cutoff point for local recurrence subdividing T3 tumors into uT3a and uT3b was established.

RESULTS

Median follow-up was 41 months (range, 24-59). The 5-year actuarial local and overall recurrence rates were 9.82 percent (n = 7) and 42.46 percent (n = 23), respectively. uN stage(P = 0.05), circumferential resection margin involvement (P = 0.002), an ultrasound maximum tumor thickness (P = 0.01), and locally advanced tumors (P = 0.001) were related to a significantly increased risk of local recurrence. An ultrasound maximum tumor thickness (hazard ratio, 1.15; 95 percent confidence interval, 1.0-1.2) and locally advanced tumor (hazard ratio, 17.21; 95 percent confidence interval, 2.99-98.84) were preoperative independent variables for predicting local recurrence. Locally advanced tumor was the only preoperative independent prognostic factor for overall recurrence (P = 0.004; hazard ratio, 1.09; 95 percent confidence interval, 1.0-1.1). An ultrasound maximum tumor thickness with a 19-mm cutoff point, subdividing the T3 tumors into uT3a and uT3b, can be used to predict local recurrence. Locally advanced tumors (P = 0.02) and circumferential resection margin involvement (P = 0.005) showed a significant association with an ultrasound maximum tumor thickness >19 mm.

CONCLUSIONS

A maximum tumor thickness measured by endorectal ultrasound in pT3 rectal cancer is an independent prognostic factor for local and overall recurrence. An ultrasound maximum tumor thickness cutoff point of 19 mm may be useful to classify patients preoperatively and to select them for primary surgery or neoadjuvant therapy.

Magnetic resonance imaging of anorectal neoplasms

Among imaging techniques, magnetic resonance imaging (MRI) has evolved as the most robust technique for the detection, characterization, and staging of anorectal cancers. With its superior contrast resolution, multiplanar imaging capability, and nil radiation risk, it has become the standard preoperative imaging tool in rectal tumors. In this article we aim to outline the various types of anorectal cancers, highlight the complex anatomy of this region, and discuss the immensely useful role of MRI in the management of anorectal cancers. Existing limitations and future applications in this area will also be discussed. Because rectal adenocarcinomas constitute the majority of tumors in this region, we will be discussing the input of MRI in the management of this condition in greater detail. This will be followed by an overview of MRI in anal carcinoma and other less common anorectal neoplasms.

Locally advanced rectal cancer: MR imaging in prediction of response after preoperative chemotherapy and radiation therapy

PURPOSE

To prospectively differentiate, at magnetic resonance (MR) imaging, patients with locally advanced nonmucinous rectal cancer who will respond to long-course chemotherapy and radiation therapy (CRT) from those who will not respond, with histopathologic results as the reference standard.

MATERIALS AND METHODS

Institutional review board approval for this study was obtained, and all patients provided written informed consent. High-spatial-resolution T2-weighted MR images were acquired before and 6-8 weeks after CRT in 53 patients (33 men, 20 women; mean age, 63 years; age range, 42-79 years). Patients were categorized as responders to CRT (patients with T3 cancer that converted to T2 or a lower stage, patients with T4 cancer that converted to T3 or a lower stage) or as nonresponders (patients with stable or progressive disease). At the posttreatment MR imaging examination, a decrease in signal intensity was considered to represent a morphologic response with fibrosis. Before CRT and surgery, tumor volume was calculated at MR imaging by multiplying cross-sectional area by section thickness. Tumor length was measured at MR imaging and in the histopathologic specimen. Nodal downstaging was evaluated. The relationship between pathologic response, morphologic MR imaging response, and percentage volume reduction was evaluated with the Mann-Whitney-Wilcoxon two-sample test.

RESULTS

Morphologic response assessment with MR imaging achieved a positive predictive value (PPV) of 84.2% (32 of 38) and a negative predictive value (NPV) of 66.7% (10 of 15). Volume reduction extent (> or = 70%) was significantly different between patients in whom disease was downstaged and those in whom it was not downstaged (P = .000005) and showed additional diagnostic value, with an overall accuracy of 86.8% (46 of 53). Presurgical MR imaging and histopathologic tumor length did not show a significant difference. MR imaging accuracy for lymph node (N) stage was 86.8% (46 of 53) on the basis of morphologic criteria.

CONCLUSION

After CRT, morphologic and volumetric evaluation at MR imaging had a high PPV and a low NPV for response assessment. The detection of small clusters of residual tumor cells within fibrosis remains a problem.

SUPPLEMENTAL MATERIAL

http://radiology.rsnajnls.org/cgi/content/full/250/3/730/DC1.

Magnetic resonance imaging in locoregional staging of rectal adenocarcinoma

A comprehensive overview of the current status of magnetic resonance imaging (MRI) in the locoregional assessment and management of rectal adenocarcinoma is presented. Staging systems for rectal cancer and treatment strategies in its management are discussed to give the reader the context that shapes MRI acquisition techniques and interpretation. Findings on MRI are detailed and their accuracy reviewed based on currently available evidence. Optimization of MRI acquisition and relevant pelvic anatomy are reviewed. A detailed description of our approach in interpreting MRI for locoregional staging of rectal cancer is given and future directions are also introduced.

Metabolomic characterization of human rectal adenocarcinoma with intact tissue magnetic resonance spectroscopy

PURPOSE

This study was designed to test whether metabolic characterization of intact, unaltered human rectal adenocarcinoma specimens is possible using the high-resolution magic angle spinning proton (1H) magnetic resonance spectroscopy technique.

METHODS

The study included 23 specimens from five patients referred for ultrasonographic staging of suspected rectal cancer. Multiple biopsies of macroscopically malignant rectal tumors and benign rectal mucosa were obtained from each patient for a total of 14 malignant and 9 benign samples. Unaltered tissue samples were spectroscopically analyzed. Metabolic profiles were established from the spectroscopy data and correlated with histopathologic findings.

RESULTS

Metabolomic profiles represented by principle components of metabolites measured from spectra differentiated between malignant and benign samples and correlated with the volume percent of cancer (P = 0.0065 and P = 0.02, respectively) and benign epithelium (P = 0.0051 and P = 0.0255, respectively), and with volume percent of stroma, and inflammation.

CONCLUSIONS

Magnetic resonance spectroscopy of rectal biopsies has the ability to metabolically characterize samples and differentiate between pathological features of interest. Future studies should determine its utility in in vivo applications for non-invasive pathologic evaluations of suspicious rectal lesions.

Magnetic resonance imaging accuracy in assessing tumour down-staging following chemoradiation in rectal cancer

OBJECTIVE

Magnetic resonance imaging (MRI) is increasingly accepted as the radiological modality of choice staging rectal cancer but is subject to error. Neoadjuvant therapy is increasingly used in rectal cancer and MRI is used to stage response and occasionally plan surgery. We aim to assess the staging accuracy of MRI following chemoradiotherapy in rectal cancer.

METHOD

Retrospective analysis of 86 patients with MRI stage pre- and postlong-course chemoradiotherapy and comparison with pathological assessment.

RESULTS

Fourty-nine patients (34 men, 15 women) with median age 68 years (60-74) were analysed. The median time from completion of CRT to MRI was 32 days (16-37). Chemoradiotherapy led to significant down-staging (P < 0.001). MRI-staging accuracy was 43% (21/49) with over- and under-staging in 43% (21/49) and 14% (7/49) respectively. T-stage accuracy was 45% (22/49) with over-staging in 33% (16/49) and under-staging in 22% (11/49). MRI stage correlated poorly with pathological assessment for International Union Against Cancer (kappa = 0.255) and T stages (kappa = 0.112). MRI nodal assessment was 71% (35/49) accurate, with 82% (9/11) sensitivity, 68% (26/38) specificity and positive predictive value (PPV) of 43% (9/21) and negative predictive value of 93% (26/28). There was a significant difference in node positivity between MRI and pathological staging (P = 0.005, Fisher's exact). Complete radiological response was observed in 4% (2/49). Complete pathological response was observed in 10% (5/49), which were staged 0(1), I(1), II(2) and III(1) postchemoradiotherapy by MRI.

CONCLUSION

MRI staging following chemoradiation is poor. Over-staging occurs three times more commonly than under-staging. Over-staging is due to poor PPV of nodal assessment.

MR vs CT imaging: low rectal cancer tumour delineation for three-dimensional conformal radiotherapy

Modern three-dimentional radiotherapy is based upon CT. For rectal cancer, this relies upon target definition on CT, which is not the optimal imaging modality. The major limitation of CT is its low inherent contrast resolution. Targets defined by MRI could facilitate smaller, more accurate, tumour volumes than CT. Our study reviewed imaging and planning data for 10 patients with locally advanced low rectal cancer (defined as < 6 cm from the anal verge on digital examination). Tumour volume and location were compared for sagittal pre-treatment MRI and planning CT. CT consistently overestimated all tumour radiological parameters. Estimates of tumour volume, tumour length and height of proximal tumour from the anal verge were larger on planning CT than on MRI (p < 0.05). Tumour volumes defined on MRI are smaller, shorter and more distal from the anal sphincter than CT-based volumes. For radiotherapy planning, this may result in smaller treatment volumes, which could lead to a reduction in dose to organs at risk and facilitate dose escalation.

A systematic approach to the interpretation of preoperative staging MRI for rectal cancer

OBJECTIVE

The purpose of this article is to provide an aid to the systematic evaluation of MRI in staging rectal cancer.

CONCLUSION

MRI has been shown to be an effective tool for the accurate preoperative staging of rectal cancer. In the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study (MERCURY), imaging workshops were held for participating radiologists to ensure standardization of scan acquisition techniques and interpretation of the images. In this article, we report how the information was obtained and give examples of the images and how they are interpreted, with the aim of providing a systematic approach to the reporting process.

Local staging of rectal cancer using the black lumen magnetic resonance imaging technique

BACKGROUND AND AIMS

The treatment of rectal cancer is comprised of surgery and possible adjuvant therapy depending on the stage of the tumour. This prospective study evaluates the accuracy of magnetic resonance imaging (MRI) in the preoperative staging of rectal cancer using an endorectal and intravenous contrast.

MATERIALS AND METHODS

37 consecutive patients with rectal cancer were imaged using a mixture of ferumoxsil and methylcellulose endorectally, and a gadolinium contrast intravenously. 33 tumours were resected and 4 tumours were considered unresectable during operation. The images were reviewed for local staging of the tumours. A tumour confined to the rectal wall was classified as a negative finding and a tumour invading through muscularis propria as a positive finding. The results were correlated with the histopathologic t stage (n = 33), or the clinical status (n = 4).

RESULTS AND CONCLUSIONS

of 37 cases, 20 (51 %) were true positive, and 11 (28%) were true negative. There were 3 false negative and 3 false positive cases. The sensitivity was 87%, specificity 79%, and diagnostic accuracy 84%. for the non-contrast images the figures were 78%, 79% and 78%, respectively. We consider black lumen magnetic resonance imaging to be a useful method for preoperative local staging of rectal cancer.

Magnetic resonance imaging (MRI)-based indication for neoadjuvant treatment of rectal carcinoma and the surrogate endpoint CRM status

AIM

Is it possible to reduce the frequency of neoadjuvant therapy for rectal carcinoma and nevertheless achieve a rate of more than 90% circumferential resection margin (CRM)-negative resection specimens by a novel concept of magnetic resonance imaging (MRI)-based therapy planning?

MATERIALS AND METHODS

One hundred eighty-one patients from Berlin and Mainz, Germany, with primary rectal carcinoma, without distant metastasis, underwent radical surgery with curative intention. Surgical procedures applied were anterior resection with total mesorectal excision (TME) or partial mesorectal excision (PME; PME for tumours of the upper rectum) or abdominoperineal excision with TME.

RESULTS

With MRI selection of the highest-risk cases, neoadjuvant therapy was given to only 62 of 181 (34.3%). The rate of CRM-negative resection specimens on histology was 170 of 181 (93.9%) for all patients, and in Berlin, only 1 of 93 (1%) specimens was CRM-positive. Patients selected for primary surgery had CRM-negative specimens on histology in 114 of 119 (95.8%). Those selected for neoadjuvant therapy had a lower rate of clear margin: 56 of 62 (90%).

CONCLUSION

By applying a MRI-based indication, the frequency of neoadjuvant treatment with its acute and late adverse effects can be reduced to 30-35% without reduction of pathologically CRM-negative resection specimens and, thus, without the danger of worsening the oncological long-term results. This concept should be confirmed in prospective multicentre observation studies with quality assurance of MRI, surgery and pathology.

The importance of rectal cancer MRI protocols on interpretation accuracy

Background

Magnetic resonance imaging (MRI) is used for preoperative local staging in patients with rectal cancer. Our aim was to retrospectively study the effects of the imaging protocol on the staging accuracy.

Patients and methods

MR-examinations of 37 patients with locally advanced disease were divided into two groups; compliant and noncompliant, based on the imaging protocol, without knowledge of the histopathological results. A compliant rectal cancer imaging protocol was defined as including T2-weighted imaging in the sagittal and axial planes with supplementary coronal in low rectal tumors, alongside a high-resolution plane perpendicular to the rectum at the level of the primary tumor. Protocols not complying with these criteria were defined as noncompliant. Histopathological results were used as gold standard.

Results

Compliant rectal imaging protocols showed significantly better correlation with histopathological results regarding assessment of anterior organ involvement (sensitivity and specificity rates in compliant group were 86% and 94%, respectively vs. 50% and 33% in the noncompliant group). Compliant imaging protocols also used statistically significantly smaller voxel sizes and fewer number of MR sequences than the noncompliant protocols

Conclusion

Appropriate MR imaging protocols enable more accurate local staging of locally advanced rectal tumors with less number of sequences and without intravenous gadolinium contrast agents.

Sonography transmission gel as endorectal contrast agent for tumor visualization in rectal cancer

OBJECTIVE

The purpose of our study is to show the usefulness and safety of sonography transmission gel as an endorectal contrast agent in preoperative rectal MRI for tumor visualization in rectal cancer.

CONCLUSION

Sonography transmission gel is an effective and safe endorectal contrast agent for rectal MRI.

Preoperative staging of rectal cancer

Detailed preoperative staging using high resolution magnetic resonance imaging (MRI) enables the selection of patients that require preoperative therapy for tumour regression. This information can be used to instigate neoadjuvant therapy in those patients with poor prognostic features prior to disturbing the tumour bed and potentially disseminating disease. The design of trials incorporating MR assessment of prognostic factors prior to therapy has been found to be of value in assessing treatment modalities and outcomes that are targeted to these preoperative prognostic subgroups and in providing a quantifiable assessment of the efficacy of particular chemoradiation treatment protocols by comparing pre-treatment MR staging with post therapy histology assessment. At present, we are focused on achieving clear surgical margins of excision (CRM) to avoid local recurrence. We recommend that all patients with rectal cancer should undergo pre-operative MRI staging. Of these, about half will have good prognosis features (T1-T3b, N0, EMVI negative, CRM clear) and may safely undergo primary total mesorectal excision. Of the remainder, those with threatened or involved margins will certainly benefit from pre-operative chemoradiotherapy with the aim of downstaging to permit safe surgical excision. In the future, our ability to recognise features predicting distant failure, such as extramural vascular invasion (EMVI) may be used to stratify patients for neo-adjuvant systemic chemotherapy in an effort to prevent distant relapse. The optimal pre-operative treatment regimes for these patients (radiotherapy alone, systemic chemotherapy alone or combination chemo-radiotherapy) is the subject of current and future trials.

Endorectal ultrasonography versus phased-array magnetic resonance imaging for preoperative staging of rectal cancer

AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma.

METHODS: Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma.

RESULTS: The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases using phased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively.

CONCLUSION: ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.

Evidence and research in rectal cancer

The main evidences of epidemiology, diagnostic imaging, pathology, surgery, radiotherapy, chemotherapy and follow-up are reviewed to optimize the routine treatment of rectal cancer according to a multidisciplinary approach. This paper reports on the knowledge shared between different specialists involved in the design and management of the multidisciplinary ESTRO Teaching Course on Rectal Cancer. The scenario of ongoing research is also addressed. In this time of changing treatments, it clearly appears that a common standard for large heterogeneous patient groups have to be substituted by more individualised therapies based on clinical-pathological features and very soon on molecular and genetic markers. Only trained multidisciplinary teams can face this new challenge and tailor the treatments according to the best scientific evidence for each patient.

3-T MRI of rectal carcinoma: preoperative diagnosis, staging, and planning of sphincter-sparing surgery

OBJECTIVE

The purpose of this study was to assess the accuracy of 3-T MRI in the preoperative diagnosis, staging, and planning of surgical management of rectal carcinoma.

SUBJECTS AND METHODS

Thirty-eight patients (23 men, 15 women) with clinically suspected rectal carcinoma underwent 3-T MRI. Coronal, axial, and sagittal T2-weighted sequences with and without fat suppression; axial T1-weighted spin-echo sequences; axial T1-weighted gradient-echo sequences with and without fat suppression; oblique 2D MR hydrography; and 3D fat-suppressed dynamic contrast-enhanced MRI were performed. Image quality with these sequences was evaluated by three radiologists experienced in body MRI. The significance of difference in results with the sequences was tested. The manner in which MRI staging and feasibility of sphincter-sparing surgery agreed with operative and pathologic findings was evaluated with kappa statistics.

RESULTS

Rectal carcinoma was identified on MRI and confirmed histologically in all 38 patients. MRI findings were correctly predictive of T category in 35 cases (accuracy, 92.1%). In 31 (96.9%) of 32 resectable cases,sphincter-sparing surgical approaches were accurately chosen on the basis of MRI findings. Among the 11 sequences, 3D fat-suppressed dynamic contrast-enhanced MRI best delineated tumor margins. Coronal and axial T2-weighted images also well depicted tumor margins with minimal artifact. T2-weighted images were superior to unenhanced T1-weighted images.

CONCLUSION

MRI of rectal cancer at 3 T is accurate for prediction of T category and the feasibility of sphincter-sparing surgery. The best images were obtained with coronal, sagittal, and axial T2-weighted sequences and 3D fat-suppressed dynamic contrast-enhanced MRI.

Magnetic resonance imaging in rectal cancer downstaged using neoadjuvant chemoradiation: accuracy of prediction of tumour stage and circumferential resection margin status

OBJECTIVE

The aim was to examine the accuracy of magnetic resonance imaging (MRI) in predicting circumferential resection margin (CRM) involvement, T- and N-stage in patients with locally advanced carcinoma of the rectum, who had undergone long-course downstaging chemoradiation (CRT).

METHOD

Patients with rectal cancer were selected for long-course downstaging CRT if their tumour was considered to threaten (< or = 1 mm) or involve the CRM on MRI. Eighty such patients had a repeat MRI at a median of 6 weeks post-CRT followed by surgical excision soon thereafter. The findings on the post-CRT MRI were compared with histological examination of the surgical specimen.

RESULTS

For CRM involvement, post-CRT restaging MRI had an accuracy of 81% (65/80) a sensitivity of 54% (7/13), a specificity of 87% (58/67), a positive predictive value of 44% (7/16) and a negative predictive value of 91% (58/64). Accuracy for T- and N-staging was 43% (34/80) and 78% (62/80), respectively. 38% of T-stages were overstaged and 20% understaged. 4% of N-stages were overstaged and 19% understaged. The 13 patients with histological positive CRM had worse clinical outcomes than the 67 patients with negative CRM in terms of disease-free survival (relative risk of reduced DFS 4.6, P = 0.001) and overall survival (relative risk of death 3.6, P = 0.016).

CONCLUSION

Magnetic resonance imaging has good specificity and negative predictive value for predicting an uninvolved CRM post downstaging CRT in locally advanced rectal cancer although sensitivity and positive predictive value for an involved CRM were unsatisfactory. The shortcomings of MRI stem from poor differentiation of viable tumour from posttreatment changes and inability to identify small nodal and tumour deposits. Clinical correlates in this group of patients have confirmed the importance of achieving a clear CRM at surgery.

[MR-endoscopic US correlation for loco-regional staging of rectal carcinoma]

INTRODUCTION

To correlate findings at high-resolution MR and endoscopic US (EUS) for preoperative loco-regional staging of rectal carcinoma.

PATIENTS AND METHODS

Fifty-two patients with rectal carcinoma underwent high-resolution MR imaging. Only 43 of these patients underwent EUS due to technical limitations and stenosing carcinomas. Morphological imaging features and TNM staging were evaluated for both imaging modalities. The degree of correlation and accuracy were calculated for both.

RESULTS

The correlation between MR and EUS was good for tumor length and thickness (r=0.7 and 0.61) for for nodal (N) staging (k=0.53). Correlation was good for T1 and T2 stages (k=0.51) and T3 stage (k=0.43) and very poor for stage 4 (k= -0.09), because no T4 lesion was detected at EUS. 81.8% of patients where T stage was over-estimated on MRI and 100% of patients where T stage was over-estimated on EUS had received preoperative radiation therapy. Therefore, results should be interpreted with caution. The predictive evaluation of tumor resectability (absence of perirectal fascia invasion) with a circumferential margin on MR> or =5 mm was 93%.

CONCLUSION

Correlation between MR and EUS was moderate for T staging, because of limitations of EUS for large tumors. Results confirm that high-resolution MRI is useful for loco-regional staging of rectal carcinoma, especially for large tumors. EUS should be limited to the valuation of superficial tumors of the rectum.

How do we manage early rectal cancer? A national questionnaire survey among members of the ACPGBI after the preliminary results of the MRC CR07/NCIC CO16 randomized trial

OBJECTIVE

The role of neoadjuvant radiotherapy in the management of rectal cancers has not reached a consensus in colorectal surgical practice. In the light of the preliminary results of the CRO7 trial, we undertook a national questionnaire survey to assess the current pattern of practice in the UK. The aim of this study was to assess the correlation between CRO7 trial results and current practice amongst consultant members of the Association of Coloproctology of Great Britain and Ireland (ACPGBI).

METHOD

A 14-item questionnaire was designed to inquire into the current management strategy of operable rectal cancers and the possible role of neoadjuvant radiotherapy. The postal questionnaire survey was sent to all the 400 active consultant surgical members of the ACPGBI.

RESULTS

Of 400 questionnaires, 200 (50%) were returned fully completed. One hundred and sixty-six (83%) of surgeons did not routinely use neoadjuvant short course radiotherapy (NASCRT) in clinically operable rectal cancers (T1/T2) <15 cm from anal verge with no metastases (The CR07 eligible cohort). Sixty-four (32%) used NASCRT for T3 cancers routinely whereas 76 (38%) used neoadjuvant long course radiotherapy instead. One hundred and fifty-sixty (78%) of the surgeons felt the height of the tumour from the anal verge influenced their decision on NASCRT, while 104 (52%) felt position was important (Anterior/Posterior). Positive anticipated margins of excision on magnetic resonance imaging was a deciding factor for 185 (92.5%) of surgeons in favour of neoadjuvant therapy. Postoperatively in patients who have not had preoperative radiotherapy, 154 (77%) recommended radiotherapy and 155 (77.5%) recommended chemotherapy if the circumferential resection margin was +ve on final pathology. Seventy-eight (39%) of the surgeons have changed their practice after the preliminary results of the CRO7 by adopting NASCRT for treating early rectal cancers.

CONCLUSION

Despite the evidence of the CRO7 trial supporting the use of NASCRT for operable rectal cancer, approximately two-third of consultant surgeons in the UK have yet to implement this treatment regime routinely. A change in practice in 39% of surgeons following the early dissemination of trial results indicate that colorectal surgeons practice is guided by scientific evidence. Because the mature trial data have yet to be published, a further survey of practice is warranted after that publication to determine the ultimate impact of this trial. This survey measures the baseline practice to compare changes over the next 2 years.

MRI demonstration of the effect of neoadjuvant radiotherapy on rectal carcinoma

BACKGROUND AND PURPOSE

In patients with locally advanced rectal cancer, neoadjuvant long course (45-54 Gy in 25-30 fractions) chemoradiotherapy (CRT) may reduce tumour size and result in downstaging. In patients with primary resectable tumour short course (25 Gy in 5 fractions) radiotherapy (SCRT) reduces local recurrence but downstaging the disease or altering tumour size has not been described. We aimed to assess change in tumour size on MRI after SCRT or CRT.

MATERIALS AND METHODS

Nineteen patients with rectal carcinoma underwent MRI before and after SCRT or CRT. In each case, tumour length and width were documented and number of locoregional lymph nodes recorded. Total mesorectal excision was performed in 15 patients and MR findings correlated with histopathology.

RESULTS

Ten patients received SCRT and nine CRT. Tumour length reduced by 19% overall (15% following SCRT, 23% following CRT). Greater than 30% reduction (partial response) in maximum tumour thickness was seen in 4/10 (40%) following SCRT and 5/9 (56%) following CRT.

CONCLUSIONS

Significant reduction in tumour size can be achieved with preoperative long course CRT and SCRT. This unexpected finding following SCRT has not been previously described.

cT3N0 rectal cancer: potential overtreatment with preoperative chemoradiotherapy is warranted

PURPOSE

Although combined-modality therapy (CMT) is the preferred treatment for T3 and/or lymph node (LN)-positive rectal cancer, the German rectal cancer study published in 2004 demonstrated that 18% of patients deemed suitable for preoperative CMT by endorectal ultrasound (ERUS) may be overstaged. Because data also suggest that LN-negative rectal cancer after total mesorectal excision may not require radiotherapy, it is reasonable to consider omitting radiotherapy for the cT3N0 subset. We therefore determined the accuracy of pre-CMT ERUS or magnetic resonance imaging (MRI) staging, to explore the validity of a nonpreoperative CMT approach for cT3N0 disease.

PATIENTS AND METHODS

One hundred eighty-eight ERUS-/MRI-staged T3N0 rectal cancer patients received preoperative CMT (fluorouracil based and 45-50.4 Gy) followed by radical resection. Rates of pathologic complete response (pCR) and mesorectal LN involvement were determined.

RESULTS

Tumors were located a median of 5 cm from the anal verge. Sphincter-preserving surgery was performed in 143 patients (76%). Overall pCR was 20%, and 41 patients (22%) had pathologically positive mesorectal LNs. The incidence of positive LNs significantly increased with T stage: ypT0, 3%; ypT1, 7%; ypT2, 20%; ypT3-4, 36% (P = .001).

CONCLUSION

The accuracy of preoperative ERUS/MRI for staging mid to distal cT3N0 rectal cancer is limited because 22% of patients have undetected mesorectal LN involvement despite CMT. Therefore, ERUS-/MRI-staged T3N0 rectal cancer patients should continue to receive preoperative CMT. Although 18% may be overstaged and therefore overtreated, our data suggest that an even larger number would be understaged and require postoperative CMT, which is associated with significantly inferior local control, higher toxicity, and worse functional outcome.

Optimal methods for staging rectal cancer

At present, several modalities exist for the preoperative staging of rectal lesions, including computed tomography (CT), body coil or endorectal coil magnetic resonance imaging (MRI), endoscopic ultrasonography (EUS) done by rigid or flexible probes, and positron emission tomography (PET). Staging accuracy for CT ranges from 53% to 94% for T-stage accuracy and from 54% to 70% for N-stage accuracy. Improved CT accuracy is observed at higher disease stages. Body coil MRI has shown T- and N-stage accuracy ranging from 59% to 95% and 39% to 95%, respectively. Endorectal coil MRI has shown improved T- and N-stage accuracy, with rates of 66% to 91% and 72% to 79%, respectively. The development of phased-array MRI, combining high spatial resolution with a larger field of view, offers promise to improve on these rates. EUS, considered the current gold standard, has shown T-stage accuracy ranging from 75% to 95%, with N-stage accuracy ranging from 65% to 80%. Flexible EUS probes have the advantage of being able to access and sample iliac nodes. Recent studies also suggest that three-dimensional EUS may provide greater accuracy than conventional two-dimensional EUS. Limited studies exist on the use of PET in primary tumor staging. PET may upstage disease in 8% to 24% of patients and has also been used in posttreatment restaging and surveillance. Postradiation edema, necrosis, and fibrosis seem to decrease restaging accuracy in all modalities. This article reviews the current literature about the staging accuracy of the various modalities and suggests a staging algorithm for rectal cancer.

Evaluating mesorectal lymph nodes in rectal cancer before and after neoadjuvant chemoradiation using thin-section T2-weighted magnetic resonance imaging

PURPOSE

To apply thin-section T2-weighted magnetic resoance imaging (MRI) to evaluate the number, size, distribution, and morphology of benign and malignant mesorectal lymph nodes before and after chemoradiation treatment compared with histopathologic findings.

METHODS AND MATERIALS

Twenty-five patients with poor-risk adenocarcinoma of the rectum treated with neoadjuvant chemoradiation were evaluated prospectively. Thin-section T2-weighted MR images obtained before and after chemoradiation treatment were independently reviewed in consensus by 2 expert radiologists to determine the tumor stage, nodal size, nodal distribution, and nodal stage. Total mesorectal excision surgery after chemoradiation allowed MR nodal stage to be compared with histopathology using kappa statistics. Nodal downstaging was compared using the Chi-square test.

RESULTS

Before chemoradiation, 152 mesorectal nodes were visible (mean, 6.2 mm; 100 benign, 52 malignant) and 4 of 52 malignant nodes were in contact with the mesorectal fascia. The nodal staging was 7/25 N0, 10/25 N1, and 7/25 N2. After chemoradiation, only 29 nodes (mean, 4.1 mm; 24 benign, 5 malignant) were visible, and none were in contact with the mesorectal fascia. Nodal downstaging was observed: 20/25 N0 and 5/25 N1 (p < 0.01, Chi-square test). There was good agreement between MRI and pathologic T-staging (kappa = 0.64) and N-staging (kappa = 0.65) after chemoradiation.

CONCLUSIONS

Neoadjuvant chemoradiation treatment resulted in a decrease in size and number of malignant- and benign-appearing mesorectal nodes on MRI. Nodal downstaging and nodal regression from the mesorectal fascia were observed after treatment. MRI is a useful tool for assessing nodal response to neoadjuvant treatment.

Preoperative 3T MR imaging of rectal cancer: local staging accuracy using a two-dimensional and three-dimensional T2-weighted turbo spin echo sequence

PURPOSE

The purpose of our study was to evaluate the image quality and diagnostic performance of two-dimensional (D) turbo spin echo (TSE) and 3D T2-weighted TSE MR imaging in local staging of rectal cancer at 3T.

MATERIALS AND METHODS

3T phased-array MR imaging was performed in 36 consecutive patients with biopsy-proven rectal cancer. High-resolution 2D TSE images in three planes and 3D TSE images of the rectum were obtained. Two independent observers performed an image quality assessment using eight image quality characteristics. All 2D and 3D datasets were evaluated separately. MR images were prospectively evaluated by two experienced radiologists in consensus with regard to local disease. Total mesorectal excision was used as the standard of reference. The sensitivity, specificity, positive and negative predictive value, and overall accuracy were calculated. Areas under the receiver operating characteristic (ROC) curve (AUC) were determined.

RESULTS

Twenty-two patients who underwent a total mesorectal excision were enrolled in this study. Significantly more motion artifacts were present with 3D TSE imaging (P=0.04). The overall sensitivity, specificity, and accuracy of muscularis propria invasion in rectal cancer using 2D T2-weighted images were 100%, 66%, and 95%, respectively. There was a statistical significant greater AUC using 2D T2-weighted images compared to 3D T2-weighted MR images (P=0.04). The ROC curves describing the results of the interpretation of 2D and 3D T2-weighted datasets regarding perirectal tissue invasion showed no statistical significant difference (P=0.41).

CONCLUSIONS

In this study, high local staging accuracies with 3T 2D T2-weighted MR imaging were demonstrated. 3D T2-weighted MR imaging cannot replace 2D MR imaging for local staging of rectal cancer. However, 3D MR imaging can be used for visualization of the complex pelvic anatomy for treatment planning purposes.

MR imaging of the peritoneal spread of malignancy

MR imaging provides a highly sensitive and accurate means to depict tumor involving the peritoneum and bowel serosa. The ability of MR imaging to depict subtle peritoneal metastases plays a critical role in diagnosing and monitoring the oncologic patient with known or suspected peritoneal spread of malignancy. In this review I will describe the mechanisms of peritoneal tumor spread, and MR techniques and protocols for peritoneal imaging. A detailed description of the MR appearance of peritoneal tumor at different anatomic sites will be provided followed by a discussion of clinical applications for MR imaging of peritoneal malignancy.

Staging rectal cancer: MRI compared to MDCT

PURPOSE

To audit the accuracy with which pre-operative MRI and multi-detector row CT determine the relationship between rectal tumour and the circumferential resection margin (CRM).

MATERIALS AND METHODS

The MR and CT scans of 72 patients with rectal adenocarcinoma were retrieved. The relationship between tumour and the mesorectal fascia was determined by two observers, who classified appearances into three categories: no tumour within 5 mm of the mesorectal fascia; tumour within 5 mm of the mesorectal fascia ('threatened' margin); tumour at the mesorectal fascia ('involved' margin). Agreement with post-operative histopathology was assessed by Kappa statistics.

RESULTS

There was poor agreement between both MRI and CT, and post-operative histology, both in all 72 patients and in the 42 who had received no pre-operative therapy or short-course radiotherapy only. Both imaging modalities had a tendency to overstage patients whose CRM was uninvolved subsequently. However, the negative predictive value for an uninvolved margin was 81.8% by MRI and 84.6% by CT. There was no patient with an involved margin by histopathology whose imaging had suggested the margin was uninvolved.

CONCLUSION

Both pre-operative MRI and multi-detector row CT have high negative predictive values for a subsequently uninvolved resection margin.

Preoperative staging of rectal carcinoma by endorectal ultrasound: is there a learning curve?

BACKGROUND AND AIMS

Endorectal ultrasound (ERUS) is becoming an essential tool in the management of rectal cancer. However, accuracy in the assessment of disease staging may be dependent on operator experience. The aim of this study was to determine if a learning curve exists.

MATERIALS AND METHODS

From October 1999 to December 2004, all patients with rectal cancer had a pre-operative ERUS performed by a single radiologist. ERUS staging was compared with post-operative pathology findings using the tumour, node, metastases (TNM) classification. The accuracy of ERUS in tumour (T) and node (N) staging after each additional consecutive ten patients was calculated.

RESULTS

One hundred and thirty one patients were investigated by ERUS, of which 36 were excluded, leaving 95 patients in the study (60 men). Overall accuracy for T staging was 71.6%. No improvement with experience was noted (p > 0.05). With regard to T staging, ERUS tended to overstage more frequently than understage (24.2 versus 4.2%). The sensitivity, specificity, positive predictive value and negative predictive value of uT3 staging were 96.6, 33.3, 70.4 and 85.7%, respectively. Overall accuracy of uN staging was 68.8%. ERUS tended to overstage nodal disease more frequently than understage (16.1 versus 15.1%). Sensitivity, specificity, positive predictive value and negative predictive value were calculated for ultrasound-detected nodal disease (73.2, 62.2, 74.5 and 60.5%, respectively). Nodal staging accuracy improved from 50% after assessment of 10 cases to 77% after 30 cases were examined.

CONCLUSIONS

ERUS is an accurate method for staging rectal cancer pre-operatively. Accurate assessment of tumour stage can be achieved immediately by an experienced radiologist without specific training in ERUS. Nodal staging accuracy tends to improve with experience but reaches a plateau after 30 cases.

Variations in pelvic dimensions do not predict the risk of circumferential resection margin (CRM) involvement in rectal cancer

BACKGROUND

The objective of this study was to assess the value of preoperative pelvimetry, using magnetic resonance imaging (MRI), in predicting the risk of an involved circumferential resection margin (CRM) in a group of patients with operable rectal cancer.

METHODS

A cohort of 186 patients from the MERCURY study was selected. These patients' histological CRM status was compared against 14 pelvimetry parameters measured from the preoperative MRI. These measurements were taken by one of the investigators (G.S.), who was blinded to the final CRM status.

RESULTS

There was no correlation between the pelvimetry and the CRM status. However, there was a difference in the height of the rectal cancer and the positive CRM rate (p = 0.011). Of 61 patients with low rectal cancer, 10 had positive CRM at histology (16.4% with CI 8.2%-22.1%) compared with 5 of 110 patients with mid/upper rectal cancers (4.5% with CI 0.7%-8.4%).

CONCLUSIONS

Magnetic resonance imaging can predict clear margins in most cases of rectal cancer. Circumferential resection margin positivity cannot be predicted from pelvimetry in patients with rectal cancer selected for curative surgery. The only predictive factor for a positive CRM in the patients studied was tumor height.

Effect of using endorectal coil in preoperative staging of rectal carcinomas by pelvic MR imaging

PURPOSE

To assess the accuracy of magnetic resonance imaging with pelvic phased-array and endorectal coils prospectively, and evaluate if endorectal coil provides any additional information to high resolution pelvic MR imaging in rectal carcinoma staging.

MATERIALS AND METHODS

Preoperative MRI of 25 patients with rectal carcinoma was performed with pelvic phased-array coil alone, and with both phased-array coil and endorectal coil placed. Staging was made by evaluating images obtained by using both coils prospectively, and correlated with histopathologic staging. The images were then assessed separately, and compared to each other retrospectively.

RESULTS

Two and 3 of the 5 histopathologically proved T1 tumors were staged correctly on MRI with pelvic phased-array coil alone and after the endorectal coil placement, respectively. Histopathologically identified five T2 tumors were staged correctly as T2 in 4 of the cases, 1 was understaged and 10 of 14 patients who had T3 tumor were staged as T3, 4 of them were understaged as T2 on both techniques. Specificity, sensitivity and accuracy rates for staging of T3 tumors were found as 71%, 100% and 84%, respectively, for each technique. Sensitivity and positive predictive value of N staging were both 88% on both techniques.

CONCLUSION

Pelvic MR imaging after the placement of endorectal coil in addition to the phase-array coil was not superior to the imaging with phased-array coil alone in T staging of rectal carcinomas and the latter achieved better visualization of the lymph nodes by means of larger field of view.

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

AIM: 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.

METHODS: In a prospective study of 67 patients with primary rectal cancer, high-resolution magnetic resonance imaging (in-plane resolution, 0.66 × 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.

RESULTS: 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 ≤ 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.

CONCLUSION: High-resolution MRI enables accurate preoperative assessment for T staging and mesorectal fascia infiltration in rectal cancer with rectal distention.