Rectal tumour staging: MR imaging using pelvic phased-array and endorectal coils vs endoscopic ultrasonography

Contemporary management of rectal cancer

The management of rectal cancer has undergone significant changes over the past 50 years, and this has been associated with major improvements in overall outcomes and quality of life. From standardization of total mesorectal excision to refinements in radiation delivery and shifting of chemoradiotherapy treatment to favor a neoadjuvant approach, as well as the development of targeted chemotherapeutics, these management strategies have continually aimed to achieve locoregional and systemic control while limiting adverse effects and enhance overall survival. This article highlights evolving aspects of rectal cancer therapy including improved staging modalities, total neoadjuvant therapy, the role of short-course and more selective radiotherapy strategies, as well as organ preservation. We also discuss the evolving role of minimally invasive surgery and comment on lateral pelvic lymph node dissection.

Key message

Rectal cancer management is constantly evolving through refinements in radiation timing and delivery, modification of chemoradiotherapy treatment schedules, and increasing utilization of minimally invasive surgical techniques and organ preservation strategies. This manuscript aims to provide a synopsis of recent changes in the management of rectal cancer, highlighting contemporary modifications in neoadjuvant approaches and surgical management to enhance the knowledge of surgeons who care for this challenging population.

Outcomes and potential impact of a virtual hands-on training program on MRI staging confidence and performance in rectal cancer

OBJECTIVES

To explore the potential impact of a dedicated virtual training course on MRI staging confidence and performance in rectal cancer.

METHODS

Forty-two radiologists completed a stepwise virtual training course on rectal cancer MRI staging composed of a pre-course (baseline) test with 7 test cases (5 staging, 2 restaging), a 1-day online workshop, 1 month of individual case readings (n = 70 cases with online feedback), a live online feedback session supervised by two expert faculty members, and a post-course test. The ESGAR structured reporting templates for (re)staging were used throughout the course. Results of the pre-course and post-course test were compared in terms of group interobserver agreement (Krippendorf's alpha), staging confidence (perceived staging difficulty), and diagnostic accuracy (using an expert reference standard).

RESULTS

Though results were largely not statistically significant, the majority of staging variables showed a mild increase in diagnostic accuracy after the course, ranging between + 2% and + 17%. A similar trend was observed for IOA which improved for nearly all variables when comparing the pre- and post-course. There was a significant decrease in the perceived difficulty level (p = 0.03), indicating an improved diagnostic confidence after completion of the course.

CONCLUSIONS

Though exploratory in nature, our study results suggest that use of a dedicated virtual training course and web platform has potential to enhance staging performance, confidence, and interobserver agreement to assess rectal cancer on MRI virtual training and could thus be a good alternative (or addition) to in-person training.

CLINICAL RELEVANCE STATEMENT

Rectal cancer MRI reporting quality is highly dependent on radiologists' expertise, stressing the need for dedicated training/teaching. This study shows promising results for a virtual web-based training program, which could be a good alternative (or addition) to in-person training.

KEY POINTS

• Rectal cancer MRI reporting quality is highly dependent on radiologists' expertise, stressing the need for dedicated training and teaching. • Using a dedicated virtual training course and web-based platform, encouraging first results were achieved to improve staging accuracy, diagnostic confidence, and interobserver agreement. • These exploratory results suggest that virtual training could thus be a good alternative (or addition) to in-person training.

Accuracy of MRI in early rectal cancer: national cohort study

MRI plays a pivotal role in the staging of early rectal cancer, resulting in allocation of patients to surgery or organ-sparing treatment. In this large population-based retrospective cohort study, MRI substantially understaged pT3 and overstaged pT1 rectal cancer, in addition to unreliable nodal staging. Based on these findings, MRI is not adequate in allocating patients with rectal cancer to organ-sparing treatment.

Interobserver variability in MRI measurements of mesorectal invasion depth in rectal cancer

PROPOSE

To assess the interobserver variability in MRI measurements of mesorectal invasion depth (MID) in rectal adenocarcinomas primarily staged as T3, by determining the level of interobserver agreement in the differentiation of individual T3 substages and of T3a-b vs. T3c-d disease, between readers with different levels of expertise.

METHODS

A retrospective analysis of 60 patients classified by MRI as having T3 rectal cancers was performed. Each patient underwent MR examination in a 1.5 T machine and the standard imaging protocol included a high-resolution axial T2-weighted sequence in which the measurements were determined by independent radiologists (readers A and B, with 15 years and 1 year of experience, respectively). The rectum was further divided into quadrants and each reader selected the quadrant where the measurement was taken. The patients were grouped according to the MID (T3a < 1 mm; T3b 1-5 mm; T3c > 5-15 mm; T3d > 15 mm) and the interobserver reliability was tested using Cohen's kappa.

RESULTS

Population included 40 males and 20 females with a median age of 65.9 years. Interobserver agreement on individual substage differentiation (T3 a, b, c and d) was moderate (K = 0.428) and in the quadrant evaluation the level of agreement was also moderate (K = 0.414). Nevertheless, the interobserver reliability for the differentiation between stages T3a-b vs. T3c-d was substantial (K = 0.697).

CONCLUSIONS

There is no considerable interobserver variability when distinguishing T3a-b from T3c-d tumors, regardless of the quadrant where the MID is measured. Therefore, assessment of MID, for that purpose, is a reproducible MR parameter, irrespectively of the readers' experience.

Highlights of the development in ultrasound during the last 70 years: A historical review

This review looks at highlights of the development in ultrasound, ranging from interventional ultrasound and Doppler to the newest techniques like contrast-enhanced ultrasound and elastography, and gives reference to some of the valuable articles in Acta Radiologica. Ultrasound equipment is now available in any size and for any purpose, ranging from handheld devices to high-end devices, and the scientific societies include ultrasound professionals of all disciplines publishing guidelines and recommendations. Interventional ultrasound is expanding the field of use of ultrasound-guided interventions into nearly all specialties of medicine, from ultrasound guidance in minimally invasive robotic procedures to simple ultrasound-guided punctures performed by general practitioners. Each medical specialty is urged to define minimum requirements for equipment, education, training, and maintenance of skills, also for medical students. The clinical application of contrast-enhanced ultrasound and elastography is a topic often seen in current research settings.

Challenges in Crohn's Disease Management after Gastrointestinal Cancer Diagnosis

Simple Summary

Crohn’s disease (CD) is a chronic inflammatory bowel disease affecting both young and elderly patients, involving the entire gastrointestinal tract from the mouth to anus. The chronic transmural inflammation can lead to several complications, among which gastrointestinal cancers represent one of the most life-threatening, with a higher risk of onset as compared to the general population. Moreover, diagnostic and therapeutic strategies in this subset of patients still represent a significant challenge for physicians. Thus, the aim of this review is to provide a comprehensive overview of the current evidence for an adequate diagnostic pathway and medical and surgical management of CD patients after gastrointestinal cancer onset.

Abstract

Crohn’s disease (CD) is a chronic inflammatory bowel disease with a progressive course, potentially affecting the entire gastrointestinal tract from mouth to anus. Several studies have shown an increased risk of both intestinal and extra-intestinal cancer in patients with CD, due to long-standing transmural inflammation and damage accumulation. The similarity of symptoms among CD, its related complications and the de novo onset of gastrointestinal cancer raises difficulties in the differential diagnosis. In addition, once a cancer diagnosis in CD patients is made, selecting the appropriate treatment can be particularly challenging. Indeed, both surgical and oncological treatments are not always the same as that of the general population, due to the inflammatory context of the gastrointestinal tract and the potential exacerbation of gastrointestinal symptoms of patients with CD; moreover, the overlap of the neoplastic disease could lead to adjustments in the pharmacological treatment of the underlying CD, especially with regard to immunosuppressive drugs. For these reasons, a case-by-case analysis in a multidisciplinary approach is often appropriate for the best diagnostic and therapeutic evaluation of patients with CD after gastrointestinal cancer onset.

Improving staging of rectal cancer in the pelvis: the role of PET/MRI

PURPOSE

The role of positron emission tomography/magnetic resonance (PET/MR) in evaluating the local extent of rectal cancer remains uncertain. This study aimed to investigate the possible role of PET/MR versus magnetic resonance (MR) in clinically staging rectal cancer.

METHODS

This retrospective two-center cohort study of 62 patients with untreated rectal cancer investigated the possible role of baseline staging PET/MR versus stand-alone MR in determination of clinical stage. Two readers reviewed T and N stage, mesorectal fascia involvement, tumor length, distance from the anal verge, sphincter involvement, and extramural vascular invasion (EMVI). Sigmoidoscopy, digital rectal examination, and follow-up imaging, along with surgery when available, served as the reference standard.

RESULTS

PET/MR outperformed MR in evaluating tumor size (42.5 ± 21.03 mm per the reference standard, 54 ± 20.45 mm by stand-alone MR, and 44 ± 20 mm by PET/MR, P = 0.004), and in identifying N status (correct by MR in 36/62 patients [58%] and by PET/MR in 49/62 cases [79%]; P = 0.02) and external sphincter infiltration (correct by MR in 6/10 and by PET/MR in 9/10; P = 0.003). No statistically significant differences were observed in relation to any other features.

CONCLUSION

PET/MR provides a more precise assessment of the local extent of rectal cancers in evaluating cancer length, N status, and external sphincter involvement. PET/MR offers the opportunity to improve clinical decision-making, especially when evaluating low rectal tumors with possible external sphincter involvement.

Rectal Cancer: Staging

The imaging of rectal cancer has evolved noticeably over the past 2 decades, paralleling the advances in therapy. The methods for imaging rectal cancer are increasingly used in clinical practice with the purpose of helping to detect, characterize and stage rectal cancer. In this setting, MR imaging emerged as the most useful imaging method for primary staging of rectal cancer; the present review focuses on the role of MR imaging in this regard.

Indistinguishable T2/T3-N0 rectal cancer on rectal magnetic resonance imaging: comparison of surgery-first and neoadjuvant chemoradiation therapy-first strategies

PURPOSE

We compared the treatment outcome between surgery-first and neoadjuvant chemoradiation therapy (nCRT)-first strategies in patients with indistinguishable T2/T3-N0 rectal cancer on rectal magnetic resonance imaging (MRI).

METHODS

Our institutional review board approved this retrospective study, and informed consent was waived. Among 1910 patients who underwent rectal MRI between 2008 and 2012, 79 patients (mean age, 59.4 years, 49 men and 30 women) who had indistinguishable T2/T3-N0 rectal cancer on rectal MRI were included. Local recurrence-free survival (LRFS), recurrence-free survival (RFS), overall survival (OS), and disease-specific survival (DSS) were compared between the two groups. Treatment-related complications were evaluated.

RESULTS

Among 79 patients, 51 were treated by surgery first and 28 were treated by nCRT first. In comparison of survival of the surgery- and nCRT-first groups at 5 years, the LRFS rate was 95.6 and 96.3%, RFS rate was 91.0 and 92.4%, OS rate was 93.7 and 92.6%, and DSS rate was 98.0 and 92.6%, respectively. LRFS, RFS, OS, and DSS showed no significant difference between the two groups (p = 0.862, 0.677, 0.953, and 0.479). The complication rate was not significantly different between the groups (20.0% for surgery-first group vs. 10.7% for nCRT-first group, p = 0.357).

CONCLUSION

Treatment outcomes were not significantly different between surgery-first and nCRT-first strategies for indistinguishable T2/T3-N0 rectal cancer on rectal MRI.

Rectal cancer confined to the bowel wall: the role of 3 Tesla phased-array MR imaging in T categorization

OBJECTIVE

To determine the diagnostic value of 3 Tesla MR imaging in detection of mucosal (Tis), submucosal (T₁) and muscularis propria (T₂) invasion in patients with early rectal cancer.

METHODS

A total of 50 consecutive patients who underwent 3 Tesla MR imaging and curative-intent intervention for MRI-staged Tis/T₁/T₂ rectal cancer from March 2012 to December 2016 were included. The radiological T category of each rectal tumour was compared retrospectively with histopathological results assessed according to the tumor, node, metastasis (TNM) classification. The sensitivities, specificities, and overall accuracy rates of 3 Tesla MR imaging for Tis, T₁, and T₂ cases were calculated using MedCalc statistical software v. 16.

RESULTS

The sensitivity, specificity, PPV, NPV of 3 Tesla MR imaging in T categorization for T₂ were: 93.7% [95% CI (0.79-0.99)], 77.7% [95% CI (0.52-0.93)], 88.2% [95% CI (0.75-0.94)] and 87.5% [95% CI (0.64-0.96)]; for T₁ were 92% [95% CI (0.63-0.99)], 91.8% [95% CI (0.78-0.98)], 80% [95% CI (0.57-0.92)] and 97.1% [95% CI (0.83-0.99)]; for Tis were: 20% [95% CI (0.51-0.71)], 100% [95% CI (0.92-1)], 100%, 91.8% [95% CI (0.87-0.94)], respectively. MR categorization accuracy rates for T₂, T₁ and Tis were calculated as 88, 92 and 92%, respectively.

CONCLUSION

3 Tesla MR imaging seems to be useful for accurate categorization of T-stage in early rectal cancer, especially for T₁ cancers. The method is not a reliable tool to detect Tis cases. The potential for overstaging and understaging of the technique should be realized and taken into consideration when tailoring the treatment protocol for each patient. Advances in knowledge: High-resolution MR with phased-array coil is being increasingly used in the pre-operative assessment of rectal cancer. 3 Tesla high-resolution MR imaging allows improved definition of bowel wall and tumour infiltration.

Imaging for Colorectal Cancer

A comprehensive approach to colorectal cancer includes thorough radiologic imaging, which allows appropriate initial staging of the disease, as well as subsequent surveillance for disease recurrence. Several imaging modalities are used with different associated advantages and disadvantages, which are outlined in this article with specific attention paid to the local staging of rectal cancer.

Anorectal Cancer: Critical Anatomic and Staging Distinctions That Affect Use of Radiation Therapy

Although rectal and anal cancers are anatomically close, they are distinct entities with different histologic features, risk factors, staging systems, and treatment pathways. Imaging is at the core of initial clinical staging of these cancers and most commonly includes magnetic resonance imaging for local-regional staging and computed tomography for evaluation of metastatic disease. The details of the primary tumor and involvement of regional lymph nodes are crucial in determining if and how radiation therapy should be used in treatment of these cancers. Unfortunately, available imaging modalities have been shown to have imperfect accuracy for identification of nodal metastases and imaging features other than size. Staging of nonmetastatic rectal cancers is dependent on the depth of invasion (T stage) and the number of involved regional lymph nodes (N stage). Staging of nonmetastatic anal cancers is determined according to the size of the primary mass and the combination of regional nodal sites involved; the number of positive nodes at each site is not a consideration for staging. Patients with T3 rectal tumors and/or involvement of perirectal, mesenteric, and internal iliac lymph nodes receive radiation therapy. Almost all anal cancers warrant use of radiation therapy, but the extent and dose of the radiation fields is altered on the basis of both the size of the primary lesion and the presence and extent of nodal involvement. The radiologist must recognize and report these critical anatomic and staging distinctions, which affect use of radiation therapy in patients with anal and rectal cancers.

Benign and malignant tumors of the rectum and perirectal region

Although most rectal masses are histologically characterized as adenocarcinomas, the rectum and perirectal region can be affected by a wide variety of tumors and tumor-like conditions that can mimic the symptoms caused by rectal adenocarcinoma, including mucosal or submucosal rectal tumors such as lymphoma, gastrointestinal stromal tumor, leiomyosarcoma, neuroendocrine tumor, hemangioma, and melanoma, as well as tumors of the perirectal region such as developmental cyst, neurogenic tumor, osseous tumor, and other miscellaneous conditions. As a group, tumors of the rectum are considerably different from the group of tumors that arise in the perirectal region: they are most often neoplastic, symptomatic, and malignant, whereas tumors arising in the perirectal region are most commonly congenital, asymptomatic, and benign. Proctoscopy with biopsy is the most important method for the diagnosis of rectal tumors, but this procedure cannot determine the precise intramural extension of a rectal tumor and cannot accurately distinguish submucosal and intramural tumors from extramural tumors. Cross-sectional imaging, especially transrectal ultrasound and magnetic resonance imaging, allows evaluation of the entire bowel wall thickness and the perirectal tissues, helping further characterize these tumors. Recognition of the existence of these masses and their key clinical and imaging features is crucial for clinicians to accurately diagnose and appropriately manage these conditions.

MRI in local staging of rectal cancer: an update

Preoperative imaging for staging of rectal cancer has become an important aspect of current approach to rectal cancer management, because it helps to select suitable patients for neoadjuvant chemoradiotherapy and determine the appropriate surgical technique. Imaging modalities such as endoscopic ultrasonography, computed tomography, and magnetic resonance imaging (MRI) play an important role in assessing the depth of tumor penetration, lymph node involvement, mesorectal fascia and anal sphincter invasion, and presence of distant metastatic diseases. Currently, there is no consensus on a preferred imaging technique for preoperative staging of rectal cancer. However, high-resolution phased-array MRI is recommended as a standard imaging modality for preoperative local staging of rectal cancer, with excellent soft tissue contrast, multiplanar capability, and absence of ionizing radiation. This review will mainly focus on the role of MRI in preoperative local staging of rectal cancer and discuss recent advancements in MRI technique such as diffusion-weighted imaging and dynamic contrast-enhanced MRI.

Synchronous rectal and prostate cancer--the impact of MRI on incidence and imaging findings

OBJECTIVE

To evaluate the incidence of synchronous diagnosis of rectal and prostate cancer and to identify how the role of magnetic resonance imaging (MRI) for preoperative staging of rectal cancer has affected the incidence.

METHODS

Regional data from the Swedish Colorectal Cancer Registry and the Regional Cancer Registry in Stockholm-Gotland area (two million inhabitants) between the years 1995-2011 were used. Patients were included when the rectal cancer was diagnosed prior to the prostate cancer. Medical records and pre-treatment MRI were retrospectively reviewed.

RESULTS

Of 29,849 patients diagnosed with either disease, synchronous diagnosis was made in 29 patients (0.1%). Two patients were diagnosed in the years 1995-1999, seven patients between the years 2000-2005 and 20 patients between the years 2006-2011. The most common presentation, for the prostate cancer was incidental finding during staging for rectal cancer, n=20, and of those led MRI to the diagnosis in 14 cases. At retrospective review, all patients had focal lesions in the prostate on MRI and patients with higher suspicion of malignancy on MRI had more locally advanced disease.

CONCLUSION

Synchronous rectal and prostate cancer are a rare entity, but a strong increase in synchronous diagnosis is seen which may be attributed to improved diagnostic methods, including the use of pre-treatment MRI in routine work-up for rectal cancer.

Multidisciplinary treatment of rectal cancer in 2014: where are we going?

In the present review we discuss the recent developments and future directions in the multimodal treatment of locally advanced rectal cancer, with respect to staging and re-staging modalities, to the current role of neoadjuvant chemo-radiation and to the conservative and more limited surgical approaches based on tumour response after neoadjuvant combined therapy. When initial tumor staging is considered a high accuracy has been reported for T pre-treatment staging, while preoperative lymph node mapping is still suboptimal. With respect to tumour re-staging, all the current available modalities still present a limited accuracy, in particular in defining a complete response. The role of short vs long-course radiotherapy regimens as well as the optimal time of surgery are still unclear and under investigation by means of ongoing randomized trials. Observational management or local excision following tumour complete response are promising alternatives to total mesorectal excision, but need further evaluation, and their use outside of a clinical trial is not recommended. The preoperative selection of patients who will benefit from neoadjuvant radiotherapy or not, as well as the proper identification of a clinical complete tumour response after combined treatment modalities,will influence the future directions in the treatment of locally advanced rectal cancer.

A practical review of the performance and interpretation of staging magnetic resonance imaging for rectal cancer

OBJECTIVES

The purpose of this article was to outline key technical considerations in performing rectal magnetic resonance imaging (MRI) along with a practical, systematic approach to the interpretation of rectal MRI.

CONCLUSIONS

Following validation by the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study group, rectal MRI is mandatory for the local staging of rectal cancer in many countries. The systematic interpretation of high-quality, high-resolution T2-weighted images should form the basis for discussing the management of patients with rectal cancer, including aiding surgical planning and enabling the appropriate use of neoadjuvant therapy. In this article, we discuss the methods for obtaining high-quality rectal magnetic resonance images and a systematic approach for the accurate interpretation of these images.

Multiparametric MRI of rectal cancer in the assessment of response to therapy: a systematic review

BACKGROUND

Conventional MRI is limited in the assessment of nodal status and T status after neoadjuvant chemoradiotherapy. Multiparametric MRI strives to overcome these issues by directly measuring the local microcirculation and cellular environment, thus possibly allowing for a more reliable evaluation of response to therapy.

OBJECTIVE

We assessed the available literature for the value of multiparametric MRI sequences (diffusion-weighted and dynamic contrast-enhanced imaging) in determining the response to neoadjuvant chemoradiotherapy in patients with rectal cancer.

DATA SOURCES

We conducted a systematic literature research in the PubMed database.

STUDY SELECTION

English-language publications of the years 2000-2013 that applied multiparametric MRI in the neoadjuvant setting were included in this study.

INTERVENTION

Patients received neoadjuvant chemoradiotherapy and MRI examinations for staging and assessment of response.

MAIN OUTCOME MEASURES

Accuracy, specificity, and sensitivity of MRI in prediction/assessment of response to therapy were the included measures.

RESULTS

Forty-three studies were included in this review; 30 of them included diffusion-weighted imaging sequences, and 13 included dynamic contrast-enhanced MRI. Conventional MRI is limited in the accuracy of both T and N stages and response assessment. Diffusion-weighted imaging and dynamic contrast-enhanced MRIs showed additional value in both the prediction and detection of (complete) response to therapy compared with conventional sequences alone, as well as in correct N staging along with new experimental contrast agents.

LIMITATIONS

The lack of standardization represents an important technical limitation. Most studies are conducted in an experimental setting; therefore, larger multicenter prospective studies are needed to verify the present findings.

CONCLUSIONS

Advanced, functional MRI techniques allow for the quantification of tumor biological processes, such as microcirculation, vascular permeability, and tissue cellularity. This new technology has begun to show potential advantages over standard morphologic imaging in the restaging of rectal cancer, allowing for more accurate prognostication of response and potentially introducing an era allowing earlier treatment alteration and more accurate noninvasive surveillance, which could improve patient outcomes.

Transanal endoscopic microsurgery: a review

Rectal adenomas and cancers occur frequently. Small adenomas can be removed colonoscopically, whereas larger polyps are removed via conventional transanal excision. Owing to technical difficulties, adenomas of the mid- and upper rectum require radical resection. Transanal endoscopic microsurgery (TEM) was first designed as an alternative treatment for these lesions. However, since its development TEM has been also used for a variety of rectal lesions, including carcinoids, rectal prolapse and diverticula, early stage carcinomas and palliative resection of rectal cancers. The objective of this review is to describe the current status of TEM in the treatment of rectal lesions. Since the 1980s, TEM has advanced substantially. With low recurrence rates, it is the method of choice for resection of endoscopically unresectable adenomas. Some studies have shown benefits to its use in treating early T1 rectal cancers compared with radical surgery in select patients. However, for more advanced rectal cancers TEM should be considered palliative or experimental. This technique has also been shown to be safe for the treatment of other uncommon rectal tumours, such as carcinoids. Transanal endoscopic microsurgery may allow for new strategies in the treatment of rectal pathology where technical limitations of transanal techniques have limited endoluminal surgical innovations.

Eastern Canadian Colorectal Cancer Consensus Conference: standards of care for the treatment of patients with rectal, pancreatic, and gastrointestinal stromal tumours and pancreatic neuroendocrine tumours

The annual Eastern Canadian Colorectal Cancer Consensus Conference was held in Halifax, Nova Scotia, October 20-22, 2011. Health care professionals involved in the care of patients with colorectal cancer participated in presentation and discussion sessions for the purposes of developing the recommendations presented here. This consensus statement addresses current issues in the management of rectal cancer, including pathology reporting, neoadjuvant systemic and radiation therapy, surgical techniques, and palliative care of rectal cancer patients. Other topics discussed include multidisciplinary cancer conferences, treatment of gastrointestinal stromal tumours and pancreatic neuroendocrine tumours, the use of folfirinox in pancreatic cancer, and treatment of stage ii colon cancer.

Efficacy of high resolution magnetic resonance imaging in preoperative local staging of rectal cancer

OBJECTIVE

To assess the efficacy of high-resolution magnetic resonance imaging (HRMRI) for preoperative local staging in patients with rectal cancer who did not receive preoperative radiochemotherapy.

METHODS

In this retrospective study, 30 patients with biopsy proved primary rectal cancer were evaluated by HRMRI. Two observers independently scored the tumour and lymph node stages, and circumferential resection margin (CRM) involvement. The sensitivity, specificity, the negative predictive value and the positive predictive value of HRMRI findings were calculated within the 95% confidence interval. The area under the curve was measured for each result. Agreement between two observers was assessed by means of the Kappa test.

RESULTS

In T staging the accuracy rate of HRMRI was 47-67%, overstaging was 10-21%, and understaging was 13-43%. In the prediction of extramural invasion with HRMRI, the sensitivity was 79-89%, the specificity was 72-100%, the PPV was 85-100%, the NPV was 73-86%, and the area under the curve was 0.81-0.89. In the prediction of lymph node metastasis, the sensitivity was 58-58%, the specificity was 50-55%, the PPV was 43-46%, and the NPV was 64-66%. The area under the curve was 0.54-0.57. When the cut off value was selected as 1 mm, the sensitivity of HRMRI was 38-42%, the specificity was 73-82%, the PPV was 33-42%, and NPV was 79-81% in the prediction of the CRM involvement. The correlation between the two observers was moderate for tumour staging, substantial for lymph node staging and predicting of CRM involvement.

CONCLUSION

Preoperative HRMRI provides good predictive data for extramural invasion but poor prediction of lymph node status and CRM involvement.

CONFLICT OF INTEREST

None declared.

Optimizing adjuvant treatment decisions for stage t2 rectal cancer based on mesorectal node size: a decision analysis

RATIONALE AND OBJECTIVES

The aim of this study was to optimize treatment decisions for patients with suspected stage T2 rectal cancer on the basis of mesorectal lymph node size at magnetic resonance imaging.

MATERIALS AND METHODS

A decision-analytic model was developed to predict outcomes for patients with stage T2 rectal cancer at magnetic resonance imaging. Node-positive patients were assumed to benefit from chemoradiation prior to surgery. Imperfect magnetic resonance imaging performance for primary cancer and mesorectal nodal staging was incorporated. Five triage strategies were considered for administering preoperative chemoradiation: treat all patients; treat for any mesorectal node >3, >5, and >7 mm in size; and treat no patients. If nodal metastases or unsuspected stage T3 disease went untreated preoperatively, postoperative chemoradiation was needed, resulting in poorer outcomes. For each strategy, rates of acute and long-term chemoradiation toxicity and of 5-year local recurrence were computed. Effects of input parameter uncertainty were evaluated in sensitivity analysis.

RESULTS

The optimal strategy depended on the outcome prioritized. Acute and long-term chemoradiation toxicity rates were minimized by triaging only patients with nodes >7 mm to preoperative chemoradiation (18.9% and 10.8%, respectively). A treat-all strategy minimized the 5-year local recurrence rate (5.6%). A 7-mm nodal triage threshold increased the 5-year local recurrence rate to 8.0%; when no patients were treated preoperatively, the local recurrence rate was 10.1%. With improved primary tumor staging, all outcomes could be further optimized.

CONCLUSIONS

Mesorectal nodal size thresholds for preoperative chemoradiation should depend on the outcome prioritized: higher size thresholds reduce chemoradiation toxicity but increase recurrence rates. Improvements in nodal staging will have greater impact if primary tumor staging can be improved.

T-staging of rectal cancer: accuracy of 3.0 Tesla MRI compared with 1.5 Tesla

Objectives

Magnetic resonance imaging (MRI) is not accurate in discriminating T1-2 from borderline T3 rectal tumors. Higher resolution on 3 Tesla-(3T)-MRI could improve diagnostic performance for T-staging. The aim of this study was to determine whether 3T-MRI compared with 1.5 Tesla-(1.5T)-MRI improves the accuracy for the discrimination between T1-2 and borderline T3 rectal tumors and to evaluate reproducibility.

Methods

13 patients with non-locally advanced rectal cancer underwent imaging with both 1.5T and 3T-MRI. Three readers with different expertise evaluated the images and predicted T-stage with a confidence level score. Receiver operator characteristics curves with areas under the curve (AUC) and diagnostic parameters were calculated. Inter- and intra-observer agreements were calculated with quadratic kappa-weighting. Histology was the reference standard.

Results

Seven patients had pT1-2 tumors and six had pT3 tumors. AUCs ranged from 0.66 to 0.87 at 1.5T vs. 0.52–0.82 at 3T. Mean overstaging rate was 43% at 1.5T and 57% at 3T (P = 0.23). Inter-observer agreement was κ 0.50–0.71 at 1.5T vs. 0.15–0.68 at 3T. Intra-observer agreement was κ 0.71 at 1.5T and 0.76 at 3T.

Conclusions

This is the first study to compare 3T with 1.5T MRI for T-staging of rectal cancer within the same patients. Our results showed no difference between 3T and 1.5T-MRI for the distinction between T1-2 and borderline T3 tumors, regardless of expertise. The higher resolution at 3T-MRI did not aid in the distinction between desmoplasia in T1-2-tumors and tumor stranding in T3-tumors. Larger studies are needed to acknowledge these findings.

MR imaging for preoperative evaluation of primary rectal cancer: practical considerations

High-resolution magnetic resonance (MR) imaging plays a pivotal role in the pretreatment assessment of primary rectal cancer. The success of this technique depends on obtaining good-quality high-resolution T2-weighted images of the primary tumor; the mesorectal fascia, peritoneal reflection, and other pelvic viscera; and superior rectal and pelvic sidewall lymph nodes. Although orthogonal axial high-resolution T2-weighted MR images are the cornerstone for the staging of primary rectal cancer, high-resolution sagittal and coronal images provide additional value, particularly in tumors that arise in a redundant tortuous rectum. Coronal high-resolution T2-weighted MR images also improve the assessment of nodal morphology, particularly for superior rectal and pelvic sidewall nodes, and of the relationship between advanced-stage tumors and adjacent pelvic structures. Rectal gel should be used in MR imaging examinations conducted for the staging of polypoid tumors, previously treated lesions, and small rectal tumors. However, it should not be used in examinations performed to stage large or low rectal tumors. Diffusion-weighted imaging is useful for identifying nodes and, occasionally, the primary tumor when the tumor is difficult to visualize with other sequences. Three-dimensional T2-weighted imaging provides multiplanar capability with a superior signal-to-noise ratio compared with two-dimensional T2-weighted imaging.

A single-centre experience of chemoradiotherapy for rectal cancer: is there potential for nonoperative management?

AIM

The aim of the study was to assess the outcome of patients who received chemoradiotherapy (CRT) for locally advanced rectal cancer, specifically those with complete clinical response (CCR) and who were then managed nonoperatively with a 'Watch and Wait' follow-up protocol.

METHOD

A retrospective study was carried out of patients undergoing preoperative CRT for rectal cancer, conducted in a district general hospital managing rectal cancer through the multidisciplinary team process.

RESULTS

Forty-nine patients received preoperative CRT over a 5-year period (2004-2009). Twelve (24%) were considered potentially to have had a complete response on MRI. Of these, six subsequently had clinical evidence of residual disease, leading to surgery (mean time to surgery, 24 weeks; range, 12-36 weeks). The remaining six had CCR, avoiding surgery (mean follow up, 26 months; range, 12-45 months), with all six patients disease free to date. A further six patients had complete pathological response (CPR) following surgery after comprehensive histopathological assessment of the specimen.

CONCLUSION

In this consecutive series of patients with locally advanced rectal cancer treated with CRT, 12% demonstrated a CCR and have been actively managed conservatively, thereby avoiding surgery. With further improvements in diagnostic assessment of response to CRT, this figure may rise.

Preoperative rectal cancer staging with phased-array MR

Background

We retrospectively reviewed magnetic resonance (MR) images of 96 patients with diagnosis of rectal cancer to evaluate tumour stage (T stage), involvement of mesorectal fascia (MRF), and nodal metastasis (N stage).

Our gold standard was histopathology.

Methods

All studies were performed with 1.5-T MR system (Symphony; Siemens Medical System, Erlangen, Germany) by using a phased-array coil. Our population was subdivided into two groups: the first one, formed by patients at T1-T2-T3, N0, M0 stage, whose underwent MR before surgery; the second group included patients at Tx N1 M0 and T3-T4 Nx M0 stage, whose underwent preoperative MR before neoadjuvant chemoradiation therapy and again 4-6 wks after the end of the treatment for the re-staging of disease.

Our gold standard was histopathology.

Results

MR showed 81% overall agreement with histological findings for T and N stage prediction; for T stage, this rate increased up to 95% for pts of group I (48/96), while for group II (48/96) it decreased to 75%.

Preoperative MR prediction of histologically involved MRF resulted very accurate (sensitivity 100%; specificity 100%) also after chemoradiation (sensitivity 100%; specificity 67%).

Conclusions

Phased-array MRI was able to clearly estimate the entire mesorectal fat and surrounding pelvic structures resulting the ideal technique for local preoperative rectal cancer staging.

Preoperative tumour staging with multidisciplinary team assessment improves the outcome in locally advanced primary rectal cancer

AIM

Multidisciplinary team meetings have been introduced as a result of developments in preoperative radiological tumour staging and neoadjuvant treatment. Multidisciplinary team recommendations will influence treatment decisions but their effect on patient outcome is unknown. The aim of this study was to assess outcome in relation to preoperative local and distant staging, with or without multidisciplinary team assessment.

METHODS

A population-based registry of all patients with rectal cancer, treated in the Stockholm region from 1995 to 2004, identified 303 patients with locally advanced primary rectal cancer. The patients were classified into three groups: group 1, preoperative local and distant radiological tumour staging with discussion at a multidisciplinary team meeting; group 2, preoperative staging but no multidisciplinary team assessment; and group 3, no proper preoperative radiological staging.

RESULTS

Neoadjuvant treatment was more prevalent in groups 1 and 2 than in group 3. The incidence of R0 resection differed significantly between the groups (52% in group 1, 43% in group 2 and 21% in group 3; P < 0.001). Local tumour control was achieved in 57%, 36%, and 19% of patients in groups 1, 2 and 3, respectively (P < 0.001). The estimated overall 5-year survival of patients was 30%, 28% and 12% in groups 1, 2 and 3, respectively.

CONCLUSION

Preoperative radiological tumour staging in patients with locally advanced primary rectal cancer and discussion at a multidisciplinary team meeting increases the proportion of patients receiving neoadjuvant treatment and cancer-specific end-points.

Local staging of rectal cancer: a review of imaging

During the past decades the management of patients with rectal cancer has substantially changed, with a significant reduction in local recurrence rates following the introduction of better imaging, better surgery, and more efficient neoadjuvant therapy. This review discusses the clinically relevant information radiologists should know on staging of rectal cancer patients. The crucial role of the radiologist in patient management is explained. Furthermore, the evidence for the use of magnetic resonance imaging (MRI) in staging and restaging of rectal cancer patients as well as the main features that need to be evaluated when interpreting rectal cancer MRI are given. New diagnostic challenges as a result of new treatment options are also discussed.

Extended abdominoperineal excision vs. standard abdominoperineal excision in rectal cancer--a systematic overview

BACKGROUND

After introduction of total mesorectal excision (TME) as the gold standard for rectal cancer surgery, oncologic results appeared to be inferior for abdominoperineal excision (APE) as compared to anterior resection. This has been attributed to the technique of standard APE creating a waist at the level of the tumor-bearing segment. This systematic review investigates outcome of both standard and extended techniques of APE regarding inadvertent bowel perforation, circumferential margin (CRM) involvement, and local recurrence.

METHODS

A literature search was performed to identify all articles reporting on APE after the introduction of TME using Medline, Ovid, and Embase. Extended APE was defined as operations that resected the levator ani muscle close to its origin. All other techniques were taken to be standard. Studies so identified were evaluated using a validated instrument for assessing nonrandomized studies. Rates for perforation, CRM involvement, and local recurrence were compared using chi-square statistics.

RESULTS

In the extended group, 1,097 patients, and in the standard group, 4,147 patients could be pooled for statistical analysis. The rate of inadvertent bowel perforation and the rate of CRM involvement for extended vs. standard APE was 4.1% vs. 10.4% (relative risk reduction 60.6%, p = 0.004) and 9.6% vs. 15.4% (relative risk reduction 37.7%, p = 0.022), respectively. The local recurrence rate was 6.6% vs. 11.9% (relative risk reduction 44.5%, p < 0.001) for the two groups.

CONCLUSION

This systematic review suggests that extended techniques of APE result in superior oncologic outcome as compared to standard techniques.

Role of radiation in intermediate-risk rectal cancer

The treatment of rectal cancer has greatly evolved during the last several decades as a result of the understanding of the pathways of cancer spread, natural history of the disease, stages prognosis and prognostic markers. The tendency is clearly to move toward a more personalized approach to these patients based on preoperative staging and response to therapy. Although in the past we have been adding more treatment modalities to surgery to the point that every stage II/III cancer was treated with neoadjuvant chemo and radiotherapy followed by radical surgery by total mesorectal excision with or without sphincter preservation and more chemotherapy to follow, more recently this algorithm has been under discussion and scrutiny. Two of the major topics of controversy are: the use of local excision or even a watch-and-wait approach after a clinical complete response and the need for radiotherapy in the intermediate risk group. In this manuscript we will present the historical perspective that has brought the treatment of rectal cancer to the current standard of care and present the evidence supporting further investigation in the intermediate risk group.

Postgraduate multidisciplinary development program: impact on the interpretation of pelvic MRI in patients with rectal cancer: a clinical audit in West Denmark

BACKGROUND

Pelvic MRI in patients with rectal cancer is an accepted tool for the identification of patients with poor prognostic tumors who may benefit from neoadjuvant therapy. In Denmark, this examination has been mandatory in the workup on rectal cancer since 2002.

OBJECTIVE

This study aimed to assess the impact of a multidisciplinary team course for doctors in West Denmark on the technical quality, reporting, and interpretation of pelvic MRI in rectal cancer.

DESIGN

This study is interventional and observational. Two expert reviewers served as reference standard in the evaluation of consecutively performed pelvic MRI scans against which the evaluations from the participating centers were compared.

SETTINGS

Five imaging centers in West Denmark performed pelvic MRI in rectal cancer from March 1 to December 31, 2007.

PATIENTS

One hundred and eighty patients with newly diagnosed rectal cancer were enrolled.

INTERVENTIONS

This study involved a multidisciplinary team course including on-site visits.

MAIN OUTCOME MEASURES

The MR scans were evaluated concerning technical performance, reporting, interpretation, and the ability to correctly allocate patients to chemoirradiation based on imaging findings pre- and postcourse.

RESULTS

Eighteen percent of the scans were of satisfying technical quality for staging rectal cancer before the course compared with 74% after (P < .001). After the course, the T-stage subclassification, the depth of extramural spread, the N stage, and the presence of extramural vascular invasion was reported significantly more frequently. Based on imaging findings, we observed no significant effect on the ability to perform correct treatment stratification according to Danish guidelines.

LIMITATIONS

The evaluation process itself may have improved the performance of the participating centers.

CONCLUSIONS

Performance and reporting of pelvic MRI in patients with rectal cancer can be improved significantly through multidisciplinary development courses and on-site visits, whereas improvements in image interpretation with regard to treatment stratification may demand more intensive efforts.

Management of stage IV rectal cancer: Palliative options

Approximately 30% of patients with rectal cancer present with metastatic disease. Many of these patients have symptoms of bleeding or obstruction. Several treatment options are available to deal with the various complications that may afflict these patients. Endorectal stenting, laser ablation, and operative resection are a few of the options available to the patient with a malignant large bowel obstruction. A thorough understanding of treatment options will ensure the patient is offered the most effective therapy with the least amount of associated morbidity. In this review, we describe various options for palliation of symptoms in patients with metastatic rectal cancer. Additionally, we briefly discuss treatment for asymptomatic patients with metastatic disease.

Pretherapy imaging of rectal cancers: ERUS or MRI?

ERUS and MRI should be seen more as complementary rather than competitive techniques. Each has its own strengths and weaknesses. ERUS is better in showing the tumor extent in small superficial tumors, whereas MRI is superior in imaging the more advanced tumors. The choice of imaging technique depends also on the amount of information that is required for choosing certain treatment strategies, like the distance to the mesorectal fascia for a short course of preoperative radiotherapy. For lymph node imaging, both techniques are at present only moderately accurate, although this could change with advances in new MR techniques.

3-T MRI with phased-array surface coil in the local staging of rectal cancer

PURPOSE

This study sought to evaluate the diagnostic accuracy of surface-coil 3T magnetic resonance (MR) imaging in the preoperative study of patients with rectal cancer.

MATERIALS AND METHODS

Thirty patients with histologically proven rectal cancer underwent surface-coil 3T MR imaging with sagittal, paracoronal and para-axial T2-weighted turbo spin echo (TSE) sequences. Slice thickness was 3 mm without gap, field of view 24 cm, matrix 400 × 512. Images were assessed for infiltration of the rectal wall, perirectal fat and pelvic structures. Tumours were staged according to the TNM system, and the MR imaging results were correlated with histopathology.

RESULTS

In the patients who underwent MR imaging before and after radiotherapy (group 1), the diagnostic accuracy of 3T MR imaging was 88% for T2, 94% for T3 and 88% for T4 cancers. In those who underwent surgical treatment without preoperative radiotherapy (group 2), the diagnostic accuracy was 90% for T2, 87% for T3 and 87% for T4 cancers.

CONCLUSIONS

The high signal-to-noise ratio coupled with a large field of view enables surface-coil 3T MR imaging to achieve high levels of diagnostic accuracy in the local staging of rectal cancer, and in particular in assessing infiltration of mesorectum and mesorectal fascia.

Tumor volume reduction rate measured by magnetic resonance volumetry correlated with pathologic tumor response of preoperative chemoradiotherapy for rectal cancer

PURPOSE

To determine whether the tumor volume reduction rate (TVRR) measured using three-dimensional region-of-interest magnetic resonance volumetry correlates with the pathologic tumor response after preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer.

METHODS AND MATERIALS

The study included 405 patients with locally advanced rectal cancer (cT3-T4) who had undergone preoperative CRT and radical proctectomy. The tumor volume was measured using three-dimensional region-of-interest magnetic resonance volumetry before and after CRT but before surgery. We analyzed the correlation between the TVRR and the pathologic tumor response in terms of downstaging and tumor regression grade (TRG). Downstaging was defined as ypStage 0-I (ypT0-T2N0M0), and the TRG proposed by Dworak et al. was used.

RESULTS

The mean TVRR was 65.0% +/- 22.3%. Downstaging and complete regression occurred in 167 (41.2%) and 58 (14.3%) patients, respectively. The TVRRs according to ypT classification (ypT0-T2 vs. ypT3-T4), ypN classification (ypN0 vs. ypN1-N2), downstaging (ypStage 0-I vs. ypStage II-III), good regression (TRG 3-4 vs. TRG 1-2), and complete regression (TRG 4 vs. TRG 1-3) were all significantly different (p <.05). When the TVRR was categorized into three groups (<60%, 60-80%, and >80%), the rates of ypT0-T2, ypN0, downstaging, and good regression were all significantly greater for patients with a TVRR of >or=60%, as was the complete regression rate for patients with a TVRR >80% (p <.05).

CONCLUSION

The TVRR measured using three-dimensional region-of-interest magnetic resonance volumetry correlated significantly with the pathologic tumor response in terms of downstaging and TRG after preoperative CRT for locally advanced rectal cancer.

Endorectal ultrasound: its role in the diagnosis and treatment of rectal cancer

With development over the past 25 years of new surgical techniques and neoadjuvant therapy regimens for rectal cancer, physicians now have a range of treatment options that minimize morbidity and maximize the potential for cure. Accurate pretreatment staging is critical, ensuring adequate therapy and preventing overtreatment. Many options exist for staging primary rectal cancer. However, endorectal ultrasound (ERUS) remains the most attractive modality. It is an extension of the physical examination, and can be performed easily in the office. It is cost effective and is generally well tolerated by the patient, without need for general anesthesia. The authors discuss the data currently available on ERUS, including its accuracy and limitations, as well as the technical aspects of performing ERUS and interpreting the results. They also discuss new ultrasound technologies, which may improve rectal cancer staging in the future.

Role of tumor size in the pre-operative management of rectal cancer patients

Background

Clinical management of rectal cancer patients relies on pre-operative staging. Studies however continue to report moderate degrees of over/understaging as well as inter-observer variability. The aim of this study was to determine the sensitivity, specificity and accuracy of tumor size for predicting T and N stages in pre-operatively untreated rectal cancers.

Methods

We examined a test cohort of 418 well-documented patients with pre-operatively untreated rectal cancer admitted to the University Hospital of Basel between 1987 and 1996. Classification and regression tree (CART) and logistic regression analysis were carried out to determine the ability of tumor size to discriminate between early (pT1-2) and late (pT3-4) T stages and between node-negative (pN0) and node-positive (pN1-2) patients. Results were validated by an external patient cohort (n = 28).

Results

A tumor diameter threshold of 34 mm was identified from the test cohort resulting in a sensitivity and specificity for late T stage of 76.3%, and 67.4%, respectively and an odds ratio (OR) of 6.67 (95%CI:3.4-12.9). At a threshold value of 29 mm, sensitivity and specificity for node-positive disease were 94% and 15.5%, respectively with an OR of 3.02 (95%CI:1.5-6.1). Applying these threshold values to the validation cohort, sensitivity and specificity for T stage were 73.7% and 77.8% and for N stage 50% and 75%, respectively.

Conclusions

Tumor size at a threshold value of 34 mm is a reproducible predictive factor for late T stage in rectal cancers. Tumor size may help to complement clinical staging and further optimize the pre-operative management of patients with rectal cancer.

Rectal cancer: comparison of accuracy of local-regional staging with two- and three-dimensional preoperative 3-T MR imaging

PURPOSE

To compare the local-regional staging accuracy of the conventional two-dimensional (2D) T2-weighted imaging protocol and of the three-dimensional (3D) T2-weighted imaging protocol for preoperative magnetic resonance (MR) imaging in rectal cancer patients.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, and a waiver of informed consent was obtained. A review was conducted of 109 preoperative 3-T MR images obtained with 2D and 3D T2-weighted imaging protocols in rectal cancer patients. Two radiologists independently assessed the radiologic findings for T and N category lesions, conspicuity of tumor margin, and image quality of 2D and 3D data. Interactive multiplanar reconstruction was performed for 3D data analysis. The linear weighted kappa values for T2-weighted imaging staging results (2D and 3D data) and histopathologic staging results were calculated and compared. Wilcoxon signed rank test was performed to compare tumoral conspicuity and overall image quality.

RESULTS

T category lesion staging accuracy values for 2D and 3D data, respectively, were 66.0% and 67.0% for reviewer 1 (P = .465) and 63.3% and 56.9% for reviewer 2 (P = .402). N category lesion staging accuracy values for 2D and 3D T2-weighted images, respectively, were 64.2% and 57.8% for reviewer 1 (P = .427) and 47.7% and 62.4% for reviewer 2 (P = .666). Tumor conspicuity was better for 2D T2-weighted imaging, but no significant difference in image quality was observed.

CONCLUSION

Preoperative MR imaging in rectal cancer patients for staging with conventional 2D and multiplanar reconstruction 3D T2-weighted imaging protocols showed no significant differences in accuracy of T and N category staging and overall image quality, as determined by degree of artifact. However, the 3D T2-weighted imaging protocol had limitations in regard to lesion conspicuity.