Primary rectal cancer local staging

Development of orthotopic mouse models for mid-low rectal cancer

Mid-low rectal cancer is one of the most common types of rectal cancer and has a poor prognosis. Surgery and chemoradiotherapy are the main treatments for early and advanced rectal cancer with an overall 5-year relative survival rate of only 56.9%. Development of novel antitumor agents is needed. Animal models of disease are indispensable for drug development. The most commonly used animal models of rectal cancer are established by inducing tumors by the subcutaneous transplantation, cecum or peritoneal injection, but not injection in the rectum. Their tumor microenvironment differs from that of rectal tumors in situ, which is hard to precisely simulate the occurrence and development process and drug response of human rectal cancer. In this study, we established orthotopic mouse models of mid-low rectal cancer with primary tumors originating from the rectum, including two models that could simulate the early and advanced stages of the disease, respectively. In the first model, the local primary tumor was restricted to the rectal area of the anal verge by rectal submucosal injection, its growth could be monitored with IVIS live imaging and magnetic resonance imaging. Histological analysis confirmed that the tumor originated from the submucosal layer and then invaded the muscular layer without metastatic tumors. This model may be useful for evaluating drugs for early mid-low rectal cancer in the future. The second model featuring a rectal primary tumor accompanied with abdominal metastases was established via rectal serosal injection. In this model, a large tumor formed at the rectal injection site and then metastasized to the abdominal cavity, reproducing the process from occurrence to metastasis of mid-low rectal cancer, and may be a good tool for the evaluation of drugs for advanced-stage disease. The injection methods used in these models do not require the aid of special colonoscopes, are simple and easy to operate, and have high tumor tumorigenicity and reproducibility. These results suggest that our staged modeling can provide targeted choices for preclinical drug research of mid-low rectal cancer at different stages.

Imaging of young-onset colorectal cancer: what the radiologist needs to know

Young-onset colorectal cancer (YOCRC) refers to colorectal cancer diagnosed in individuals under the age of 50. Whilst the overall incidence of colorectal cancer is decreasing, YOCRC cases are increasing and now accounts for up to 10% of all colorectal cancers. YOCRC more frequently presents with acute symptoms, where radiologists play an important role in identifying malignancy and distinguishing it from benign colonic pathologies. Risk factors associated with YOCRC, such as inflammatory bowel disease and hereditary syndromes, may exhibit specific imaging manifestations. In addition, YOCRC is frequently associated with a mucinous histopathological subtype which may be identifiable based on the presence of specific imaging features. Given their younger age, these patients are more likely to undergo aggressive treatment and complex surgical interventions. Specific considerations such as fertility preserving surgical techniques must be factored in when managing these patients. As the incidence of YOCRC increases, guidance for colonoscopy screening protocols may need revision. This includes evaluating the role of ionising imaging techniques in both diagnosing and follow-up to balance early detection and minimising radiation exposure in this younger patient population.

Diagnostic Performance of Rectal CT for Staging Rectal Cancer: Comparison with Rectal MRI and Histopathology

Purpose

To compare the diagnostic performance of rectal CT with that of high-resolution rectal MRI and histopathology in assessing rectal cancer.

Materials and Methods

Sixty-seven patients with rectal cancer who underwent rectal CT with rectal distension using sonographic gel and high-resolution MRI were enrolled in this study. The distance from the anal verge/anorectal junction, distance to the mesorectal fascia (MRF), extramural depth (EMD), extramesorectal lymph node (LN) involvement, extramural venous invasion (EMVI), and T/N stages in rectal CT/MRI were analyzed by two gastrointestinal radiologists. The CT findings of 20 patients who underwent radical surgery without concurrent chemoradiotherapy were compared using histopathology. Interclass correlations and kappa statistics were used.

Results

The distance from the anal verge/anorectal junction showed an excellent intraclass correlation between CT and MRI for both reviewers. For EMD, the distance to the MRF, presence of LNs, extramesorectal LN metastasis, EMVI, T stage, and intermodality kappa or weighted kappa values between CT and MRI showed excellent agreement. Among the 20 patients who underwent radical surgery, T staging, circumferential resection margin involvement, EMVI, and LN metastasis on rectal CT showed acceptable concordance rates with histopathology.

Conclusion

Dedicated rectal CT may be on par with rectal MRI in providing critical information to patients with rectal cancer.

How do they measure up: Assessing the height of rectal cancer with digital rectal exam, endoscopy, and MRI,

Background

Outcomes in rectal cancer are dependent on tumor height. Modalities for assessing tumor height include MRI, endoscopy, and digital rectal exam (DRE). We seek to identify correlations between these modalities.

Methods

Retrospective analysis of 120 rectal cancer patients at a single institution. Correlation coefficients and distance of the tumor to anal verge between MRI, endoscopy, and DRE were compared by region.

Results

The distances of tumor (cm) from anal verge were: MRI: 6.2 ± 3.0, endoscopy: 5.9 ± 2.9, DRE: 5.4 ± 2.4 (p = 0.238). Endoscopy and DRE strongly correlated with MRI (spearman coefficient 0.899 and 0.842, respectively). Endoscopy and DRE also strongly correlated (spearman coefficient 0.876). Correlation coefficients were highest in the middle rectum, weak in the low rectum, and non-correlated in the upper rectum.

Conclusions

MRI, endoscopy, and DRE strongly correlated overall. DRE demonstrated the lowest average distance. Correlations differed by region, suggesting high or low rectal tumors are difficult to characterize.

Structured and shared MRI staging lexicon and report of rectal cancer: A consensus proposal by the French Radiology Group (GRERCAR) and Surgical Group (GRECCAR) for rectal cancer

PURPOSE

To develop French guidelines by experts to standardize data acquisition, image interpretation, and reporting in rectal cancer staging with magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Evidence-based data and opinions of experts of GRERCAR (Groupe de REcherche en Radiologie sur le CAncer du Rectum [i.e., Rectal Cancer Imaging Research Group]) and GRECCAR (Groupe de REcherche en Chirurgie sur le CAncer du Rectum [i.e., Rectal Cancer Surgery Research Group]) were combined using the RAND-UCLA Appropriateness Method to attain consensus guidelines. Experts scoring of reporting template and protocol for data acquisition were collected; responses were analyzed and classified as "Recommended" versus "Not recommended" (when ≥ 80% consensus among experts) or uncertain (when < 80% consensus among experts).

RESULTS

Consensus regarding patient preparation, MRI sequences, staging and reporting was attained using the RAND-UCLA Appropriateness Method. A consensus was reached for each reporting template item among the experts. Tailored MRI protocol and standardized report were proposed.

CONCLUSION

These consensus recommendations should be used as a guide for rectal cancer staging with MRI.

MRI Evaluation of Extramural Venous Invasion (EMVI) with Rectal Carcinoma Using High Resolution T2 and Combination of High Resolution T2 and Contrast Enhanced T1 Weighted Imaging

Background:

EMVI is a direct invasion of a vein by a tumor. As a predictor of hematogenous metastasis, it is a poor prognostic factor in rectal cancer and can be accurately identified on MRI prior to surgical procedure.

Objective:

To evaluate the role of contrast-enhanced T1-weighted magnetic resonance imaging (CET1WI) in addition to high-resolution T2-weighted imaging (HRT2WI) in assessing extramural venous invasion (EMVI) of rectal cancer.

Methods:

In all 195 patients with rectal cancer, HRT2WI and CET1WI sequences were produced within pre-operative MRI for the purpose of assessing for the presence of EMVI (mrEMVI). CET1WI sequences were produced following administration of Gadolinium contrast medium. mrEMVI assessment results were classified into two groups. Group A consisted of mrEMVI assessment results obtained using HRT2WI sequences only. Group B consisted of mrEMVI assessment results obtained using a combination of HRT2WI + CET1WI sequences. Results obtained for each group (A and B) were correlated with a histopathological finding (pEMVI) as a reference standard.

Results:

Out of a total of 195 rectal cancer patients, mrEMVI was positive in 41 (21%) patients in group A, and in 45 (23%) patients in group B. Histopathological finding demonstrated pEMVI in 54 (27.7%) patients. A statistical analysis of group A (HRT2WI sequences) resulted in 75.9% sensitivity to mrEMVI and 96.4% specificity, Positive Predictive Value of 89.1% and Negative Predictive Value of 91.2% (95% confidence interval (CI), p< 0.05). Statistical analysis of group B (HRT2WI + CET1WI sequences) resulted in 83.3% sensitivity to mrEMVI and 98.5% specificity, Positive Predictive Value of 89.1% and Negative Predictive Value of 91.2% (CI 95%, p< 0.05).

Conclusion:

T1-weighted magnetic resonance imaging (CET1WI) in addition to high-resolution T2-weighted imaging (HRT2WI) increased evaluation of extramural venous invasion (EMVI) of rectal cancer.

How to accurately measure the distance from the anal verge to rectal cancer on MRI: a prospective study using anal verge markers

PURPOSE

To determine an accurate method for localizing rectal cancer using the distance from the anal verge on preoperative MRI.

METHODS

This prospective study included 50 patients scheduled for MRI evaluation of rectal cancer. After rectal filling with gel, MRI was performed with two markers attached at the anal verge. The distance between the tumor and the anal verge on a sagittal T2-weighted image (T2WI) was measured independently by two radiologists using six methods divided into three groups of similar measurement approaches, and compared to those obtained on rigid sigmoidoscopy. The anal verge location relative to the external anal sphincter was assessed on oblique coronal T2WI in reference to the markers. Correlation analysis was performed using the intraclass correlation coefficient (ICC) for verification, and a paired t test was used to evaluate the mean differences.

RESULTS

The highest correlation (ICC 0.797-0.815) and the least mean difference (0.74-0.85 cm) with rigid sigmoidoscopy, and the least standard deviation (3.12-3.17 cm) were obtained in the direct methods group using a straight line from the anal verge to the tumor. The anal verge was localized within a range of - 1.4 to 1.5 cm (mean - 0.31 cm and - 0.22 cm) from the lower end of the external anal sphincter.

CONCLUSION

The direct methods group provided the most accurate tumor distance among the groups. Among the direct methods, we recommend the direct mass method for its simplicity. Despite minor differences in location, the lower end of the external anal sphincter was a reliable anatomical landmark for the anal verge.

MRI of Rectal Cancer: Tumor Staging, Imaging Techniques, and Management

Rectal cancer is prone to local recurrence and systemic metastasis. However, owing to improvements in TNM staging and treatment, including a more widespread use of rectal MRI and increased radiologist awareness of the key rectal cancer TNM staging features, the mortality rate of rectal cancer has been declining over the past few decades in adults over 50 years of age. Currently, rectal MRI plays a key role in the pre- and posttreatment evaluation of rectal cancer, assisting the multidisciplinary team in tailoring the most appropriate treatment option. The benefits achieved with rectal MRI are strictly dependent on obtaining good-quality images, which is important for the characterization of the main anatomic structures and their relationship with the tumor. In primary staging, rectal MRI helps the radiologist (a) describe the tumor location and morphology, (b) provide its T and N categories, (c) detect the presence of extramural vascular invasion, and (d) identify its relationship with surrounding structures, including the sphincter complex and involvement of the mesorectal fascia. These features help diagnose locally advanced rectal tumors (categories T3c-d, T4, N1, and N2), for which neoadjuvant chemoradiotherapy (CRT) is indicated. In restaging after neoadjuvant CRT, in addition to reassessing the features noted during primary staging, rectal MRI can help in the assessment of treatment response, especially with the emergence of nonsurgical approaches such as "watch and wait." ^©RSNA, 2019.

Reliability and validity assessment of administrative databases in measuring the quality of rectal cancer management

PURPOSE

Measurement and monitoring of the quality of care using a core set of quality measures are increasing in health service research. Although administrative databases include limited clinical data, they offer an attractive source for quality measurement. The purpose of this study, therefore, was to evaluate the completeness of different administrative data sources compared to a clinical survey in evaluating rectal cancer cases.

METHODS

Between May 2012 and November 2014, a clinical survey was done on 498 Lombardy patients who had rectal cancer and underwent surgical resection. These collected data were compared with the information extracted from administrative sources including Hospital Discharge Dataset, drug database, daycare activity data, fee-exemption database, and regional screening program database. The agreement evaluation was performed using a set of 12 quality indicators.

RESULTS

Patient complexity was a difficult indicator to measure for lack of clinical data. Preoperative staging was another suboptimal indicator due to the frequent missing administrative registration of tests performed. The agreement between the 2 data sources regarding chemoradiotherapy treatments was high. Screening detection, minimally invasive techniques, length of stay, and unpreventable readmissions were detected as reliable quality indicators. Postoperative morbidity could be a useful indicator but its agreement was lower, as expected.

CONCLUSIONS

Healthcare administrative databases are large and real-time collected repositories of data useful in measuring quality in a healthcare system. Our investigation reveals that the reliability of indicators varies between them. Ideally, a combination of data from both sources could be used in order to improve usefulness of less reliable indicators.

Pelvic MRI: Is Endovaginal or Rectal Filling Needed?

Magnetic resonance imaging is the optimal modality for pelvic imaging. It is based on T2-weighted magnetic resonance (MR) sequences allowing uterine and vaginal cavity assessment as well as rectal evaluation. Anatomical depiction of these structures may benefit from distension, and conditions either developing inside the lumen of cavities or coming from the outside may then be better delineated and localized. The need for distension, either rectal or vaginal, and the way to conduct it are matters of debate, depending on indication for which the MR examination is being conducted. In this review, we discuss advantages and potential drawbacks of this technique, based on literature and our experience, in the evaluation of various gynecological and rectal diseases.

Diffusion-weighted magnetic resonance imaging in colorectal cancer

Magnetic resonance imaging (MRI) plays now a major role in patients with colorectal cancer regarding tumor staging, surgical planning, therapeutic decision, assessment of tumor response to chemoradiotherapy and surveillance of rectal cancer, and detection and characterization of liver or peritoneal metastasis of colorectal cancers. Diffusion-weighted MRI (DW-MRI) is a functional imaging tool that is now part of the standard MRI protocol for the investigation of patients with colorectal cancer. DW-MRI reflects micro-displacements of water molecules in tissues and conveys high degrees of accuracy to discriminate between benign and malignant colorectal conditions. Thus, in addition to morphological imaging, DW-MRI has an important role to accurately detect colorectal neoplasms and peritoneal implants, to differentiate benign focal liver lesions from metastases and to detect tumor relapse within fibrotic changes. This review provides a comprehensive overview of basic principles, clinical applications and future trends of DW-MRI in colorectal cancers.

Current imaging of rectal cancer

Recent advances in rectal cancer surgery and treatment as well as new developments in magnetic resonance imaging (MRI) technique have led to extensive research in the field of preoperative imaging of rectal cancer and to an abundant literature. Pelvic MRI has indeed become an important part of the decision-making process for patients with rectal cancer. The aim of this article is to give current guidelines in terms of which imaging method to perform and also to review the role of imaging, with emphasis on MRI, not only for tumor primary staging but also for reevaluation of the tumor after neoadjuvant therapy, highlighting the role of new so-called "functional MR techniques". Future trends are also discussed.

Magnetic resonance imaging and endorectal ultrasound for diagnosis of rectal lesions

Endorectal ultrasonography (ERUS) and magnetic resonance imaging (MRI) allow exploring the morphology of the rectum in detail. Use of such data, especially assessment of the rectal wall, is an important tool for ascertaining the perianal fistula localization as well as stage of the cancer and planning it appropriate treatment, as stage T3 tumors are usually treated with neoadjuvant therapy, whereas T2 tumors are initially managed surgically. The only advantage of ERUS over MRI is the possibility of assessing T1 tumors that could be treated by transanal endoscopic microsurgery. However, MRI is better for visualizing most radiological prognostic features in rectal or anal cancer such as a circumferential resection margin less than 1 mm, T stage at T1-T2 or T3 tumors with extramural extension less than 5 mm, absence of extramural vascular invasion, N stage at N0/N1, and tumors located in the middle or upper third of the rectum. It can also evaluate the intersphincteric space or levator ani muscle involvement. Increased signal on diffusion weighted imaging (DWI) and low apparent diffusion coefficient (ADC) values as well as an irregular contour and heterogeneous internal signal intensity seem to predict the involvement of pelvic lymphatic nodes better than their size alone. Computed tomography as well as other examination techniques, including digital rectal examination, contrast edema, recto- and colonoscopy, are less useful in staging of rectal cancer but still are very important screening tools.