Height of Rectal Cancer: A Comparison between Rectoscopic and Different MRI Measurements

Defining the tumor location in rectal cancer - Practice variations and impact on treatment decision making

OBJECTIVE

To summarize differences in current guideline recommendations for rectal tumor localization and generate an overview of published MRI measurement methods and their correlation with endoscopy.

SUMMARYOF BACKGROUND DATA

Rectal tumor location is a well-known factor that impacts treatment planning, but there is currently no consensus on the optimal method to define it.

METHODS

A literature search was conducted to retrieve clinical and radiological rectal cancer guidelines as well as original research studies on MRI-based measurements. Guidelines were assessed for definitions, landmarks, modalities and measurement methods to define tumor location, and how these impact treatment planning. Research studies were evaluated to compare MRI-methods and their correlation with endoscopy.

RESULTS

18 clinical and 6 radiological guidelines were retrieved. In 83 % of clinical guidelines tumor location (low/middle/high) is included in the treatment algorithm as a factor impacting surgical and/or neoadjuvant treatment. Measurement cut-offs and landmarks vary significantly with the anal verge being the most commonly used landmark (28 %). Thirty-nine percent of clinical guidelines offer no definitions to define rectal tumor location. The majority of research studies (67 %) reported good-excellent agreement between MRI and endoscopy, though measurement differences of up to 2.5 cm were reported.

CONCLUSION

There is substantial variation in definitions and landmarks recommended in current guidelines to measure and classify rectal tumor location. This may affect treatment planning as well as trial inclusions, highlighting the need for standardized methods that better align between clinical and radiological guidelines.

A boundary-guided transformer for measuring distance from rectal tumor to anal verge on magnetic resonance images

Accurate measurement of the distance from the tumor's lowest boundary to the anal verge (DTAV) provides an important reference value for treatment of rectal cancer, but the standard measurement method (colonoscopy) causes substantial pain. Therefore, we propose a method for automatically measuring the DTAV on sagittal magnetic resonance (MR) images. We designed a boundary-guided transformer that can accurately segment the rectum and tumor. From the segmentation results, we estimated the DTAV by automatically extracting the anterior rectal wall from the tumor's lowest point to the anal verge and then calculating its physical length. Experiments were conducted on a rectal tumor MR imaging (MRI) dataset to evaluate the efficacy of our method. The results showed that our method outperformed surgeons with 6 years of experience (p < 0.001). Furthermore, by referring to our segmentation results, attending and resident surgeons could improve their measurement precision and efficiency.

Lesion-to-anal-verge distance in rectosigmoid endometriosis on transvaginal sonography vs magnetic resonance imaging: prospective study

OBJECTIVES

To compare transvaginal sonography (TVS) and magnetic resonance imaging (MRI) with intraoperative measurement (IOM) using a rectal probe in the estimation of the location of rectosigmoid endometriotic lesions, i.e. lesion-to-anal-verge distance (LAVD), and to compare two different MRI techniques for measuring LAVD.

METHODS

This was a prospective single-center observational study that included women undergoing surgery for symptomatic rectosigmoid endometriosis by discoid (DR) or segmental (SR) resection from December 2018 to December 2019. TVS and MRI were performed presurgically for each participant to evaluate LAVD, and the measurements on imaging were compared with IOM using a rectal probe. Clinically acceptable difference and limits of agreement (LoA) between TVS and MRI compared with IOM were set at ± 20 mm. Two different measuring methods for MRI, MRI_Center and MRI_Direct , were proposed and evaluated, as there is currently no guideline to describe deep endometriosis on MRI. Bland-Altman plots and LoA were used to assess agreement of TVS and both MRI methods with IOM. Systematic and proportional biases were assessed using paired t-test and Bland-Altman plots.

RESULTS

Seventy-five women were eligible for inclusion. Twenty-eight women were excluded, leaving 47 women for the analysis. Twenty-three DR and 26 SR procedures were performed, with both procedures performed in two women. The Bland-Altman plots showed that there were no systematic differences between TVS or MRI_Center when compared with IOM for all included participants. MRI_Direct systematically underestimated LAVD for lesions located further from the anal verge. TVS, MRI_Center and MRI_Direct had LoA outside the preset clinically acceptable difference when compared with IOM. LAVD was within the clinically acceptable difference from IOM of ± 20 mm in 70% (33/47) of women on TVS, 72% (34/47) of women on MRI_Center and 47% (22/47) of women on MRI_Direct .

CONCLUSIONS

TVS should be the preferred method to estimate the location of a rectosigmoid endometriotic lesion, i.e. LAVD, as it is more available, less expensive and has a similar accuracy to that of MRI. Estimating LAVD can be relevant for planning colorectal surgery for rectosigmoid endometriosis. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Comparison of flexible endoscopy and magnetic resonance imaging in determining the tumor height in rectal cancer

BACKGROUND

Several modalities are available for the diagnosis of rectal cancer, including conventional gold standard rigid endoscopy and recent flexible endoscopy and magnetic resonance imaging (MRI). Each modality affects the management of these patients.

AIM

To compare the accuracy of flexible endoscopy and MRI in the measurement of tumor height in patients with rectal cancer.

METHODS AND RESULTS

This study included 174 patients with rectal cancer who underwent flexible endoscopy and MRI for the measurement of tumor height. Data on patient demographics, comorbidities, treatment, and histopathology were identified and collected. We evaluate intraclass correlation coefficient (ICC) and Bland-Altman plot to test the agreement between the measurements. ICC were excellent with an ICC of 89% (95%CI 48%-99%). The mean ± standard deviation of the distance from the anal verge to the distal part of the tumor was 7.73 ± .47 for flexible endoscopy and 6.21 ± 0.39 for MRI, with mean difference of 1.52 (p ˂ .001). The accordance between the two modalities was not affected by sex, age, body mass index, histopathology, or metastasis.

CONCLUSION

Excellent agreement between flexible endoscopy and MRI was noted, and no factor was found to affect such concordance.

Evaluation of Nursing Effects of Pelvic Floor Muscle Rehabilitation Exercise on Gastrointestinal Tract Rectal Cancer Patients Receiving Anus-preserving Operation by Intelligent Algorithm-based Magnetic Resonance Imaging

Based on magnetic resonance imaging (MRI) technology under artificial intelligence algorithm, the postoperative nursing effects of pelvic floor muscle rehabilitation exercise on gastrointestinal tract rectal cancer (RC) patients were investigated. A total of 88 patients receiving RC anus-preserving surgery in hospital were selected. The included patients were divided randomly into the experimental group (44 cases) and the control group (44 cases). Patients in the control group engaged in Kegel motion, while patients in the experimental group underwent self-designed comprehensive pelvic floor training. Anorectum function rating scale and quality of life questionnaire for colorectal cancer (EORTC QLQ-CR29) were utilized to compare and analyze anus functions and living quality of patients in the two groups. Besides, all patients in two groups received MRI examinations, and images were processed by a convolutional neural network (CNN) algorithm. The results showed that in MRI images, there were significant signal differences between lesion tissues and normal tissues. After being processed by an artificial intelligence algorithm, the definition of MRI images was remarkably enhanced with clearer lesion edges. The quality of images was also significantly improved. Besides, the comparison of anus functions of patients in two groups showed that the differences demonstrated statistical meaning after the intervention (P < 0.05). In conclusion, artificial intelligence algorithm-based MRI and comprehensive pelvic floor muscle exercise showed significant application prospects and values in the recovery of patients' intestinal functions after RC anus-preserving surgery.

High failure rates following ligation of the intersphincteric fistula tract for transsphincteric anal fistulas: are preoperative MRI measurements of the fistula tract predictive of outcome?

AIM

Treatment of transsphincteric fistulas (TSFs) with fistulotomy after an indwelling seton is tempered by risks of incontinence and litigation. Thus, ligation of the TSF tract has been popularized as an alternative option. We previously reported on 107 patients who underwent ligation of the intersphincteric fistula tract (LIFT), with a 46% failure rate. Posterior fistula was the only predictor of recurrence. The aim of the present work was to investigate whether the length, width or depth of the fistula measured on preoperative MRI was correlated with recurrence.

METHOD

Following institutional review board approval, a retrospective analysis of our prospective Complex Anal Fistula Database from 1 January 2011 to 31 August 2019 was performed. Patients with TSF who underwent preoperative MRI and LIFT were included. Fistula location was classified as anterior, posterior or lateral. MRI measurements of fistula length, width and depth (in the intersphincteric groove) were performed. The type and rate of postoperative recurrence were analysed.

RESULTS

173 patients underwent MRI for an anal fistula; of these 40 underwent LIFT and 22/40 (55%) had preoperative MRI. There was no difference in the length, width or depth of anterior (n = 9), posterior (n = 7) or lateral (n = 6) fistula tracts. The overall recurrence rate was 9/22 (41%). Posterior TSFs had the highest recurrence rate (5/7, 71%).

CONCLUSION

The mean length, width, and depth of the fistula tract, measured at the preoperative site of LIFT in the intersphincteric groove, did not correlate with recurrence regardless of fistula location.

Emerging Trends for Radio-Immunotherapy in Rectal Cancer

Rectal cancer is a heterogeneous disease at the genetic and molecular levels, both aspects having major repercussions on the tumor immune contexture. Whilst microsatellite status and tumor mutational load have been associated with response to immunotherapy, presence of tumor-infiltrating lymphocytes is one of the most powerful prognostic and predictive biomarkers. Yet, the majority of rectal cancers are characterized by microsatellite stability, low tumor mutational burden and poor T cell infiltration. Consequently, these tumors do not respond to immunotherapy and treatment largely relies on radiotherapy alone or in combination with chemotherapy followed by radical surgery. Importantly, pre-clinical and clinical studies suggest that radiotherapy can induce a complete reprograming of the tumor microenvironment, potentially sensitizing it for immune checkpoint inhibition. Nonetheless, growing evidence suggest that this synergistic effect strongly depends on radiotherapy dosing, fractionation and timing. Despite ongoing work, information about the radiotherapy regimen required to yield optimal clinical outcome when combined to checkpoint blockade remains largely unavailable. In this review, we describe the molecular and immune heterogeneity of rectal cancer and outline its prognostic value. In addition, we discuss the effect of radiotherapy on the tumor microenvironment, focusing on the mechanisms and benefits of its combination with immune checkpoint inhibitors.

Measurement of rectal tumor height from the anal verge on MRI: a comparison of internal versus external anal sphincter

PURPOSE

To determine the most accurate measurement technique to assess rectal tumor height on MRI using two different anatomic landmarks for the anal verge.

INTRODUCTION

Accurate measurements and standardized reporting of MRI for rectal cancer staging is essential. It is not known whether measurements starting from the internal anal sphincter (IAS) or external anal sphincter (EAS) more closely correlate with tumor height from the anal verge on endoscopy.

METHODS

This retrospective study included baseline staging MRI examinations for 85 patients after exclusions. Two radiologists blinded to endoscopic results measured the distance of rectal tumors from the internal anal sphincter and external anal sphincter on sagittal T2 images. The reference standard was endoscopic measurement of tumor height; descriptive statistics were performed.

RESULTS

For reader 1, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.45 cm (SD ± 1.76 cm, range - 6.0 to 3.9 cm) for the IAS and 0.51 cm (SD ± 1.75 cm range - 4.7 to 4.8 cm) for the EAS. For reader 2, the mean difference in measurement of tumor height between MRI and endoscopy was - 0.57 (STD ± 1.81, range - 5.9 to 4.8 cm) for the IAS and 0.52 cm (STD ± 1.85, range - 4.3 to 5.6 cm) for the EAS. Interobserver ICC was excellent between reader 1 and reader 2 for measurements from both the IAS (0.955 95% CI 0.931-0.97) and EAS (0.952, 95% CI 0.928, 0.969).

CONCLUSION

Measurement of tumor height on MRI was highly reproducible between readers; beginning measurements from the EAS tends to slightly overestimate tumor height on average and from the IAS tends to slightly underestimate tumor height on average.