Shear Wave Elastography in Rectal Cancer Staging, Compared with Endorectal Ultrasonography and Magnetic Resonance Imaging

Differentiating rectal cancer grades using virtual magnetic resonance elastography and fractional order calculus diffusion model

BACKGROUND

To investigate the value of virtual magnetic resonance elastography (vMRE), fractional order calculus (FROC) model, and diffusion-weighted imaging (DWI) in differentiating rectal cancer grades.

METHODS

This prospective study included 74 patients with rectal cancer who underwent a pelvic MRI. The Mann-Whitney U test or independent samples t-test was employed to compare the parameters of vMRE (µMRE), the FROC model (D, β, and µ), and DWI (ADC). Logistic regression analysis and area under the receiver operating characteristic curve (AUC) were utilized separately for multiparameter co-diagnosis and to assess diagnostic performance. Pearson's correlation analysis was conducted to evaluate the relationship of different parameters.

RESULTS

Compared to the low-grade group, the high-grade group had higher µMRE and µ values and lower D, β, and ADC values (all P < 0.05). In terms of the different parameters, the D value demonstrated the highest diagnostic efficacy with an AUC of 0.852(95% CI: 0.750-0.924). In terms of the various methods, the FROC model (D + β + µ) had the highest diagnostic performance with an AUC of 0.943(95% CI: 0.864-0.984), which was significantly higher than those of DWI and vMRE (Z = 3.586, 2.430, and 2.081, all P < 0.05). µMRE showed moderately negative correlations with ADC, D, and β (r = - 0.553, - 0.683, and - 0.530, respectively, all P < 0.05) and a moderately positive correlation with µ (r = 0.443, P < 0.05).

CONCLUSION

FROC, vMRE, and DWI can be utilized for assessing rectal cancer grades, with FROC offering comparatively better diagnostic performance.

Elastography of the Male Pelvic Region-Perspectives on Malignant Lesions

Ultrasound elastography is widely used to assess tissue stiffness for lesion characterization, including differentiation between benign and malignant lesions. This study focuses on the use of elastography in the male pelvis, including the prostate, testicles, and rectum, by comparing elastography types (shear wave and strain). This article provides a summary of the existing literature on the use of elastography in the male pelvic region and outlines the clinical perspective. Ultrasound elastography is a good technique for evaluating and monitoring lesions in the male pelvic region.

A prospective study on using shear wave elastography to predict the ypT0 stage of rectal cancer after neoadjuvant therapy: a new support for the watch-and-wait approach?

Introduction

The diagnostic accuracy of traditional imaging examination in predicting ypT stage of rectal cancer after neoadjuvant therapy is significantly reduced, which would affect patients' subsequent treatment choices. This study aimed to investigate the use of endorectal shear wave elastography (SWE) for diagnosing ypT0 stage of rectal cancer after neoadjuvant chemoradiotherapy (nCRT).

Methods

Sixty patients with rectal cancer were prospectively recruited in this study. Data on endorectal ultrasound (ERUS) and SWE parameters were collected before nCRT and 6-8 weeks after nCRT. Postoperative pathological results were the gold standard for evaluating the diagnostic accuracy of SWE and ERUS in predicting the ypT0 stage of rectal cancer after nCRT. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off values of the SWE parameters that best corresponded to the ypT0 stage and analyze the sensitivity, specificity, and accuracy.

Results

The diagnostic accuracies of using ERUS to predict the ypT and ypT0 stages of rectal cancer after nCRT were 58.1% (18/31) and 64.3% (9/14), respectively. The ROC curve was constructed with the lesion's Emean, Emean corrected (EC), Emean difference (ED), Emean corrected differencede (ECD), Emean descendding rate (EDR) and Emean corrected descendding rate (ECDR) values after nCRT, the cut-off values of diagnosing the ypT0 stage were 64.40 kPa, 55.45 kPa, 72.55 kPa, 73.75 kPa, 50.15%, and 55.93%, respectively; the area under the curve (AUC) for diagnosing the ypT0 stage was 0.924, 0.933, 0.748, 0.729, 0.857 and 0.861, respectively. The EC value showed the best diagnostic performance.

Conclusion

SWE could improve the accuracy of conventional ERUS in diagnosing the ypT0 stage of rectal cancer after nCRT. It is expected to become a new method to help predict pathological complete responses in clinical practice and provide new evidence for the watch-and-wait approach.

Diagnostic performance of endorectal ultrasound combined with shear wave elastography for rectal tumors staging

OBJECTIVE

This study aims to analyze the performance of endorectal ultrasound (ERUS) combined with shear wave elastography (SWE) for rectal tumor staging.

METHODS

Forty patients with rectal tumors who had surgery were enrolled. They underwent ERUS and SWE examinations before surgery. Pathological results were used as the gold standard for tumor staging. The stiffness values of the rectal tumor, peritumoral fat, distal normal intestinal wall, and distal perirectal fat were analyzed. The diagnostic accuracy of ERUS stage, tumor SWE stage, ERUS combined with tumor SWE stage, and ERUS combined with peritumoral fat SWE stage were compared and evaluated by receiver operating characteristic (ROC) curve to select the best staging index.

RESULTS

From T1 to T3 stage, the maximum elasticity (Emax) of the rectal tumor increased gradually (p < 0.05). The cut-off values of adenoma/T1 and T2, T2 and T3 tumors were 36.75 and 85.15kPa, respectively. The diagnostic coincidence rate of tumor SWE stage was higher than that of ERUS stage. Overall diagnostic accuracy of ERUS combined with peritumoral fat SWE Emax restaging was significantly higher than that of ERUS.

CONCLUSIONS

ERUS combined with peritumoral fat SWE Emax for tumor restaging can effectively distinguish between stage T2 and T3 rectal tumors, which provides an effective imaging basis for clinical decisions.

Intra- and Interobserver Variability of Shear Wave Elastography in Rectal Cancer

Simple Summary

For a diagnostic tool to be important, there must be a high level of agreement between different observers. If not, the reliability of the measurement can not be considered valid. Previous studies have evaluated the reproducibility of tissue stiffness measurements of rectal tumors, but only on previously obtained images. Therefore, we aimed to investigate the issue in a clinical setting and found a high level of agreement between observers.

Abstract

Background: Endorectal ultrasound (ERUS) is an important tool when evaluating complex rectal adenomas and rectal cancer, and the accuracy is improved by adding elastography measurements. A high interobserver agreement is imperative in clinical practice. Therefore, the aim of this study was to evaluate interobserver agreement assessed on real-time images. Additionally, we investigated the intra- and interobserver agreement between experienced and inexperienced observers. Materials and methods: We prospectively included patients referred to an ERUS at the Department of Radiology with a complex rectal polyp or suspected rectal malignancy. Two operators independently scanned each patient in turn. Furthermore, four observers assessed previously obtained images using three different methods for placing the region of interest (ROI). Three months later, the four observers reassessed the images to assess intraobserver variability. Results: A total of 19 patients were included for live assessment. Agreement of tumor classification was substantial for T stage (kappa: 0.86) and fair for N stage (kappa: 0.73), with an absolute agreement for T and N stages of 84% and 89%, respectively. Agreement of SWE was good for Emean (ICC 0.94, 95% CI 0.86–0.98) and fair for Emax (ICC 0.85, 95% CI 0.66–0.94). Intra- and interobserver agreement between inexperienced and experienced observers showed good to excellent agreement with all ROI methods. Conclusion: Interobserver agreement is high in SWE when performed in a clinical setting. We found the best agreement using the mean value of several ROIs. Intra- and interobserver agreement was high regardless of operator experience.

Comparison of Clinical Efficacy and Safety Between da Vinci Robotic and Laparoscopic Intersphincteric Resection for Low Rectal Cancer: A Meta-Analysis

Background and Aims: The intersphincteric resection (ISR) is beneficial for saving patients' anus to a large extent and restoring original bowel continuity. Laparoscopic ISR (L-ISR) has its drawbacks, such as two-dimensional images, low motion flexibility, and unstable lens. Recently, da Vinci robotic ISR (R-ISR) is increasingly used worldwide. The purpose of this article is to compare the feasibility, safety, oncological outcomes, and clinical efficacy of R-ISR vs. L-ISR for low rectal cancer. Methods: PubMed, EMBASE, Cochrane Library, and Web of Science were searched to identify comparative studies of R-ISR vs. L-ISR. Demographic, clinical, and outcome data were extracted. Mean difference (MD) and risk ratio (RR) with their corresponding confidence intervals (CIs) were calculated. Results: Five studies were included. In total, 510 patients were included, of whom 273 underwent R-ISR and 237 L-ISR. Compared with L-ISR, R-ISR has significantly lower estimated intraoperative blood loss (MD = -23.31, 95% CI [-41.98, -4.64], P = 0.01), longer operative time (MD = 51.77, 95% CI [25.68, 77.86], P = 0.0001), hospitalization days (MD = -1.52, 95% CI [-2.10, 0.94], P < 0.00001), and postoperative urinary complications (RR = 0.36, 95% CI [0.16, 0.82], P = 0.02). Conclusions: The potential benefits of R-ISR are considered as a safe and feasible alternative choice for the treatment of low rectal tumors.

Can Ultrasound Elastography Discriminate between Rectal Adenoma and Cancer? A Systematic Review

BACKGROUND

Rectal cancer is a common malignancy. Since the introduction of bowel-screening programs, the number of patients with advanced adenomas and early rectal cancer has increased. Despite improved diagnostics, the discrimination between rectal adenomas and early rectal cancer (i.e., pT1-T2) remains challenging. The purpose of this systematic review was to evaluate the diagnostic performance of endorectal ultrasound (ERUS) elastography in discriminating rectal adenomas from cancer.

METHOD

Using PRISMA guidelines, a systematic search was performed on PubMed, Embase, and MEDLINE databases. Studies evaluating the primary staging of rectal adenomas and cancer using ERUS elastography were included.

RESULTS

Six studies were identified; three evaluated the discrimination between adenomas and cancer; two evaluated adenomas and early rectal cancer (i.e., pT1-T2); one evaluated performance on different T categories. All studies reported increased diagnostic accuracy of ERUS elastography compared to ERUS. Sensitivity, specificity and accuracy ranged 0.93-1.00, 0.83-1.00 and 0.91-1.00, respectively, when discriminating adenomas from cancer. In the differentiation between adenomas and early rectal cancer, the sensitivity, specificity and accuracy were 0.82-1.00, 0.86-1.00 and 0.84-1.00, respectively.

CONCLUSION

Elastography increases the accuracy of ERUS and may provide valuable information on malignant transformation of rectal lesions.

Using shear wave elasticity in normal terminal ileum of a healthy southwest Chinese population: a pilot study of reference elasticity ranges

Background

Elastography has not been widely applied to the gastrointestinal tract. The bowel wall's normal elasticity values are still unknown and are necessary for studies of gastrointestinal diseases. This study explores the feasibility of using shear wave elastography (SWE) to measure the terminal ileum wall stiffness in healthy subjects and establish the corresponding normal ranges of elasticity values.

Methods

This observational study recruited 139 healthy adult volunteers from April to July 2020. All examinations were performed in the anterior terminal ileum wall. Shear wave velocity (SWV) and Young's modulus (E) values were measured in the midline on longitudinal sections and replicated different operators' obtained data. Also, bowel wall thickness (BWT) and depth were recorded. Subgroups were classified according to the volunteers' gender, age, body mass index (BMI), BWT, and depth. The intra-class correlation coefficient was calculated to analyze inter- and intra-operator consistency, and independent t-tests and one-way analysis of variance were used to explore the differences in variables.

Results

The inter- and intra-operator agreements were good to excellent by different operators and in the replicated measurements (intra-operator consistency: 0.963; inter-operator consistency: 0.842). In all volunteers, the mean SWV was 1.08±0.25 m/s, the mean E value was 3.84±1.84 kPa, and the median BWT was 2 mm. SWV and E did not show significant differences according to gender (P=0.589), age (P=0.738), BMI (P=0.678), depth (P=0.375), or BWT (P=0.410). BWT did not show significant differences according to age (P=0.142), BMI (P=0.863), or depth (P=0.368).

Conclusions

SWE can be used in terminal ileum wall stiffness measurements with good reliability, and the SWE values do not appear to vary significantly according to different physiological factors. The corresponding elasticity ranges of the terminal ileum in normal adults were acquired.

New modality for the quantitative evaluation of tissue elasticity using a forward-viewing radial-array echoendoscope for colorectal neoplasms

PURPOSE

Sound speed correction (SSC) is a non-invasive modality that quantifies the hardness of neoplasms. The aim of our study was to evaluate the usefulness of SSC for the diagnostic accuracy of colorectal neoplasms and to differentiate the depth of invasion.

METHODS

Forty colorectal neoplasms, contributed by 40 patients, were included in the analysis. The primary outcome was the diagnostic ability of SSC for the depth of invasion of colorectal neoplasms, with the secondary endpoint being the clinical efficacy of SSC to distinguish between a neoplasm and normal mucosa.

RESULTS

The median sound speeds for colorectal neoplasms and normal mucosa were 1580 m/s and 1515 m/s, respectively (p < 0.001), with a median sound speed of 1583 m/s for lesions with a depth shallower than that of the muscularis propria and 1610 m/s for depths deeper than that of the muscularis propria (p = 0.002). The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 80.0%, 100%, 100%, 83.3%, 90.0%, and 100%, respectively, for the diagnosis of neoplasms (using a cut-off sound speed of 1557 m/s) and 100%, 77.8%, 33.3%, 100%, 80.0%, respectively, for the diagnosis of the depth of invasion (using a cut-off of 1590 m/s).

CONCLUSION

We identified absolute sound speeds for colorectal neoplasms and the depth of invasion of neoplasms which yielded a good diagnostic performance. SSC provides an objective evaluation of colorectal neoplasms and the depth of invasion of neoplasms and, thus, might be a useful modality in practice.

TRIAL REGISTRATION

UMIN000038235 , Date of registration; October 8, 2019.