Accuracy of endoscopic ultrasound in rectal cancer and its use in transanal endoscopic microsurgery

The Value of Transanal Normal Saline Infusion-Assisted Multipath Ultrasonography in the Diagnosis of T1/T2 Rectal Cancer

ABSTRACT

This study aims to assess the application value of transanal normal saline infusion-assisted multipath ultrasonography (TNSI-MU) in the diagnosis of T1/T2 rectal cancer (RC). All patients first received single-path 360-degree transrectal ultrasonography and then received 360-degree transrectal ultrasonography, transabdominal ultrasonography, or transvaginal ultrasonography after TNSI to determine the T stage. With surgical pathology as the criterion standard, the detection rates of T1/T2 RC lesions and the T-staging results of single-path 360-degree transrectal ultrasonography, TNSI-MU, and contrast-enhanced magnetic resonance imaging (MRI) were compared and analyzed. T1/T2 RC was surgically and pathologically confirmed in 52 patients. Single-path 360-degree transrectal ultrasonography had a lesion detection rate of 57.69% (30/52) and a T-staging accuracy of 80.0% (24/30), the sensitivity was 57.69%, and the specificity was 88.46%. Transanal normal saline infusion-assisted multipath ultrasonography had a lesion detection rate of 100%, and its T-staging accuracy was 84.62% (44/52), the sensitivity was 100%, and the specificity was 88.61%. Transanal normal saline infusion-assisted multipath ultrasonography had a significantly higher detection rate of T1/T2 RC lesions than single-path 360-degree transrectal ultrasonography ( P < 0.001), but the 2 methods had similar T-staging accuracy for T1/T2 RC (χ 2 = 0.286, P = 0.593). Contrast-enhanced MRI had a lesion detection rate of 100% and a T-staging accuracy of 40.38% (21/52), the sensitivity was 98.07%, and the specificity was 61.54%. Transanal normal saline infusion-assisted multipath ultrasonography had significantly higher diagnostic accuracy than contrast-enhanced MRI for T staging of T1/T2 RC ( P < 0.001), and the diagnostic results of the 2 methods were not consistent (κ = 0.151). Transanal normal saline infusion-assisted multipath ultrasonography outperformed single-path 360-degree transrectal ultrasonography in the detection rate of T1/T2 RC lesions and contrast-enhanced MRI in the staging accuracy for T1/T2 RC.

Diagnosis of rectal cancer based on the Xception-MS network

Objective. Accurate T staging of rectal cancer based on ultrasound images is convenient for doctors to determine the appropriate treatment. To effectively solve the problems of low efficiency and accuracy of traditional methods for T staging diagnosis of rectal cancer, a deep-learning-based Xception-MS diagnostic model is proposed in this paper. Approach. The proposed diagnostic model consists of three steps. First, the model preprocesses rectal cancer images to solve the problem of data imbalance and deficiency of sample size, and reduces the risk of model overfitting. Second, a new Xception-MS network with stronger feature extraction capability, which is a combination of the Xception network and MS module, is proposed. The MS module is a new function module that can more effectively extract multi-scale information from rectal cancer images. In addition, to solve the deficiency of the small sample size of rectal cancer, the proposed network is combined with transfer learning technology. At last, the output layer of the network is modified, in which the global average pooling and a fully connected softmax layer are employed to replace the original ones, and then the rectal cancer 4 classification (T1, T2, T3, T4 staging) is output. Main results. Experiments of rectal cancer T staging are conducted on a dataset of 1078 rectal cancer images in 4 categories collected from the Department of Colorectal Surgery of the Third Affiliated Hospital of Kunming Medical University. The experimental results show that the accuracy, precision, recall and F1 values obtained by the model are 94.66%, 94.70%, 94.65%, and 94.67%, respectively. Significance. The experimental results show that our model is superior to the existing classification models, can effectively and automatically classify ultrasound images of rectal cancer, and can better assist doctors in the diagnosis of rectal cancer.

Accuracy of magnetic resonance imaging staging of tumour and nodal stage in rectal cancer treated by primary surgery: a population-based study

AIM

The preoperative stage of rectal cancer is an important prognostic factor affecting treatment recommendations. Currently, magnetic resonance imaging (MRI) is used for clinical staging to identify patients who should be recommended for neoadjuvant oncological treatment. The aim of this work was to investigate the accuracy of the preoperative T- and N-stage and also involvement of the mesorectal fascia (MRF) as determined by MRI in a Swedish national cohort.

METHOD

Patients who had undergone resectional surgery for rectal cancer without neoadjuvant treatment in Sweden in the period 2013-2017 were identified through the Swedish Colorectal Cancer Registry (n = 2062). The T- and N-stage determined by preoperative MRI were compared with the histopathological results. The MRI-assessed MRF status was compared with the circumferential resection margin.

RESULTS

Sensitivity for differentiating T1-2 from T3-4 was 69% and specificity 77%. Sensitivity to detect N1-2 was 42% and specificity 81%. Sensitivity for MRF positivity was 50% and specificity 92%. Agreement analysed by weighted kappa analysis was 0.47 for T-stage [confidence interval (CI) 0.44-0.51], 0.24 for N-stage (CI 0.19-0.24) and 0.20 for MRF status (CI 0.12-0.29).

CONCLUSION

In this study, accuracy of the preoperative MRI was lower than expected for rectal cancers. Overstaging might lead to potentially harmful neoadjuvant treatment and understaging can lead to a higher risk of tumour recurrence. The results of this study show that efforts should be made to increase the accuracy of the preoperative evaluation in order to optimize treatment recommendations.

Local full-thickness excision for sessile adenoma and cT1-2 rectal cancer: long-term oncological outcome

PURPOSE

We analyzed all patients who underwent local transanal surgery at our institution to determine oncological outcomes and perioperative risk.

METHODS

In 1997, we developed a prospective protocol for rectal tumors: transanal local full-thickness excision was considered curative in patients with benign adenoma and early cancers. In this analysis, 404 patients were included. To analyze survival, only those patients exposed to the risk of dying for at least 5 years were considered for the study.

RESULTS

The final pathological analysis revealed that 262 (64.8%) patients had benign lesions, whereas 142 had malignant lesions. Postoperative complications were recorded in 12.6%. At the median time of 21 months, 14% of the adenomas and 12% of cancers had recurred, half of which were surgically resected. The overall 5-year survival rate was 94%.

CONCLUSION

With similar outcomes and significantly lower morbidity, we found local surgery to be an adequate alternative to radical surgery in selected cases of early rectal cancer.

Transanal Local Excision or Endoscopic Dissection for Benign and Large Lesions of the Rectum

Since the introduction of transanal endoscopic microsurgery, local excision of "early" rectal lesions has offered the possibility to reduce the invasiveness of treatment for the limited disease. Flexible endoscopy techniques allow today different alternatives consisting of endoscopic mucosal resection or endoscopic submucosal dissection. The first is a straightforward and relatively easy technique, but it prevents a correct pathological staging of the lesion due to fragmentation and the verification of disease-free margins. The second relies on operators' audacity depending on their increasing experience due to the limited progress in technology. What is the preferable technique today is questionable. All the methods have pros and cons. The future certainly will see the use of ideal systems, allowing the possibility of precision surgery for partial- or full-thickness excision, depending on intraoperative findings, and the extension above the rectosigmoid junction. Miniaturized flexible robotic devices may represent the solution for both issues.

How Useful Is Endoscopic Ultrasound in Differentiating T3/T4a T Stage of Colorectal Cancer: A Prospective Study

Objective

Endoscopic ultrasound (EUS) is an established method for staging of colorectal cancer. Nevertheless, prior assessments of its T stage accuracy have been limited, particularly ambiguity in assessed T3 and T4a stage. This study was to characterize the EUS image features and pay attention to distinguish T3 from T4a T stage.

Methods

A total of 638 patients who prospectively underwent colorectal EUS were recorded. The final diagnoses were compared with the concurrent or follow-up histopathology. Univariate and multivariate logistic regressions were used to assess variation in diagnostic performance with case attributes.

Results

The accuracies of EUS in classifying colorectal cancer for overall, T1, T2, T3, and T4a stages are 73.04, 62.32, 67.46, 71.26, and 83.52%, respectively. With attention to EUS image features, the lesion penetrates the entire wall and locates below the seminal vesicles or cervix is T3 stage. If the lesion locates above clearly-defined space between the anterior rectal wall and the posterior surface of the seminal vesicles or cervix, we identify as T4a stage; However, when located above seminal vesicles or cervix but on the posterior wall of the rectum, the lesion still considers as T3 stage. The tumor location and histological type are associated with inaccuracy T stage.

Conclusions

EUS provides reliable diagnostic accuracy in the colorectal cancer stage. The seminal vesicles and cervix are the important markers to predict infiltration depth for T3/T4a stage. Furthermore, the tumor location, histological type, and EUS image features for each tumor T stage should warrant attention.

Endoscopic Ultrasound Elastography in the Assessment of Rectal Tumors: How Well Does It Work in Clinical Practice?

Endorectal ultrasound applications in the evaluation of rectal tumors could be a useful tool in achieving proper staging of rectal cancer. The purpose of this study was to compare the efficacy of rectal tumor staging by flexible endoscopic ultrasound (EUS) with real-time elastography (RTE) using the gold standard post-surgery histological analysis of the resected tissue as the control. The second aim of our research was to establish cutoff values for the EUS-RTE strain ratio corresponding to stages by independently comparing the stiffness values obtained with histology and EUS-RTE staging in order to minimize observation bias. We evaluated the records of 130 patients with a rectal tumor confirmed by biopsy. EUS was used in 70 patients, EUS-RTE-in the other 60. We found no statistically significant differences in staging accuracy when comparing EUS to EUS-RTE. Through a correspondence method between staging assessment and the EUS-RTE stain ratio, we identified cutoff intervals for T2, T3, and T4 staging that were nonoverlapping and proved to be statistically significant in terms of EUS-RTE values (significantly different ascending values from one interval to the other). We found that EUS-RTE offers slightly better, although not statistically significant sensitivity and specificity for T and N stage predictions compared to 2D EUS. Our results showed that EUS-RTE offers slightly higher sensitivity and specificity compared to EUS. Reliable cutoff intervals were found for strain rate elastography, previously available only for shear wave elastography (SWE) which is currently unavailable on any EUS system. Thus, these commonly available EUS-RTE systems can serve as a complementary tool in the staging of rectal tumors.

A New Technique to Repair Vesicorectal Fistula: Overlapping Rectal Muscle Plasty by Transanal Endoscopic Surgery

OBJECTIVE

To evaluate clinical results of a novel surgical technique, we developed to repair vesicorectal fistula (VRF) occurring after prostatectomy, hospital records of the patients, who underwent the new surgical treatment, were assessed.

METHODS

The novel surgical technique is called "overlapping rectal muscle plasty," which is performed under transanal endoscopic microsurgery (TEM). During the new procedure, a complete fistulectomy was first performed, and then the proper muscle layer of the rectum was folded, overlapped, and sutured to create a thick wall between the rectum and urinary bladder. This operation was carried out in 15 patients with VRF following radical prostatectomy.

RESULTS

The operation was safely performed in all patients with an average time of 127.2 min. Fistula was corrected in 13 patients (86.7%), who were then freed from both urinary and intestinal diversions.

CONCLUSIONS

Overlapping rectal muscle plasty by TEM is a safe procedure. The success rate seems to be acceptable in selected patients. This new repair method may be considered as a minimally invasive option in the surgical treatment of VRF after prostatectomy.

Robotic endoscopic submucosal dissection and full-thickness excision for laterally spreading tumors of the rectum

Endoscopic submucosal dissection (ESD) is technically demanding and time-consuming. Moreover, it bears a high risk of adverse events compared to other endoscopic methods, due to the lack of tissue manipulation. Robotic technology can significantly reduce the time of the procedure and increase the rate of complete resection for ESD. In the case of an unclear deep margin it allows to proceed to the full-thickness excision of the bowel wall. While the gain over transanal endoscopic microsurgery (TEM) is limited today, the longer systems currently under development will allow these complex procedures to be performed at least in the left side of the colon. The Supplementary video shows the application of the Flex Robotic System to perform an ESD and a full-thickness excision.