Synthetic magnetic resonance imaging predicts the prognostic evaluation of rectal cancer
Letter to the Editor

Synthetic magnetic resonance imaging predicts the prognostic evaluation of rectal cancer

Lejia Sun1,2,3, Yifei Feng1,2,3, Yueming Sun1,2,3

1Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China; 2The First School of Clinical Medicine, Nanjing Medical University, Nanjing, China; 3Colorectal Institute of Nanjing Medical University, Nanjing, China

Correspondence to: Yueming Sun; Yifei Feng. Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China. Email:;

Comment on: Ma L, Lian S, Liu H, et al. Diagnostic performance of synthetic magnetic resonance imaging in the prognostic evaluation of rectal cancer. Quant Imaging Med Surg 2022;12:3580-91.

Submitted Jun 17, 2022. Accepted for publication Oct 10, 2022. Published online Oct 19, 2022.

doi: 10.21037/qims-22-624

We read with interest the article by Ma et al. (1) published in the journal of Quantitative Imaging in Medicine and Surgery. The authors conducted a prospective, single-centre study involving eighty-seven patients who had pathologically confirmed rectal cancer and underwent synthetic magnetic resonance imaging (SyMRI) before therapy. Ma et al. found that T2 and proton density (PD) values obtained by SyMRI decreased significantly among patients with poor differentiation and lymph node metastasis and concluded that T2 and PD. values were noninvasively prognostic factors of rectal cancer. We appreciate their efforts to provide insights into the noninvasive evaluation of patients with rectal cancer. However, some points merit further discussion.

Firstly, the article included important prognostic indicators such as mrT, mrN stage and tumour differentiation. However, many other critical prognostic factors which surgeons are greatly concerned about were still not included, like mesorectal fascia (MRF) status, lateral lymph node, and histological type. MRF is an essential structure in rectal cancer, defined as the fine linear structure enveloping the mesorectal compartment harbouring the rectum perirectal fat. If it is violated, the further use of total mesorectal excision and neoadjuvant radiotherapy might be needed (2,3). Besides, the incidence of lateral pelvic lymph node metastasis has been estimated to range from 11% to 22% in patients with T3/4 rectal cancer below the peritoneal reflection, which is significantly associated with the surgery of lateral lymph node dissection (LLND) (4). Though this article included the mrN stage, the complement of lateral lymph node assessment could make this study more clinically significant.

Furthermore, histological type, including adenocarcinoma, squamous cell carcinoma, undifferentiated carcinoma, etc., is a routine item in biopsy and postoperative pathology reports and affects prognosis and treatment options. It is also worth mentioning that perineural invasion is an essential prognostic factor. Though this article said it collected these pathological characteristics, it did not represent the results and explored them further in the following analysis. This study could have improved if it included the above factors.

Secondly, the receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic efficacy of T2 and PD values in tumour differentiation and the mrN stage. However, several clinically relevant influencing factors exist, and univariate analysis cannot rule out potential confounding. Multivariate analysis, such as logistic regression, is recommended to improve the outcomes’ credibility.

Thirdly, this study used the mrN stage as the outcome when exploring the diagnostic performance of SyMRI, which was not so appropriate as they were both MRI features. If the mrN stage can be obtained directly from imaging, it is not so necessary to calculate parameters derived from SyMRI to predict the mrN stage.

Moreover, studies have shown that 20% to 34% of patients with colorectal cancer (CRC) present with synchronous liver metastases (5). Different locations and metastases of primary rectal cancer lesions directly affect treatment goals, surgical approaches, and patient prognosis (5-7). However, essential clinical characteristics in this study, including distant metastatic status and location of rectal cancer, were not included, which will affect the applicability of the conclusions.

Lastly, neoadjuvant therapy is one of the effective treatments for patients with cancer (8), especially among patients with low-risk, intermediate-advanced rectal cancer (9). However, only a portion of the patients is effective (10). The prediction of efficacy is a current clinical difficulty that needs to be solved urgently. In this article, 79.3% (69/87) of the patients received neoadjuvant therapy, but the predictive value of T2 and PD values in the efficacy of neoadjuvant treatment was not explored. If this study carries out further related research, It would be more clinically meaningful.

In summary, we appreciate the authors for their important and promising study. It highlights the noninvasively diagnostic value of SyMRI in patients with rectal cancer and the necessity of higher quality research in the future.

Supplementary file: Reply: ‘Synthetic magnetic resonance imaging predicts the prognostic evaluation of rectal cancer’.


Funding: None.


Provenance and Peer Review: This article was a standard submission to the journal. The article did not undergo external peer review.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See:


  1. Ma L, Lian S, Liu H, Meng T, Zeng W, Zhong R, Zhong L, Xie C. Diagnostic performance of synthetic magnetic resonance imaging in the prognostic evaluation of rectal cancer. Quant Imaging Med Surg 2022;12:3580-91. [Crossref] [PubMed]
  2. Bahadoer RR, Dijkstra EA, van Etten B, Marijnen CAM, Putter H, Kranenbarg EM, et al. Short-course radiotherapy followed by chemotherapy before total mesorectal excision (TME) versus preoperative chemoradiotherapy, TME, and optional adjuvant chemotherapy in locally advanced rectal cancer (RAPIDO): a randomised, open-label, phase 3 trial. Lancet Oncol 2021;22:29-42. [Crossref] [PubMed]
  3. Simunovic M, Grubac V, Zbuk K, Wong R, Coates A. Role of the status of the mesorectal fascia in the selection of patients with rectal cancer for preoperative radiation therapy: a retrospective cohort study Can J Surg 2018;61:332-8. [Crossref] [PubMed]
  4. Malakorn S, Yang Y, Bednarski BK, Kaur H, You YN, Holliday EB, Dasari A, Skibber JM, Rodriguez-Bigas MA, Chang GJ. Who Should Get Lateral Pelvic Lymph Node Dissection After Neoadjuvant Chemoradiation? Dis Colon Rectum 2019;62:1158-66. [Crossref] [PubMed]
  5. Benson AB, Venook AP, Al-Hawary MM, Cederquist L, Chen YJ, Ciombor KK, et al. Rectal Cancer, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw 2018;16:874-901. [Crossref] [PubMed]
  6. Giglio MC, Troisi RI. Laparoscopic surgery for colorectal liver metastases: moving forward while keeping feet on the ground. Hepatobiliary Surg Nutr 2021;10:107-9. [Crossref] [PubMed]
  7. Guest RV, Søreide K. Addressing the variation in hepatic surgery for colorectal liver metastasis. Hepatobiliary Surg Nutr 2021;10:103-6. [Crossref] [PubMed]
  8. Chopra A, Paniccia A. Does neoadjuvant therapy improve survival in pancreatic adenocarcinoma? Hepatobiliary Surg Nutr 2021;10:728-30. [Crossref] [PubMed]
  9. Benson AB, Venook AP, Al-Hawary MM, Arain MA, Chen YJ, Ciombor KK, et al. NCCN Guidelines Insights: Rectal Cancer, Version 6.2020. J Natl Compr Canc Netw 2020;18:806-15. [Crossref] [PubMed]
  10. Petrelli F, Trevisan F, Cabiddu M, Sgroi G, Bruschieri L, Rausa E, Ghidini M, Turati L. Total Neoadjuvant Therapy in Rectal Cancer: A Systematic Review and Meta-analysis of Treatment Outcomes. Ann Surg 2020;271:440-8. [Crossref] [PubMed]
Cite this article as: Sun L, Feng Y, Sun Y. Synthetic magnetic resonance imaging predicts the prognostic evaluation of rectal cancer. Quant Imaging Med Surg 2023;13(3):2026-2028. doi: 10.21037/qims-22-624

Download Citation