AUTHOR=Liu Wenjuan , Li Yuyi , Zhang Xue , Li Jia , Sun Jing , Lv Han , Wang Zhenchang 

TITLE=Preoperative T and N Restaging of Rectal Cancer After Neoadjuvant Chemoradiotherapy: An Accuracy Comparison Between MSCT and MRI

JOURNAL=Frontiers in Oncology

VOLUME=Volume 11 - 2021

YEAR=2022

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.806749

DOI=10.3389/fonc.2021.806749

ISSN=2234-943X

ABSTRACT=Background It’s well established that magnetic resonance imaging (MRI) is better than multi-slice computed tomography (MSCT) for the accurate diagnosis of pretreatment tumor (T) and nodes (N) staging of rectal cancer. However, the diagnostic value of MRI and MSCT in local restaging of rectal cancer after neoadjuvant chemoradiotherapy (NCRT) is controversial. The aim of this study is to investigate the performance of the two imaging exams in restaging of patients with rectal cancer.
Methods Patients with rectal cancer from April 2015 to April 2021 were analyzed retrospectively. The inclusion criteria: (1) diagnosis of rectal cancer through pathological; (2) NCRT had been performed; (3) all patients had undergone both MSCT and MRI examination before the surgery. Exclusion criteria: (1) incomplete clinical and imaging data; (2) previous history of pelvic surgery. Two radiologists performed T and N staging of patient images. Diagnostic accuracy, consistency analysis and error restaging distribution of the two imaging exams for T and N restaging of rectal cancer were assessed using postoperative pathological staging as the gold standard. 
Results 62 patients (49 men; mean age: 59; age range 29-83) were included in the study. The diagnostic accuracy of MSCT and MRI for T restaging were 51.6% (95%CI 39.3%-63.9%) and 41.9% (95%CI 29.6%-54.2%), respectively, and no statistical difference was found between them (p > 0.05). The diagnostic accuracy of MSCT and MRI for N retaging was 56.5% (95%CI 44.2%-68.8%) and 53.2% (95%CI 40.8%-65.6%), respectively, and no statistical difference was found between them (p > 0.05). The consistency analysis showed that T restaging (κ = 0.583, p < 0.001) and N restaging (κ = 0.644, p < 0.001) were similar between MSCT and MRI. There was no significant difference in the distribution of over, accurate, or low staging in T restaging (p > 0.05) and N restaging (p > 0.05) between MSCT and MRI.

Conclusions MSCT and MRI have similar poor performance in the diagnosis of preoperative T and N restaging of rectal cancer after NCRT. Neither of them can not effectively staging the ypT0-1 of rectal cancer. These findings may be of clinical relevance for planning less imaging exam.