Application of liver acquisition with volume acceleration enhanced sequence in improving the accuracy of reassessing organ-invasive rectal mucinous adenocarcinoma after chemoradiation

Objectives To explore the ability of liver acquisition with volume acceleration contrast-enhanced sequence (LAVA-ce) to improve the accuracy of reassessing adjacent organ involvement by rectal mucinous adenocarcinoma (MC) after neoadjuvant therapy (NAT). Methods This study retrospectively enrolled twenty-five patients with MC who underwent pre- and post-NAT MRI, were staged as T4b using pre-NAT T2 weighted imaging, received NAT and underwent radical resection. All MR images were divided into two schemes, T2 weighted plus diffusion weighted imaging (T2Dw protocol) and plus LAVA-ce (T2DwLce protocol). All patients were scored on a 0−4 scale to reassess organ-invasive mucus components. Postoperative pathology was used to identify the involvement of surrounding organs (ypT4b). The receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to evaluate the consistency of the results with pathology after adding fs-CE sequence. Results Among 25 MC patients (15 males and 10 females, aged 21–89 years), 21 were restaged as yT4b after NAT by using T2Dw, with an accuracy of 44.0 % (11/25), which was lower than the accuracy of staging patients with non-mucinous rectal adenocarcinoma (94.1 %, 96/102). The accuracy of MC restaging was improved by using T2DwLce (23/25). The AUC of T2DwLce was 0.857 (95 % CI, 0.660∼0.964), which was higher than that of T2Dw (AUC, 0.611 [95 % CI, 0.397∼0.798]) (P = 0.019). Conclusion The LAVA-ce sequence can improve the accuracy of reevaluation and should be included in the MRI protocol for MC patients.