VAI TRÒ CỦA CỘNG HƯỞNG TỪ TRONG CHẨN ĐOÁN GIAI ĐOẠN UNG THƯ TRỰC TRÀNG THẤP SAU HÓA XẠ TRỊ TIỀN PHẪU TẠI BỆNH VIỆN ĐẠI HỌC Y HÀ NỘI

Abstract

Objective: To evaluate the diagnostic performance of magnetic resonance imaging (MRI) in staging and response assessment of low rectal cancer following neoadjuvant chemoradiotherapy (nCRT), compared with histopathology. Subjects and Methods: A prospective study was conducted on 31 patients with low rectal adenocarcinoma who underwent nCRT, followed by MRI and radical surgery at Hanoi Medical University Hospital between January 2023 and January 2025. MRI examinations were independently reviewed by two experienced radiologists blinded to pathology results. Data were analyzed using SPSS 25.0 to calculate sensitivity, specificity, predictive values, and Cohen’s kappa coefficient. Results: The overall accuracy of MRI for T staging was 74.2%. The kappa coefficient (κ = 0.65, p < 0.001) indicated substantial agreement between MRI and histopathology. The sensitivity of MRI for detecting residual disease was 100%. For nodal assessment, the accuracy for N0 and N1 was 88.9% and 75%, respectively. The positive predictive value (PPV) for mesorectal fascia involvement (MRF+) was 100%. According to mrTRG, the negative predictive value (NPV) for mrTRG 4–5 was 100%. Conclusion: MRI demonstrates high accuracy and reliability in restaging low rectal cancer after nCRT, particularly for T2–T3 tumors and nodal status. However, differentiating fibrosis from residual disease and accurately identifying pathological complete response (pCR) remain challenging. The incorporation of functional sequences such as DWI/ADC and standardized scoring systems (e.g., mrTRG) may further improve diagnostic performance in the future