Value of adding dynamic contrast-enhanced MRI visual assessment to conventional MRI and clinical assessment in the diagnosis of complete tumour response to chemoradiotherapy for rectal cancer.


Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY, 10065, USA. [Email]


OBJECTIVE : To determine if DCE-MRI adds diagnostic value to the combined use of T2WI and DWI-MRI in the determination of clinical complete response (cCR) after neoadjuvant treatment (NAT) in patients with locally advanced rectal cancer.
METHODS : In this IRB-approved, HIPAA-compliant retrospective study, response was assessed using a 5-point confidence score by T2WI and DWI-MRI only ('standard MRI'), then with addition of DCE-MRI. Review of digital rectal exams and endoscopy notes produced a clinical overall response score. The reference standard was CR by histopathology or cCR determined after a minimum of 18 months' follow-up. Diagnostic accuracy and ROC curves were calculated for standard MRI and added DCE-MRI (to detect complete or good response), for clinical evaluation (to detect CR) and for MRI and clinical methods combined.
RESULTS : Of 65 patients undergoing NAT, 20 had cCR (31%). Sensitivity, specificity and area under the ROC (AUC) were 0.55, 0.87 and 0.69 for clinical evaluation; 0.42, 0.77 and 0.66 for standard MRI, and 0.53, 0.76 and 0.68 for added DCE-MRI, respectively. Combined clinical evaluation and standard MRI with DCE-MRI resulted in the highest specificity of 0.96 and highest AUC of 0.72.
CONCLUSIONS : For the assessment of cCR after neoadjuvant therapy using clinical and multi-sequence MRI reading strategies, the addition of DCE-MRI increased specificity and PPV, but not significantly.
CONCLUSIONS : • The addition of dynamic contrast-enhanced MRI to standard MRI, including DWI-MRI, may not significantly improve accuracy of response assessment in rectal cancer treatment. • Clinical assessment consisting of digital rectal examination and endoscopy is the most accurate standalone test to assess response to chemoradiotherapy in rectal cancer. • Combining MRI using DWI and DCE with the clinical assessment may potentially improve the accuracy for response assessment in rectal cancer.


Chemoradiotherapy,Magnetic resonance imaging,Rectal cancer,