Tnm staging of rectum cancer with 1.5 tesla MRI and the role of diffusion MRI in the evaluation efficiency of neoadjuvan chemoradyotherapy

ABSTRACT TNM STAGING OF RECTUM CANCER WITH 1.5 TESLA MRI AND THE ROLE OF DIFFUSION MRI IN THE EVALUATION EFFICIENCY OF NEOADJUVAN CHEMORADYOTHERAPY Treatment in rectum cancer varies according to the stage of the disease, so it is of great importance to perform the correct staging before treatment. The aim of this study, as prospective with 1.5 Tesla Magnetic Resonance Imaging (MRI) was to determine the T-N staging, determine the tumor differentiation and to predict the tumor regression of patients receiving neoadjuvant therapy in rectal cancer patients. The study consisted of 36 patients and 22 control groups. 12 cases were evaluated before and after neoadjuvant treatment. MRI and Diffusion Weighted Imaging (DWI) was performed to all patients and apparent diffusion coefficient map (ADC) was made. T staging accuracy was 72.2% in MRI. N staging accuracy rate was 75% in T2 sequence and 72.2% in DAG. Tumoral rectal ADC values were significantly decreased compared to normal rectal wall (p <0.001). According to the cut-off ADC value of 1.52x10-3 mm2/sn, the sensitivity between the normal wall and the tumoral wall was 94% and the specificity was 100%. Mean T3 and T4 (extramural) ADC values were significantly decreased compared to T2 stage (intramural) ADC values (p <0.001). ADC and relative ADC (lymph node / primary tumor ADC) values of the metastatic lymph nodes were significantly decreased compared to benign lymph nodes (p <0.001). According to 1.33x10-3 lymph node ADC cut-off value, sensitivity was 75%, specificity was 100%, according to relative ADC cut-off value of 1.47x10-3 sensitivity was %90.62, specificity was %88.24. According to the value of ADC accuracy of lymph node, N staging accuracy was found to be 83%. The ADC values of the low differentiated group were significantly decreased compared to the medium and well-differentiated group (p <0,011). In the control MRI of patients receiving neoadjuvant therapy, the ADC increase in the group that responded well to the treatment was significantly higher than the group with partial response (p <0.004). In conclusion, MRI is important in staging of rectal cancer. DWI and ADC are useful in tumor staging, show the effect of treatment and tumor differentiation. Key words: Rectum cancer, staging, Diffusion MRI