RESUMO
PURPOSE: We aimed to prospectively determine if analyzing pre- and post-chemoradiotheraphy (CRT) changes in the signal intensity (SI) and apperent diffusion coefficient (ADC) values from diffusion-weighted magnetic resonance imaging (DW-MRI) can accurately predict complete responders for locally advanced rectal cancer. MATERIALS AND METHODS: Thirty patients (mean age, 54.3 years) with locally advanced rectal cancer who underwent neoadjuvant CRT and subsequent surgery were included in this study. All patients were evaluated pre- and post-CRT by standardized turbo spin echo and DW-MRI. Pre- and post-CRT tumor and normal rectal wall SI (which were gradually scored as very high, high, intermediate, low, and no signal) and ADC values were recorded. RESULTS: Tumor SIs were decreased in all of the patients that had a therapy response. However, complete tumor SI loss was only seen in two (22.2%) of nine patients with a pathological complete response, while it regressed to low and/or intermediate SI levels in the remaining seven patients (77.8%). Post-CRT ADC values of rectal tumors were significantly higher from the preCRT ADC values (P < 0.0001; Z=-9.39). However, post-CRT ADC values from the complete and partial/no response patient groups were not significantly different (P = 0.071; Z=-1.99). CONCLUSION: In re-staging of rectal tumors by DW-MRI, an increase in ADC values and decrease in SIs can predict therapy response but cannot unequivocally determine a complete response.
