Can diffusion-weighted MRI determine complete responders after neoadjuvant chemoradiation for locally advanced rectal cancer?
OBJECTIVE
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.


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).


CONCLUSIONS
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.
Oncology Institute, Istanbul University, İstanbul, Turkey. gengin@istanbul.edu.tr
Gülgün
G
Engin
Rasul
R
Sharifov
Zeynep
Z
Güral
Esra Kaytan
EK
Sağam
Sezer
S
Sağlam
Emre
E
Balik
Oktar
O
Asoğu
Sümer
S
Yamaner
Mine
M
Güllüoğu
Yersu
Y
Kapran
Sevda
S
Özel
D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000628:therapy*; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D016896:Treatment Outcome