T2 weighted signal intensity evolution may predict pathological complete response after treatment for rectal cancer.
OBJECTIVE
To determine the diagnostic value of T2-weighted signal intensity evolution in the tumour for detection of complete response to neoadjuvant chemoradiotherapy in patients with rectal cancer.


METHODS
Thirty-nine patients diagnosed with locally advanced adenocarcinoma and treated with chemoradiotherapy (CRT), followed by surgery, underwent magnetic resonance imaging (MRI) before and after CRT on 1.5-T MRI using T2-weighted fast spin-echo (FSE) imaging. The relative T2-weighted signal intensity (rT2wSI) distribution in the tumour and post-CRT residual tissue was characterised by means of the descriptive statistical parameters, such as the mean, 95th percentile and standard deviation (SD). Receiver operating characteristic curves were used to determine the diagnostic potential of the CRT-induced alterations (Δ) in rT2wSI descriptives. The tumour regression grade (TRG) served as a histopathological reference standard.


RESULTS
CRT induced a significant decrease of approximately 50% in all rT2wSI descriptives in complete responders (TRG1). This drop was significantly larger than for incomplete response groups (TRG2-TRG4). The ΔrT2wSI descriptives produced a high diagnostic performance for identification of complete responders, e.g. Δ95th percentile, ΔSD and Δmean resulted in accuracy of 92%, 90% and 82%, respectively.


CONCLUSIONS
Quantitative assessment of the CRT-induced changes in the tumour T2-weighted signal intensity provides high diagnostic performance for selection of complete responders.
Department of Radiology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands. e.kluza@maastrichtuniversity.nl
Ewelina
E
Kluza
Esther D
ED
Rozeboom
Monique
M
Maas
Milou
M
Martens
Doenja M J
DM
Lambregts
Jos
J
Slenter
Geerard L
GL
Beets
Regina G H
RG
Beets-Tan
D000230:Adenocarcinoma / Q000473:pathology / Q000628:therapy*; D000368:Aged; D000704:Analysis of Variance; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D018365:Neoplasm, Residual / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012680:Sensitivity and Specificity