Objective: To evaluate the value of T2WI signal intensity related parameters that can be obtained by magnetic resonance imaging (MRI) for predicting pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanved rectal cancer (LARC). Methods: Signal Intensity of Tumor (SIT) and Signal Intensity of Tumor/Muscle (SIT/M) of MR T2WI before and after neoadjuvant chemoradiotherapy of 101 patients with locally advanced rectal cancer were evaluated by two experienced readers independently. Signal Intensity of Tumor Reduction Rate (SITRR) and Signal Intensity of Tumor/Muscle Reduction Rate (SIT/MRR) were calculated. The difference of related parameters of T2WI tumor signal intensity between the pCR and the non-pCR group were analyzed. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance for predicting pCR. Results: Of the 101 patients, 18 were in pCR group and 83 were in non-pCR group. In all patients, the SITpre, SITpost, SITRR, SIT/Mpre, SIT/Mpost and SIT/MRR measured by reader 1 were 197.0 (133.0), 144.2 (69.7), 0.4% (0.5%), 2.6 (0.6), 3.0 (2.3) and 0.4 (0.2)% in pCR group, and 227.0 (99.0), 205 (95.4), 0.1% (0.6%), 2.6 (0.6), 2.6 (1) in non-pCR group, respectively. SITpre, SITpost, SITRR, SIT/Mpre, SIT/Mpost and SIT/MRR measured by reader 2 were 193.0 (135.0), 143.0 (69.8), 0.4% (0.2%), 2.6 (0.6), 1.5 (0.5) and 0.39% (0.2%) in pCR group, and 234.0(108.0), 203(96.5), 0.1% (0.3%), 2.6 (0.6%), 1.7 (0.7) and 0.25% (0.2%) in non-pCR group, respectively. Between the pCR and non-pCR group, there were significant differences in SITpost, SIT/Mpost and SIT/MRR measured by both readers (all P<0.01), but there was no significant differences in SITpre and SIT/Mpre (P>0.05). The difference of SITRR measured by reader 1 was not statistically significant (P=0.415), while the difference of SITRR measured by reader 2 was statistically significant (P=0.001). In patients with rectal non-mucinous adenocarcinoma, SITpost, SIT/Mpost, SITRR and SIT/MRR measured by two physicians were still statistically significant between the pCR and non-pCR group (all P<0.01), but SITpre and SIT/Mpre had no significant difference (P>0.05). ROC curve analysis showed that in all patients, the area under curve (AUC) of SITpost, SIT/Mpost and SIT/MRR for predicting pCR to neoadjuvant chemoradiotherapy in locally advanced rectal cancer was 0.694-0.762, the sensitivity was 68.2%-77.3%, and the specificity was 63.6%-77.3%. In rectal non-mucinous adenocarcinoma patients, the AUC, sensitivity and specificity was 0.704-0.764, 62.7%-78.9% and 66.2%-84.2%, respectively. Conclusions: T2WI signal intensity related parameters are potential predictors for pCR in locally advanced rectal cancer after neoadjuvant chemoradiptherapy. The predictive value is higher in non-mucinous adenocarcinoma.
目的： 评估磁共振(MR)图像中T2WI肿瘤相关信号指标预测局部进展期直肠癌新辅助放化疗后病理完全缓解(pCR)的应用价值。 方法： 由2位临床经验丰富的诊断科医师分别独立测量101例局部进展期直肠癌患者新辅助放化疗前后的MR T2WI肿瘤绝对信号强度(SIT)、肿瘤相对信号强度(SIT/M)，计算SIT减低率(SITRR)和SIT/M减低率(SIT/MRR)，比较pCR组和非病理完全缓解(non－pCR)组T2WI肿瘤相关信号指标的差异。采用受试者工作特征(ROC)曲线分析评估各指标预测局部进展期直肠癌新辅助放化疗后pCR的效能。 结果： 101例患者中，pCR组18例，non－pCR组83例。全部患者中，医师1测量的pCR组SITpre、SITpost、SITRR、SIT/Mpre、SIT/Mpost和SIT/MRR分别为197.0(133.0)、144.2(69.7)、0.4%(0.5%)、2.6(0.6)、3.0(2.3)和0.4(0.2)%，non－pCR组分别为227.0(99.0)、205(95.4)、0.1%(0.6%)、2.6(0.6)、2.6(1.5)和0.3%(0.2%)；医师2测量的pCR组SITpre、SITpost、SITRR、SIT/Mpre、SIT/Mpost和SIT/MRR分别为193.0(135.0)、143.0(69.8)、0.4%(0.2%)、2.6(0.6)、1.5(0.5)和0.39%(0.2%)，non－pCR组分别为234.0(108.0)、203(96.5)、0.1%(0.3%)、2.6(0.6)、1.7(0.7)和0.25%(0.2%)。pCR组与non－pCR组比较，2位医师测量的SITpost、SIT/Mpost和SIT/MRR差异均有统计学意义(均P<0.01)，SITpre和SIT/Mpre差异均无统计学意义(均P>0.05)；第1位医师测量的SITRR差异无统计学意义(P＝0.415)，而第2位医师测量的SITRR差异有统计学意义(P＝0.001)。仅直肠非黏液腺癌患者中，2位医师测量的SITpost、SIT/Mpost、SITRR和SIT/MRR在pCR组与non－pCR组间差异仍然有统计学意义(均P<0.01)，而SITpre和SIT/Mpre差异均无统计学意义(均P>0.05)。ROC曲线分析显示，在全部患者，SITpost、SIT/Mpost和SIT/MRR预测局部进展期直肠癌新辅助放化疗后pCR的曲线下面积(AUC)为0.694～0.762，灵敏度为68.2%～77.3%，特异度为63.6%～77.3%。在直肠非黏液腺癌患者，AUC为0.704～0.764，灵敏度为62.7%～78.9%，特异度为66.2%～84.2%。 结论： MR T2WI肿瘤相关信号强度可作为预测局部进展期直肠癌新辅助放化疗后pCR的指标，且在非黏液腺癌中的预测价值较高。.
Keywords: Magnetic resonance; Neoadjuvant chemoradiotherapy; Pathological complete response; Rectal neoplasms; T2WI signal intensity.