| Part one:The Value of MR imaging for Assessing Treatment Response of Neoadjuvant Chemoradiotherapy of Rectal CancerSection IPurpose To evaluate the feasibility and value of diffusion kurtosis(DK)imaging in assessing treatment response to neoadjuvant chemoradiotherapy(CRT)in patients with locally advanced rectal cancer(LARC).Materials and methods Forty-one patients with LARC were included.All patients underwent pre-and post-CRT DKI on a 3.0 Tesla MRI scanner.Imaging indices(Dapp,Kapp and ADC values)were measured.Change value(?X)and change ratio(r ?X)were calculated.Pathological tumor regression grade scores(Mandard)was the standard reference(good responders,pTRG 1-2,poor responders,pTRG 3-5).Diagnostic performance was compared using ROC analysis.Results For the pre-CRT measurements,pre-Dapp-10th was significantly lower in the good responder group than that of poor responder group(p = 0.036).For assessing treatment response to neoadjuvant CRT,pre-Dapp-10th resulted in AUCs of 0.753(p =0.036)with sensitivity of 66.67%,and specificity of 77.78%.The rADapp had a relatively high AUC(0.859)and high sensitivity(100%)when compared with other image indices.Conclusion DKI is feasible for selecting good responders for neoadjuvant CRT for LARC.Section IIPurpose To investigate the value of DCE-MRI in predicting pCR in patients with LARC who underwent CRT in our institutional patient cohort.Materials and methods Thirty-five consecutive patients with LARC were enrolled in this prospective study.Quantitative parameters Ktrans,Kep and Ve from DCE-MRI,percentage change of Ktrans[?Ktrans?(post-Ktrans-pre-Ktrans)/pre-Ktrans]were calculated.Sensitivity,specificity and area under curve(AUC)of receiver operating characteristic were used to verify the predictive value of each parameter.Results ?Ktrans were significantly higher in patients with pCR compared with those non-pCR patients(45.437±10.703%vs.34.063±15.856%,P=0.022).?Ktrans showed an AUC of 0.777,sensitivity of 80%,and specificity of 75%.Conclusion DCE-MRI was capable for predicting pCR of LARC.Part two:The Value of MR imaging for Assessing Distant Metastasis of Rectal CancerSection IPurpose To investigate the correlation of standard diffusion-weighted imaging(DWI)and diffusion kurtosis imaging(DKI)with distant metastases of rectal carcinoma.Materials and methods Fifty-eight patients with rectal carcinoma(27 with distant metastasis and 31 with no metastasis)were included in this study.ADC value from standard DWI(b values of 0 and 1000 sec/mm2),Dapp,and Kapp from DKI(b values of 0,700,1400 and 2000 sec/mm2)were acquired.These quantitative parameters were calculated from the whole-transverse region of interest(ROI)of entire tumors.Receiver operating characteristic curve analyses were conducted to assess the utility for discrimination of tumor with distant metastasis and those without metastasis.Parameters were compared using the independent-samples t test.Results Histogram metrics 10th of Dapp(Dapp-10th),min of ADC values(ADC-min)were significantly lower in the distant metastasis group than those without metastasis(0.972±0.119 vs 1.121±0.134,0.486±0.228 vs 0.596±0.086×10-3 mm2/s,p<0.05).Max of Kapp(Kapp-max)was significantly higher in the distant metastasis group(1.407±0.337 vs 1.215±0.147;P = 0.014).Dapp-10th showed relatively higher AUC(0.856 vs.0.677),and higher specificity(100%vs 60%)than ADC-min did for differentiation of lesions with distant metastasis from those without metastasis.Conclusion DKI was relatively better than standard DWI did in discriminating rectal carcinoma with distant metastasis from those without metastasis.Section IIPurpose To explore the correlations between DCE-MRI quantitative parameters and synchronous distant metastasis and the clinicopathologic factors in rectal cancers.Materials and methods Sixty-three patients with rectal cancer(synchronous distant metastasis,n=31;non-metastasis,n=32)were enrolled in this study.Student's t test and ANOVA were used to compare DCE-MRI parameters(Ktrans,Kep and Ve).The receiver operating characteristic(ROC)analysis was used to find the reasonable threshold of DCE-MRI parameters to differentiate lesions with synchronous distant metastasis from those without metastasis.Results The Ktrans,Kep,and Ve value were significantly higher in the lesions with distant metastasis than in the lesions without distant metastasis(0.536±0.242 vs 0.299±0.118 min-1,<0.001;1.598±0.477 vs 1.341±0.390min-1,p = 0.022;and 0.324±0.173 vs 0.249±0.091,p = 0.034;respectively).The Ktrans showed the highest AUCs of 0.788(p<0.001),with sensitivity of 61.29%and specificity of 87.5%,respectively.Conclusion DCE-MRI parameters may represent a prognostic indicator for synchronous distant metastases in patients with rectal cancer. |
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