Purpose To evaluate the value of 3D amide proton transfer imaging(3D APT)and reduced field-of-view diffusion weighted imaging(rFOV DWI)in predicting histologic grade of rectal adenocarcinoma.Materials and Methods A total of 64 cases of rectal adenocarcinoma confirmed by pathology were analyzed from February 2020 to April 2023,with 28 cases in the high and 36 cases in the medium-low differentiation group,retrospectively.MRI sequences including reduced field-of-view high-resolution T2WI(rFOV T2WI),rFOV DWI and 3D APT before surgery.Two neuroradiologists delineated the solid part of the tumor layer by layer,and extracted its apparent diffusion coefficient(ADC)and magnetization transfer ratio asymmetry(MTRasym)values.Combined-parameter model(MTRasym+rADC)was constructed by binary Logistic regression.The efficacy of the single-parameter and combined-parameter model was assessed using receiver operating characteristic curve.Results The mean value of MTRasym of the medium-low group[(2.93±0.61)%]was higher than that of high differentiation group[(1.74±0.63)%](t=-7.60,P＜0.001),and the mean value of rADC of the medium-low group[(0.98±0.17)×10-3 mm2/s]was lower than that of the high differentiation group[(1.19±0.18)×10-3 mm2/s](t=4.50,P＜0.001).In the identification of histopathological grades of rectal adenocarcinoma,receiver operating characteristic analysis showed that compared with MTRasym and rADC,the combined parameter model had the highest diagnostic performance,with an area under the curve of 0.94,sensitivity and specificity of 0.86 and 0.96.Conclusion 3D APT and rFOV DWI are helpful in identifying the histopathological grade of rectal adenocarcinoma.

Purpose To evaluate the value of 3D amide proton transfer imaging(3D APT)and reduced field-of-view diffusion weighted imaging(rFOV DWI)in predicting histologic grade of rectal adenocarcinoma.Materials and Methods A total of 64 cases of rectal adenocarcinoma confirmed by pathology were analyzed from February 2020 to April 2023,with 28 cases in the high and 36 cases in the medium-low differentiation group,retrospectively.MRI sequences including reduced field-of-view high-resolution T2WI(rFOV T2WI),rFOV DWI and 3D APT before surgery.Two neuroradiologists delineated the solid part of the tumor layer by layer,and extracted its apparent diffusion coefficient(ADC)and magnetization transfer ratio asymmetry(MTRasym)values.Combined-parameter model(MTRasym+rADC)was constructed by binary Logistic regression.The efficacy of the single-parameter and combined-parameter model was assessed using receiver operating characteristic curve.Results The mean value of MTRasym of the medium-low group[(2.93±0.61)%]was higher than that of high differentiation group[(1.74±0.63)%](t=-7.60,P＜0.001),and the mean value of rADC of the medium-low group[(0.98±0.17)×10-3 mm2/s]was lower than that of the high differentiation group[(1.19±0.18)×10-3 mm2/s](t=4.50,P＜0.001).In the identification of histopathological grades of rectal adenocarcinoma,receiver operating characteristic analysis showed that compared with MTRasym and rADC,the combined parameter model had the highest diagnostic performance,with an area under the curve of 0.94,sensitivity and specificity of 0.86 and 0.96.Conclusion 3D APT and rFOV DWI are helpful in identifying the histopathological grade of rectal adenocarcinoma.