| ObjectiveTo investigate the value of magnetic resonance imaging dynamic contrast-enhanced(DCE-MRI)subtraction and diffusion-weighted imaging(DWI)in assessing treatment response after loco-regional therapies for primary liver cancer,and explore the advantages of DCE-MRI subtraction especially in evaluating the lesions that showed high signal intensity on non-enhanced T1WI after loco-regional therapies.Materials and MethodsThe patients with primary liver cancer confirmed clinically or pathologically were collected from February 2017 to September 2019 in Qilu Hospital of Shandong University.The enrollment criteria were as follows:DCE-MRI were performed at six months after patients received loco-regional therapies such as Radiofrequency ablation(RFA),microwave ablation(MWA),or transarterial chemoembolization(TACE),all the therapied lesions were Greater than 1 cm and showed high signal intensity on non-enhanced T1WI.A total of 56 patients with 74 lesions were enrolled in the study.According to lesions' performance on the enhanced CT/MRI images and the modified Response Evaluation Criteria in Solid Tumors(mRECIST),74 lesions were divided into complete remission group(42 lesions)and incomplete remission group(32 lesions).Two physicians performed visual analysis on conventional DCE-MRI,DCE-MRI subtraction and DWI(combined ADC)images,and the physicians'confidence scores of the three kinds of technique in evaluating treatment efficacy were compared.The CNRs for the lesion to normal liver parenchyma in arterial and portal phase were calculated pre-and post-subtraction,respectively.The differences of the CNR pre-and post-subtraction were analysised.The ADC values of all lesions were measured,and the mean ADC values of the complete remission group and incomplete remission group were compared.ResultsFor the complete remission group:(1)the confidence scores determined by the physicians according to the conventional DCE-MRI,DCE-MRI subtraction,and DWI(combined ADC)images were not significantly different(Reader 1,P=0.168>0.05;Reader2,P=0.079>0.05).(2)the CNRs for the lesion to normal liver parenchyma that pre-and post-subtraction in arterial phase were not significantly different(13.33±9.80/14.00±11.07,P=0.754>0.05);but the CNR of post-subtraction in portal phase was significantly greater than that of pre-subtraction(53.42±17.74/41.85±25.59,P=0.000<0.05).For the incomplete remission group:(1)the confidence score that determining the presence of active tumoral tissue in the lesion from high to low was:DCE-MRI subtraction>conventional DCE-MRI>DWI(Reader1,P=0.001<0.05;Reader2,P=0.000<0.05).(2)the CNR for the lesion to normal liver parenchyma that post-subtraction was significantly greater than pre-subtraction in both arterial phase(77.08±35.95/47.79±29.09,P=0.000<0.05)and portal phase(44.15±21.0/34.24±22.09,P=0.001<0.05).The mean ADC values of the complete remission group were significantly greater than that incomplete remission group.ConclusionsAfter loco-regional therapies for primary liver cancer,some lesions show hyperintensity on non-enhanced T1WI because of hemorrhage or coagulative necrosis,and it is difficult to distinguish the arterial enhancement caused by residual or recurrent tumor component from necrosis by conventional DCE-MRI.In the images of the DCE-MRI subtraction,the treatment area in the complete necrosis group shows hypointensity after the hemorrhage or necrosis part was subtracted,and also the viable tumor enhancement could be clearly displayed in the residual disease group.After subtraction,the visual diagnostic confidence level of physicians will be significantly higher than that from conventional DCE-MRI,and the CNR for the lesion to normal liver will significantly increase(P<0.05).Quantitative analysis of ADC images could assist the DCE-MRI subtraction in identifying the viable tumor components in the treatment area.After treatment,the ADC values of the residual or recurrent lesions are significantly lower than that of the complete necrosis lesions(P<0.05).DCE-MRI subtraction with DWI could significantly improve the diagnostic accuracy in assessing the efficacy of loco-regional therapies for primary liver cancer. |
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