Clinical application of MR diffusion-weighted imaging in evaluating the short-term curative effect of cryoablation for pancreatic carcinoma / 介入放射学杂志

ABSTRACT

Objective To discuss the clinical value of magnetic resonance diffusion-weighted imaging (MR-DWI) in distinguishing tumor remnants from tumor necrosis of pancreatic carcinoma after cryoablation treatment.Methods Conventional MRI T1WI,T2WI scan,DWI sequence and dynamic enhanced MRI scan were performed in 26 patients with pancreatic carcinoma who were received cryoablation treatment.The changes in MRI signals after cryoablation treatment were recorded.The apparent diffusion coefficient (ADC) values of the normal pancreas,preoperative tumor tissue,postoperative remnants and necrosis tissue were calculated,and the results were compared.The correlation between the ADC values and the size of the tumor was evaluated,and the differences in ADC values among the tumors that had different diameter,location and staging were statistically analyzed.Results Of the 26 patients,complete necrosis of tumor was obtained in 16.The necrotic tumor tissue displayed low-signal on T1WI,high-signal on T2WI and low-signal on DWI,with no enhancement on dynamic enhanced imaging.Active residual tumor tissue was detected in 9 patients,among them the residual tumor diameter ＞5 cm was seen in 7 patients;the residual rate was 34.6％.ADC values of the following tissue,from low to high in order,were preoperative pancreatic tumor tissue (1.022± 0.126)x10-3 mm2/s,postoperative residual tumor tissue (1.130±0.155)x10-3 mm2/s,normal pancreatic tissue (1.924±-0.124)×10-3 mm2/s and postoperative necrosis tissue (2.312-±0.214)×10-3 mm2/s.No statistically significant difference in ADC values existed between preoperative pancreatic tumor tissue and postoperative residual tumor tissue (P=0.452),while statistically significant difference in ADC values existed between normal pancreatic tissue and postoperative necrosis tissue (P＜0.001).The ADC values of pancreatic tumor tissue bore a negative correlation with the tumor size (R=-0.43,P=0.027 2),while the ADC values lacked the relationship to the tumor location as well as to the tumor staging (P=0.738 8 and P=0.089 5 respectively).Conclusion MR-DWI can effectively distinguish the residual tumor tissue from the necrotic tumor tissue of pancreatic carcinoma after cryoablation treatment,which provides reliable basis for further clinical diagnosis and treatment.