Abstract： Objective To investigate the diagnostic values of T1 mapping imaging for evaluating myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM).Methods Forty-eight subjects with HCM and 18 healthy volunteers underwent conventional late gadolinium enhancement (LGE) MR imaging and T1 mapping imaging.According to the characteristics of LGE,the myocardium in HCM was divided into remote area of LGE,peri-LGE,LGE (halo-like LGE and typical patchy LGE).The changing rates of contrast-enhanced T1 value of these regions were measured and compared with normal volunteers'myocardium.The Chi-square test,pairwise comparison and ROC curve were used for statistical analysis.Results The changing rate of T1 value (CRT) in healthy volunteers was no significant difference from that in the remote area of LGE (3.98 ±3.19 vs.3.36 ±2.77,t =0.98,P ＞0.05).There were significant differences in CRT between healthy volunteers' myocardium and the peri-LGE (13.51 ± 5.67),halo-likeLGE (17.70±5.57) and typical patchy LGE(36.62 ±8.03,t =15.28,17.13 and 47.48,respectively,all P ＜ 0.01),between remote area-LGE and peri-LGE,halo-like LGE and typical patchy LGE (t =19.64,20.76 and 56.64,respectively,all P ＜ 0.01),between peri-LGE and halo-like LGE and typical patchy LGE(t =6.12 and 39.90,respectively,both P ＜ 0.01),between halo-like LGE and typical patchy LGE(t =25.63,P ＜0.01).ROC curves indicated that T1 mapping imaging has a greater area under the curve than that of traditional LGE imaging (0.974 ±0.050 vs.0.751 ±0.180).Conclusion T1 mapping imaging can be a useful method to evaluate the severity of the fibrosis,especially at the early stage.