Introduction

End-stage renal disease (ESRD) patients treated with hemodialysis have high levels of interstitial myocardial fibrosis which causes structural abnormalities including left ventricular hypertrophy (LVH), termed uremic cardiomyopathy (UCM). Meanwhile, coronary artery calcium score (CACS) is an independent risk predictor of cardiac complications in chronic kidney disease as demonstrated in previous studies. As non-contrast native T1 value has been shown to have good correlation with cardiac fibrosis, the objective of this study is to investigate the value of native T1 mapping for the assessment of myocardial fibrosis in UCM for monitoring the cardiac status of ESRD patients.

Methods

12 ERSD patients treated with hemodialysis who underwent both 3T CMR imaging (Philips Ingenia 3T) and Cardiac Calcium Scoring Scan (Siemens Somatom Definition Flash) were enrolled in this study. The CMR imaging protocol included cine SSFP and pre-contrast T1 mapping sequences. The full left ventricle was covered in around 10 short axis slices in both cine and T1 mapping, with the same in-plane resolution, slice thickness and gap. Left ventricular ejection fraction (EF) was measured from short axis cine. Global and segmental native T1 was measured from short axis slices using MASS software (research version 2017, Leiden University Medical Center). Segmental myocardial mass was measured using Mass as well. Based on both short and long axis cine, the standardized segments (AHA) were identified by a radiologist with 6 year experience. Segmental native T1 were measured by the mean value of the same segments in consecutive slices. CACS AJ-130 and Volume-130 were quantified using the multimodality workplace (syngoMMWP VE50A, Siemens). Statistical analysis was performed using SPSS-23 software (IBM, Chicago, IL). Native T1 between low EF group and preserved LVEF group were compared by one-way ANOVA. Correlations between native T1, CACS and myocardial mass were assessed using Pearson’s analysis. K independent sample test was used to analyse the mean rank difference of native T1 among 16 segments (segment 17 of apex is not included).

Results

The mean global native T1 was 1285.9±36.5 ms. There was a significant difference of native T1 between low EF group and preserved LVEF group (1324.2±30.6 ms vs 1266.7±20.7 ms, p=0.003). Global native T1 was significantly correlated with the CACS AJ-130 and Volume-130 (r=0.789, p=0.002 and r=0.791, p=0.002, respectively). Bases on septal thickness ≥15mm, 66.7% (8/12) subjects showed myocardial hypertrophy. Segments 2, 14, 9 and 8 had the highest ranks of native T1 value (X2=15.702, p=0.402), which indicated that septal segments appeared to be more prone to develop fibrosis.

Conclusions

Native T1 value of ERSD patients is associated with structural abnormalities of the heart and highly correlated with structural and functional abnormalities of the left ventricle and CACS. Thus, native T1 is potentially clinically valuable for monitoring the cardiac status of ESRD patients treated with hemodialysis.

Acknowledgements

Here and now, I would like to extend my sincere thanks to all those who have helped me make this study possible and better. Firstly, I am deeply grateful to my honorable supervisor, Wenjie Yang, who have checked through my thesis with patience and given me instructive suggestions, and she also played an important role in indicating a bright road in my future writing.Then thanks to the teachers and professors who have taught me on this study. Finally, I am very grateful to my family for supporting me all the time.