Measuring Renal Tissue Relaxation Times at 7T

• Published in: NMR in biomedicine 2014-10, Vol.28 (1), p.63-69
• Main Authors: Li, Xiufeng, Bolan, Patrick J., Ugurbil, Kamil, Metzger, Gregory J.
• Format: Article
• Language: English
• ISSN: 0952-3480; 1099-1492
• DOI: 10.1002/nbm.3195

As developments in RF coils and RF management strategies make performing ultrahigh field renal imaging feasible, understanding the relaxation times of the tissue becomes increasingly important for tissue characterization and sequence optimization. By using a magnetization prepared single breath-hold fast spin echo imaging method, human renal T 1 and T 2 imaging studies were successfully performed at 7T while addressing challenges of B1+ inhomogeneity and peak short-term specific absorption rate (SAR). At 7T, measured renal T 1 values for the renal cortex and medulla (mean ± S.D.) were 1661 ± 68 ms and 2094 ± 67 ms, and T 2 values were 108 ± 7 ms and 126 ± 6 ms. For comparison, similar measurements were made at 3T where renal cortex and medulla T 1 values of 1261 ± 86 ms and 1676 ± 94 ms, and T 2 values of 121 ± 5 ms and 138 ± 7 ms were obtained. Measurements at 3T and 7T were significantly different for both T 1 and T 2 values in both renal tissues. Reproducibility studies at 7T demonstrated that T 1 and T 2 estimations were robust with group mean percentage differences of less than 4%.