Diffusion tensor imaging of kidneys with respiratory triggering: Optimization of parameters to demonstrate anisotropic structures on fraction anisotropy maps

Purpose: To demonstrate the feasibility of diffusion tensor imaging(DTI) of kidneys with respiratory triggering, and determine the optimal imaging parameters for fraction an-isotropy(FA) maps. Materials and Methods: DTI of kidneys from 16 healthy volunteers was performed using a 1.5T scanner. Five different sequences with different parameters including respiration-triggered acquisition or multiple breath-holding, slice thicknesses of 3 or 5 mm, and different numbers of signal averaging and b values were compared. FA and apparent diffusion coefficients(ADCs) of the cortex and medulla were measured. Measurement error within the same and repeated examination was examined using within-individual standard deviation(Sw). Results: FAs of the renal cortex were lower than the medulla(mean value of a sequence ranging 0.148-0.224, 0.433-0.476) and the ADCs of the cortex were higher than the medulla(2.26-2.69 X 10̃ ³ mm ²/s, 1.77-2.19 X 10̃ ³ mm ²/s) in all sequences(P < 0.001). The renal cortex- medulla difference was the largest, with respiratorytrigger-ing including a 3-mm slice thickness, three signal averages,and a b-value = 0, 200, or 400 s/mm ²(P < 0.001). Sw tended to be smaller in the sequence with a b-value of 400 s/mm ². Conclusion: DTI of kidneys with respiratory triggering is feasible with excellent cortex-medulla differentiation.