Diffusion tensor MRI of the kidney at 3.0 and 1.5 Tesla

Abstract

Background: Diffusion tensor imaging (DTI) at 3 T provides information on the microstructure and pathophysiology of tissues that is not available from conventional imaging with an advantage of high signal to noise ratio (SNR). Purpose: To evaluate the feasibility of DTI of the normal kidney at 3.0 T compared to results obtained at 1.5 T. Material and Methods: DTI of the normal kidney of 15 healthy volunteers obtained with 3.0 and 1.5 T scanners using respiration-triggered acquisition was examined. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of both the renal cortex and the medulla and SNRs were measured (b-values 0 and 400 s/mm2, diffusion direction of 6). The image quality of FA and ADC maps was also compared subjectively. Results: The FA values of the renal cortex were 0.15 ± 0.03 at 3.0 T and 0.14± 0.03 at 1.5 T on average. This difference was not significant. The FA values of the renal medulla were 0.49 ±0.04 at 3.0 T and 0.42 ± 0.05 at 1.5 T. ADC values of the renal cortex were 2.46 × 10−3± 0.09 mm2/s at 3.0 T and 2.20 ×10−3±0.11 mm2/s at 1.5 T. The ADC values of the renal medulla were 2.08 × 10−3 ± 0.08 mm2/s at 3.0 T and 1.90 × 10−3± 0.11 mm2/s at 1.5 T. These FA and ADC values were consistent with previous publications. The difference was significant for the FA value of the medulla ( P< 0.01) and ADC values in both cortex and medulla ( P < 0.01). The subjective image quality of the FA map with the 3.0 T scanner was significantly superior to that with the 1.5 T scanner ( P< 0.01), but not significant for the ADC map ( P = 0.18). There was a significant difference in SNR between 3.0 T (48.8 ± 6.6) and 1.5 T images (32.8 ± 5.0). Conclusion: The feasibility of renal DTI with a 3.0 T magnet resulting in improved SNR was demonstrated.