Diffusion tensor MRI of the kidney at 3.0 and 1.5 Tesla.
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).


OBJECTIVE
To evaluate the feasibility of DTI of the normal kidney at 3.0 T compared to results obtained at 1.5 T.


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 x 10⁻³± 0.09 mm<²/s at 3.0 T and 2.20 x 10⁻³±0.11 mm²/s at 1.5 T. The ADC values of the renal medulla were 2.08 x 10⁻³ ± 0.08 mm²/s at 3.0 T and 1.90 x 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).


CONCLUSIONS
The feasibility of renal DTI with a 3.0 T magnet resulting in improved SNR was demonstrated.
Kido
Aki
A
Department of Diagnostic Imaging and Nuclear Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto, Japan. akikido@kuhp.kyoto-u.ac.jp
Kataoka
Masako
M
Yamamoto
Akira
A
Nakamoto
Yuji
Y
Umeoka
Shigeaki
S
Koyama
Takashi
T
Maetani
Yoji
Y
Isoda
Hiroyuki
H
Tamai
Ken
K
Morisawa
Nobuko
N
Saga
Tsuneo
T
Mori
Susumu
S
Togashi
Kaori
K
D000328:Adult; D016880:Anisotropy; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000033:anatomy & histology*; D008297:Male; D018709:Statistics, Nonparametric