MR diffusion-weighed imaging of rabbit liver.

AIM

To study the techniques of MR diffusion-weighed imaging (DWI) for normal rabbit liver.

METHODS

After 15 normal New Zealand white rabbits and one New Zealand white rabbit implanted with VX-2 tumor were anesthetized with 3% soluble pentobarbitone, DWI was performed respectively for different b values, repetition times (TR) or thicknesses, when other parameters were the same and magnetic resonance imaging (MRI) was performed respectively, or with different field of views (FOV) or coil when other parameters were the same. The distinction between groups was analyzed by SPSS10.0 with apparent diffusion coefficient (ADC), quality index (QI) or signal-noise ratio (SNR).

RESULTS

As b value increased, liver ADC, QI and SNR of DWI became smaller and simultaneously (F = 292.87, 156.1, 88.23, P<0.01). QI of DWI was high, when b value was 10, 50 or 100 respectively, but the distinction between them was insignificant; when b value was 800, QI and SNR of DWI were low. QI and SNR of DWI had no significant difference between TR = 4 000, 6 000 and 8 000. QI of DWI with 2 mm thickness was bigger than that with 5 mm thickness (t = 3.04, P<0.01), but SNR of DWI with 2 mm thickness was significantly smaller (t = -17.86, P<0.01). SNR of MRI with knee joint coil was obviously bigger than that with cranium coil (t = -5.77 (T1WI) or -4.02 (T2WI), P<0.01), but QI of MRI was smaller on the contrary (t = 7.10 (T1WI) or 3.97 (T2WI), P<0.01). When FOV was enlarged gradually, SNR of MRI increased (F = 85.81 (T1WI) or 221.96 (T2WI), P<0.01), but QI firstly increased, then decreased (F = 68.67 (T1WI) or 69.46 (T2WI), P<0.01) and QI of MRI was the biggest when FOV was 20 cm x 15 cm.

CONCLUSION

The scanning technique is very important in DWI of rabbit liver and the overall quality of DWI with b (100 s/mm2), thickness (2 mm), cranium coils and FOV (20 cm x 15 cm) was best in our study, when other parameters were the same.