Abstract：Objective: To evaluate the effect of intravenous Gd-DTPA on diffusion weighted imaging(DWI) and apparent diffusion coefficient(ADC) value. Materials and Methods: Forty-one patients were prospectively recruited with mean age (43.3±17.3) years. Transverse single shot echo planar imaging DWI was performed immediately before, and about 3.4 min after the injection of 0.1 mmol/kg Gd-DTPA on GE Signa HDxt 3.0T MR scanner. Signal-to-noise ratio(SNR) and contrast-to-noise ratio(CNR) of the lesion, and the SNR of normal brain tissue were calculated on b=0 s/mm2 and b=1 000 s/mm2 DWI images respectively. ADC values were measured on ADC maps. A paired t-test was used to determine the significance of differences between the values before and after administration of contrast medium. P<0.05 was considered statistically significant. Results: Images before and after contrast administration were not significantly different regarding SNR and CNR on DWI of either normal brain or 44 intraxial lesions. SNR and CNR were slightly decreased on b=0 s/mm2 DWI of 11 extraaxial lesions(P=0.026 and 0.017). ADC values decreased the most after contrast medium injection on DWI for extraaxial lesions(about 5.9%, P=0.002), and no significant statistical difference for ADC decrease shown in normal brain or intraaxial lesions. Conclusion: In routine clinical practice, Gd-DTPA has slight effects on low b-value DWI images and ADC values for extraaxial lesions. Therefore, it is better to perform DWI before contrast medium injection for those lesions with rich blood supply, especially extraaxial lesions.
2013, Vol. 24 
