title: Effect of intravenous gadolinium-DTPA on diffusion-weighted imaging for prostate lesions and normal tissue at 3.0-Tesla magnetic resonance imaging.
abstract: BACKGROUND
  Post-contrast diffusion-weighted imaging (DWI) is occasionally necessary when the results of the pre-contrast DWI differ from that of the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), however, the effects of contrast material on DWI image and apparent diffusion coefficient (ADC) values have not been fully examined.
  
  
  OBJECTIVE
  To assess whether the administration of gadolinium-DTPA (Gd-DTPA) significantly affects the DWI of prostate lesions or normal tissue at the 3.0 Tesla magnetic resonance imaging (3.0 T MRI).
  
  
  METHODS
  Fifty-one patients with 52 prostate lesions, including 32 prostate cancer (25 in the peripheral zone [PZ] and seven that could not be confidently located) and 20 benign lesions (11 in PZ and nine in central grand [CG]), underwent echo-planar imaging (EPI)-DWI with b values of 0, 1000 s/mm(2) before and after administration of Gd-DTPA at 3.0 T MRI. Regions of interest (ROI) were drawn in all lesions, 42 normal PZ, 44 CG tissue and air to calculate the signal-to-noise ratio (SNR) and ADC values of lesions and normal tissue, and contrast-to-noise ratio (CNR) of lesions for pre- and post-contrast images. Statistical differences between pre- and post-contrast data were assessed by use of a paired t test.
  
  
  RESULTS
  No significant differences between pre- and post-contrast images were found in the CNR of lesions and SNR of all the tissue except CG, which showed a statistically significant decline (9.6%, p < 0.0001) in SNR after contrast relative to the pre-contrast images. The post-contrast ADC values were statistically significantly lower than pre-contrast for prostate cancer (0.80 ± 0.11 mm(2)/s Vs 0.89 ± 0.12 mm(2)/s, p < 0.0001) and benign lesions (1.14 ± 0.30 mm(2)/s vs. 1.2 ± 0.29 mm(2)/s, p < 0.0001). No significant differences were detected for normal tissue.
  
  
  CONCLUSIONS
  The administration of Gd-DTPA can slightly affect the DWI image quality of the prostate and reduce the ADC value of lesions at 3.0T MRI. Applications of post-contrast DWI require caution in interpretation.
authors.affiliation: Department of Radiology, Cancer Hospital/Cancer Institute, Fudan University, Shanghai, China.
authors.forename: Xiaohang
authors.initials: X
authors.lastname: Liu
authors.forename: Liangping
authors.initials: L
authors.lastname: Zhou
authors.forename: Weijun
authors.initials: W
authors.lastname: Peng
authors.forename: Min
authors.initials: M
authors.lastname: Qian
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery; D020728:Transurethral Resection of Prostate
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA