• Sachiko Yuen, Kei Yamada, Mariko Goto, Kaori Nishida, Akiko Takahata, and Tsunehiko Nishimura.
• Department of Radiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan. syuen@koto.kpu-m.ac.jp
• J Magn Reson Imaging. 2009 May 1; 29 (5): 1080-4.

PurposeTo investigate the effect of gadolinium (Gd)-DTPA on the apparent diffusion coefficient (ADC) of breast carcinoma and to analyze the relationship between pre/postcontrast ADC and the degree of contrast enhancement.Materials And MethodsNineteen histopathologically confirmed breast carcinomas (mean size = 22 mm) were analyzed. Their ADCs before and after contrast administration were measured. The contrast-to-noise ratios (CNRs) of the tumors were measured on fat-suppressed 3D T1-weighted images in precontrast, early, and late postcontrast phases. These results were correlated with the measured ADC values.ResultsA significant decrease in the measured ADC was noted after contrast administration (-23%, P = 0.01). Lesions with relatively high ADC before contrast (>1.3 x 10(-3) mm(2)/sec; n = 12) demonstrated a larger degree of ADC reduction (mean 34%) than lesions with low ADC (< or =1.3 x 10(-3) mm(2)/sec; n = 7) (mean 4.5%). When an early postcontrast image was used as a surrogate marker of malignant potential, we found a significant inverse correlation with postcontrast ADC (gamma = -0.57, P = 0.02).ConclusionPostcontrast ADC exhibited lower values than precontrast ADC, which is thought to reflect suppression of the microperfusion-induced effect on diffusion-weighted imaging. Postcontrast ADC may be a better indicator than precontrast ADC to reflect malignant potential of tumors.

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