Microperfusion‐induced elevation of ADC is suppressed after contrast in breast carcinoma

Abstract

Purpose:To 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 Methods:Nineteen histopathologically confirmed breast carcinomas (mean size ϭ 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.Results: A significant decrease in the measured ADC was noted after contrast administration (Ϫ23%, P ϭ 0.01). Lesions with relatively high ADC before contrast (Ͼ1.3 ϫ 10 Ϫ3 mm 2 /sec; n ϭ 12) demonstrated a larger degree of ADC reduction (mean 34%) than lesions with low ADC (Յ1.3 ϫ 10 Ϫ3 mm 2 /sec; n ϭ 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 (␥ ϭ Ϫ0.57, P ϭ 0.02). Conclusion:Postcontrast 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.

Diffusion-Weighted MR Imaging of Benign and Malignant Breast Lesions Before and After Contrast Enhancement

“…However, in benign lesions this decrease was not significant. Yuen et al also found a decrease of the ADC value after CM application in 19 breast carcinomas [19]. In contrast to our study, Yuen et al did not have benign lesions as a control group.…”

“…The mechanism of the effect of CM on the ADC value is not yet understood. Yuen et al supposed a decrease of microperfusion due to CM which leads to a drop of the ADC value in regions with a high content of microvessels like in malignant breast tumors [19]. In our study we used b50 as the lowest b-value in order to reduce the effect of macroperfusion on the ADC value.…”

Response

“…This may be indirectly supported by the fact that lesions with hypervascularity tended to demonstrate low ADC values after contrast (2). Suppression of the microperfusion effect should also affect T2 signal intensity, which did not change significantly in our study, probably due to using a relatively short TR.…”

Comment on ADC reductions in postcontrast breast tumors

“…It was with interest that we read the article by Yuen et al (1) who reported measurable decreases in the apparent diffusion coefficient (ADC) of breast tumors following Gd contrast agent administration. The reduction was largest (34%) in lesions deemed to have particularly high vascularity.…”

“…Additional experimentation is required before definitive conclusions regarding the mechanisms for observed ADC reductions following Gd contrast in high uptake lesions is warranted. Both T2* measurements and the use of more sophisticated diffusion sensitization schemes (4,7) would be valuable assets in furthering our understanding of the clinically relevant phenomena observed by Yuen et al (1).…”