Bonnie N. Joe MD, PhD, Presenter: Nothing to Disclose

Kyongtae Tyler Bae, Abstract Co-Author: Nothing to Disclose

Victoria Chen BS, Abstract Co-Author: Nothing to Disclose

Pornpim Fuangtharntip MD, Abstract Co-Author: Nothing to Disclose

Jie Zheng PhD, Abstract Co-Author: Nothing to Disclose

Charles Floyd Hildebolt DDS, PhD, Abstract Co-Author: Nothing to Disclose

Premsri T. Barton MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Our earlier work demonstrated a significant (p<.001) increase in enhancement rate of breast cancers as a function of faster injection rate. Given the potential implications for lesion characterization, this study determines the effect of contrast injection rate on contrast washout in breast cancer.

Women (n=27, mean age 50 yrs) with breast cancers  1-cm underwent dynamic breast MR imaging at 1.5T using gadolinium (20 cc) injected at 2cc/s one day and 0.5cc/s another day. Images encompassing tumors and right ventricles/aortas were acquired every second for 180sec after contrast injection and then intermittently for approximately 10min. Signal-intensity time curves were generated for tumors and right ventricles/aortas. Delayed (washout) slopes were calculated for tumor and blood signal intensity-time curves. Differences were tested with paired t tests (alpha=0.05). Delayed enhancement was assessed qualitatively as progressively rising, plateau, or washout.

Analysis of blood signal intensity-time curves demonstrated that the faster injection rate yielded faster mean down slopes (washout) of –0.445 sec-1 for the 2cc/s and –0.196 sec-1 for the 0.5cc/s injection rates (p <0.05, n=27). Breast cancer signal intensity-time curves also demonstrated a trend toward more rapid washout using the faster injection rate with mean down slopes of –0.231 sec-1 for the 2cc/s and –0.162 sec-1 for 0.5cc/s injection rates although the difference did not reach statistical significance (p = 0.198, n=24). No delayed washout was measured in 3 patients whose tumors demonstrated progressive enhancement only. In 8 of 24 patients, the delayed enhancement pattern changed between washout and plateau on qualitative assessment of the signal intensity-time curves for 2cc/s vs. 0.5cc/s injection rates.

Faster contrast injection rate results in faster washout of blood enhancement. Faster blood washout does not directly translate to faster tumor washout, but the delayed phase of tumor enhancement can vary with changes in contrast injection rate. It is critical, therefore, to incorporate injection rate into pharmacokinetic analysis of breast cancer.

Joe, B, Bae, K, Chen, V, Fuangtharntip, P, Zheng, J, Hildebolt, C, Barton, P, et al, , Dynamic Breast MRI: Effect of Contrast Injection Rate on Delayed Phase of Enhancement in Breast Cancer.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4408648.html