Vincent Vandecaveye MD, Presenter: Nothing to Disclose

Frederik De Keyzer MS, Abstract Co-Author: Nothing to Disclose

Willy Landuyt PhD, Abstract Co-Author: Nothing to Disclose

Hilde Bosmans PhD, Abstract Co-Author: Nothing to Disclose

Xihe Sun MD, Abstract Co-Author: Nothing to Disclose

Feng Chen MD, Abstract Co-Author: Nothing to Disclose

Yicheng Ni, Abstract Co-Author: Nothing to Disclose

Robert Hermans MD, PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To evaluate the potential predictive value of early vascular changes on contrast-enhanced Doppler ultrasound (CDU) in a rodent tumor model after administration of a vascular targeting agent towards treatment-induced necrosis measured by diffusion-weighted magnetic resonance imaging (DW-MRI).

Rhabdomyosarcomas implanted on both flanks (n=10) of WAG/RIJ rats were examined by CDU and DW-MRI. Following baseline imaging of the tumors, a dose of 25 mg/kg of Combretastatin A-4-phosphate (CA-4-P) was administered intraperitoneally. Early follow-up at three hours was done by CDU. At three days another CDU was performed for evaluation of tumor perfusion as well as a DW-MRI for evaluation of tumor necrosis. For CDU a clinical ultrasound system was used. Standard slices were obtained in the transversal plane during and after the injection of a microbubble contrast agent. The MR scans were performed on a clinical 1.5T MR unit. For the DW-MRI, an echoplanar sequence with a large range of b-values was used; the ADC was calculated specifically from the high b-values only (b>500sec/mm2) for differentiation between necrotic and viable tissue.

Six tumors showed complete loss of perfusion 3 hours after CA-4-P administration and did not show increase of flow at three days. In these tumors necrotic tumor area increased strongly on the DW-MRI scan, leaving only a thin viable rim. Limited persistent flow in the feeding artery and the intratumoral vessels was seen in 3 tumors at 3 hours post treatment; these showed strong peripheral (re)perfusion after 3 days. A thick viable peripheral rim was visible on the DW-MRI images with only limited enlargement of the central necrotic area. Despite a substantial loss of peripheral perfusion at 3 hours post treatment, one tumor did show moderate peripheral (re)perfusion without substantial increase in necrosis three days later.

The vascular changes after CA-4-P administration assessed by CDU show a strong association with the amount of treatment-induced necrosis, measured by DW-MRI, in 9 of 10 tumors. The early CDU measurement may therefore be used as a predictive parameter for therapy outcome in this tumor model.

Vandecaveye , V, De Keyzer, F, Landuyt, W, Bosmans, H, Sun, X, Chen, F, Ni, Y, Hermans, R, et al, , Predictive Value of Early Perfusion Changes on Contrast-enhanced Doppler Ultrasound for Vascular Targeting-induced Necrosis on Diffusion MRI: Study in a Rat Tumor Model.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4413868.html