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. 2009 Dec;93(3):618-24.
doi: 10.1016/j.radonc.2009.08.012. Epub 2009 Sep 9.

DCEMRI of Spontaneous Canine Tumors During Fractionated Radiotherapy: A Pharmacokinetic Analysis

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DCEMRI of Spontaneous Canine Tumors During Fractionated Radiotherapy: A Pharmacokinetic Analysis

Ste Søvik et al. Radiother Oncol. .

Abstract

Purpose: To estimate pharmacokinetic parameters from dynamic contrast-enhanced magnetic resonance (DCEMR) images of spontaneous canine tumors taken during the course of fractionated radiotherapy, and to quantify treatment-induced changes in these parameters.

Materials and methods: Six dogs with tumors in the oral or nasal cavity received fractionated conformal radiotherapy with 54 Gy given in 18 fractions. T(1)-weighted DCEMR imaging was performed prior to each treatment fraction. Time-intensity curves in the tumor were extracted voxel-by-voxel, and were fitted to the Brix pharmacokinetic model. The dependence of the pharmacokinetic parameters on the accumulated radiation dose was calculated.

Results: The Brix model reproduced the time-intensity curves well. A reduction in the k(ep) parameter with accumulated radiation dose was found for five (three significant) out of six cases, while the results for the A parameter were less consistent. Both pre-treatment k(ep) and the change in k(ep) with accumulated dose correlated significantly with tumor regression.

Conclusions: Pharmacokinetic parameters derived from DCEMR images taken during fractionated radiotherapy may predict response to radiotherapy. This may potentially impact on patient stratification and monitoring of treatment response for image-guided treatment strategies.

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