Limitations of dynamic contrast-enhanced MRI in monitoring radiation-induced changes in the fraction of radiobiologically hypoxic cells in human melanoma xenografts

Autor: Ilana C. Benjaminsen, Berit Mathiesen, Einar K. Rofstad, Elin A. Melås
Rok vydání: 2008
Předmět:
Zdroj: Journal of magnetic resonance imaging : JMRI. 28(5)
ISSN: 1053-1807
Popis: Purpose To investigate the potential of gadopentetate dimeglumine (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in detecting radiation-induced changes in the fraction of radiobiologically hypoxic cells in A-07 human melanoma xenografts. Materials and Methods A-07 tumors were randomly assigned to an unirradiated control group or a group given a single radiation dose of 20 Gy. DCE-MRI and measurement of fraction of hypoxic cells were performed immediately before and 24 h after the radiation exposure. Tumor images of E · F (E is the initial extraction fraction of Gd-DTPA and F is blood perfusion) and λ (λ is proportional to extracellular volume fraction) were produced by subjecting DCE-MRI series to Kety analysis. Fraction of hypoxic cells was measured by using a radiobiological assay based on the paired survival curve method. Results Fraction of radiobiologically hypoxic cells was higher in irradiated tumors (26.2 ± 5.8%) than in unirradiated tumors (7.5 ± 2.7%) by a factor of 3.5 ± 1.5 (P = 0.0093), whereas only minor radiation-induced changes in E · F and λ could be detected. Conclusion DCE-MRI does not seem to offer insight into the changes in fraction of radiobiologically hypoxic cells occurring in A-07 tumors within 24 h after irradiation with 20 Gy. J. Magn. Reson. Imaging 2008;28:1209–1218. © 2008 Wiley-Liss, Inc.
Databáze: OpenAIRE