Ultra-high field 1H magnetic resonance imaging approaches for acute hypoxia. (October 2013)

• Record Type: Journal Article
• Authors: Nielsen, Thomas; Nielsen, Niels Chr.; Holm, Thomas H.; Østergaard, Leif; Horsman, Michael R.; Busk, Morten
• Is Part Of: Acta oncologica. Volume 52:Number 7(2013)
• Page Start: 1287
• Page End: 1292
• Publication Date: 2013-10
• Subjects: Oncology -- Periodicals; Cancer -- Treatment -- Periodicals; 616.992
• DOI: 10.3109/0284186X.2013.824608
• Languages: English
• ISSNs: 0284-186X

Abstract

<abstract> <title>Abstract</title> <p> <italic>Background.</italic> Currently, radiation treatments are being optimised based on in vivo imaging of radioresistant, hypoxic tumour areas. This study aimed at detecting nicotinamide's reduction of acute hypoxia in a mouse tumour model by two clinically relevant magnetic resonance imaging (MRI) methods at ultra-high magnetic field strength. <italic>Material and methods.</italic> The C3H mammary carcinoma was grown to 200 mm<sup>3</sup> in the right rear foot of CDF<sub>1</sub> mice. The mice were anaesthetised with ketamine and xylazine prior to imaging. A treatment group received nicotinamide intraperitoneally (i.p.) at the dose 1000 mg/kg, and a control group received saline. MRI was performed at 16.4 T with a spatial resolution of 0.156 × 0.156 × 0.5 mm<sup>3</sup>. The imaging protocol included BOLD imaging and two DCE-MRI scans. Initial area under the curve (IAUC) and the parameters from the extended Toft's model were estimated from the DCE-MRI data. Tumour median values of 1) T<sub>2</sub>* mean, 2) T<sub>2</sub>* standard deviation, 3) DCE-MRI parameters, and 4) DCE-MRI parameter differences between scans were compared between the treatment groups using Student's t-test (significance level p < 0.05). <italic>Results.</italic> Parametric maps showed intra- and inter-tumour heterogeneity. Blood volume was significantly larger in the nicotinamide-treated group, and also the blood volume difference between the two DCE-MRI scans was significantly larger in the treatment group. <italic>Conclusion.</italic> Higher blood volume and blood volume variation was observed by DCE-MRI in the treatment group. Other DCE-MRI parameters showed no significant differences, and the higher blood volume was not detected by BOLD MRI. The higher blood volume variation seen with DCE-MRI may be influenced by the drug effect reducing over time, and furthermore the anaesthesia may play an important role.</p> </abstract>