There are a number of T1- and T2-based dynamic contrast-enhanced magnetic resonance imaging pharmacokinetic modeling approaches to study cancer microvasculature. Alternatively, model-free approaches offer an easy, quantitative assessment of microcirculation. In this work, we investigate a 6-parameter model-free approach applied to a T2*-weighted echo-planar imaging bolus response curve. We tested this new approach on a small cohort of patients with clinically diagnosed primary rectal carcinoma before adjuvant chemoradiotherapy and surgical excision. Comparison with healthy muscle tissue shows that logistic parameters P 1/P 2, P 4, and P 5 offer good discrimination between tumor and healthy tissue. Bolus response logistic parameters P 4 and P 5 have been implicated in previous T1-based works as being important in the assessment of cancer malignancy. Further comparison of T2* parameters with signal attenuation amplitude (maximum signal drop) and percentage baseline signal loss also corroborates the models’ ability to quantify the microenvironment.
From the *Medical Physics & Applied Radiation Sciences, McMaster University; †Brain-Body Institute, St. Joseph’s Healthcare; ‡Department of Oncology, Medicine, McMaster University; §Department of Diagnostic Imaging, St. Joseph’s Healthcare; and ∥Electrical & Computer Engineering and¶School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada.
Received for publication March 11, 2011; accepted May 11, 2011.
Reprints: Michael D. Noseworthy, PhD, PEng, The Brain-Body Institute, Imaging Research Centre, St Joseph’s Healthcare, 50 Charlton Ave, East Hamilton, Ontario, Canada L8N 4A6 (e-mail: email@example.com).
Dr Wardlaw is currently with the Consumer & Clinical Radiation Protection Bureau, 775 Brookfield Rd, PL 6301 A. Ottawa, Ontario, Canada K1A 1C1.
Funding for this study was provided by the Natural Sciences and Engineering Research Council of Canada (M.D.N.).
The authors have no conflict of interest and source of funding to declare.