Rationale and objectives: The study of vascular targeted cancer therapies is critically dependent on the development of noninvasive methods for assessing changes in vascular permeability and blood flow in small-animal tumor models.
Materials and methods: A multicoil apparatus consisting of two receive-only surface coils for observation of the rat brain and chest, a whole-body transmit-only volume coil, and the switching circuitry necessary for sharing a single receiver channel between the two surface coils was constructed for the parallel observation of left ventricular arterial input function and magnetic resonance imaging (MRI) signal intensity kinetics in the rat brain. Dynamic contrast-enhanced MRI was performed on four Fischer rats bearing intracranial 9L gliomas, and the dynamic data were evaluated using the bolus-enhanced relaxation overview (BOLERO) model yielding maps of K(trans), v(e), and tau(i) values from the tumor.
Results: The use of the multicoil apparatus resulted in images with high signal-to-noise ratios from the rat brain and chest in parallel, with no detectable crosstalk between the surface coils. The BOLERO method accurately fit the observed data to within experimental error. Mean values of the parameters generated by the BOLERO analysis for the tumor were K(trans) = 0.023 +/- 0.014 s(-1), tau(i) = 1.3 +/- 0.6 seconds, and v(e) = 0.51. K(trans) and tau(i) values were slightly elevated in the tumor periphery, whereas v(e) was elevated in the tumor core.
Conclusion: These results demonstrate the feasibility of measuring quantitative dynamic contrast-enhanced MRI parameters in a rat brain tumor model using a multicoil apparatus. These methods might play an important role in determining the efficacy of antiangiogenic therapies in small-animal models.