Simultaneous Quantification of Perfusion and Permeability in the Prostate Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging with an Inversion-Prepared Dual-Contrast Sequence

Abstract

The aim of the present study was to quantify both perfusion and extravasation in the prostate to discriminate tumor from healthy tissue, which might be achieved by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a nonspecific low-molecular-weight contrast medium (CM). To determine extravasation as well as tissue perfusion an inversion-prepared dual-contrast sequence employing a parallel acquisition technique (PAT) was designed for interleaved acquisition of T(1)-weighted images for extravasation measurement and T(2)*-weighted images for determination of the highly concentrated bolus with a sufficiently high temporal and spatial resolution at an acceptable signal-to-noise ratio. Thirteen patients with proven prostate cancer were examined with the sequence using a combined body-array prostate coil. Before pharmacokinetic evaluation the images were intensity-corrected and, if required, motion-corrected. The pharmacokinetic model used to calculate perfusion, permeability, blood volume, interstitial volume, transit time, and vessel size index included two compartments and a correction of delay and dispersion of the arterial input function. The information provided by the dual-contrast sequence allowed application of a more elaborate model for evaluation and enabled quantification of all parameters. Peripheral prostate tumors were found to differ from peripheral healthy prostate tissue in perfusion (1.38 mL/(min cm(3)) vs. 0.23 mL/(min cm(3)), p=0.004), mean transit time (2.88 vs. 4.88 s, p=0.039), and blood volume (1.9 vs. 0.7%, p=0.019). A inversion-prepared dual-contrast sequence acquiring T(1)- and T*(2)-weighted images with sufficient temporal resolution and signal-to-noise ratio was successfully applied in patients with prostate cancer to quantify all pharmacokinetic parameters of inflow and extravasation of a low-molecular-weight inert tracer.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging in the Evaluation of the Prostate

“…Ludemann et al 26 developed an inversion-prepared dual-contrast RF-spoiled gradient echo technique to quantify perfusion and permeability in the prostate simultaneously.…”

“…25 Elaborate models exist for correction of the AIF for tracer delay and bolus dispersion, and inversion-prepared dual-contrast sequences have been developed for simultaneous assessment of perfusion and permeability in the prostate. 26 A common compartment model used in prostate DCE is a 2-compartment model of the EES and vascular space, with the inflow kinetic constant K trans , the outflow kinetic constant k ep , and the input AIF. The complexity of compartmental modeling is variable, and models that may include more than 2 compartments exist.…”

Dynamic contrast-enhanced magnetic resonance imaging and pharmacokinetic models in prostate cancer

“…Here, the extraction coefficient is a function of permeability, vessel surface area, and blood flow [33,45]. Assuming that blood vessels are cylindrical, the vessel surface can be calculated from the blood volume and the radius; permeability and blood flow can thus be calculated as independent parameters [47]. A diagram of how pharmacokinetic parameters are calculated from SI measured with DCE-MRI and using a sequential 3-compartment model is presented in Fig.…”

“…Therefore, an open sequential 3-compartment model has been proposed and used for the prostate and prostate cancer. This model comprises blood plasma as one compartment and two EES compartments [25,47]. Using this model, quantification of blood flow in a tissue voxel is based on the so-called indicator dilution method and the calculated AIF [48].…”

On Post-Acquisition Motion Compensation for Prostate Perfusion Analysis

“…For example, L udemann et al [5] used normalized mutual information and Breeuwer et al [6] relied on cross correlation (CC) to achive motion compensation in perfusion image series. However, these statistical measures still expect a globally consistent material-intensity mapping but the intensity change due to perfusion happens locally, and because of the cancer perfusion may happen at different rates in different areas of the prostate the statistics may not model the intensitytissue relation properly.…”