Delay and dispersion correction for simultaneous quantification of perfusion and permeability in the prostate using DCE-MRI with a dual-contrast sequence

摘要

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 Tl-weighted images for extravasation measurement and T2*-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>cm3) vs. 0.23 ml/(min>cm3), P=0.001), blood volume approximately two times higher, 1.9 % vs. 0.7 %; and mean transit time in tumors approximately half that of normal prostate tissue, 2.88±2.30 s vs. 4.88±3.21 s.A inversion-prepared dual-contrast sequence acquiring Tl-and T2*-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.