RESUMO
PURPOSE: To present a technique for non-contrast-enhanced in vivo imaging of the blood volume fraction of the human lung. The technique is based on the intravoxel incoherent motion (IVIM) approach. However, a substantial novelty is introduced here: the need for external diffusion sensitizing gradients is eliminated by exploiting the internal magnetic field gradients typical of the lung tissue, due to magnetic susceptibility differences at air/tissue interfaces. MATERIALS AND METHODS: A single shot turbo spin-echo sequence with stimulated-echo preparation and electrocardiograph synchronization was used for acquisition. Two images were acquired in a single breath-hold of 10 seconds duration: one reference image and one blood-suppressed image. The blood volume fraction was quantified using a two-compartment signal decay model, as given by the IVIM theory. Experiments were performed at 1.5T in eight healthy volunteers. RESULTS: Values of the blood volume fraction obtained within the lung parenchyma (36 ± 16%) are in good agreement with previous reports, obtained using contrast-enhanced magnetic resonance angiography (33%), and show relatively good reproducibility. CONCLUSION: The presented technique offers a robust way to quantify the blood volume fraction of the human lung parenchyma without using contrast agents. Image acquisition can be accomplished in a single breath-hold and could be suitable for clinical applications on patients with lung diseases. J. Magn. Reson. Imaging 2015;41:1454-1464. © 2014 Wiley Periodicals, Inc.
