Ultrashort Echo Time Magnetic Resonance Imaging of the Lung Using a High-Relaxivity T Blood-Pool Contrast Agent

The lung remains one of the most challenging organs to image using magnetic resonance imaging (MRI) due to intrinsic rapid signal decay. However, unlike conventional modalities such as computed tomography, MRI does not involve radiation and can provide functional and morphologic information on a regional basis. Here we demonstrate proof of concept for a new MRI approach to achieve substantial gains in a signal to noise ratio (SNR) in the lung parenchyma: contrast-enhanced ultrashort echo time (UTE) imaging following intravenous injection of a high-relaxivity blood-pool manganese porphyrin T 1 contrast agent. The new contrast agent increased relative enhancement of the lung parenchyma by over 10-fold compared to gadolinium diethylene triamine pentaacetic acid (Gd-DTPA), and the use of UTE boosted the SNR by a factor of 4 over conventional T 1 -weighted gradient echo acquisitions. The new agent also maintains steady enhancement over at least 60 minutes, thus providing a long time window for obtaining high-resolution, high-quality images and the ability to measure a number of physiologic parameters.