Traditional Posters: Body Imaging

Josephine Helen Naish^1,2, Geoff J M Parker<sup>1,2

1</sup>Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, University of Manchester, Manchester, United Kingdom; ²Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom

We present a two-compartment model of pulmonary oxygen-enhanced MRI (OE-MRI) based on known gas exchange processes in the lung. The model relates the rate of change of oxygen partial pressure to physiological parameters describing ventilation, perfusion and blood oxygen solubility and allows quantitative V/Q maps to be extracted from OE-MRI data.

2517. Fast, High Resolution T1-Mapping of the Human Lung Using an Inversion Recovery Radial Golden Angle Acquisition.

Simon Triphan¹, Philipp Ehses², Martin Blaimer¹, Jakob Kreutner², Felix Breuer¹, Peter Jakob, <sup>12

1</sup>Research Center Magnetic Resonance Bavaria e.V., Würzburg, Bayern, Germany; ²Experimentelle Physik 5, Universität Würzburg, Würzburg, Bayern, Germany

The quantification of T1 in the human lung at 1.5T using an Inversion Recovery Snapshot FLASH experiment was improved by employing an asymmetric radial readout scheme: By measuring k-space with golden angle radial projections with maximal echo asymmetry, echo times could be significantly reduced yielding improved signal from lung tissue. The acquisition scheme was combined with a KWIC-filter technique to reconstruct images at subsequent points in time along signal recovery, thereby achieving a higher temporal resolution compared to a cartesian measurement. The improved SNR and higher temporal resolution was used to calculate T1 maps at an increased spatial resolution.

2518. Feasibility Study of in Situ Lung MRE in a Porcine Model: Correlation of Shear Stiffness and Transpulmonary Pressures

Yogesh K. Mariappan¹, Arunark Kolipaka¹, Richard L. Ehman¹, Kiaran P. McGee<sup>1

1</sup>Department of Radiology, Mayo Clinic, Rochester, MN, United States

Previous lung magnetic resonance elastography (MRE) animal experiments have indicated that it is feasible to quantitate the shear modulus of lungs with ¹H MRI with the driver in direct contact with the lungs. Here, we tested the applicability of this technique in an in situ porcine model with a noninvasive mechanical driver placed on the chest wall. Further, the feasibility of this technique to measure the change in stiffness of the lung parenchyma as a function of transpulmonary pressure was also evaluated. It was found that lung stiffness can be quantified with this setup and that shear stiffness increases with increasing transpulmonary pressure.

2519. MRE of in Vivo Human Lung Parenchyma: Feasibility Study of Motion Encoding Using the Imaging Gradients with ¹H MRI

Yogesh K. Mariappan¹, Kevin J. Glaser¹, Armando Manduca¹, Richard L. Ehman¹, Kiaran P. McGee<sup>1

1</sup>Department of Radiology, Mayo Clinic, Rochester, MN, United States

Application of Magnetic Resonance Elastography within the lung is challenging because of the inherently low ¹H MR signal. The additional motion-sensitizing gradients inserted into the conventional MR sequence necessary for MRE results in longer echo times, further degrading the signal from lung parenchyma. We hypothesized that with appropriate manipulations, the crusher gradients of a spin echo sequence can be used for motion detection, while maintaining a short echo time. We tested this hypothesis in healthy human volunteers and found that it is feasible to detect motion within the lungs with the imaging gradients while maintaining sufficient lung tissue signal.

2520. A Novel Method Using Proton MRI and Image Registration to Investigate Relative Regional Pulmonary Compliance