Oxygen enhanced lung MRI by simultaneous measurement of <i>T</i>₁ and <i>T</i>₂* during free breathing using ultrashort TE

<jats:sec><jats:title>Purpose</jats:title><jats:p>To provide a robust method for the simultaneous quantification of <jats:italic>T</jats:italic><jats:sub>1</jats:sub> and <jats:italic>T</jats:italic><jats:sub>2</jats:sub>* in the human lung during free breathing. Breathing pure oxygen accelerates <jats:italic>T</jats:italic><jats:sub>1</jats:sub> and <jats:italic>T</jats:italic><jats:sub>2</jats:sub>* relaxation in the lung. While <jats:italic>T</jats:italic><jats:sub>1</jats:sub> shortening reflects an increased amount of dissolved molecular oxygen in lung tissue, <jats:italic>T</jats:italic><jats:sub>2</jats:sub>* shortening shows an increased concentration of oxygen in the alveolar gas. Therefore, both parameters reflect different aspects of the oxygen uptake and provide complementary lung functional information.</jats:p></jats:sec><jats:sec><jats:title>Materials and Methods</jats:title><jats:p>A segmented inversion recovery Look–Locker multiecho sequence based on a multiecho 2D ultrashort TE (UTE) was employed for simultaneous <jats:italic>T</jats:italic><jats:sub>1</jats:sub> and <jats:italic>T</jats:italic><jats:sub>2</jats:sub>* quantification. The radial projections follow a modified golden angle ordering, allowing for respiratory self‐gating and thus the reconstruction of a series of differently <jats:italic>T</jats:italic><jats:sub>1</jats:sub> and <jats:italic>T</jats:italic><jats:sub>2</jats:sub>*‐weighted images in arbitrary breathing states. The method was evaluated in nine healthy volunteers while breathing room air and pure oxygen, with two volunteers examined at five oxygen concentrations.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Relative differences of Δ<jats:italic>T</jats:italic><jats:sub>1</jats:sub> between 7.9% and 12.7% and of Δ<jats:italic>T</jats:italic><jats:sub>2</jats:sub>* between 13.2% and 6.0% were found.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>The proposed method provides inherently coregistered, quantitative <jats:italic>T</jats:italic><jats:sub>1</jats:sub> and <jats:italic>T</jats:italic><jats:sub>2</jats:sub>* maps in both expiration and inspiration from a single measurement acquired during free breathing and is thus well suited for clinical application.<jats:bold>J. Magn. Reson. Imaging 2015;41:1708–1714.</jats:bold> © <jats:bold>2014 Wiley Periodicals, Inc.</jats:bold></jats:p></jats:sec>