Simon M. F. Triphan, Bertram J. Jobst, Angela Anjorin, Oliver Sedlaczek, Ursula Wolf, Maxim Terekhov, Christian Hoffmann, Sebastian Ley, Christoph Düber, Jürgen Biederer, Hans-Ulrich Kauczor, Peter M. Jakob, Mark O. Wielpütz

• T\(_1\) maps have been shown to yield useful diagnostic information on lung function in patients with chronic obstructive pulmonary disease (COPD) and asthma, both for native T\(_1\) and ΔT\(_1\), the relative reduction while breathing pure oxygen. As parameter quantification is particularly interesting for longitudinal studies, the purpose of this work was both to examine the reproducibility of lung T\(_1\) mapping and to compare T\(_1\) found in COPD and asthma patients using IRSnapShotFLASH embedded in a full MRI protocol. 12 asthma and 12T\(_1\) maps have been shown to yield useful diagnostic information on lung function in patients with chronic obstructive pulmonary disease (COPD) and asthma, both for native T\(_1\) and ΔT\(_1\), the relative reduction while breathing pure oxygen. As parameter quantification is particularly interesting for longitudinal studies, the purpose of this work was both to examine the reproducibility of lung T\(_1\) mapping and to compare T\(_1\) found in COPD and asthma patients using IRSnapShotFLASH embedded in a full MRI protocol. 12 asthma and 12 COPD patients (site 1) and further 15 COPD patients (site 2) were examined on two consecutive days. In each patient, T\(_1\) maps were acquired in 8 single breath-hold slices, breathing first room air, then pure oxygen. Maps were partitioned into 12 regions each to calculate average values. In asthma patients, the average T\(_{1,RA}\) = 1206ms (room air) was reduced to T\(_{1,O2}\) = 1141ms under oxygen conditions (ΔT\(_1\) = 5.3%, p < 5⋅10\(^{−4})\), while in COPD patients both native T\(_{1,RA}\) = 1125ms was significantly shorter (p < 10\(^{−3})\) and the relative reduction to T\(_{1,O2}\) = 1081ms on average ΔT\(_1\) = 4.2%(p < 10\(^{−5}\)). On the second day, with T\(_{1,RA}\) = 1186ms in asthma and T\(_{1,RA}\) = 1097ms in COPD, observed values were slightly shorter on average in all patient groups. ΔT\(_1\) reduction was the least repeatable parameter and varied from day to day by up to 23% in individual asthma and 30% in COPD patients. While for both patient groups T\(_1\) was below the values reported for healthy subjects, the T\(_1\) and ΔT\(_1\) found in asthmatics lies between that of the COPD group and reported values for healthy subjects, suggesting a higher blood volume fraction and better ventilation. However, it could be demonstrated that lung T\(_1\) quantification is subject to notable inter-examination variability, which here can be attributed both to remaining contrast agent from the previous day and the increased dependency of lung T\(_1\) on perfusion and thus current lung state.…