A multislice single breath-hold scheme for imaging alveolar oxygen tension in humans

Reliable, noninvasive, and high-resolution imaging of alveolar partial pressure of oxygen (pAO2) is a potentially valuable tool in the early diagnosis of pulmonary diseases. Several techniques have been proposed for regional measurement of pAO2 based on the increased depolarization rate of hyperpolarized 3He. In this study, we explore one such technique by applying a multislice pAO2-imaging scheme that uses interleaved-slice ordering to utilize interslice time-delays more efficiently. This approach addresses the low spatial resolution and long breath-hold requirements of earlier techniques, allowing pAO2 measurements to be made over the entire human lung in 1015 s with a typical resolution of 8.3 X 8.3 X 15.6 mm3. PO2 measurements in a glass syringe phantom were in agreement with independent gas analysis within 4.7 +/- 4.1% (R = 0.9993). The technique is demonstrated in four human subjects (healthy nonsmoker, healthy former smoker, healthy smoker, and patient with COPD), each imaged six times on 3 different days during a 2-week span. Two independent measurements were performed in each session, consisting of 12 coronal slices. The overall pAO2 mean across all subjects was 95.9 +/- 12.2 Torr and correlated well with end-tidal O2 (R = 0.805, P < 0.0001). The alveolar O2 uptake rate was consistent with the expected range of 12 Torr/s. Repeatable visual features were observed in pAO2 maps over different days, as were characteristic differences among the subjects and gravity-dependent effects. Magn Reson Med, 2012. (c) 2011 Wiley Periodicals, Inc.