Ventilation-perfusion (V/Q) scan is an established technique used to monitor lung dysfunction in conditions such as pulmonary embolism.1 However, there are safety concerns regarding its use in several important populations e.g. pregnant women and children. Recent advances have transformed the use of standard clinical MRI equipment in functional lung imaging.2 We recently presented a clinically appropriate dynamic oxygen-enhanced MRI (dOE-MRI) protocol.3 In this work, we interpret dOE-MRI data with a novel physiological model of gas exchange4 that maps the regional distribution of lung ventilation and perfusion, simulating results from a standard V/Q scan.
3D dOE-MRI data were acquired using a 1.5 T Philips scanner as in:3 a 5 min baseline T1 acquisition, followed by a 15 min dynamic acquisition, during which the subject breathed 100% O2 for the middle 5 min. Total scan time is under 30 min throughout which the subject breathes normally. The partial pressure of oxygen in the alveolar compartment was derived as proposed in5 and maps of regional alveolar ventilation and perfusion were produced using a novel two-compartmental model of gas exchange based on.4
Figure 1 shows an example of whole-chest ventilation and perfusion maps from a healthy subject overlaid on a single volume of the acquired MRI (left column). The same maps are displayed as anterior/posterior and right/left anterior oblique projections (right column), equivalent to those achieved with V/Q scintigraphy.1
Estimation of alveolar ventilation and perfusion distribution from 3D dynamic OE-MRI is feasible and can be obtained under clinically acceptable conditions using standard radiological equipment without ionising radiation risks. This approach opens the possibility for regional assessment of lung physiology using a single short scanning session.
References 1 Bajc, et al. Eur J Nucl Med Mol Imaging 2009;36(8):1356–70
2 Wild, et al. Insights Imaging 2012;3(4):345–53
3 Ulloa, et al. Proc Intl Soc Mag Reson Med. 2015;23:3973
4 Naish, et al. Proc Intl Soc Mag Reson Med. 2010;18:2516
5 Kershaw, et al. MRM 2010;64:1838–42