Functional Thoracic MRI: Recent Advances in Pulmonary Assessment

Functional thoracic MRI provides regional assessment of the three principal components of lung function: ventilation, perfusion, and gas exchange. It offers advantages over pulmonary function tests like spirometry, which yield only global measurements. MRI enables comprehensive evaluation of respiratory mechanics, including chest wall and diaphragm motion, dynamic large airway instability, and lung ventilation using various contrast mechanisms and gas agents. Perfusion imaging, with or without exogenous contrast material, further supports the assessment of mechanical lung properties in both healthy and diseased states. Advanced MRI techniques also allow for quantification of distal airspace dimensions and gas exchange or diffusion capacity using inert noble gases, at both global and regional levels. Dynamic contrast-enhanced perfusion MRI enables assessment of key pathophysiologic mechanisms, such as hypoxic pulmonary vasoconstriction, and provides direct visualization of ventilation-perfusion mismatch across various lung diseases. Emerging noninvasive, non-contrast-enhanced techniques, including combined ventilation-perfusion imaging based on signal oscillations from blood flow and respiration, hold substantial promise for clinical translation. This review provides an overview of recent advances in functional thoracic MRI for evaluating regional lung function and pathophysiology.