Three-dimensional Multifunctional Lung Imaging With Simultaneous Acquisition of Three-dimensional Perfusion-weighted and Ventilation-weighted Maps

To propose simultaneous acquisition of free-breathing, noncontrast-enhanced 3D perfusion-weighted (QW) and ventilation-weighted (VW) maps using 3D ultrashort echo-time (UTE) magnetic resonance imaging (MRI).

This prospective study included 1 healthy volunteer (25 years; female) and 5 patients (65 ± 10 y; 1 female) with diffuse pulmonary diseases [2 chronic obstructive pulmonary disease (COPD), 2 interstitial lung disease (ILD), 1 asthma], conducted between January 2022 and March 2024. Three-dimensional QW and VW maps were obtained through retrospective cardiac and respiratory gating using 3D UTE MRI on a 3T clinical scanner (Magnetom Prisma; Siemens Healthineers). QW maps were generated by voxel-wise subtraction between maximum and minimum values of 8 cardiac phase-resolved images at end-expiration, and VW maps by subtraction between end-inspiration and end-expiration images. Validation of QW maps involved: (1) assessment of coefficient of variation (CV) across 12 lung segments compared with SPECT, (2) structural similarity index measure (SSIM) analysis compared with SPECT, and (3) evaluation of anteroposterior gravity-dependence by 1D coronal slice profiles. Repeatability was tested in one healthy subject with multiple scans on separate days. In patients, regional perfusion was assessed in lesions identified on CT, and V/Q match or mismatch was evaluated in asthma and emphysema-predominant COPD. Statistical analysis included SSIM and Mann-Whitney U tests ( P < 0.05).

UTE MRI-based QW and VW maps showed high similarity with corresponding SPECT maps [SSIM: 0.86 (QW), 0.87 (VW); P >0.05 for CV across 12 lung segments]. Both maps demonstrated gravity-dependence with high correlation to SPECT (correlation coefficient: QW = 0.91, VW = 0.96). QW maps show reduced perfusion in emphysema regions and increased perfusion in regions with consolidation, ground-glass opacity (GGO), and inflammation around fibrotic cysts. Comparing asthma and emphysema-predominant COPD, QW and VW maps demonstrated V/Q mismatch in asthma but matched defects in COPD.

Simultaneous noncontrast-enhanced 3D UTE MRI effectively provides reliable regional perfusion and ventilation information for pulmonary disease evaluation without exposure to ionizing radiation. By providing perfusion and ventilation information simultaneously, the proposed method can help to provide precise and comprehensive functional assessment of pulmonary diseases, including differentiation of pathophysiological conditions and improved evaluation of disease severity and prognosis.