Pulmonary function tests (PFT) are routinely used to assess lung function but they do not provide information about regional pulmonary dysfunction. We aimed to assess correlation of quantitative ventilation/perfusion (V/Q) PET/CT with PFT indices.

METHODS: 30 patients underwent V/Q PET/CT and PFT. Respiratory-gated images were acquired following inhalation of (68)Gallium-carbon nanoparticles and administration of (68)Gallium-macroaggregated albumin. Functional volumes were calculated by dividing the volume of normal ventilated and perfused (%NVQ), unmatched and matched defects from the total lung volume. These functional volumes were correlated with forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, and diffusing capacity for carbon monoxide (DLCO).

RESULTS: All functional volumes were significantly different in patients with chronic obstructive pulmonary disease (COPD) (p<0.05). FEV1/FVC and %NVQ had the highest correlation (r=0.82). FEV1 was also best correlated with %NVQ (r=0.64). DLCO was best correlated with the volume of unmatched defects (r=-0.55). Considering %NVQ only, a cut-off value of 90% correctly categorized 28/30 patients with or without significant pulmonary function impairment.

CONCLUSION: Our study demonstrates strong correlations between V/Q PET/CT functional volumes and PFT parameters. Since V/Q PET/CT is able to assess regional lung function, these data support the feasibility of its use in radiation therapy, preoperative planning and assessing pulmonary dysfunction in a variety of respiratory diseases.