Free-breathing Pulmonary MR Imaging to Quantify Regional Ventilation

Area of Science:

• Pulmonary imaging
• Respiratory medicine
• Medical physics

Background:

• Assessing regional lung ventilation is crucial for diagnosing and managing respiratory diseases.
• Hyperpolarized helium 3 (³He) MRI is a gold standard but requires specialized equipment and gas.
• Hydrogen 1 (¹H) MRI offers a potential alternative without exogenous contrast agents.

Purpose of the Study:

• To measure regional specific ventilation using free-breathing ¹H MR imaging.
• To evaluate correlations between ¹H MRI, hyperpolarized ³He MRI, and pulmonary function tests.
• To assess ventilation differences in healthy volunteers versus asthma patients.

Main Methods:

• Subjects underwent free-breathing ¹H MR imaging and static breath-hold hyperpolarized ³He MR imaging.
• Pulmonary function tests including spirometry and plethysmography were performed.
• ¹H and ³He MR imaging datasets were coregistered to quantify regional specific ventilation.

Main Results:

• Free-breathing ¹H MRI demonstrated significantly lower specific ventilation in asthma patients compared to healthy volunteers.
• ¹H MRI-derived specific ventilation showed strong correlations with plethysmography, ³He MRI ventilation percentage, FEV₁, FVC, RV/TLC, and airway resistance.
• In asthma patients, ¹H MRI revealed diminished specific ventilation in regions with defects identified by ³He MRI.

Conclusions:

• Free-breathing ¹H MR imaging is a viable method for assessing regional lung ventilation.
• ¹H MRI findings correlate well with established pulmonary function tests and hyperpolarized ³He MRI.
• This technique shows promise for evaluating ventilation abnormalities in asthma.