Hyperpolarized ¹²⁹Xenon MRI Ventilation Defect Quantification via Thresholding and Linear Binning in Multiple...

Area of Science:

• Pulmonary Medicine
• Medical Imaging
• Quantitative MRI

Background:

• Standardized quantification of ventilation defect percentage (VDP) from hyperpolarized (HP) gas MRI is lacking for multi-site pediatric and adult pulmonary disease trials.
• Current HP gas MRI research often focuses on single diseases with disease-specific VDP quantification methods.

Purpose of the Study:

• To evaluate and compare different VDP quantification methods from HP ¹²⁹Xe MRI.
• To identify the most sensitive and specific methods for VDP assessment across various pulmonary diseases.

Main Methods:

• HP ¹²⁹Xe MRI was performed on 176 subjects (pediatric and adult) with conditions including CF, LAM, asthma, sJIA, ILD, and BMT recipients, plus healthy controls.
• Five VDP quantification schemes were compared: linear binning and thresholding (≤60%, ≤75%) with different bias-field corrections (linear, N4ITK).

Main Results:

• All methods identified defects similarly, with lower VDPs in controls than most patient groups (p<0.05).
• N4ITK bias-field corrected 60% thresholding showed the highest efficacy in distinguishing combined disease from controls (VDP cut-point 2.3%).
• Linear binning better identified subtle low-ventilation regions in milder conditions like asthma compared to thresholding methods.

Conclusions:

• No single VDP quantification method is universally superior across all pulmonary diseases.
• N4ITK 60% thresholding excels at differentiating disease from health, while linear binning captures subtle ventilation changes.
• A consensus on VDP quantification is needed for future multi-center clinical trials, considering the nuanced advantages of each method.