Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using 68Ga-labeled...

Area of Science:

• Medical Imaging
• Pulmonary Function Testing
• Radiology

Background:

• CT ventilation imaging utilizes deformable image registration for functional lung assessment.
• Positron emission tomography with (68)Ga-labeled nanoparticles (PET-Galligas) offers a complementary functional imaging approach.
• Validation of CT ventilation against PET-Galligas is crucial for its clinical adoption.

Purpose of the Study:

• To validate CT ventilation imaging against PET-Galligas in lung cancer patients.
• To quantify the agreement between different CT ventilation metrics and PET reconstruction parameters.
• To assess the impact of image quality and filtering on CT ventilation accuracy.

Main Methods:

• PET-Galligas scans were acquired in 12 lung cancer patients.
• CT ventilation images were generated using B-spline deformable image registration.
• Four ventilation metrics (VHU, VJac, ρVHU, ρVJac) were tested, along with varying PET image quality and median filtering (σm = 0 or 3 mm).

Main Results:

• The density-scaled HU metric (ρVHU) with standard PET images and σm = 3 mm filtering showed the best agreement (r = 0.42 ± 0.16, d20 = 0.52 ± 0.09).
• HU-based metrics demonstrated statistically significant improvements over Jacobian-based metrics (p < 0.05).
• Density scaling and improved PET image quality (standard vs. gated, median filtering) significantly enhanced correlation (p < 0.02).

Conclusions:

• Modified CT ventilation metrics, PET-Galligas, and image filtering improve correlation compared to previous nuclear medicine ventilation studies.
• CT ventilation and PET-Galligas provide complementary functional information, with agreement enhanced by tissue density scaling and PET image quality.
• CT ventilation imaging shows significant potential for regional lung air volume change assessment, warranting further development.