Prospective respiratory gated XXXX nanotube micro computed tomography.

@entity19 @entity5161 @entity505
RATIONALE AND OBJECTIVES: Challenges remain in the imaging of the lungs of free-breathing @entity19 . Although computed tomographic (CT) imaging is near optimal from a contrast perspective, the rapid respiration rate, limited temporal resolution, and inflexible x-ray pulse control of most micro-CT scanners limit their utility in pulmonary imaging. @entity505 nanotubes (CNTs) have permitted the development of field emission cathodes, with rapid switching and precise pulse control. The goal of this study was to explore the utility of a CNT-based micro-CT system for application in quantitative pulmonary imaging. MATERIALS AND METHODS: Twelve CB57/B6 @entity19 were imaged during peak inspiration and end-exhalation using the CNT micro-CT system. The respiratory trace was derived from a sensor placed underneath the abdomen of the animal. Animals were allowed to breathe freely during the imaging under @entity5161 anesthesia. Images were reconstructed using isotropic voxels of 77- m resolution (50 kVp, 400 projections, 30-ms x-ray pulse). Lung volumes were measured with region-growing techniques and thresholds derived from the surrounding air and soft tissues. Basic functional parameters, including tidal volume, functional reserve capacity and minute volume, were also calculated. RESULTS: The average scan time was 13.4    1.8 minutes for each phase of the respiratory cycle. Mean lung volumes at peak inspiration and end-expiration were 0.23    0.026 and 0.11    0.024 mL, respectively. The average minute volume was 11.93    2.64 mL/min. CONCLUSIONS: The results of this study demonstrate the utility of a CNT-based micro-CT system in acquiring prospectively gated images from free-breathing @entity19 for obtaining physiologic data. This technique provides an alternative to breath-hold techniques requiring intubation and offers greater dose efficiency than retrospective gating techniques.
