Volume-monitored chest CT: a simplified method for obtaining motion-free images near full inspiratory and end expiratory lung volumes.

BACKGROUND: Lung inflation and respiratory motion during chest CT affect diagnostic accuracy and reproducibility. OBJECTIVE: To describe a simple volume-monitored (VM) method for performing reproducible, motion-free full inspiratory and end expiratory chest CT examinations in children. MATERIALS AND METHODS: Fifty-two children with cystic fibrosis (mean age 8.8 ± 2.2 years) underwent pulmonary function tests and inspiratory and expiratory VM-CT scans (1.25-mm slices, 80-120 kVp, 16-40 mAs) according to an IRB-approved protocol. The VM-CT technique utilizes instruction from a respiratory therapist, a portable spirometer and real-time documentation of lung volume on a computer. CT image quality was evaluated for achievement of targeted lung-volume levels and for respiratory motion. RESULTS: Children achieved 95% of vital capacity during full inspiratory imaging. For end expiratory scans, 92% were at or below the child's end expiratory level. Two expiratory exams were judged to be at suboptimal volumes. Two inspiratory (4%) and three expiratory (6%) exams showed respiratory motion. Overall, 94% of scans were performed at optimal volumes without respiratory motion. CONCLUSION: The VM-CT technique is a simple, feasible method in children as young as 4 years to achieve reproducible high-quality full inspiratory and end expiratory lung CT images.