Free-Breathing Three-Dimensional Computed Tomography of the Lung Using Prospective Respiratory Gating: Charge-Coupled Device Camera and Laser Sensor Device in an Animal Experiment

Purpose:The aim was to investigate the feasibility and image quality of prospective respiratory gating for 3-D computed tomography (CT) of the lung. Material and Methods:Eight anesthetized pigs underwent prospectively gated multidetector computed tomography using 2 devices: a charge-coupled device (CCD) camera and a laser sensor. The output signal of both gating devices was connected to the scanner instead of ECG unit. Inspiratory and expiratory images were obtained during “free-breathing” and analyzed in MPR mode for sharpness of bronchi, diaphragm and lung using a 4-point-score (1, excellent to 4, severe artifacts). Results:The CCD camera worked in all animals. Using the laser sensor, only 50% of expiratory scans could be acquired. All acquired images showed excellent sharpness (CCD camera vs. laser sensor) for trachea (1.1 ± 0.3 vs. 1.3 ± 0.5), bronchi (1.4 ± 0.7 vs. 1.8 ± 0.6), lung fissures (1.0 vs. 1.1 ± 0.3), and lung parenchyma (1.0 ± 0.2 vs. 1.4 ± 0.6), and minor to major artifacts for diaphragm (1.5 ± 0.8 vs. 2.0 ± 1.0, P < 0.05) and pericardial lung structures (1.9 ± 0.7 vs. 2.3 ± 0.5). Conclusion:High image quality for inspiratory and expiratory scans was achieved by free-breathing 3-D CT of the lung using noncontact prospective respiratory gating.