Small pulmonary nodules: volume measurement at chest CT--phantom study

Area of Science:

• Radiology and Imaging Science
• Medical Physics

Background:

• Accurate pulmonary nodule volume quantification is crucial for diagnosis and treatment monitoring.
• Existing methods for volume measurement at computed tomography (CT) require evaluation for precision and reliability.

Purpose of the Study:

• To assess three-dimensional (3D) methods for quantifying pulmonary nodule volume using CT.
• To investigate the impact of imaging variables on the accuracy of pulmonary nodule volume measurement.

Main Methods:

• A realistic phantom with 40 plastic nodules (<5 mm) of known volume was used.
• Two fixed-threshold methods, including a partial-volume method (PVM) and a variable method, were employed.
• Variables studied included tube current (20 and 120 mAs), reconstruction algorithms (high/low frequency), and nodule characteristics (solid/ground-glass).

Main Results:

• Higher precision in volume quantification was achieved using a PVM with predetermined pure nodule attenuation.
• Optimal results were obtained with a high-frequency reconstruction algorithm and a diagnostic CT technique (120 mAs).
• The PVM demonstrated improved accuracy compared to the variable method under specific conditions.

Conclusions:

• The partial-volume method (PVM) is a promising technique for precise pulmonary nodule volume quantification.
• Optimizing CT imaging parameters and employing specific PVM settings enhances measurement accuracy.
• PVM shows potential for reliable nodule volume assessment in clinical follow-up scenarios.