Frame Rate Exposimetry for Pulmonary Capillary Hemorrhage During Lung Ultrasound

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Pulmonary Diagnostics

Background:

• Lung ultrasound (LUS) is a valuable diagnostic tool for pulmonary conditions.
• Pulmonary capillary hemorrhage (PCH) is a potential safety concern associated with LUS.
• Understanding the relationship between LUS parameters and PCH is essential for safe clinical application.

Purpose of the Study:

• To evaluate the dependence of pulmonary capillary hemorrhage (PCH) on image frames-per-second (fps) during lung ultrasound (LUS).
• To assess the impact of on-screen Mechanical Index (MI_OS) and Thermal Index (TI) on PCH.
• To determine safe ultrasound parameters for LUS to minimize PCH risk.

Main Methods:

• Anesthetized rats were scanned using a Philips iE33 machine with an L15-7io probe.
• B-mode ultrasound was applied at 9 MHz with varying fps (34, 61, 118).
• Pulmonary capillary hemorrhage (PCH) areas were assessed post-exposure, and in situ Mechanical Index (MI_IS) was measured.

Main Results:

• Pulmonary capillary hemorrhage (PCH) area decreased as frames-per-second (fps) increased (19.5 mm² at 34 fps to 7.5 mm² at 118 fps).
• Increasing fps led to lower on-screen Thermal Index (TI) values.
• No significant PCH was observed at an MI_OS setting of 0.5, corresponding to MI_IS values of 0.35-0.39.

Conclusions:

• Higher frame rates (fps) in lung ultrasound (LUS) are associated with reduced pulmonary capillary hemorrhage (PCH).
• Slower scan speeds (lower fps) may increase PCH due to prolonged exposure to higher amplitude pulses.
• Specific MI_OS and TI settings can be indicative of PCH risk, guiding safer ultrasound practices.