Imaging Aerosol Deposition with Two-Dimensional Gamma Scintigraphy

Area of Science:

• Pharmacokinetics and Pharmacodynamics
• Medical Imaging
• Inhalation Therapy

Background:

• Quantifying lung dose and aerosol distribution in vivo is crucial for inhaled therapies.
• Two-dimensional (2D) gamma scintigraphy is a widely used imaging modality for this purpose.
• Standardized methods are needed to ensure data comparability across studies.

Purpose of the Study:

• To provide detailed guidelines for acquiring and analyzing 2D gamma scintigraphy images.
• To standardize methods for quantifying lung dose and aerosol distribution from inhaled formulations.
• To facilitate multi-center studies and accelerate the development of inhaled medications and devices.

Main Methods:

• Admix drug formulation with ^99mtechnetium as a radiolabel surrogate.
• Perform quality control on gamma cameras and confirm formulation integrity.
• Acquire lung transmission images for attenuation correction.
• Instruct subjects on inhalation technique and record breathing parameters.
• Acquire anterior/posterior lung views and other regions of interest.
• Analyze images for total and regional lung dose, including outer/inner deposition ratio (O/I) and penetration index (PI).

Main Results:

• Standardized methods enable accurate quantification of total and regional lung dose.
• Calculation of outer/inner deposition ratio (O/I) and penetration index (PI) provides regional dose information.
• Mass balance assessment can be performed as needed.
• Consistent methodology allows for data comparison and combination across different laboratories.

Conclusions:

• Adherence to standardized 2D gamma scintigraphy methods ensures reliable and comparable data.
• This standardization supports multi-center studies, leading to more efficient drug and device development.
• The described methods enhance the precision of lung dose and aerosol distribution assessment for inhaled therapies.