A combined procedure for 99mTc aerosol ventilation and perfusion imaging

Area of Science:

• Nuclear Medicine
• Radiology
• Pulmonary Imaging

Background:

• Radioaerosols are established for regional lung ventilation imaging in pulmonary embolism diagnosis.
• Current methods advocate ventilation scans follow perfusion scans with a 3:1 aerosol-to-perfusion dose ratio.

Purpose of the Study:

• To develop an alternative radioaerosol imaging approach for pulmonary embolism diagnosis.
• To optimize imaging by controlling aerosol deposition and activity ratios.

Main Methods:

• A reversed imaging sequence: aerosol ventilation scan followed by perfusion scan.
• Tailoring perfusion scan activity to the patient's retained aerosol dose.
• Utilizing the differential clearance rates of 99mTc-DTPA aerosol and 99mTc-sulphur-colloid.

Main Results:

• Achieved a 10:1 microsphere-to-aerosol activity ratio, effectively masking ventilation with perfusion.
• Enabled use of high-resolution collimators due to faster 99mTc-DTPA aerosol clearance.
• A 1-hour delay in perfusion scans did not necessitate increased perfusion activity.

Conclusions:

• The modified radioaerosol imaging technique provides superior masking of ventilation by perfusion.
• This method enhances diagnostic accuracy for pulmonary embolism through improved image quality.
• The approach offers flexibility and improved efficiency in pulmonary imaging procedures.