Optimizing imaging protocols for overweight and obese patients: a lutetium orthosilicate PET/CT study

Area of Science:

• Nuclear medicine
• Medical imaging
• Radiochemistry

Background:

• Obese patients present challenges in PET imaging due to increased photon attenuation and scatter.
• Optimizing acquisition protocols is crucial for maintaining image quality and diagnostic accuracy in this population.

Purpose of the Study:

• To determine the optimal acquisition time per bed position for lutetium orthosilicate (LSO) PET/CT in patients weighing over 91 kg.
• To evaluate the impact of varying scan durations on lesion detection and image quality.

Main Methods:

• Twenty-five obese patients underwent LSO PET/CT after 18F-FDG injection.
• Scans were acquired for 7 minutes per bed position, with data reconstructed in 1-minute intervals (1-7 minutes).
• Three reviewers assessed lesion detection and image quality using a region-of-interest approach.

Main Results:

• Interobserver concordance for lesion detection improved with scan duration, peaking at 78% for 4-minute scans.
• Image noise decreased significantly as scan time increased, from 21% at 1 minute to 11% at 7 minutes.
• Lesion detection rates improved substantially, with only 3% of lesions missed on 4-minute scans compared to 24% on 1-minute scans. Five-minute scans detected all reference lesions.

Conclusions:

• A 5-minute acquisition time per bed position is sufficient for optimal hypermetabolic lesion detection in obese patients using LSO PET/CT.
• Extending scan duration beyond 5 minutes per bed position does not yield further diagnostic benefits.
• Optimized protocols can enhance diagnostic accuracy in challenging patient populations.