Towards standardization of absolute SPECT/CT quantification: a multi-center and multi-vendor phantom study

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiopharmaceutical Therapy

Background:

• Accurate quantification of radiotracer distribution using SPECT/CT is vital for personalized radionuclide therapy.
• Quantitative accuracy is influenced by various factors including imaging systems, patient size, and software.
• Evaluating inter-system variability is essential for reliable dosimetry.

Purpose of the Study:

• To assess the quantitative accuracy and inter-system variability of SPECT/CT systems.
• To investigate the impact of patient size, processing software, and reconstruction algorithms on recovery coefficients (RC).
• To establish a foundation for standardized absolute quantitative SPECT imaging.

Main Methods:

• Utilized five SPECT/CT systems from multiple vendors in a multi-center phantom study.
• Employed NEMA IEC body phantoms simulating different body mass indexes (BMI) and filled with 99mTc-pertechnetate.
• Determined recovery coefficients (RC) for various sphere sizes and background activity, analyzing inter-system variability (MAD).
• Compared vendor-specific and vendor-neutral reconstruction algorithms.

Main Results:

• Recovery coefficients decreased with smaller sphere diameters across all systems.
• Initial inter-system variability for RCmean and RCmax was 16% and 17%, respectively.
• Standardized reconstruction reduced variability to 4% (RCmean) and 5% (RCmax).
• Higher BMI negatively impacts quantification of smaller lesions (<10 mL).

Conclusions:

• Absolute SPECT quantification is achievable in multi-center, multi-vendor settings.
• Standardization of reconstruction protocols is key to reducing variability and improving accuracy.
• This study supports the development of a standard for absolute quantitative SPECT imaging.