An alternative method for radioactivity measurement in quantitative bone SPECT/CT imaging

Area of Science:

• Nuclear Medicine
• Radiology
• Oncology

Background:

• Bone scintigraphy with combined single-photon emission computed tomography (SPECT) and computed tomography (CT) is crucial for detecting bone metastases.
• Calculating semi-quantitative standardized uptake values (SUV) typically requires precise pre- and post-injection radiopharmaceutical radioactivity measurements.

Purpose of the Study:

• To evaluate the feasibility of using fixed radiopharmaceutical radioactivity values as an alternative to measured values in quantitative SPECT/CT bone imaging.
• To compare different methods of quantifying Tc-99m hydroxymethylene diphosphonate input radioactivity for SUV analysis.

Main Methods:

• Four methods were compared: fully measured, pre-injection measured/post-injection fixed, pre-injection fixed/post-injection measured, and fully fixed radioactivity measurements.
• Semi-quantitative parameters (SUVpeak and SUVmean) were calculated and compared across all analytical methods using bone SPECT analysis software.

Main Results:

• Significant differences in SUVpeak and SUVmean were observed between certain measured and fixed radioactivity quantification methods (A vs. B, A vs. D, C vs. D).
• However, a subgroup analysis of patients with median post-injection radioactivity <1.5 MBq revealed no significant differences between any analytical methods.

Conclusions:

• Fixed radiopharmaceutical radioactivity measurement can serve as a practical alternative in quantitative bone SPECT/CT, particularly when direct measurement is challenging or missed.
• This simplified approach may streamline SUV calculations without compromising diagnostic accuracy in specific patient subgroups.