Quantification of [^99mTc]Tc-HDP bone SPECT/CT: can we improve the body weight based standardized uptake value with a...

Area of Science:

• Nuclear Medicine
• Radiology
• Medical Imaging

Background:

• Quantitative SPECT/CT enables objective assessment of tracer accumulation.
• Standardized uptake values (SUV) have limited use in orthopedic and oncologic imaging.
• Improved normalization could enhance the objective assessment of lesions using quantitative SPECT/CT.

Purpose of the Study:

• To develop and evaluate a more reliable normalization method for quantitative [99mTc]-HDP bone SPECT/CT.
• To assess the correlation between tracer uptake and clinical parameters (body weight, height, age, bone density).
• To calculate a correction formula to improve the objectivity of quantitative SPECT/CT measurements.

Main Methods:

• Retrospective analysis of quantitative [99mTc]-HDP bone SPECT/CT scans of the lumbar spine.
• Measurement of bone activity (kBq/cc) and bone density (HU) in the femur and lumbar vertebrae.
• Multiple regression analysis to assess correlations between tracer uptake and clinical parameters; calculation of a correction formula.

Main Results:

• Body weight showed the strongest correlation with measured activity in L1 (r=-0.64, p<0.001), followed by age and height.
• A weak positive correlation was found between tracer accumulation and bone density (r=0.35, p<0.001).
• The developed correction formula, based on weight, age, and bone density, resulted in more robust uptake values with non-significant associations to these clinical variables, although interindividual variability remained.

Conclusions:

• Normalization based on age, bone density, and weight significantly reduced interindividual variability in quantitative SPECT/CT uptake compared to body weight-adjusted SUV.
• A generalized normalization remains challenging due to significant patient-specific effects not accounted for by the measured clinical variables.
• This improved normalization enhances the potential for objective lesion assessment in quantitative bone SPECT/CT.