Validation of the Semiautomatic Quantification of ¹⁸F-Fluoride PET/CT Whole-Body Skeletal Tumor Burden

Abstract

Our purpose was to validate a semiautomatic quantification of the skeletal tumor burden on ¹⁸F-fluoride PET/CT using manual quantification as a reference. <b>Methods:</b> We quantified 51 ¹⁸F-fluoride PET/CT examinations performed on female breast cancer patients. Clinical information (age; time of disease presentation; presence of visceral metastases; and time to death, progression, or a bone event) was recorded. The total volume of ¹⁸F-fluoride-avid skeletal metastases and the total activity of ¹⁸F-fluoride-avid metastases were calculated manually and semiautomatically. <b>Results:</b> Manual and semiautomatic metrics correlated strongly (<i>P</i> < 0.0001; 95% confidence interval, 0.9300-0.9769). On multivariable analysis, the semiautomatic measures of total activity for ¹⁸F-fluoride-avid metastasis correlated significantly with overall survival (<i>P</i> = 0.0001) and progression-free survival (<i>P</i> = 0.0006). Approximate times for calculating skeletal tumor burden (semiautomatic vs. manual) were, respectively, 30 s versus 321 s in patients with fewer than 5 metastases, 120 s versus 640 s in patients with 5-10 metastases, and 240 s versus 1207s in patients with more than 10 metastases. <b>Conclusion:</b> Semiautomatic quantification of whole-body ¹⁸F-fluoride PET/CT skeletal tumor burden can replace manual quantification in breast cancer patients and is a strong independent biomarker of prognosis.