Comparison of ¹⁸F-fluoride PET/CT, ¹⁸F-FDG PET/CT and bone scintigraphy (planar and SPECT) in detection of bone metastases of differentiated thyroid cancer: a pilot study

We compared the efficacies of ¹⁸F-fluoride positron emission tomography (¹⁸F-fluoride PET)/CT, ¹⁸F-fludeoxyglucose PET (¹⁸F-FDG PET)/CT, and ⁹⁹mTc bone scintigraphy [planar and single photon emission CT (SPECT)] for the detection of bone metastases in patients with differentiated thyroid carcinoma (DTC).We examined 11 patients (8 females and 3 males; mean age 6 standard deviation, 61.968.7 years) with DTC who had been suspected of having bone metastases after total thyroidectomy and were hospitalized to be given ¹³¹I therapy. Bone metastases were verified either when positive findings were obtained on both ¹³¹I scintigraphy and CT or when MRI findings were positive if MRI was performed.Metastases were confirmed in 24 (13.6%) of 176 bone segments in 9 (81.8%) of the 11 patients. The sensitivities of ¹⁸F-fluoride PET/CT and ⁹⁹mTc bone scintigraphy (SPECT) were significantly higher than those of ¹⁸F-FDG PET/CT and ⁹⁹mTc bone scintigraphy (planar) (p,0.05). The accuracies of ¹⁸F-fluoride PET/CT and mTc bone scintigraphy (SPECT) were significantly higher than that of ⁹⁹mTc bone scintigraphy (planar) (p,0.05).The sensitivity and accuracy of ¹⁸F-fluoride PET/CT for the detection of bone metastases of DTC are significantly higher than those of ⁹⁹mTc bone scintigraphy (planar). However, the sensitivity and accuracy of ⁹⁹mTc bone scintigraphy (planar) are improved near to those of ¹⁸F-fluoride PET/CT when SPECT is added to a planar scan. The sensitivity of ¹⁸F-FDG PET/CT is significantly lower than that of 18F-fluoride PET/CT or ⁹⁹mTc bone scintigraphy (SPECT).