Imaging patients with breast and prostate cancers using combined ¹⁸F NaF/¹⁸F FDG and TOF simultaneous PET/ MRI

Objectives We previously reported the evaluation of a simultaneous PET/MRI scanner with TOF capability, as well as the use of combined ¹⁸F NaF/¹⁸F FDG PET/CT in cancer patients. Here we compared the combined ¹⁸F NaF/¹⁸F FDG PET/ MRI against ^99mTc-MDP in patients with breast and prostate cancers.

Methods 9 patients referred for ^99mTc-MDP bone scans were prospectively enrolled from Oct-Dec 2014. The cohort included 6 men with prostate cancer and 3 women with breast cancer, 41 - 85 year-old (average 64 ± 15). ¹⁸F NaF (0.7-2.2 mCi, mean: 1.33 mCi) and ¹⁸F FDG (3.9-5.2 mCi, mean: 4.6 mCi) were subsequently injected from separate syringes. The PET/MRI was done 6-12 days (average 9.3 ± 3.2) after bone scan. The whole body MRI protocol consisted of T2-weighted, SSFSE, DWI, and contrast-enhanced T1-weighted imaging. Lesions detected with each test were tabulated and the results were compared.

Results All patients tolerated the PET/MRI exam, and PET image quality was diagnostic despite the marked reduction in the administered dosage of radiopharmaceuticals (80% less for ¹⁸F NaF and 67% less for ¹⁸F FDG). Two patients had no bone metastases identified on either scans. Bone scintigraphy and PET/MRI showed osseous metastases in 7 patients, but more numerous bone findings were noted on PET/MRI than on bone scintigraphy in 3 patients. Lesions outside the skeleton were identified by PET/MRI in 2 patients.

Conclusions The combined ¹⁸F NaF/¹⁸F FDG PET/MRI is superior to ^99mTc-MDP scintigraphy for evaluation of skeletal disease extent. Further, it detected extra-skeletal disease that may change the management of these patients, while allowing a significant reduction in radiation exposure from lower dosages of PET radiopharmaceuticals administered. A combination of ¹⁸F NaF/¹⁸F FDG PET/MRI may provide the most accurate staging of patients with breast and prostate cancers prior to the start of treatment.

Research Support GE Healthcare