Combined 18F-Fluoride and 18F-FDG PET/CT Scanning for Evaluation of Malignancy: Results of an International Multicenter Trial

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FIGURE 1.
A 74-y-old man with metastatic prostate cancer. (A–C) Extensive pelvic osseous metastases (arrows) are not identified on ¹⁸F-FDG PET scan (A) but are clearly seen on ¹⁸F⁻ (B) and combined PET (C) scans. (D) CT demonstrates sclerotic changes.
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FIGURE 2.
A 45-y-old woman with metastatic breast cancer. Extensive soft-tissue metastases (arrowheads) are seen on ¹⁸F-FDG (A) and combined PET (C) scans. A single bone metastasis (arrow) is visualized on all 3 scans.
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FIGURE 3.
Skull lesions (arrows) are identified in 2 participants on CT (A) and ¹⁸F⁻ PET (B) scans but not on combined ¹⁸F⁻ scans (C).
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FIGURE 4.
A 53-y-old woman with soft-tissue sarcoma. Lung nodule (arrowheads) is seen on CT (A) and ¹⁸F-FDG PET (B) scans but is not easily identifiable on combined ¹⁸F⁻/¹⁸F-FDG scans (C).

TABLE 1

Clinical Data of Patient Population Included in This Study

Characteristic	Male	Female
N	63	52
Mean age ± SD (y)	60.2 ± 15.4	55.7 ± 13.6
Stage
I	2	1
II	21	20
III	21	5
IV	19	26
Initial treatment strategy	10	9
Subsequent treatment strategy	53	43
Primary tumor
Prostate	41	0
Breast	0	39
Sarcoma	13	9
Lung	2	1
Bladder	2	0
Colon/rectum	2	0
Cervix	0	1
Kidney	1	1
Non-Hodgkin lymphoma	1	0
Larynx	0	1
Paraganglioma	1	0

TABLE 2

Clinical Data of Participants for Whom ¹⁸F⁻ PET/CT and Combined ¹⁸F⁻/¹⁸F-FDG PET/CT Resulted in More Lesions Detected Than Did ¹⁸F-FDG PET/CT

Characteristic	¹⁸F⁻/¹⁸F-PET/CT showed more lesions than ¹⁸F⁻ PET/CT	¹⁸F⁻/¹⁸F-PET/CT showed lesions; ¹⁸F-FDG PET/CT was negative
Male	9	21
Female	10	8
Initial treatment strategy	4	4
Subsequent treatment strategy	15	25
Stage
I	0	1
II	1	10
III	4	12
IV	14	6
Primary tumor
Prostate	5	18
Breast	8	5
Sarcoma	4	1
Colon	1	0
Lung	1	0
Bladder	0	1
Kidney	0	2
Larynx	0	1
Cervix	0	1
Prior treatment
Surgery	1	4
Chemotherapy	1	1
Radiotherapy	0	4
Surgery/chemotherapy	4	4
Surgery/radiotherapy	0	5
Chemotherapy/radiotherapy	4	5
Surgery/chemotherapy/radiotherapy	5	2
None	4	4

TABLE 3

Limitations and Issues Identified in this Trial, as Well as Potential Solutions to Investigate Them

Issue	Potential solution
Ratio of ¹⁸F⁻ and ¹⁸F-FDG dosages	Conduct dose modeling or phantom studies to determine optimal ratio of ¹⁸F⁻ to ¹⁸F-FDG for combined scan
Sensitivity and specificity of ¹⁸F⁻/¹⁸F-FDG PET/CT	Conduct prospective trials with pathology or follow-up evaluation of detected lesions
Quantitation of radiotracer uptake	Conduct experiments to determine influence of ¹⁸F⁻ uptake on ¹⁸F-FDG maximum standardized uptake value and vice versa
Interpretation of follow-up studies	Conduct prospective studies to evaluate feasibility or usefulness of ¹⁸F⁻/¹⁸F-FDG PET/CT in posttherapy setting
¹⁸F⁻ nonspecific uptake	Analyze CT data to increase specificity

TABLE 4

Cost Estimates for Separate ^99mTc-MDP Bone Scan and ¹⁸F-FDG PET/CT vs. Combined ¹⁸F⁻/¹⁸F-FDG PET/CT Scan

^99mTc-MDP bone scan	¹⁸F-FDG PET/CT	¹⁸F⁻/¹⁸F-FDG PET/CT
Technical reimbursement: $275	Technical reimbursement: $1,421	Technical reimbursement: $1,421
Professional reimbursement: $48	Professional reimbursement: $140	Professional reimbursement: $140
^99mTc-MDP: $100	¹⁸F-FDG: $250	¹⁸F-FDG: $250
Total: $423	Total: $1,811	¹⁸F⁻: $150
Total: $2,234		Total: $1,961