3′-18F-Fluoro-3′-Deoxy-l-Thymidine: A New Tracer for Staging Metastatic Melanoma?

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FIGURE 1.
¹⁸F-FLT PET of 34-y-old man (patient 6) 2 mo after resection of primary melanoma on back. Metastases (large arrows) are observed in left and right axillae and left supraclavicular area. Physiologic uptake (small arrows) is observed in liver and 1 marrow—for example, in pelvis, vertebrae, ribs, and bony structures of shoulder; less intense, uniform tracer uptake is present in lungs. Uptake of tracer in brain is negligible, and no uptake is observed in mediastinum and myocardium.

TABLE 1

Patient Characteristics

Patient no.	Age (y)	Sex	Clark level	Breslow thickness (mm)	Locoregional disease
1	48	F	*	*	Groin
2	39	F	IV	1.8	Groin
3	42	M	IV	4.1	Axilla
4	73	M	IV	4.4	Groin
5	78	M	IV	1	Groin
6	34	M	^†	6	Axillae
7	40	M	IV	1.35	Axilla
8	29	M	*	*	Groin
9	40	F	III	0.7	Axilla
10	54	M	^†	>4	Groin

TABLE 3

False-Negative, False-Positive, and Additional FLT PET Findings

Location	No. of lesions	PA	Result	Diagnostics
Deep groin	1	Pos	FN	Aspiration cytology
Dermal or subcutaneous metastases on back	9	Pos	FN	Histopathology
Back (primary tumor)	1	Pos	FN	Histopathology
Deep groin	1	Neg	FP	Histopathology
Leg (heel)	1	Neg	FP	Reresection in 1998 negative and clinically negative, follow-up of 5 y
Mediastinal	3	NP	FN	CT
Thoracic vertebra	1	NP	FN	CT
Lumbar vertebra	1	NP	NA	Bone scan with multiple bone metastases (also spinal) 2.5 mo after PET
Fossa poplitea	1	NP	NA	Clinically negative, follow-up of 4 mo
Mediastinal	1	NP	TN	CT
Paraaortal	1	NP	TN	CT
Head and neck	2	NP	TN	Clinically negative, follow-up of 3 mo
Mediastinal	2	NP	TP	CT
Paraaortal	2	NP	TP	CT
Supraclavicular	1	NP	TP	Physical examination

PA = pathologic examination.
Pos = positive; FN = false-negative; Neg = negative; FP = false-positive; NP = not performed; NA = not assessable; TN = true-negative; TP = true-positive.

TABLE 4

Staging

Patient no.	Clinical staging					PET staging					Pathologic staging
Patient no.		T	N	Stage	N	M	Stage	T	N*	M	Stage
1	^†	+	III	+	0	III	^†	p2b	0	IIIB
2	2a	+	III	+	1	IV	2a	p3	1c	IV
3	4b	+	III	+	0	III	4b	p3	0	IIIC
4	4b	+	III	+	1	IV	4b	p3	1c	IV
5	1a	+	III	+	0	III	1a	p3	0	IIIC
6	4b	+	III	+	0	III	4b	p3	0	IIIC
7	2a	+	III	+	0	III	2a	p1b	0	IIIB
8	^†	+	III	+	0	III	^†	p3	0	IIIC
9	1a	+	III	+	0	III	1a	p1b	0	IIIB
10	4b	+	III	+	0	III	4b	p3	0	IIIC