TABLE 1

Retention of 123I-2-Iodo-d-Phenylalanine Activity in Tumors, as Determined by Planar γ-Scintigraphy (n = 3)

Time (h)Tumor contrast (mean ± SD %)*Tumor retention (mean ± SD %)†
2-I-l-Phe2-I-d-Phe2-I-l-Phe2-I-d-Phe
1100 ± 0100 ± 0100.0 ± 0.0100.0 ± 0.0
6.5100 ± 2120 ± 2267.8 ± 2.552.6 ± 10.7
1675 ± 19314 ± 3623.2 ± 5.615.5 ± 1.6
1971 ± 17352 ± 3123.1 ± 7.96.7 ± 2.1
2195 ± 25213 ± 3421.1 ± 8.55.0 ± 1.7
2491 ± 16251 ± 3617.1 ± 6.35.0 ± 2.0
3186 ± 16197 ± 1011.6 ± 3.94.0 ± 1.1

  • ↵* Percent contrast enhancement in comparison with initial 123I-2-iodo-l-phenylalanine (2-I-l-Phe) or 123I-2-iodo-d-phenylalanine (2-I-d-Phe) tumor contrast.

  • ↵† Percentage of initial 123I-2-iodo-l-phenylalanine or 123I-2-iodo-d-phenylalanine uptake that remained in tumors.