TABLE 1

Features, Advantages, and Disadvantages of Isotopes and Radiopharmaceuticals

RadiopharmaceuticalEmissions and energyPhysical half-lifeAdvantages (Pro) or Disadvantages (Con)
99mTc-AnxA5 (general)γ, 140.5 keV6.02 hPro: 99mTc can be obtained easily at low cost by use of 99Mo/99mTc generators; excellent imaging properties
Con: difficult radiochemistry for technetium; biodistribution influenced by conjugation method
99mTc-Imino-anxA5γ, 140.5 keV6.02 hPro: labeling can be performed easily
Con: RCP ≈ 80%; high uptake of radiopharmaceutical in liver, kidneys, and spleen; long biologic half-life
99mTc-BTAP-anxA5γ, 140.5 keV6.02 hPro: RCP > 93%; short biologic half-life
Con: labeling method very laborious; high radioactivity uptake in liver, kidneys, spleen, and abdomen; low radiochemical yield
99mTc-HYNIC-anxA5γ, 140.5 keV6.02 hPro: labeling method well established; prefabricated kit, so labeling can be performed easily
Con: high uptake of radiopharmaceutical in kidneys and liver; long biologic half-life
99mTc-EC-anxA5γ, 140.5 keV6.02 hPro: prefabricated kit, so labeling can be performed easily
Con: to establish this method, more research is required
94mTc-AnxA5 (general)β+, 2.5 MeV53 minPro: easiest way to transform SPECT into PET; when HYNIC-anxA5 is used, labeling can be performed easily
Con: difficult radiochemistry for technetium; biodistribution influenced by conjugation method; expensive and difficult to obtain
123I-AnxA5γ, 160 keV13 hPro: no uptake in liver and kidneys after 12 h; good imaging expected in abdominal region, compared to that with known 99mTc compounds; good radiochemical purity
Con: laborious labeling method; more expensive than 99mTc labeling
124I-AnxA5β+, E = 1.53, 2.14 MeV, γ (complex decay under emission of several high-energy γ-photons)4.2 dPro: long-lived PET tracer; suitable for animal studies and studies in humans with terminal disease; labeled compound with long shelf-life (4 d without detectable deiodination); RCP > 95%
Con: high radiation burden and therefore less suitable for patient imaging; laborious labeling method
125I-AnxA5EC, 35 keV60 dPro: long-lived isotope; very useful for research purposes to test iodine labeling techniques in animals; low radiation burden for research workers
Con: no imaging possibility
111In-AnxA5γ, 173 keV, 247 keV (ratio of both energies is 1:1), electron capture gives x-ray energy of 23 keV2.8 dPro: longer-lived isotope; may be suitable for imaging of tumor response in patients
Con: difficult radiochemistry for indium; biodistribution influenced by conjugation method; biodistribution of pegylated In-conjugated anxA5 appears to be poor; rather high radiation burden in patients
18F-AnxA5β+, 633 keV110 minPro: PET tracer with optimal half-life for imaging; promising agent for patient imaging
Con: more research is required to establish its use in patients; labeling method is not yet standardized