Table 2.

Common radioisotopes used in HIV nuclear imaging.

Radioisotope	Half-lives	Pros and cons
11C	20 min	Short half-life good for repeat studies, carbon-11 for carbon-12 exchange in small molecules/drugs produce the same labeled molecule/drug, half-life may be too short to achieve adequate signal-to-noise ratio, may not be transported to distant scanners
18F	110 min	Ideal positron emission characteristics for high-resolution PET imaging may incorporate into small-molecules/drugs. Half-life suitable for longer imaging and delivery to remote scanner sites. May not be long enough for larger biologic molecules. Free 18F-Fluoride ion accumulates in bone
64Cu	12.7 h	Half-life compatible with imaging larger molecules like mAbs. However, half-life may limit utility when using HIV gp120-specific or other mAb, which take time to penetrate certain target tissues
89Zr	78 h	Half-life compatible with imaging larger molecules like mAbs. Radiation dose to patient is higher so lower administered dose is necessary. Takes a long time to clear from body so repeat studies limited but allows for serial imaging over days with a single radioisotype injection. May be beneficial when using HIV gp120-specific mAb, which takes time to penetrate certain target tissues. Ideal for transport to distant scanners. 89ZrCl3 may accumulate in active bone