Radiation risk caused by [F18]BAY 94-9172, a new PET tracer for detection of cerebral β-amyloid plaques

Objectives [F-18]BAY 94-9172 is a new and promising PET tracer for detection of β-amyloid plaques in the brain. To assess the putative radiation risk and, thereby, ensure appropriate clinical application, the biodistribution, resulting organ doses (OD) and effective dose (ED) were determined.

Methods Up to present, 12 healthy volunteers (age: 62.8±4.8; 6 female, 6 male) have been investigated. All subjects were imaged up to 7h after i.v. injection of 300MBq±20% [F-18]BAY 94-9172 using a SIEMENS ECAT HR⁺ PET scanner (3D mode, 8 or 9 bed-pos./frame, 1 min/bed-pos., measured attenuation correction, iterative reconstruction). All relevant organs were defined by volumes of interest and time-activity-data. Exponential curves were fitted to this data. ODs and the ED were calculated using the adult male model.

Results The gallbladder received the highest OD (103.0±31.0µSv/MBq*), followed by the urinary bladder (55.1±22.5*), liver (33.8±5.0*) and the whole intestine (24.6±10.3*). The highest contribution to the ED were derived from the lower large intestine (3.03±0.97*), ovaries (2.81±0.42*), urinary bladder (2.76±1.12*) and the liver (1.69±0.25*). The ED by this i.v. application of [F18]BAY 94-9172 results in an ED of 16.5±2.6*.

Conclusions The ED upon i.v. application of 300MBq [F-18]BAY 94-9172 is 5.0±0.8 mSv. This is well within the range of that resulting from application of other [F18]-labeled compounds. This favourable dosimetry data encourage further development of [F-18]BAY 94-9172 as a clinical tool for PET brain imaging.

Research Support The trial is sponsored and supported by the Bayer-Schering Pharma AG