Radiation dosimetry and biodistribution of BAY86-9596 (O-([18F]fluoromethyl)-D-tyrosine)

Objectives Despite the fact that FDG is the ‘workhorse’ of PET in oncology, it has a well known drawback in terms of specificity. New tracers avoiding this drawback are actively researched for, amongst which is BAY86-9596.

Methods Five healthy volunteers were subject to a series of seven whole-body PET scans in three time windows following an injection with approximately 200 MBq of BAY86-9596. Time-points included 0, 10, 20, 30, 40 minutes and 2 and 4 hours post-injection. Data were acquired using 1 minute per bed-position on a Siemens Biograph mCT PET/CT camera featuring TrueV and UHD technology. Data were fully corrected for decay, randoms, scatter and attenuation. Dosimetry was performed using the MIRD scheme as implemented by OLINDA/EXM. Source organs were identified as organs showing uptake that was significantly different from the average. Cumulated activities were obtained from the time-activity curves of regions of interest drawn in the source organs and were fed into OLINDA for organ level dosimetry. Parameters for the urinary bladder model were obtained by fitting the bladder data from the PET images and assuming subjects voiding the bladder at regular intervals. The dose on the blood/red-marrow was estimated from PET data on a lumbar vertebra.

Results Table 1 shows the organ doses for the standard male and standard female as well as the effective dose according to ICRP 103. For a bladder voiding interval of 45 minutes, in agreement with patient scanning protocol, the effective doses were 14.3 ± 0.4 μSv/MBq for the standard male and 18.0 ± 0.4 μSv/MBq for the standard female.

Conclusions The new PET tracer BAY86-9596 showed a favorable radiation dosimetry with an ED being comparable to that of [18F]-FDG