Potential time benefit in the assessment of recurrent rat rhabdomyosarcoma using positron emission tomography (PET) with (18)fluorodeoxyglucose depends on therapy-specific growth delay.
OBJECTIVE
To correlate the potential time benefit of (18)F-fluorodeoxyglucose positron emission tomography ((18)FDG-PET) in terms of early detection of recurrences of subcutaneously growing R1H tumors with therapy-specific parameters of recurrent tumor.


METHODS
Twelve, eleven, and seven recurrences were followed after fractionated radiotherapy, surgery, and chemotherapy for 6 months, respectively, and (18)FDG-PET was performed weekly using a conventional full-ring whole-body PET scanner. By comparing PET results and actual tumor volume, the time benefit of (18)FDG-PET in detection of recurrent tumors of 0.1, 0.2, and 0.5 cm(3) was determined for the different treatment strategies.


RESULTS
A significant time benefit of (18)FDG-PET of 26.9 days and 67 days was solely determined for recurrences after radiotherapy of 0.2 cm(3) and 0.5 cm(3), respectively. The potential time benefit showed a strong correlation with growth delay, which was increased after radiotherapy due to a pronounced tumor-bed effect.


CONCLUSIONS
The potential time benefit of (18)FDG-PET is strongly determined by the growth kinetics of the recurrence. A tumor-bed effect, which is a phenomenon solely seen after radiotherapy, favors early detection by (18)FDG-PET. The experimental data, clinical experience and theoretical consideration all indicate a noticeable benefit of (18)FDG-PET especially after radiotherapeutic treatment.
Raabe
Annette
A
Department of Radiotherapy and Radiooncology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. araabe@uke.uni-hamburg.de
Buchert
Ralph
R
Seegers
Barbara
B
de Wit
Maike
M
D000818:Animals; D005240:Feasibility Studies; D019788:Fluorodeoxyglucose F18; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D051381:Rats; D015203:Reproducibility of Results; D012208:Rhabdomyosarcoma / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D012680:Sensitivity and Specificity; D013997:Time Factors
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18