|
|
Volumetric
Analysis of 18F-FDG PET in Glioblastoma Multiforme: Prognostic
Information and Possible Role in Definition of Target Volumes in Radiation Dose
Escalation
Kevin
S. Tralins, MD1, James G. Douglas, MD, MS1, Keith J.
Stelzer, MD, PhD1, David A. Mankoff, MD2, Daniel L.
Silbergeld, MD3, Robert Rostomilly, MD3, Sharon Hummel, MS1,
Jeff Scharnhorst, BS4, Kenneth A. Krohn, PhD2 and
Alexander M. Spence, MD4
1Department of Radiation Oncology, University of Washington Medical Center,
Seattle, Washington.
2 Department of Nuclear Medicine, University of Washington Medical
Center, Seattle, Washington.
3 Department of Neurosurgery, University of Washington Medical
Center, Seattle, Washington.
4 Department of Neuro-Oncology, University of Washington Medical
Center, Seattle, Washington
The use of 18F-FDG PET for brain tumors has been shown to be
accurate in identifying areas of active disease.
Radiation dose escalation in the treatment of glioblastoma multiforme
(GBM) may lead to improved disease control.
On the basis of these premises, we initiated a pilot study to
investigate the use of 18F-FDG PET for the guidance of
radiation dose escalation in the treatment of GBM.
Methods. Patients were considered eligible to
participate in the study if they had a diagnosis of GBM, were at
least 18 y old, and had a score of at least 60 on the Karnofsky
Scale.
Patients were treated with standard conformal fractionated
radiotherapy (1.8 Gy per fraction, to 59.4 Gy), with volumes defined
by MRI.
At a dose of 45–50.4 Gy, patients underwent 18F-FDG PET
for boost target delineation.
Final noncoplanar fields (3–4) were designed to treat the
volume of abnormal 18F-FDG uptake plus a 0.5-cm margin for an
additional 20 Gy (2 Gy per fraction), to a total dose of 79.4
Gy.
If no abnormal 18F-FDG uptake was observed, treatment was
stopped after the conventional course of 59.4 Gy.
Age, Karnofsky score, MRI-based volumes, and 18F-FDG PET
volume were analyzed as prognostic variables for time to tumor
progression (TTP) and overall survival.
18F-FDG PET volumes and MRI-based volumes were compared to
assess concordance.
Results. For the 27 patients who could be evaluated,
median actuarial TTP was 43 wk, and median actuarial survival was 70
wk.
On univariate analysis, 18F-FDG PET, T1-weighted MRI gadolinium
enhancement (excluding nonenhancing resection cavity), and
T2-weighted MRI volumes were significantly predictive of TTP.
On multivariate analysis, only 18F-FDG PET volume retained
significance for predicting TTP.
Similar results were obtained on analysis of these variables as
prognostic factors for survival.
When 18F-FDG PET-based volumes were compared with
MRI-based volumes, a difference of at least 25% was detected in all
patients, with all but 2 having smaller 18F-FDG PET volumes.
Of patients in whom 18F-FDG uptake was initially present
but treatment subsequently failed, 83% demonstrated the first tumor
progression within the region of abnormal 18F-FDG uptake.
Conclusion. In comparison with MRI, 18F-FDG PET defined
unique volumes for radiation dose escalation in the treatment of
GBM.
18F-FDG PET volumes were predictive of survival and time to
tumor progression in the treatment of patients with GBM.
Key Words:
glioblastoma multiforme, PET , radiation dose escalation
Copyright
© 2002 by the Society of Nuclear Medicine.
Source:
http://jnm.snmjournals.org/cgi/content/abstract/43/12/1667
|
