[68Ga]-DOTATOC-PET/CT for meningioma IMRT treatment planning.
OBJECTIVE
The observation that human meningioma cells strongly express somatostatin receptor (SSTR 2) was the rationale to analyze retrospectively in how far DOTATOC PET/CT is helpful to improve target volume delineation for intensity modulated radiotherapy (IMRT).


METHODS
In 26 consecutive patients with preferentially skull base meningioma, diagnostic magnetic resonance imaging (MRI) and planning-computed tomography (CT) was complemented with data from [(68)Ga]-DOTA-D Phe(1)-Tyr(3)-Octreotide (DOTATOC)-PET/CT. Image fusion of PET/CT, diagnostic computed tomography, MRI and radiotherapy planning CT as well as target volume delineation was performed with OTP-Masterplan((R)). Initial gross tumor volume (GTV) definition was based on MRI data only and was secondarily complemented with DOTATOC-PET information. Irradiation was performed as EUD based IMRT, using the Hyperion Software package.


RESULTS
The integration of the DOTATOC data led to additional information concerning tumor extension in 17 of 26 patients (65%). There were major changes of the clinical target volume (CTV) which modify the PTV in 14 patients, minor changes were realized in 3 patients. Overall the GTV-MRI/CT was larger than the GTV-PET in 10 patients (38%), smaller in 13 patients (50%) and almost the same in 3 patients (12%). Most of the adaptations were performed in close vicinity to bony skull base structures or after complex surgery. Median GTV based on MRI was 18.1 cc, based on PET 25.3 cc and subsequently the CTV was 37.4 cc. Radiation planning and treatment of the DOTATOC-adapted volumes was feasible.


CONCLUSIONS
DOTATOC-PET/CT information may strongly complement patho-anatomical data from MRI and CT in cases with complex meningioma and is thus helpful for improved target volume delineation especially for skull base manifestations and recurrent disease after surgery.
Gehler
Barbara
B
Department of Radiation Oncology, LMU München, Marchioninistr, 15, 81377 München, Germany. barbara.gehler@med.uni-tuebingen.de
Paulsen
Frank
F
Oksüz
Mehmet O
MO
Hauser
Till-Karsten
TK
Eschmann
Susanne M
SM
Bares
Roland
R
Pfannenberg
Christina
C
Bamberg
Michael
M
Bartenstein
Peter
P
Belka
Claus
C
Ganswindt
Ute
U
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005710:Gallium Radioisotopes; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000532:radiotherapy*; D008579:Meningioma / Q000532:radiotherapy*; D008875:Middle Aged; D015282:Octreotide / Q000031:analogs & derivatives; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed
D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D015282:Octreotide; C106246:Edotreotide