A retrospective comparison between 68Ga-DOTA-TOC PET/CT and 18F-DOPA PET/CT in patients with extra-adrenal paraganglioma.
OBJECTIVE
(18)F-Fluoro-L-dihydroxyphenylalanine ((18)F-DOPA) PET offers high sensitivity and specificity in the imaging of nonmetastatic extra-adrenal paragangliomas (PGL) but lower sensitivity in metastatic or multifocal disease. These tumours are of neuroendocrine origin and can be detected by (68)Ga-DOTA-Tyr(3)-octreotide ((68)Ga-DOTA-TOC) PET. Therefore, we compared (68)Ga-DOTA-TOC and (18)F-DOPA as radiolabels for PET/CT imaging for the diagnosis and staging of extra-adrenal PGL. Combined cross-sectional imaging was the reference standard.


METHODS
A total of 5 men and 15 women (age range 22 to 73 years) with anatomical and/or histologically proven extra-adrenal PGL were included in this study. Of these patients, 5 had metastatic or multifocal lesions and 15 had single sites of disease. Comparative evaluation included morphological imaging with CT and functional imaging with (68)Ga-DOTA-TOC PET and (18)F-DOPA PET. The imaging results were analysed on a per-patient and a per-lesion basis. The maximum standardized uptake value (SUVmax) of each functional imaging modality in concordant tumour lesions was measured.


RESULTS
Compared with anatomical imaging, (68)Ga-DOTA-TOC PET and (18)F-DOPA PET each had a per-patient and per-lesion detection rate of 100% in nonmetastatic extra-adrenal PGL. However, in metastatic or multifocal disease, the per-lesion detection rate of (68)Ga-DOTA-TOC was 100% and that of (18)F-DOPA PET was 56.0%. Overall, (68)Ga-DOTA-TOC PET identified 45 lesions; anatomical imaging identified 43 lesions, and (18)F-DOPA PET identified 32 lesions. The overall per-lesion detection rate of (68)Ga-DOTA-TOC PET was 100% (McNemar, P < 0.5), and that of (18)F-DOPA PET was 71.1% (McNemar, P < 0.001). The SUVmax (mean ± SD) of all 32 concordant lesions was 67.9 ± 61.5 for (68)Ga-DOTA-TOC PET and 11.8 ± 7.9 for (18)F-DOPA PET (Mann-Whitney U test, P < 0.0001).


CONCLUSIONS
(68)Ga-DOTA-TOC PET may be superior to (18)F-DOPA PET and diagnostic CT in providing valuable information for pretherapeutic staging of extra-adrenal PGL, particularly in surgically inoperable tumours and metastatic or multifocal disease.
Department of Nuclear Medicine, Innsbruck Medical University, Anichstrasse 35, 6020, Innsbruck, Austria, alexander.kroiss@i-med.ac.at.
Alexander
A
Kroiss
Daniel
D
Putzer
Andreas
A
Frech
Clemens
C
Decristoforo
Christian
C
Uprimny
Rudolf Wolfgang
RW
Gasser
Barry Lynn
BL
Shulkin
Christoph
C
Url
Gerlig
G
Widmann
Rupert
R
Prommegger
Georg Mathias
GM
Sprinzl
Gustav
G
Fraedrich
Irene Johanna
IJ
Virgolini
D000328:Adult; D000368:Aged; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D015282:Octreotide / Q000031:analogs & derivatives*; D009942:Organometallic Compounds; D010236:Paraganglioma, Extra-Adrenal / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
C499142:Ga(III)-DOTATOC; D009942:Organometallic Compounds; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine; D015282:Octreotide