Multimodal metabolic imaging of cerebral gliomas: positron emission tomography with [18F]fluoroethyl-L-tyrosine and magnetic resonance spectroscopy.
OBJECTIVE
The purpose of this study was to determine the predictive value of [18F]fluoroethyl-L-tyrosine (FET)-positron emission tomography (PET) and magnetic resonance (MR) spectroscopy for tumor diagnosis in patients with suspected gliomas.


METHODS
Both FET-PET and MR spectroscopy analyses were performed in 50 consecutive patients with newly diagnosed intracerebral lesions supposed to be diffuse gliomas on contrast-enhanced MR imaging. Lesion/brain ratios of FET uptake greater than 1.6 were considered positive, that is, indicative of tumor. Results of MR spectroscopy were considered positive when N-acetylaspartate (NAA) was decreased in conjunction with an absolute increase of choline (Cho) and an NAA/Cho ratio of 0.7 or less. An FET lesion/brain ratio, an NAA/Cho ratio, and signal abnormalities on MR images were compared with histological findings in neuronavigated biopsy specimens. The FET lesion/brain ratio and the NAA/Cho ratio were identified as significant independent predictors for the histological identification of tumor tissue. The accuracy in distinguishing neoplastic from nonneoplastic tissue could be increased from 68% with the use of MR imaging alone to 97% with MR imaging in conjunction with FET-PET and MR spectroscopy. Sensitivity and specificity for tumor detection were 100 and 81% for MR spectroscopy and 88 and 88% for FET-PET, respectively. Results of histological studies did not reveal tumor tissue in any of the lesions that were negative on FET-PET and MR spectroscopy. In contrast, a tumor diagnosis was made in 97% of the lesions that were positive with both methods.


CONCLUSIONS
In patients with intracerebral lesions supposed to be diffuse gliomas on MR imaging, FET-PET and MR spectroscopy analyses markedly improved the diagnostic efficacy of targeted biopsies.
Floeth
Frank Willi
FW
Department of Neurosurgery, Heinrich-Heine-University, Düsseldorf, Germany. floethf@uni-duesseldorf.de
Pauleit
Dirk
D
Wittsack
Hans-Jörg
HJ
Langen
Karl Josef
KJ
Reifenberger
Guido
G
Hamacher
Kurt
K
Messing-Jünger
Martina
M
Zilles
Karl
K
Weber
Friedrich
F
Stummer
Walter
W
Steiger
Hans-Jakob
HJ
Woebker
Gabriele
G
Müller
Hans-Wilhelm
HW
Coenen
Heinz
H
Sabel
Michael
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D001706:Biopsy; D001921:Brain / Q000473:pathology / Q000503:physiopathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D002794:Choline / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005462:Fluorine Radioisotopes; D005910:Glioma / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives*
D005462:Fluorine Radioisotopes; C117289:O-(2-fluoroethyl)tyrosine; D019275:Radiopharmaceuticals; D001224:Aspartic Acid; D014443:Tyrosine; C000179:N-acetylaspartate; D002794:Choline