Prognostic significance of amino acid transport imaging in patients with brain tumors.
OBJECTIVE
To evaluate the prognostic significance of presence, intensity, and extent of amino acid uptake in patients with suspected primary or recurrent brain tumors.


METHODS
We retrospectively analyzed 181 consecutive studies of amino acid uptake using single-photon emission computed tomography and the amino acid l-[3-(123)I]iodo-alpha-methyltyrosine (IMT). In a blinded analysis, all studies were evaluated for presence, maximal uptake (IMT(max)), and extent (IMT(ext)) of focal tracer uptake.


RESULTS
The most frequent tumors were 53 astrocytomas (World Health Organization Grade I-III), 41 glioblastomas, 16 metastases, 13 oligodendrogliomas (Grade II-III), and 10 medulloblastomas. The other patients exhibited various parenchymal tumors or nonneoplastic lesions. IMT uptake was present in 69% of the patients with IMT(max) ranging from 1.4 to 6.2. IMT(max) and IMT(ext) were significant predictors of survival in the whole group. When the group was divided according to primary versus recurrent tumor, only the primary tumors achieved a high level of significance (P < 0.01). When patients without any IMT uptake were excluded from the analysis, statistical significance for both IMT(max) and IMT(ext) was lost. Multiple regression analysis, including IMT(max), IMT(ext), age, and tumor grade, revealed only extent of IMT uptake as an independent predictor of prognosis.


CONCLUSIONS
Absence of IMT uptake is a significant predictor of long-term survival in patients with suspected primary or recurrent brain tumors. Only the extent of a given lesion provided minor supplementary prognostic information as compared with histopathology and age. These findings suggest caution in relating high amino acid uptake values to poor prognosis, despite the capability of amino acid imaging to help determine the presence and extent of gliomas.
Weckesser
Matthias
M
Department of Nuclear Medicine, Münster University, Münster, Germany. m.weckesser@uni-muenster.de
Matheja
Peter
P
Schwarzrock
Antje
A
Rickert
Christian H
CH
Sträter
Ronald
R
Palkovic
Stefan
S
Riemann
Burkhard
B
Kopka
Klaus
K
Lüdemann
Peter
P
Paulus
Werner
W
Wassmann
Hansdetlef
H
Schober
Otmar
O
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007457:Iodine Radioisotopes; D008297:Male; D008781:Methyltyrosines / Q000493:pharmacokinetics; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D016037:Single-Blind Method; D016019:Survival Analysis; D015899:Tomography, Emission-Computed, Single-Photon
D000596:Amino Acids; D007457:Iodine Radioisotopes; D008781:Methyltyrosines; C030855:3-iodo-alpha-methyltyrosine