Clinical value of iodine-123-alpha-methyl-L-tyrosine single-photon emission tomography in the differential diagnosis of recurrent brain tumor in patients pretreated for glioma at follow-up.
OBJECTIVE
To assess the clinical potential of iodine-123-alpha-methyl-L-tyrosine (IMT) and single-photon emission tomography (SPET) in the differential diagnosis of recurrences in patients pretreated for gliomas at follow-up.


METHODS
Seventy-eight patients were examined after primary therapy over 36 months. Histopathologic diagnoses of all patients was known at first treatment; magnetic resonance and/or computed tomography examination was performed in addition to IMT-SPET. Cerebral SPET images were acquired 20 minutes after intravenous application of 190 +/- 10 MBq of IMT. SPET images were classified as positive or negative for recurrent tumor visually and by calculating the ratios between tracer accumulation in the lesion and the unaffected contralateral regions of reference using region of interest. Final diagnoses were based on prospective clinicopathologic findings obtained independently of IMT-SPET.


RESULTS
IMT-SPET detected all high-grade recurrent gliomas (grade 4; sensitivity, 100%). A difference could be demonstrated in grade 2 and 3 recurrences (sensitivity, 84% and 92%, respectively). Moreover, benign posttherapeutic lesions (postoperative scars, radiation necrosis) were correctly diagnosed as negative for tumor recurrence. In general, IMT uptake in grade 2 (1.45 +/- 0.24) was significantly lower than that in grades 3 (1.70 +/- 0.41) and 4 (1.88 +/- 0.32). However, it was difficult to evaluate tumor grade only from the IMT accumulation in individual cases.


CONCLUSIONS
IMT-SPET seems highly useful for detecting and delineating recurrent gliomas and differentiating between benign posttherapeutic lesions and malignant tumor tissue. It may be a valuable clinical tool to diagnose recurrences in patients pretreated for gliomas at follow-up. However, it showed limitations in determining histologic tumor grade.
Samnick
Samuel
S
Department of Nuclear Medicine, Saarland University Medical Center, Homburg/Saar, Germany. rassam@med-rz.uni-saarland.de
Bader
Jochen B
JB
Hellwig
Dirk
D
Moringlane
Jean Richard
JR
Alexander
Christof
C
Romeike
Bernd F M
BF
Feiden
Wolfgang
W
Kirsch
Carl-Martin
CM
D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D004791:Enzyme Inhibitors; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007457:Iodine Radioisotopes; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D011183:Postoperative Complications / Q000175:diagnosis; D011832:Radiation Injuries / Q000175:diagnosis; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed / Q000379:methods*; D014057:Tomography, X-Ray Computed; D019805:alpha-Methyltyrosine
D004791:Enzyme Inhibitors; D007457:Iodine Radioisotopes; D019805:alpha-Methyltyrosine