Evaluation of brain tumor recurrence by (99m)Tc-tetrofosmin SPECT: a prospective pilot study.
OBJECTIVE
The differentiation between brain tumor recurrence and post-irradiation injury remains an imaging challenge. Computed tomography (CT) and magnetic resonance imaging (MRI) cannot always distinguish between the two. Although glioma cell line studies substantiated a plausible imaging superiority of (99m)Tc-tetrofosmin ((99m)Tc-TF) over other radiopharmaceuticals, little has been reported on its in vivo imaging properties. We assessed (99m)Tc-TF single-photon emission CT (SPECT) in cases where morphologic brain imaging was inconclusive between recurrence and radionecrosis.


METHODS
A total of 11 patients (7 men, 4 women) were evaluated. The initial diagnosis was glioblastoma multiforme (4), anaplastic astrocytoma (1), anaplastic oligodendroglioma (3), grade-II astrocytoma (2), and low-grade oligodendroglioma (1). All patients had been operated on and then received adjuvant external-beam radiotherapy. After a mean follow-up period of 25 months, there was clinical suspicion of recurrence, for which (99m)Tc-TF SPECT was performed.


RESULTS
In 8/11 cases, an abnormally increased tracer uptake appeared in the region that CT and/or MRI indicated as suspicious; in half of these cases, recurrence was confirmed histologically after surgery and in the other four by growth of the lesion over a 6-month follow-up period, and clinical deterioration. The remaining 3/11 patients had faint tracer uptake in the suspicious region, compatible with radiation injury; these lesions remained morphologically unaltered in a mean 12-month follow-up period, with no clinical deterioration in the patient's condition, a course strongly favoring the diagnosis of radiation injury.


CONCLUSIONS
Metabolic brain imaging by (99m)Tc-TF could offer useful information in the workup of treated brain tumors, where radiomorphologic findings between recurrence and radionecrosis are inconclusive.
Alexiou
George A
GA
Department of Neurosurgery, University of Ioannina School of Medicine, Neohoropoulo, Ioannina, Greece. alexiougrg@yahoo.gr
Fotopoulos
Andreas D
AD
Papadopoulos
Athanasios
A
Kyritsis
Athanasios P
AP
Polyzoidis
Konstantinos S
KS
Tsiouris
Spyridon
S
D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D045744:Cell Line, Tumor; D005260:Female; D005910:Glioma / Q000175:diagnosis / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds / Q000494:pharmacology*; D015609:Organotechnetium Compounds / Q000494:pharmacology*; D010865:Pilot Projects; D019275:Radiopharmaceuticals / Q000494:pharmacology*; D012008:Recurrence; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin