T. Kondo et al., Diagnostic value of Tl-201-single-photon emission computerized tomography studies in cases of posterior fossa hemangioblastomas, J NEUROSURG, 95(2), 2001, pp. 292-297
Object. The Tl-201 uptake index was evaluated for its usefulness in formula
ting a diagnosis of hemangioblastoma. Thallium-201-single-photon emission c
omputerized tomography (SPECT) studies were performed in nine patients harb
oring hemangioblastomas in the posterior fossa and in five patients (six le
sions) with gliomas in the posterior fossa.
Methods. The Tl-201 uptake index was defined as the ratio of mean counts of
isotope per pixel in the tumor to mean counts of isotope per pixel in the
homologous region of the healthy brain. The Tl-201 uptake indices of the ea
rly image (Tl-E) and that of the delayed image (Tl-D) were calculated. The
isotope retention index (RI) was calculated as (Tl-E - Tl-D)/Tl-E The Tl-E
was 2.7 +/- 0.7 in hemangioblastomas and 2.9 +/- 1.7 in gliomas (mean stand
ard deviation). The Tl-D was 1.5 +/- 0.4 in hemangioblastomas and 2.4 +/- 1
.6 in gliomas. There were no significant differences between hemangioblasto
mas and gliomas when Tl(E)s and Tl(D)s were compared. The isotope RI was 0.
43 +/- 0.07 in hemangioblastomas and 0.15 +/- 0.1 in gliomas, showing a sig
nificantly higher RI in hemangioblastomas compared with gliomas (p < 0.01).
Conclusions, Thallium-201 washout is significantly faster in hemangioblasto
mas. Hemangioblastoma is biologically benign, but contains a rich capillary
network that forms a hypervascular tumor bed. Variations in its appearance
on magnetic resonance images may cause difficulties in the differential di
agnosis of hemangioblastoma. Thallium-201 SPECT studies can be used to dist
inguish hemangioblastomas from gliomas in the posterior fossa.