title: Microcystic meningioma with late-phase accumulation on thallium-201 single-photon emission computed tomography: case report.
abstract: Microcystic meningiomas are rare but benign brain tumors. Previous reports have shown that Thallium-201 single-photon emission computed tomography ((201)Tl SPECT) demonstrated a higher late-phase accumulation of (201)Tl in malignant or recurrent meningiomas than in nonaggressive meningiomas. No study has reported (201)Tl SPECT findings in microcystic meningiomas. We here describe a case of a microcystic meningioma with a high (201)Tl SPECT retention rate in a 62-year-old woman who complained of headache. Computed tomography revealed an intracranial tumor in the right frontal lobe. Moreover, (201)Tl SPECT revealed a high uptake of (201)Tl in the tumor, which was particularly prominent in the delayed phase. The uptake index on an early image was 1.46 and that on a delayed image was 1.35. Therefore, the retention index was 0.92. After 2 years of tumor growth, we performed successful radical resection, and histological examination revealed the presence of a microcystic meningioma. Therefore, we concluded that (201)Tl SPECT may be useful for the preoperative diagnosis of microcystic meningiomas and that late-phase accumulation of (201)Tl is not a specific finding of malignant brain tumors. Therefore, we need to be careful in the evaluation and judgment of high retention in a delayed image of (201)Tl SPECT.
authors.affiliation: Department of Neurosurgery, Nippon Medical School.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Matano
authors.forename: Koji
authors.initials: K
authors.lastname: Adachi
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Murai
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kitamura
authors.forename: Ryuji
authors.initials: R
authors.lastname: Ohashi
authors.forename: Akira
authors.initials: A
authors.lastname: Teramoto
authors.forename: Akio
authors.initials: A
authors.lastname: Morita
mesh_terms: D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013794:Thallium Radioisotopes / Q000493:pharmacokinetics*; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D013794:Thallium Radioisotopes