CASE REPORT Annals of Nuclear Medicine Vol. l4, No. 5. 391-393, 2000 Gliosarcoma with thallium-201 SPECT Naoto WATANABE * Eikichi OKADA,** Masashi SHIMIZU,* Kyo NOGUCHI,* Shunro ENDO,*** Ryusuke FUTATSUYA # Yukio HORIE,## Norihisa TONAMI+ and Hikaru SETO* Departments of *Rodiology, **Pathology and ***Neurosurgery Toyama Medical and Pharmaceutical University Departments of #Radiology and ##Neurosurgery Saiseikai Toyama Hospital Department of Nuclear Medicine, Kanazawa University Thallium-201 (201Tl) chloride scintigraphy is the Imaging method use for the detection of various tumors including glioblastoma, but only limited information on 201Tl uptake in gliosarcoma is available. We investigated a patient with gliosarcoma by means of 201Tl single-photon emission computed tomography (SPECT) and MRI. SPECT Imaging revealed high 201Tl uptake in the tumor, which was closely correlated with contrast-enhancement on MRI. These results suggest that SPECT with 201Tl may be useful for detecting gliosarcoma and provide physiological information on this tumor. Key words: gliosarcoma, 201Tl, SPECT, MRI INTRODUCTION GLIOSARCOMA is an uncommon malignant brain tumor, composed of neuroectodermal and mesenchymal tissue. It has been reported as representing described 2.3% of all gliomas, 5% of astrocytomas, and 8% of glioblastomas. l Many reports have focused on histogenic and pathological aspects of this tumor, but only limited information is available concerning the MR characteristics of gliosarcoma. 2.3 One general tumor scanning agent in clinical use for the detection of brain tumors including glioblastomas is thallium-201 (201Tl) chloride 4-6 These researchers suggested that 201Tl imaging may be a useful technique for investigating patients with glioblastoma. The purpose of this paper is to report the 201Tl SPECT and MRI findings in a patient with gliosarcoma. CASE REPORT A 44-year-old woman was admitted with recent memory Received February 24, 2000, revision accepted August 1O, 2000. For reprint contact: Naoto Watanabe, M.D., Department of Radiology, Toyama Medical and Pharmaceutical University, Sugitani 2630, Toyama 930-01 94, JAPAN. E-mail: nw31456@ms.toyama-mpu.ac.jp disturbance and head heaviness. MRI (Toshiba. MRT 50A, Japan) was performed to evaluate the neurological symptoms. MRI on enhanced Tl weighted images revealed an irregular ring-enhanced mass in the left temporoparietal lobe (Fig. 1 ). Transverse reconstruction of SPECT images was performed at 15 min postinjection of 3 mCi ( 111 MBq) of 201Tl chloride with a high-resolution SPECT system with three-head rotating cameras (Toshiba, GCA 9300A, Japan). Axial SPECT images (Fig. 2) showed prominent tumor localization. SPECT findings were correlated with those of subsequent MRI. By histopathological and immunohistochemical examination of the operation site, the tumor was considered to be an anaplastic neoplasm derived from glial tissue containing a sarcomatous component as a gliosarcoma (Fig. 3A-C). DISCUSSION The tumor was first described in 1895 by Stroebe who reported a giloblastoma with sarcomatous elements and subsequently applied the terrn "gliosarcoma."7 In 1955 Feigin et al. revealed a detailed review of several cases of gliosarcoma in which they discussed the origin of the sarcomatous components of the tumor 8 The histological origin of gliosarcoma is controversial; the sarcomatous component might be the result of neoplastic degeneration of the mesenchymal cells, or of neoplastic growth of the endothelial vasal elements within gliosarcoma of glial and sarcomatous neoplastic elements that appear de novo and at the same time. 1,9,10 Galani et al. demonstrated that gliosarcoma behaves similarly to glioblastoma multiforme (GBM). When similar treatments (combined radiation and chemotherapy) were administered, there was no significant difference between patients with GBM and gliosarcoma in time to progression and overall survival time. The median survival time was 9 months for patients with gliosarcoma.11 Although, in this patient radiotherapy and chemotherapy were performed, this patient died 14 months after admission. Dwyer reported 6 gliosarcoma patients with emphasis on the MR feature. All of the tumors showed enhancement on Tl-weighted images that corresponded to the areas of intermediate signal intensity on T2-weighted images. Three of the tumors diffuse inhomogeneous enhancement with more intense peripheral enhancement. The other three tumors had intense, irregular, ring-like enhancement surrounding central hypointensity.3 Our findings of gliosarcoma on MRI were also irregular, ring-enhanced tumors similar to the above mentioned. 201Tl scintigraphy can be generally used to detect of various malignant tumors including glioblastoma.4-6 Ishibashi et al. reported thal 201Tl uptake in glioma is correlated with proliferating cell nuclear antigen 12 201Tl scintigraphy may distinguish the histologic grade of glioma, tumor uptake with 201Tl in gliosarcoma has not been extensively reported. Taki et al. recently reported that the degree of early 201Tl uptake In malignant brain tumors including glioblastoma is correlated well with that of contrast-enhancement on MRI. 201 Tl uptake depends in the main on regional blood flow, destruction of the blood brain barrier and tumor viability, whereas contrast-enhancement on MRI depends on BBB dysfunction, regional blood flow and tissue permeability.13 It is suggested that 201Tl may evaluate tumor viability. In this patient, we could visualize high 201Tl uptake in gliosarcoma on SPECT imaging. High 201Tl uptake in our case is correlated with the histological grade as with glioblastoma.4-6 This shows the precise localization and histological characteristics of the tumor, and correlates closely with the results of contrast-enhancement on MRI. We suggest that 201TI SPECT may be useful for detecting gliosarcoma and providing physiological information on this tumor. REFERENCES 1. Moranz RA, Feigin I. Ransohoff J. 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