Different thallium-201 single-photon emission tomographic patterns in benign and aggressive meningiomas

Abstract

To evaluate the possibility of preoperatively obtaining an index of aggressiveness for intracranial meningiomas, we prospectively studied 22 patients with computed tomographic or magnetic resonance imaging evidence of meningeal tumour, using single-photon emission tomography (SPET) of the brain and thallium-201 (201Tl). On a brain-dedicated SPET scanner, a rapid acquisition protocol with early, short scans was started simultaneously with the intravenous administration of 111 MBq 201Tl, covering the initial intratumoral distribution of the tracer. Twenty minutes post injection, a delayed SPET scan was also obtained. On the reconstructed and attenuation-corrected images we calculated the 201Tl concentration in tumour and normal contralateral brain tissue, and compared intratumoral tracer concentration in the initial and the final part of the rapid acquisition protocol. Benign and malignant meningiomas were classified as such based on histological examination. In malignant lesions, the ratio of the 201Tl concentration at 2-4 min post injection to that at 14-16 min was found to be significantly higher than in non-aggressive neoplasms (mean+/-1 SD: 1.14+/-0.31 and 0.56+/-0.13, respectively, P <0.01). Conversely, in the delayed scan, most lesions showed high tracer concentration, and the two groups could not be distinguished. In addition, three recurrent meningiomas displayed the same imaging behaviour as the malignant group, i.e. had similar 201Tl concentration values at 2-4 and at 14-16 min. Our findings suggest that the comparative assessment of intratumoral 201Tl concentration at 2-4 and at 14-16 min post injection could provide a fast, simple method to differentiate preoperatively intracranial meningiomas with different biological behaviour.

Diffuse glioblastoma resembling acute hemorrhagic leukoencephalitis

“…The involvement of at least three cerebral lobes by an infiltrative tissue, the lack of a single discrete mass and pathological confirmation of diffuse glioma (WHO grade IV) indicate the diagnosis. However, the imaging features may also be present in CNS inflammatory diseases, vasculitis, encephalitis, leukoencephalopathies, especially when there is no obvious mass effect (2,(5)(6)(7)(8)(9)(10). While cases of demyelinating diseases mimicking gliomas are well represented in the literature (11,12), the opposite is a rather rare occurrence, mainly reported in the pediatric (13)(14)(15) or young (16) age.…”

13N-NH3 Versus F-18 FDG in Detection of Intracranial Meningioma

“…However, the tumors with high initial uptake of 201 TlCl may not be malignant if the washout is rapid. Tedeschi et al found the early temporal pattern of T1-201 concentration in intracranial meningiomas is probably related to their biologic aggressiveness, 11 and Sugo et al suggested that dynamic 201 TlCl SPECT was useful in distinguishing malignant brain tumors from benign tumors. 23 Our current study revealed 13 N-NH 3 was unable to differentiate grade I from grade II meningiomas.…”

“…[11][12][13] There are 2 chemical forms of ammonia (NH 3 and NH 4 ϩ ) in the blood. The relative proportion of NH 3 and NH 4 ϩ in blood is determined by the pH.…”

“…Relatively high Tl-201 uptakes were found in all types of meningiomas, and 201 TlCl SPECT could predict histologic types of meningiomas and differentiate the benign and aggressive meningiomas. [11][12][13] However, a major drawback of 201 TlCl SPECT is its difficulty in detecting small meningiomas and quantifying the dynamic bio distribution of Tl-201 in the tumors because SPECTs spatial and temporal resolutions are limited for brain imaging.…”

Metabolic Imaging of Brain Tumor by 99mTc-Tetrofosmin Scintitomography

“…201 Tl was among the first single-photon emitting radiotracers studied in meningioma. Its uptake pre-operatively has been proposed to differentiate meningiomas with different biological behaviors, while tracer retention by a lesion correlated with its malignant potential (Jinnouchi et al, 1993;Tedeschi et al, 1996). Nevertheless, later reports did not verify any correlation between 201 Tl uptake and PCNA labeling index in meningiomas, dissimilar to gliomas (Gungor et al, 2000).…”