gms | German Medical Science

57th Annual Meeting of the German Society of Neurosurgery
Joint Meeting with the Japanese Neurosurgical Society

German Society of Neurosurgery (DGNC)

11 - 14 May, Essen

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Clinical value of 123I-metaiodobenzylguanidine single-photon emission computerized tomography for diagnosis of embryonal tumours – Diagnostic significance of delayed imaging

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  • corresponding author T. Sasajima - Department of Neurosurgery, Akita University School of Medicine, Akita, Japan
  • H. Kinouchi - Department of Neurosurgery, Akita University School of Medicine, Akita, Japan
  • Y. Naitoh - Department of Neurosurgery, Akita University School of Medicine, Akita, Japan
  • N. Tomura - Department of Radiology, Akita University School of Medicine, Akita, Japan
  • J. Watarai - Department of Radiology, Akita University School of Medicine, Akita, Japan
  • K. Mizoi - Department of Neurosurgery, Akita University School of Medicine, Akita, Japan

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 57. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. Essen, 11.-14.05.2006. Düsseldorf, Köln: German Medical Science; 2006. DocP 04.47

The electronic version of this article is the complete one and can be found online at: http://www.egms.de/en/meetings/dgnc2006/06dgnc264.shtml

Published: May 8, 2006

© 2006 Sasajima et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.

Outline

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Objective: 123I-metaiodobenzylguanidine (MIBG) has been developed as a functional analog of the neurotransmitter norepinephrine. MIBG enters adrenergic cells through a sodium- and energy-dependent uptake mechanism (so-called uptake-one amine transport mechanism) and then resides in and leaves the chromaffin storage vesicles of adrenomedullary tissue. The success of MIBG as an imaging agent for the neural crest tumors is derived from its chemical similarities to norepinephrine. We have reported the feasibility of 123I-MIBG in the diagnosis of intracranial embryonal tumors. The aim of this study is to explore whether delayed imaging of 123I-MIBG is suitable for preoperative differential diagnosis of embryonal tumors from other brain tumors.

Methods: Sixteen patients with histologically proven brain tumors (three medulloblastomas, one neuroblastoma, six gliomas, and six meningiomas) were examined with single-photon emission computerized tomography (SPECT) using 123I-MIBG. The uptake of the tracer for regions of tumors was calculated on SPECT images scanned 30 min (early images) and 6 hr (delayed images) after the intravenous injection of 123I-MIBG at a dose of 111 MBq. The ratio of tumor (area of highest uptake) / nontumor (T/NT) was calculated as an indicator of selective uptake in the tumor. Furthermore, retention index (RI) was calculated as follows: RI= (delayed T/NT－early T/NT) / early T/NT.

Results: The T/NT ratios on the early images for embryonal tumors (medulloblastomas and neuroblastoma), gliomas, and meningiomas were 3.2±1.7 (mean±SD), 1.4±0.3, and 1.6±0.5, respectively. The early uptake was significantly higher in the embryonal tumors than in gliomas (p<0.05). Delayed T/NT ratios for embryonal tumors were increased compared to the early T/NT ratios, while in contrast delayed T/NT ratios for the other tumors remained low (1.2 -1.7). The high retention indices of the embryonal tumors indicate specific uptake of 123I-MIBG in the tumors. 123I-MIBG was appropriated for a time-dependent strategy to reduce background radioactivity and increase the specificity of the resultant images with respect to intracellular localization of MIBG in tumor cells.

Conclusions: We confirmed the increased accumulation of 123I-MIBG on the 6-hr delayed SPECT images in the patients with medulloblastomas and neuroblastoma. 123I-MIBG SPECT, especially 6-hr delayed imaging, may provide important information on the differential diagnosis of embryonal brain tumors from gliomas and meningiomas.