ECE2007 Oral Communications Endocrine tumors & neoplasia (7 abstracts)
[123I]Iodometomidate as a radiotracer for adrenal scintigraphy – first clinical experience
Stefanie Hahner 1 , Andrea Stuermer 1 , Martin Fassnacht 1 , Michael Kreissl 2 , Christoph Reiners 2 , Felix Beuschlein 3 , Martina Zink 1 , Ilse Zolle 4 , Andreas Schirbel 2 & Bruno Allolio 1
1University of Wuerzburg, Dept. of Endocrinology and Diabetology, Wuerzburg, Germany; 2University of Wuerzburg, Dept. of Nuclear Medicine, Wuerzburg, Germany; 3University of Munich, LMU, Division of Endocrine Research, Munich, Germany; 4University of Vienna, Ludwig-Boltzmann-Institute of Nuclear Medicine, Vienna, Austria.
Adrenal masses are highly prevalent tumours comprising of a variety of entities. Therefore, therapeutic consequences also vary considerably. The CYP11B-specific PET-tracer [11C]metomidate has been shown to be suitable to characterize adrenal lesions. However, its availability is restricted to PET-centers with an on-site cyclotron. Also imaging is hindered by the short tracer half-life (20 min). Therefore, we have developed [123I]iodometomidate as a tracer for adrenal imaging. Pharmakokinetics and biodistribution after i.v.-injection of 40 MBq of [123I]iodometomidate were analyzed in mice using small animal single photon emission computed tomography (SPECT). A 49 year old woman with bilateral adrenal tumors (hounsfield units >10 suggesting a non-adenoma lesion) and borderline urinary catecholamines (patient 1) and a 22 year old man after adrenalectomy for adrenocortical carcinoma with a lesion suspicious for metastasis in the os sacrum (patient 2) were investigated with [123I]iodometomidate-SPECT. Adrenals were excellently visualized in mice with high tracer uptake and little background activity. In patients, adrenals were first detected 60 min p.i. with a maximum uptake in the adrenals after 5–6 hours indicating slow pharmacokinetics of the tracer. At 24 h.p.i. high uptake was detected exclusively in the adrenals. In patient 1 both tumours exhibited high tracer uptake confirming the adrenocortical origin of the lesions. In patient 2 the remaining hyperplastic adrenal was clearly visible. However, no uptake was detected in the os sacrum lesion. Subsequent biopsy revealed a periostal chondroma. For both patients calculated whole body radiation exposure was 3.2 mSv. This is the first description of [123I]Iodometomidate as a radiotracer in patients. Iodometomidate is a highly suitable tracer combining specific uptake in adrenocortical tissue with far lower radiation exposure compared to norcholesterol scintigraphy. Availability and pharmacokinetics are superior to [11C]metomidate-PET. Furthermore, radiotherapy of adrenocortical carcinoma using [131I]iodometomidate appears to be feasible.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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