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A Journal on Nuclear Medicine and Molecular Imaging

A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the Society of Radiopharmaceutical Sciences and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413

Frequency: Quarterly

ISSN 1824-4785

Online ISSN 1827-1936


The Quarterly Journal of Nuclear Medicine and Molecular Imaging 2015 Jan 08

Discrepant salivary gland response after radioiodine and MIBG therapies

Jentzen W., Richter M., Poeppel T. D., Schmitz J., Brandau W., Bockisch A., Binse I.

Klinik für Nuklearmedizin, Universität Duisburg-­Essen, Essen, Germany

AIM: A retrospective study using PET/CT imaging with 124I-­labeled metaiodobenzylguanidine (124I-­MIBG) was performed to estimate the (radiation) absorbed dose to the salivary glands in neuroendocrine cancer patients undergoing 131I-­MIBG therapy and to compare these results with those in radioiodine (131I-­iodide) therapy.
METHODS: Twenty-­seven patients received individual 124I-­MIBG-­PET/CT dosimetries, among whom 18 had not previously undergone any MIBG therapies (patient group before treatment) and 9 had already received MIBG therapies prior to the tracer dosimetries (patient group after treatment). For each patient, three or four 124I-­MIBG PET/CT scans were performed at approximately 4 and 24 h, as well as at approximately 48 or/and ≥96 h after tracer injection. The absorbed doses per administered 131I-­MIBG activity to the submandibular and parotid glands were calculated based on the MIRD concept, with its assumption of an uniform glandular activity distribution.
RESULTS: The mean±standard deviation of the (self-­)absorbed dose per activity averaged over both patient groups and salivary gland types was 0.53±0.24 Gy/GBq (median, 0.49 Gy/GBq; range, 0.17–1.38 Gy/GBq). The absorbed doses per activity of the patient group before treatment did not significantly deviate from those of the patient group after treatment (P=0.67). In the patient group after treatment, the mean±standard deviation of the cumulative 131I-­MIBG activity was 20±12 GBq (median, 16 GBq; range, 10–50 GBq). Among the patient groups, no significant absorbed dose difference was found between the submandibular and parotid glands (P>0.24). In comparison to radioiodine therapy, the estimated absorbed dose per activity in MIBG was significantly higher (P<0.001), on average twice as high, contradicting the relationship between the absorbed dose andì clinical observation of glandular side effects.
CONCLUSION: The discrepant salivary gland responses in MIBG and radio iodine therapies suggest a different radiotherapeutical distribution on microscopic scale within the glandular tissue and prove the clinical relevance of a microdosimetric analysis.

language: English


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