RT Journal Article
SR Electronic
T1 Tumor Dose–Response Relationship of [<sup>131</sup>I]MIBG Therapy in Patients with Neural Crest Tumors by Means of [<sup>124</sup>I]MIBG PET
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.124.269377
DO 10.2967/jnumed.124.269377
A1 Moraitis, Alexandros
A1 Prochnow, Andre
A1 Poeppel, Thorsten Dirk
A1 Schmitz, Jochen
A1 Laschinsky, Christina
A1 Herrmann, Ken
A1 Bockisch, Andreas
A1 Fragoso Costa, Pedro
A1 Kersting, David
A1 Jentzen, Walter
YR 2025
UL http://jnm.snmjournals.org/content/early/2025/03/13/jnumed.124.269377.abstract
AB [131I]Metaiodobenzylguanidine (MIBG) therapy in patients with neural crest tumors has demonstrated sustained control of catecholamine-associated hypertension and corresponding partial response. Details on how neural crest tumors respond to an absorbed dose delivered by [131I]MIBG-targeted therapies is insufficiently known. The primary aim of this retrospective study was to assess the tumor dose–response relationship by means of quantitative analysis of [124I]MIBG PET data. Methods: The tumor dose–response relationship was studied in patients with advanced malignant pheochromocytoma, neuroblastoma, or paraganglioma receiving [131I]MIBG treatment, as well as pretherapeutic and follow-up [124I]MIBG-based dosimetry. [124I]MIBG PET imaging was performed around 4, 24, 48, and 120 h after injection. Lesion uptake was projected to [131I]MIBG for every time point, and respective time-integrated activity coefficients (TIACs) for [131I]MIBG were calculated and used for tumor-absorbed dose estimation. Functional response was denoted for decrease of maximal lesion uptake or TIAC by at least 30% in the follow-up examination. In a consecutive analysis, the predictive value of a single tumor-uptake assessment from PET imaging at 24 h after administration was investigated with respect to receiving the derived target dose. Results: In total, 46 lesions from 9 patients were available for dose–response analysis. The mean ± SD tumor-absorbed dose coefficient was 13.4 ± 15.4 Gy/GBq (median, 7.2 Gy/GBq; range, 1.1–64.7 Gy/GBq). A high correlation (−0.60, P &lt; 0.001) was found between uptake decrease and tumor dose. In addition, a very high correlation (0.91, P &lt; 0.001) was found between uptake and TIAC decrease. The estimated targeted tumor dose was 200 Gy, that is, the dose at which the response rate exceeded the 90% threshold. A single 24-h uptake assessment showed predictive value with respect to receiving the target dose. Conclusion: This study demonstrated a clear correlation between tumor-absorbed dose and functional response in [131I]MIBG therapy and proposes a target dose for response at the tumor level.