Abstract
The metaiodobenzylguanidine (MIBG) scan is one of the most sensitive noninvasive lesion detection modalities for neuroblastoma. Unlike 123I-MIBG, 124I-MIBG allows high-resolution positron emission tomography (PET). We evaluated 124I-MIBG PET/CT for its diagnostic performance directly compared to paired 123I-MIBG scans. Methods: Prior to 131I-MIBG therapy, standard 123I-MIBG scans (5.2 MBq/kg) that include whole-body (anterior-posterior) planar scans and focused field of view (FOV) single photon emission computed tomography combined with CT (SPECT/CT) as well as whole-body 124I-MIBG PET/CT (1.05 MBq/kg) were performed in 7 patients. After therapy, 2 of 7 patients also completed 124I-MIBG PET/CT as well as paired 123I-MIBG planar and SPECT/CT scans. One patient received 124I-MIBG PET/CT only after therapy. We evaluated all 8 patients who showed at least one 123I-MIBG-positive lesion with a total of 10 scans. In 8 pairs, 123I-MIBG and 124I-MIBG were performed within 1 month of each other. Locations of identified lesions, the number of total lesions, and the Curie scores were recorded for 123I-MIBG and 124I-MIBG scans. Finally, for five patients who completed at least three PET/CT scans after administration of 124I-MIBG, we estimated the effective dose of 124I-MIBG. Results: 123I-MIBG whole-body planar scans, focused FOV SPECT/CT scans, and whole-body 124I-MIBG PET scans found 25, 32, and 87 total lesions respectively. There was a statistically significant difference in detecting lesions on 124I-MIBG PET/CT as compared to 123I-MIBG planar scans (P < 0.0001) and 123I-MIBG SPECT/CT (P < 0.0001). The Curie scores were also higher for 124I-MIBG PET/CT as compared to those for 123I-MIBG planar and SPECT/CT in 6 out of 10 scans. 124I-MIBG PET/CT demonstrated better detection of lesions throughout the body including chest, spine, head and neck, and extremities. The effective dose estimated for patient-specific 124I-MIBG was approximately ten times that of 123I-MIBG; however, given that we administered a very low activity of 124I-MIBG (1.05 MBq/kg), the effective dose was only approximately twice that of 123I-MIBG despite the large difference in half-lives (100 vs. 13.2 hours). Conclusion: The first in human use of low-dose 124I-MIBG PET for monitoring disease burden demonstrated superior tumor detection capability as compared to 123I-MIBG planar and SPECT/CT scans.
- Copyright © 2020 by the Society of Nuclear Medicine and Molecular Imaging, Inc.