<sup>124</sup>I-MIBG PET/CT to Monitor Metastatic Disease in Children with Relapsed Neuroblastoma
Mariam Aboian, Shih-Ying Huang, Miguel Hernandez‐Pampaloni, Randall A. Hawkins, Henry F. VanBrocklin, Yoonsuk Huh, Kieuhoa T. Vo, W. Clay Gustafson, Katherine K. Matthay, Youngho Seo
Abstract
The metaiodobenzylguanidine (MIBG) scan is one of the most sensitive noninvasive lesion detection modalities for neuroblastoma. Unlike <sup>123</sup>I-MIBG, <sup>124</sup>I-MIBG allows high-resolution PET. We evaluated <sup>124</sup>I-MIBG PET/CT for its diagnostic performance as directly compared with paired <sup>123</sup>I-MIBG scans. <b>Methods:</b> Before <sup>131</sup>I-MIBG therapy, standard <sup>123</sup>I-MIBG imaging (5.2 MBq/kg) was performed on 7 patients, including whole-body (anterior–posterior) planar imaging, focused-field-of-view SPECT/CT, and whole-body <sup>124</sup>I-MIBG PET/CT (1.05 MBq/kg). After therapy, 2 of 7 patients also completed <sup>124</sup>I-MIBG PET/CT as well as paired <sup>123</sup>I-MIBG planar imaging and SPECT/CT. One patient underwent <sup>124</sup>I-MIBG PET/CT only after therapy. We evaluated all 8 patients who showed at least 1 <sup>123</sup>I-MIBG–positive lesion with a total of 10 scans. In 8 pairs, <sup>123</sup>I-MIBG and <sup>124</sup>I-MIBG were performed within 1 mo of each other. The locations of identified lesions, the number of total lesions, and the curie scores were recorded for the <sup>123</sup>I-MIBG and <sup>124</sup>I-MIBG scans. Finally, for 5 patients who completed at least 3 PET/CT scans after administration of <sup>124</sup>I-MIBG, we estimated the effective dose of <sup>124</sup>I-MIBG. <b>Results:</b><sup>123</sup>I-MIBG whole-body planar scans, focused-field-of-view SPECT/CT scans, and whole-body <sup>124</sup>I-MIBG PET scans found 25, 32, and 87 total lesions, respectively. There was a statistically significant difference in lesion detection for <sup>124</sup>I-MIBG PET/CT versus <sup>123</sup>I-MIBG planar imaging (<i>P</i> < 0.0001) and <sup>123</sup>I-MIBG SPECT/CT (<i>P</i> < 0.0001). The curie scores were also higher for <sup>124</sup>I-MIBG PET/CT than for <sup>123</sup>I-MIBG planar imaging and SPECT/CT in 6 of 10 patients. <sup>124</sup>I-MIBG PET/CT demonstrated better detection of lesions throughout the body, including the chest, spine, head and neck, and extremities. The effective dose estimated for patient-specific <sup>124</sup>I-MIBG was approximately 10 times that of <sup>123</sup>I-MIBG; however, given that we administered a very low activity of <sup>124</sup>I-MIBG (1.05 MBq/kg), the effective dose was only approximately twice that of <sup>123</sup>I-MIBG despite the large difference in half-lives (100 vs. 13.2 h). <b>Conclusion:</b> The first-in-humans use of low-dose <sup>124</sup>I-MIBG PET for monitoring disease burden demonstrated tumor detection capability superior to that of <sup>123</sup>I-MIBG planar imaging and SPECT/CT.