Lesion Analysis of 18F-Metafluorobenzylguanidine PET Imaging in Neuroblastoma

A PET analog of metaiodobenzylguanidine (MIBG)—¹⁸F-metafluorobenzylguanidine (¹⁸F-MFBG)—allows for rapid same-day imaging. We previously reported on the safety and feasibility of ¹⁸F-MFBG PET imaging in patients with neuroendocrine tumors. We now report a comprehensive analysis of lesion detection with ¹⁸F-MFBG imaging in patients with neuroblastoma compared with ¹²³I-MIBG imaging. Methods: We analyzed concurrent ¹⁸F-MFBG and ¹²³I-MIBG scans in 37 patients (40 paired scans). Patients with relapsed or refractory neuroblastoma were included. Patients received 74.11–465.83 MBq (2.0–12.6 mCi) of ¹⁸F-MFBG intravenously, followed by imaging 60 min after injection. All patients had an ¹²³I-MIBG scan within 4 wk of ¹⁸F-MFBG imaging without any intervening therapy. ¹²³I-MIBG scans included whole-body planar and SPECT/CT of the chest, abdomen, and pelvis. All detected lesions were noted for each modality. ¹²³I-MIBG and ¹⁸F-MFBG findings were evaluated for concordance and discordance. Modified Curie scores were assigned to both ¹²³I-MIBG scans, equivalent scores were ascertained for ¹⁸F-MFBG imaging, and scores were then compared. Results: All patients with a positive ¹²³I-MIBG scan had positive ¹⁸F-MFBG imaging. In 2 patients, both ¹²³I-MIBG and ¹⁸F-MFBG scans were negative. In 1 patient, the ¹⁸F-MFBG scan was positive, whereas the ¹²³I-MIBG scan was negative. In 30 of 40 scans, ¹⁸F-MFBG showed more sites than did ¹²³I-MIBG. Overall, more lesions were noted on the ¹⁸F-MFBG scans (mean, 18; range 0–61) compared with the ¹²³I-MIBG scans (mean, 12; range, 0–44), and 455 lesions were concordant. The Curie score for ¹⁸F-MFBG was higher, with an average of 11 (range, 0–25) compared with 8 for ¹²³I-MIBG (range, 0–22). Of the 273 ¹⁸F-MFBG–positive/¹²³I-MIBG–negative lesions, follow-up clinical and imaging assessment was available for 234 lesions in 30 patients, and 100% of these were confirmed true-positive. Conclusion: ¹⁸F-MFBG PET offers faster imaging and superior detection compared with ¹²³I-MIBG imaging. ¹⁸F-MFBG had high concordance with ¹²³I-MIBG at the patient level and showed more lesions in most patients. ¹⁸F-MFBG is an attractive alternative to ¹²³I-MIBG.