Lesion Analysis of 18F-Metafluorobenzylguanidine PET Imaging in Neuroblastoma

Abstract

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.

Keywords: 123I-MIBG; 18F-MFBG; dosimetry; neuroblastoma; neuroendocrine.

Graphical abstract

FIGURE 1.

Negative ¹²³I-MIBG and ¹⁸F-MFBG scans (concurrent) of 7-y-old patient with relapsed refractory neuroblastoma (stage IV disease) after chemoimmunotherapy. ¹²³I-MIBG scan was performed to evaluate extent of disease. Patient showed no ¹²³I-MIBG uptake (A; whole-body and fused images) with concordant lack of uptake on ¹⁸F-MFBG (B; maximum-intensity-projection and fused images) in left iliac crest or right acetabular lesions (arrows). Bone marrow biopsy was negative for disease. Patient continued with maintenance treatment.

FIGURE 2.

¹²³I-MIBG–negative and ¹⁸F-MFBG–positive scans showing multiple lesions in 9-y-old male with relapsed high-risk, multiple-relapse neuroblastoma (stage IV disease) receiving chemoimmunotherapy. (A) ¹²³I-MIBG uptake is seen in lower lumbar vertebrae (arrows). Positive uptake with ¹⁸F-MFBG PET (B; black arrows) in skull, spine, pelvic bones, femora, and left tibia (B and C; blue and white arrows). Bone marrow biopsy was positive for disease. Follow-up ¹²³I-MIBG imaging (D; left) and spine MRI (D; right) performed 6 wk later showed diffuse disease in skull and spine, corresponding to ¹⁸F-MFBG–avid sites.

FIGURE 3.

¹²³I-MIBG–positive and ¹⁸F-MFBG–negative scans with multiple lesions in 17-y-old male with metastatic neuroblastoma (stage IV disease). ¹²³I-MIBG scan shows uptake in left upper chest (A) posteriorly localizing to rib (B), with additional uptake in left iliac bone and sacrum on SPECT CT (arrows). ¹⁸F-MFBG maximum-intensity-projection image (C) and fused image (D) show uptake in left rib and right scapula, but no uptake is seen in iliac bone or sacrum (lower panel), noted as stable treated disease at follow-up. Patient continued with maintenance treatment.

FIGURE 4.

¹²³I-MIBG–negative and ¹⁸F-MFBG–negative images with single additional lesion in 14-y-old male with relapsed neuroblastoma. Whole-body ¹²³I-MIBG scan (A) (upper left) and SPECT (lower left) showed no suspicious foci. ¹⁸F-MFBG maximum-intensity-projection image (A; upper right) and axial fused image (lower right) showed clear focal uptake in right pubic bone (arrow). This was only site of disease noted on ¹⁸F-MFBG scan and confirmed as disease on ¹⁸F-FDG PET performed within 2 wk (B; upper) and follow-up MRI 3 wk after (B; lower) initial scan.