Performing [18F]MFBG Long-Axial-Field-of-View PET/CT Without Sedation or General Anesthesia for Imaging of Children with Neuroblastoma

Abstract

Meta-[¹²³I]iodobenzylguanidine ([¹²³I]MIBG) scintigraphy with SPECT/CT is the standard of care for diagnosing and monitoring neuroblastoma. Replacing [¹²³I]MIBG with the new PET tracer meta-[¹⁸F]fluorobenzylguanidine ([¹⁸F]MFBG) and further improving sensitivity and reducing noise in a new long-axial-field-of-view (LAFOV) PET/CT scanner enable increased image quality and a faster acquisition time, allowing examinations to be performed without sedation or general anesthesia (GA). Focusing on feasibility, we present our first experience with [¹⁸F]MFBG LAFOV PET/CT and compare it with [¹²³I]MIBG scintigraphy plus SPECT/CT for imaging in neuroblastoma in children. Methods: A pilot of our prospective, single-center study recruited children with neuroblastoma who were referred for [¹²³I]MIBG scintigraphy with SPECT/CT. Within 1 wk of [¹²³I]MIBG scintigraphy and SPECT/low-dose CT, [¹⁸F]MFBG LAFOV PET/ultra-low-dose CT was performed 1 h after injection (1.5-3 MBq/kg) without sedation or GA, in contrast to the 24-h postinjection interval needed for scanning with [¹²³I]MIBG, the 2- to 2.5-h acquisition time, and the GA often needed in children less than 6 y old. Based on the spirocyclic iodonium-ylide precursor, [¹⁸F]MFBG was produced in a fully automated good manufacturing practice-compliant procedure. We present the feasibility of the study. Results: In the first paired scans of the first 10 children included (5 at diagnosis, 2 during treatment, 2 during surveillance, and 1 at relapse), [¹⁸F]MFBG PET/CT scan showed a higher number of radiotracer-avid lesions in 80% of the cases and an equal number of lesions in 20% of the cases. The SIOPEN score was higher in 50% of the cases, and the Curie score was higher in 70% of the cases. In particular, intraspinal, retroperitoneal lymph node, and bone marrow involvement was diagnosed with much higher precision. None of the children (median age, 1.6 y; range, 0.1-7.9 y) had sedation or GA during the PET procedure, whereas 80% had GA during [¹²³I]MIBG scintigraphy with SPECT/CT. A PET acquisition time of only 2 min without motion artifacts was the data requirement of the 10-min acquisition time for reconstruction to provide a clinically useful image. Conclusion: This pilot study demonstrates the feasibility of performing [¹⁸F]MFBG LAFOV PET/CT for imaging of neuroblastoma. Further, an increased number of radiotracer-avid lesions, an increased SIOPEN score, and an increased Curie score were seen on [¹⁸F]MFBG LAFOV PET/CT compared with [¹²³I]MIBG scintigraphy with SPECT/CT, and GA and sedation was avoided in all patients. Thus, with a 1-d protocol, a significantly shorter scan time, a higher sensitivity, and the avoidance of GA and sedation, [¹⁸F]MFBG LAFOV PET/CT shows promise for future staging and response assessment and may also have a clinical impact on therapeutic decision-making for children with neuroblastoma.

Keywords: [18F]MFBG; [18F]MFBG LAFOV PET/CT; neuroblastoma; pediatrics; total-body PET/CT.

Graphical abstract

FIGURE 1.

PET images obtained in list mode in 30-s increments, excluding periods of motion artifacts in reconstruction of images.

FIGURE 2.

Sagittal and axial view of tracer uptake in pineal gland (arrows, A) and pituitary gland (arrows, B) seen on [¹⁸F]MFBG LAFOV PET/MRI. A = anterior; P = posterior.

FIGURE 3.

(A) [¹⁸F]MFBG LAFOV PET/ULD CT (top) and [¹²³I]MIBG scintigraphy with SPECT/LD CT images (bottom) of 7-wk-old girl with neuroblastoma. [¹⁸F]MFBG image shows intraspinal and bone marrow involvement not seen on [¹²³I]MIBG image. [¹⁸F]MFBG PET/ULD CT image shows uptake in tumor in right hemithorax with intraspinal involvement with direct extension into neural foramina and spinal canal between thoracic vertebrae 4/5 and 5/6 (top red arrow), several liver lesions (middle red arrow), and in bone marrow of right tibia (bottom red arrow). [¹²³I]MIBG scintigraphy with SPECT/LD CT image shows only large thoracic tumor (top purple arrow) and liver metastases (bottom purple arrow). Spinal involvement and bone marrow involvement could not be identified on [¹²³I]MIBG scintigraphy with SPECT/LD CT. (B) [¹⁸F]MFBG LAFOV PET/ULD CT and [¹²³I]MIBG scintigraphy with SPECT/LD CT images of 6-y-old girl with paravertebral relapse of neuroblastoma stage IV in left adrenal gland without N-Myc gene amplification. [¹⁸F]MFBG image shows lymph node involvement not seen on [¹²³I]MIBG image. [¹⁸F]MFBG PET/ULD CT postoperative image, after resection of paravertebral relapse, shows uptake in left-side cervical lymph node (top left red arrows) and 2 retroperitoneal lymph nodes (top right red arrows), not identified on [¹²³I]MIBG scintigraphy with SPECT/LD CT. A = anterior; MIP = maximum-intensity projection.