How to Provide Gadolinium-Free PET/MR Cancer Staging of Children and Young Adults in Less than 1 h: the Stanford Approach
To provide clinically useful gadolinium-free whole-body cancer staging of children and young adults with integrated positron emission tomography/magnetic resonance (PET/MR) imaging in less than 1 h.
In this prospective clinical trial, 20 children and young adults (11–30 years old, 6 male, 14 female) with solid tumors underwent 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) PET/MR on a 3T PET/MR scanner after intravenous injection of ferumoxytol (5 mg Fe/kg) and [18F]FDG (2–3 MBq/kg). Time needed for patient preparation, PET/MR image acquisition, and data processing was compared before (n = 5) and after (n = 15) time-saving interventions, using a Wilcoxon test. The ferumoxytol-enhanced PET/MR images were compared with clinical standard staging tests regarding radiation exposure and tumor staging results, using Fisher’s exact tests.
Tailored workflows significantly reduced scan times from 36 to 24 min for head to mid thigh scans (p < 0.001). These streamlined PET/MR scans were obtained with significantly reduced radiation exposure (mean 3.4 mSv) compared to PET/CT with diagnostic CT (mean 13.1 mSv; p = 0.003). Using the iron supplement ferumoxytol “off label” as an MR contrast agent avoided gadolinium chelate administration. The ferumoxytol-enhanced PET/MR scans provided equal or superior tumor staging results compared to clinical standard tests in 17 out of 20 patients. Compared to PET/CT, PET/MR had comparable detection rates for pulmonary nodules with diameters of equal or greater than 5 mm (94 vs. 100 %), yet detected significantly fewer nodules with diameters of less than 5 mm (20 vs 100 %) (p = 0.03). [18F]FDG-avid nodules were detected with slightly higher sensitivity on the PET of the PET/MR compared to the PET of the PET/CT (59 vs 49 %).
Our streamlined ferumoxytol-enhanced PET/MR protocol provided cancer staging of children and young adults in less than 1 h with equivalent or superior clinical information compared to clinical standard staging tests. The detection of small pulmonary nodules with PET/MR needs to be improved.
Key wordsPositron-emission tomography Magnetic resonance imaging Nanoparticles Cancer Pediatrics
This work was supported by a grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, grant number R01 HD081123-01A1. We thank Praveen Gulaka, Dawn Holley, and Harsh Gandhi from the PET/MR Metabolic Service Centre for their assistance with the acquisition of PET/MR scans. We thank the members of Daldrup-Link lab for valuable input and discussions regarding this project.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
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