Christopher Klenk MD, Presenter: Nothing to Disclose

Rakhee Sameer Gawande MD, Abstract Co-Author: Nothing to Disclose

Vythao Tran MD, Abstract Co-Author: Nothing to Disclose

Alex McMillan, Abstract Co-Author: Nothing to Disclose

Andrew Quon MD, Abstract Co-Author: Nothing to Disclose

Heike E. Daldrup-Link MD, Abstract Co-Author: Nothing to Disclose

To evaluate if the administration of Gd-chelates is necessary for evaluation of pediatric abdominal and pelvic tumors on 18F-FDG-PET/MR scans.

In a first step, we compared the accuracy of pre-contrast T2-weighted FSE, DWI and T1-weighted LAVA scans with Gadobenate-enhanced T1-weighted MR scans for the evaluation of 14 diagnostic criteria in 119 patients with abdominal and pelvic tumors. In a second step, we identified a subset of 36 pediatric patients who had received an 18F-FDG PET scan within 3 weeks of their MR scan. In these patients, we evaluated concordance or discordance of 18F-FDG PET and gadolinium tumor enhancement, using a McNemar’s test. In addition, we evaluated the diagnostic accuracy of 18F-FDG PET/T2-FSE and 18F-FDG PET/Gd-LAVA scans regarding the 14 diagnostic criteria for tumor staging. Histopathology, surgical notes and follow up imaging served as the standard of reference.

Pre- and post contrast MR scans did not show significant differences in diagnostic accuracies of 14 diagnostic criteria that evaluated image quality and tumor origin, extent, composition and differential diagnosis (p<0.05). The 18F-FDG PET/MR subgroup showed concordant Gd-enhancement and 18F-FDG avidity in 31 of 36 patients and 106 of 123 tumors. There was no significant difference in diagnostic accuracy of integrated 18F-FDG PET/T2-FSE and 18F-FDG PET/Gd-LAVA scans (p< 0.05).

Conclusion: Gd-contrast administration is not necessary for evaluation of pediatric abdominal and pelvic tumors on integrated 18F-FDG-PET/MR scans. Exceptions may include focal liver lesions.

If Gd-administration does not provide additional information compared to 18F-FDG-PET scans, MR scans for local staging could be streamlined and Gd-chelates could be replaced by alternative, more specific MR contrast agents.

Klenk, C, Gawande, R, Tran, V, McMillan, A, Quon, A, Daldrup-Link, H, 18F-FDG PET/MR for Local Staging of Pediatric Malignancies: Is Administration of Gd-chelates Necessary?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016874.html