Baseline FDG PET/CT in free breathing versus deep inspiration breath-hold for pediatric patients with mediastinal lymphoma

Abstract

Introduction

The prospective TEDDI protocol investigates the feasibility of radiotherapy delivery in deep inspiration breath-hold (DIBH) for pediatric patients. To secure optimal radiotherapy planning, a diagnostic baseline FDG PET/CT in free breathing (FB) and DIBH was acquired. The anatomical changes in the mediastinum and the effect on PET metrics between the two breathing conditions were assessed for pediatric patients with mediastinal lymphoma.

Material and methods

Ten patients aged 5–17 were included and had a PET/CT in FB and DIBH. Metabolic active lymphoma volumes were manually delineated with a visually based segmentation method and the PET metrics were extracted. The anatomical lymphoma, lung and heart volumes were delineated on CT.

Results

The lung volume increased while the heart was displaced caudally and separated from the lymphoma in DIBH compared to FB. Both the anatomical and the metabolically active lymphoma volumes appeared different regarding shape and configuration in the two breathing conditions. The image quality of the DIBH PET was equal to the FB PET regarding interpretation and delineation of lymphoma lesions. All PET metrics increased on the DIBH PET compared to the FB PET with the highest increase observed for the maximum standardized uptake value (33%, range 7–56%).

Conclusion

Diminished respiratory motion together with anatomical changes within the lymphoma increased all PET metrics in DIBH compared to FB. The anatomical changes observed in DIBH compared to FB are expected to reduce radiation doses to the heart and lungs in pediatric patients with mediastinal lymphoma referred for radiotherapy delivery in DIBH and, thereby, reduce their risk of late effects.

Trial registration

The Danish Ethical Committee (H-16035870, approved November 24^th 2016), the Danish Data Protection Agency (2012-58-0004, approved 1 January 2017). Registered retrospectively at clinicaltrials.gov (NCT03315546, 20 October 2017).

Acknowledgments

The authors want to thank the participating children and their families.

Ethics approval

The TEDDI protocol was approved by the Danish Ethical Committee (H-16035870, approved 24 November 2016) and the Danish Data Protection Agency (2012-58-0004, approved 1 January 2017).

Disclosure statement

Professor Lena Specht is on advisory boards and received honoraria from Takeda, Kyowa Kirin, MSD, and Janssen. She has research grants from Varian and ViewRay. The remaining authors report no conflict of interest.

Additional information

Funding

This study was supported by the Danish Childhood Cancer Foundation [grant no. 2015-9] and the Danish Cancer Society [Grant no. R150-A10066].