Clinical Perspectives for 18F-FDG PET Imaging in Pediatric Oncology: Μetabolic Tumor Volume and Radiomics

Abstract

Pediatric cancer, although rare, requires the most optimized treatment approach to obtain high survival rates and minimize serious long-term side effects in early adulthood. 18F-FDG PET/CT is most helpful and widely used in staging, recurrence detection, and response assessment in pediatric oncology. The well-known 18F-FDG PET metabolic indices of metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) have already revealed an independent significant prognostic value for survival in oncologic patients, although the corresponding cut-off values remain study-dependent and not validated for use in clinical practice. Advanced tumor “radiomic” analysis sheds new light into these indices. Numerous patterns of texture 18F-FDG uptake features can be extracted from segmented PET tumor images due to new powerful computational systems supporting complex “deep learning” algorithms. This high number of “quantitative” tumor imaging data, although not decrypted in their majority and once standardized for the different imaging systems and segmentation methods, could be used for the development of new “clinical” models for specific cancer types and, more interestingly, for specific age groups. In addition, data from novel techniques of tumor genome analysis could reveal new genes as biomarkers for prognosis and/or targeted therapies in childhood malignancies. Therefore, this ever-growing information of “radiogenomics”, in which the underlying tumor “genetic profile” could be expressed in the tumor-imaging signature of “radiomics”, possibly represents the next model for precision medicine in pediatric cancer management. This paper reviews 18F-FDG PET image segmentation methods as applied to pediatric sarcomas and lymphomas and summarizes reported findings on the values of metabolic and radiomic features in the assessment of these pediatric tumors.

Comparison of the different imaging modalities used to image pediatric oncology patients: A COG diagnostic imaging committee/SPR oncology committee white paper

“…Currently, there are not always validated semiquantitative criteria available in the literature, but visual assessment correlated with the available localization technique, either CT or MR, can provide important metabolic information for patient management. It is the hope that increased standard utilization of imaging guidelines that are presented in these published monographs will enable the collection of data to provide further scientific validation 66–74 …”

“…It is the hope that increased standard utilization of imaging guidelines that are presented in these published monographs will enable the collection of data to provide further scientific validation. [66][67][68][69][70][71][72][73][74] Whole-body thyroid imaging with radioiodine in children with differentiated thyroid cancer is also a common indication as is mIBG imaging for neuroblastoma. [75][76][77] [85][86][87] These are studies that are acquired sequentially on the same gantry with the patient not moved between studies.…”

The Role of Molecular Imaging in Personalized Medicine

“…Molecular imaging is used widely in screening, detection and diagnosis, treatment, assessing disease heterogeneity and progression planning, molecular characteristics, and long-term follow-up. Moreover, it is able to detect very tiny tumors and assess their activity numerically, which makes molecular imaging one of the most scientific reasons that contributes greatly to expanding and developing the personalized medicine, research, clinical trials, and medical practice of cancer fields, evolving a new generation of platforms with greater accuracy and sensitivity for in vivo quantification and characterization of various biological processes [ 4 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ].…”