PET/CT may improve evaluation of pediatric cancers

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PET/CT exhibited better diagnostic performance than conventional imaging (CI) and showed accurate findings in 90 percent of lesions in noncentral nervous system (CNS) pediatric malignancies with discordant findings between them, according to the December issue of The Journal of Nuclear Medicine.

Mitsuaki Tatsumi, MD, and colleagues from the Johns Hopkins Medical Institutions in Baltimore reviewed their experience of 18F-FDG PET/CT in CNS pediatric malignancies and evaluated if PET/CT, providing additional information to CI examinations to determine the efficacy of the imaging modality in the clinical setting.

The researchers evaluated 151 consecutive FDG PET/CT exams for 55 pediatric patients with non-CNS malignant tumors were reviewed. Among them, 108 PET/CT exams were accompanied by CI, such as contrast CT or MRI, performed within a month of PET/CT at Johns Hopkins. Two radiologists reviewed the indication, purpose, and PET/CT findings and compared the findings with those of CI, if available, on the representative lesion in each of the six separate body regions. According to the researchers’ standards, positive findings included abnormal findings related to malignant lesions (suspected), as well as equivocal findings, in which the presence of malignancy could not be denied. They excluded findings considered to relate to past treatment. The accuracy of the findings was determined on the basis of the reference standard comprising histopathologic findings or informative follow-up of greater than one year. 

The findings included 56 PET/CT-positive–CI-positive, 26 PET/CT-positive–CI-negative, and 54 PET/CT-negative–CI-positive lesions in 108 PET/CT examinations accompanied by CI, of which 54, 20, and 52 exhibited accurate PET/CT findings, respectively. Among the findings, 17 of the 20 PET/CT true-positive–CI false-negative lesions represented small lymph nodes diagnosed as negative on CI. All 52 PET/CT true-negative–CI false-positive findings were observed in lesions in a posttreatment status including 30 mediastinal masses in lymphoma.

The examination-based analysis revealed that additional information of PET/CT to CI was found in 37 (34 percent) of the 108 exams: 23 (21 percent) as negative and 14 (13 percent) as positive PET/CT findings.

The results showed that PET/CT exhibited better diagnostic performance than CI and showed accurate findings in 90 percent (72/80) of pediatric lesions. PET/CT was demonstrated to be an accurate imaging modality in evaluating pediatric patients with non-CNS malignancies, according to the authors.