PET/CT Imaging is Best Method for Detecting Cancer in Children

Positron emission tomography/computed tomography (PET/CT) imaging exhibits significantly higher sensitivity, specificity, and accuracy than conventional imaging when it comes to detecting malignant tumors in children, according to recent research. Furthermore, PET/CT imaging provides clinicians with additional information about cancer in children, possibly sparing young patients from being overtreated.

The study was performed by researchers from Johns Hopkins Medical Institutions (Baltimore, MD, USA) and was published in the December 2007 issue of the Journal of Nuclear Medicine. "PET/CT is useful in finding small tumors in small children and is a promising imaging tool in evaluating pediatric malignancies,” said Richard L. Wahl, professor of nuclear medicine at Johns Hopkins Medical Institutions. "In our study, we found that PET/CT can detect small lymph node lesions diagnosed as negative with conventional [or anatomic] imaging and deny the presence of active disease in soft-tissue masses post-treatment--especially in children with a wide range of malignant cancers. Using PET/CT could help spare children from overtreatment while fighting their disease,” he added.

There are few findings about the use of PET/CT imaging in comparison with traditional imaging with pediatric patients, according to Dr. Wahl, explaining that investigators retrospectively reviewed cases to evaluate the efficacy of PET/CT when compared with other imaging techniques. Researchers reviewed 151 FDG PET/CT scans that were performed on 55 children with noncentral nervous system malignancies (30 patients had lymphoma).

PET/CT imaging--with the radiotracer fluorodeoxyglucose (FDG)--enables the gathering of both biologic and anatomic data during a single exam, with PET capturing metabolic signals of body cells and tissues and CT offering a detailed map of internal anatomy. "PET/CT showed its broad applicability and utility by providing additional information--in more than one-third of the children's exams--that could be used by doctors to more appropriately manage or treat the disease in children,” added Dr. Wahl. When there were inconsistencies between PET/CT and conventional anatomic imaging in analyzing cancer lesions, PET/CT was diagnostically accurate 90% of the time, reported Dr. Wahl, who pioneered the use of PET with FDG and fusion imaging in a wide range of common adult cancers.

Clinicians monitor the radiation dose given to children in imaging exams, typically using lower doses than that of adult patients, to get adequate exam results, according to Dr. Wahl. "Especially as a follow-up examination, PET/CT appears to be the best imaging modality currently, as it provides both PET and CT information simultaneously in pediatric patients, in whom fewer examinations are preferable,” Dr. Wahl added. He indicated that additional studies with specific childhood cancers are warranted.

PET is a powerful molecular imaging procedure that noninvasively demonstrates the function of organs and other tissues. When PET is used to image cancer, a radiopharmaceutical (such as FDG, which includes both a glucose and a radionuclide molecule) is injected into a patient. Cancer cells metabolize sugar at higher rates than normal cells, and the radiopharmaceutical is drawn in higher amounts to cancerous areas. PET scans show where FDG is by tracking the gamma rays given off by the radionuclide tagging the drug and producing three-dimensional images of their distribution within the body. PET/CT provides precise fusion of metabolic PET images with high-quality anatomic CT images.


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