With Pediatric Sarcoma, No Need for Bone Scans. PET/CT Sufficient.

Children with pediatric sarcoma can be spared the additional radiation of single photon emission computed tomography (SPECT). PET/CT imaging alone does the trick, according to a study presented this week at the Society of Nuclear Medicine annual meeting in San Antonio.

Sarcomas of the bone and soft tissue make up more than 13 percent of tumors among children, with approximately 1,500 new cases in the United States each year.

The study, led by Franziska Walter, MD, of the University of California Los Angeles, compared the PET/CT scans and bone scans (technetium-99m methylene diphosphonate SPECT scans) of 29 pediatric patients (26 boys and six girls, average age 12 years). The study was retrospective, considering scans from January 2006 to February 2010. Twenty one of the patients (72 percent) had bone sarcoma; eight (28 percent) had tissue sarcoma. 

A total of 39 paired scans were acquired, with some patients having been scanned more than once. Two observers read the SPECT scans, with two other readers simultaneously considered the PET/CT scans. Later, three readers assessed the PET/CT and SPECT scans side-by-side.

Twenty of the 39 studies showed malignant bone lesions, as established by reference standard. PET/CT found them all, the researchers found, compared to a SPECT accuracy of 80 percent. In three cases in which the disease was metastatic, SPECT scans spotted one; PET/CT identified them all.

“The current study strongly suggests that 99Tc-MDP bone imaging does not provide an additional diagnostic value over PET/CT imaging alone in pediatric sarcoma patients,” the researchers concluded, suggesting that physicians limit radiation exposure by omitting the SPECT scans.