JNM: FDG-PET useful for early-stage pediatric neuroblastoma
PET is an important tool for depicting the extent of neuroblastoma in some pediatric patients, particularly for those in the early stages of the disease, according to study published in the August issue of the Journal of Nuclear Medicine.

Neuroblastoma accounts for 6-10 percent of childhood cancers in the United States and 15 percent of cancer deaths in children. Identifying where in the body the disease is located and whether it is spreading is critical for choosing appropriate types of treatment, which can include surgery, chemotherapy,  radiation and--in the most advanced cases--a combination of these treatments along with bone marrow transplant or investigational therapies, the authors wrote. Long-term survival for those older than 18 months of age with advanced disease is poor, despite these aggressive treatments.

Neuroblastoma--a form of cancer that starts in certain types of very primitive developing nerve cells found in an embryo or fetus--occurs most frequently in infants and young children. There are about 650 new cases of the cancer reported in the United States each year, according to the National Cancer Institute (NCI). The cancer most often originates on the adrenal gland and often spreads to other parts of the body before any symptoms are apparent.

In recent years, 123I-metaiodobenzylguanidine (MIBG) has been the main functional imaging agent used to assess the disease. FDG-PET imaging of neuroblastoma is increasing, but the researchers noted that questions remain regarding when and in which patients FDG-PET imaging is most useful.

"Functional imaging plays an important role in assessing neuroblastoma, from initially diagnosing and staging the disease to determining whether patients are responding to treatment or whether the disease has recurred," said the study's lead author Susan E. Sharp, MD, assistant professor of clinical radiology at Cincinnati Children's Hospital Medical Center. "Our study found that while MIBG remains the front-line imaging tool for neuroblastoma, FDG-PET imaging can benefit some patients, especially those with early-stage disease."

The study also found that FDG-PET may also be useful in imaging neuroblastoma tumors that do not readily absorb MIBG. In these cases, imaging with MIBG alone may not reveal some malignant lesions in the body.

The researchers reviewed a total of 113 paired MIBG scans and FDG-PET scans in 60 patients with neuroblastoma at two major pediatric cancer institutions.

Sharp and colleagues found that PET was used in conjunction with localization CT scans, and MIBG planar and SPECT imaging were combined. The study showed that for stage 1 and stage 2 neuroblastoma patients, FDG-PET depicted more primary or residual neuroblastoma, although MIBG imaging may be needed to exclude higher-stage disease that has spread to the bone or bone marrow.

MIBG is superior in evaluating stage 4 neuroblastoma, primarily because it can detect and follow the response to treatment of tumor in the bone or bone marrow more accurately, the authors noted.