PET/CT and PET/MR in Soft Tissue Sarcoma: An Update.

Soft tissue sarcomas account for 6%-8% of pediatric cancers. The rhabdomyosarcoma family is the most frequent soft tissue sarcoma in this age group accounting for 3% of pediatric cancers. Rhabdomyosarcomas are high-grade tumors with a high propensity to metastasize. The risk-adapted, multimodal therapeutic approach for rhabdomyosarcomas incorporates a combination of surgery, radiotherapy, and multi-agent cytotoxic chemotherapy. Soft tissue sarcomas other than rhabdomyosarcoma account for 3%-4% of pediatric cancers. The nonrhabdomyosarcoma soft tissue sarcomas include both low-grade and high-grade tumors. While surgery is the mainstay of therapy in most non-rhabdomyosarcoma soft tissue sarcomas, many cases require a multimodal therapeutic approach including radiotherapy and chemotherapy. In North America, most pediatric patients with soft tissue sarcomas are treated in Children's Oncology Group clinical trials. In this article, we will primarily focus on the staging, risk stratification, imaging recommendations, and interpretations in accordance with the Children's Oncology Group trials. We will review the results and recommendations of International Soft Tissue Sarcoma Database Consortium and European trials in relevant sections where they provide complementary guidelines.

A Rare Case of Abnormal Diffuse Brain Uptake on an 123I MIBG Scan in a Patient With High-Risk Neuroblastoma.

ABSTRACT: 123I-meta-iodobenzylguanidine (123I-MIBG) is extensively used for initial staging and response evaluation in children with neuroblastoma. Physiological uptake of 123I-MIBG occurs in the salivary glands, liver, adrenal gland, myocardium, bowel, and thyroid gland. 123I-MIBG cannot cross an intact blood-brain barrier. We present the rare case of a 3-year-old boy with neuroblastoma and meningeal metastases who underwent an 123I-MIBG scan for disease restaging that showed abnormal brain uptake. Abnormal MIBG uptake in the brain can occur if there is disruption of the blood-brain barrier either secondary to metastases or after damage to blood-brain barrier.