Therapy-Related Imaging Findings in Patients with Sarcoma

Abstract

Knowledge of imaging findings related to therapy administered to patients with sarcoma is pivotal in selecting appropriate care for these patients. Imaging studies are performed as surveillance in asymptomatic patients or because symptoms, including anxiety, develop. In addition to detection of recurrent disease and assessment of response to therapy, diagnosis of conditions related to therapy that may or may not need treatment has a marked positive impact on quality of life. The purpose of this review is to assist radiologists, nuclear physicians, and others clinicians involved in the diagnosis and treatment of these patients in recognizing imaging findings related to therapy and not to activity of the previously treated sarcoma. Imaging findings are time dependent and often specific in relation to therapy given.

Presurgical Perspective and Posttreatment Evaluation of Soft Tissue Tumors of the Ankle and Foot in Adults

“…However, interference with metallic hardware may cause avascular necrosis, so metallic implants may prevent the use of proton radiation in those patients. 6 Radiation-associated sarcoma in the radiation field represents a late complication, after > 10 years post radiotherapy. Fortunately, it has become rare with optimized radiation strategies.…”

“…After additional radiation therapy, the variable extent of those changes is generally higher and the duration is prolonged. 6,66 In the subcutaneous fat, septations lead to a lattice-like appearance of those changes. Diffuse muscular alterations, with preserved architecture and low contrast enhancement, can be seen in 80% of patients after combined surgery and radiation therapy.…”

“…66 Radiation therapy also leads to focal dose-dependent osseous changes that may be exacerbated after additional chemotherapy. 6 On MRI, within 1 to 6 weeks, edema-like changes can be depicted 6 that become heterogeneous and frequently result in fatty marrow conversion after 6 weeks. 66 Radiography may show so-called radiation osteitis, with osseous atrophy, osteosclerosis, and periosteal reaction.…”

“…66 Radiography may show so-called radiation osteitis, with osseous atrophy, osteosclerosis, and periosteal reaction. 6 Chemotherapy initially also leads to suppression of hematopoietic bone marrow and inflammatory changes in the bone. Posttherapeutic hematopoietic marrow rebound and stimulation therapy lead to typical bone marrow reconversion patterns in MRI and PET/CT 6 up to 4 weeks after the termination of bone marrow stimulation.…”

PET-CT in the Evaluation of Neoadjuvant/Adjuvant Treatment Response of Soft-tissue Sarcomas

“…Finally, a common problem in patients with STS who have undergone radiation therapy is that PET-mediated differentiation of scar tissue and tumor recurrence is complicated. The nonspecific repair process after radiation can cause long-term FDG enhancement 55 . In the post-treatment setting, equivocal PET-CT findings should be correlated with MRI to differentiate tumor mimics such as myonecrosis or nodular scar because PET and MRI serve complementary roles.…”