Soft-tissue sarcomas: MR imaging findings after treatment in three pediatric patients

Local changes in bone marrow at MRI after treatment of extremity soft tissue sarcoma

OBJECTIVE

To determine the prevalence and appearance of magnetic resonance imaging (MRI) signal changes that occur in local bone marrow after radiation therapy (RT) and/or chemotherapy for extremity soft tissue sarcoma (STS).

MATERIALS AND METHODS

Seventy patients with primary STS at the level of a long bone who also had undergone pretreatment MRI and at least one post-treatment MRI of the tumor bed were identified. MRIs of each patient were retrospectively reviewed for new changes in marrow signal in the region of the tumor bed and for the morphology, relative signal intensities, heterogeneity, and progression or regression of changes over time.

RESULTS

Focal signal changes in marrow were observed in 26/70 patients (37%) at a median of 9.5 months after RT and/or chemotherapy and diffuse changes in seven (10%) at a median of 8 months. Patients who received neither RT nor chemotherapy did not develop marrow changes. Mean RT doses in patients with changes and those without were 5,867 and 6,076 cGy, respectively. In most patients with focal changes, changes were seen in all sequences and were linear-curvilinear, patchy, or mixed at the level of the tumor bed. Predominant signal intensity of changes was between muscle and fat at T1WI and between muscle and fluid at fat-saturated T2WI or short tau inversion recovery. Most focal changes enhanced heterogeneously and increased or fluctuated in size over time.

CONCLUSION

Changes in MRI appearance of long bone marrow frequently are evident after combined RT and chemotherapy for STS and most commonly increase or fluctuate in size over time. These changes have various non-mass-like configurations and often show signal intensities similar to those of red marrow and thus should not be mistaken for metastases. The marrow changes might represent an early stage of gelatinous transformation of marrow.

Optimal radiologic imaging of soft tissue sarcomas

Radiologic evaluation of the patient with soft tissue sarcoma may include conventional radiography, scintigraphy, ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging. The radiologist also plays a critical role in the evaluation of the patient with soft tissue sarcoma by guiding and performing aspiration biopsies. This review discusses the use of radiological techniques to evaluate the primary lesion and to detect recurrences. In adults, soft tissue sarcoma most commonly occurs in the extremities, and this review emphasizes the role of MR imaging in the pre- and post-treatment evaluation of extremity soft tissue sarcomas. The role of imaging studies in the evaluation of soft tissue sarcomas in the abdomen, thorax, and the head and neck region is also discussed.

Management and long-term complications of pediatric cancer

The impact of recently intensified and novel therapies for the treatment of childhood cancer has been an increased number of survivors and an increase in the number of treatment complications among survivors. Thus, it is important for the primary care practitioner to be aware of not only acute but chronic complications of therapy, including the possibility of second malignancies. Long-term follow-up is essential, and continuous education of patients and health care personnel is an important aspect for the complete success of treatment. Primary care practitioners also need to incorporate other subspecialties in the management of these patients to ensure that they receive complete evaluation and treatment.