Soft Tissue Sarcoma Follow-up Imaging: Strategies to Distinguish Post-treatment Changes from Recurrence

Sarcoma Imaging Surveillance

Soft tissue sarcomas (STS) are a heterogeneous group of solid tumors. There are many histologic subtypes. The prognosis after treatment may be estimated by the analysis of the type of tumor, grade, depth, size at diagnosis, and age of the patient. These type of sarcomas most commonly metastasize to the lungs and may have a relatively high rate of local recurrence, depending on the histologic type and surgical margins. Patients with recurrence have a poorer prognosis. The surveillance of patients with STS is therefore extremely important. This review analyzes the role of MR imaging and US in detecting local recurrence.

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

This article discusses soft tissue tumors of the ankle and foot region in adults, including tumors of the joints, and also briefly addresses tumor-simulating lesions. We offer general recommendations and describe specific aspects of common entities in that region, such as typical imaging appearance, therapeutic strategies, and posttherapeutic considerations. Focal masses and diffuse swelling are common in the foot and ankle region; most of them are non-neoplastic. Some of the tumors, such as plantar fibromatosis, tenosynovial giant cell tumor, synovial chondromatosis, or schwannoma, have a very typical appearance on magnetic resonance imaging. Sarcomas are rare among true soft tissue tumors; however, they can be small and well demarcated, may grow slowly, and are often misinterpreted as benign. This is especially true for synovial sarcoma, one of the most common sarcomas in this region. Densely packed tissues in the foot and ankle may hamper determining the tissue of origin. Adherence to diagnostic guidelines and cooperation with tumor centers is crucial including for posttherapeutic surveillance. We also describe typical posttherapeutic changes and complications after surgery, radiation therapy, and chemotherapy, as well as parameters for the detection and exclusion of recurrence of soft tissue tumors of the ankle and foot.

Imaging Features of Soft Tissue Tumor Mimickers: A Pictorial Essay

Soft tissue lesions are commonly encountered and imaging is an important diagnostic step in the diagnosis and management of these lesions. While some of these lesions are true neoplasms, others are not. These soft tissue tumor mimickers can be due to a variety of conditions including traumatic, iatrogenic, inflammatory/reactive, infection, vascular, and variant anatomy. It is important for the radiologist and clinician to be aware of these common soft tissue tumor mimickers and their characteristic imaging features to avoid unnecessary workup and provide the best treatment outcome.

Diagnostic performance of MRI in detecting locally recurrent soft tissue sarcoma: systematic review and meta-analysis

OBJECTIVE

To systematically review the diagnostic criteria and performance of MRI in detecting locally recurrent soft tissue sarcoma.

METHODS

Medline and Embase were searched for original studies on the diagnostic performance of MRI detecting locally recurrent soft tissue sarcoma. Study quality was assessed using QUADAS-2. Sensitivity and specificity were pooled using a bivariate random-effects model.

RESULTS

Ten studies were included. There was a high risk of bias with respect to patient selection in 2 studies and a high risk of bias with respect to flow and timing in 8 studies. The presence of a mass yielded a pooled sensitivity of 80.9% and a pooled specificity of 77.0%. Hyperintensity at T2-weighted imaging yielded a pooled sensitivity of 82.4% and a pooled specificity of 11.0%. Hypo- or isointensity at T1-weighted imaging yielded a pooled sensitivity of 82.0% and a pooled specificity of 14.3%. Contrast enhancement images yielded a pooled sensitivity of 95.9% and a pooled specificity of 12.3%. Low signal mass on the apparent diffusion coefficient (ADC) map yielded a pooled sensitivity of 67.5% and a pooled specificity of 95.3%. Early and rapid arterial phase enhancement at dynamic contrast-enhanced (DCE) MRI yielded a pooled sensitivity of 91.3% and a pooled specificity of 84.7%.

CONCLUSION

The presence of a mass appears a useful criterion to diagnose locally recurrent soft tissue sarcoma. Signal characteristics at standard T2- and T1-weighted imaging and contrast enhancement seem less useful because they lack specificity. Functional MRI techniques, including DWI with ADC mapping and DCE, may help to make a correct diagnosis.

KEY POINTS

• The presence of a mass at MRI appears useful to diagnose locally recurrent soft tissue sarcoma, because both sensitivity and specificity are fairly high. • Signal characteristics at standard T2- and T1-weighted sequences and contrast enhancement suffer from poor specificity. • DWI with ADC mapping and DCE may help to make a correct diagnosis, but further research is needed to better understand the value of these functional MRI techniques.

[Preoperative diagnostics and typing of abdominal soft tissue sarcomas]

BACKGROUND

Abdominal sarcomas are a heterogeneous group of rare soft tissue tumors and can be localized intraperitoneally or retroperitoneally. A pretherapeutic differentiated subtyping is essential for planning an individual, multimodal treatment concept in an interdisciplinary team of experts.

OBJECTIVE

The central aspects of histology acquisition, imaging diagnostics and (molecular) pathological subtyping of abdominal soft tissue sarcomas are described in detail.

MATERIAL AND METHODS

Imaging and pathological diagnostics are depicted based on the German S3 guidelines on adult soft tissue sarcomas, a current literature search and personal experiences at the Sarcoma Center at the National Center for Tumor Diseases in Dresden (NCT/UCC).

RESULTS

Preoperative imaging and (molecular) pathological subtyping of abdominal soft tissue sarcomas place high demands on surgeons, radiologists and pathologists. Genome analyses of sarcomas have the potential to identify points of attack for individualized treatment options. The limitations of resectability can only be assessed by experienced sarcoma surgeons at specialized centers.

CONCLUSION

The treatment of abdominal soft tissue sarcomas at an experienced center is associated with a better prognosis. Even at the first suspicion of an abdominal sarcoma, a referral to an experienced center should be made in order to guarantee optimal expertise in diagnostics and treatment.