Follow-up of recurrences of limb soft tissue sarcomas in patients with localized disease: performance of ultrasound.

OBJECTIVES

To evaluate diagnostic performance of ultrasound in the detection of local recurrences in patients with localized soft tissue sarcomas of the limb.

METHODS

An analysis of patients treated for soft tissue sarcomas between 2005 and April 2014 was performed. Sixty-eight patients (men/women, 36:32; age range, 18-84 years) were evaluated. Sensitivity, specificity with 95% confidence intervals (CIs), positive predictive value (PPV), pre-test probability (the prevalence), negative predictive value (NPV), likelihood ratio for positive results (LH+), accuracy and post-test probability (post-P) of ultrasound were reported on a per patient basis using surgical findings and clinical follow-up as reference standard. Effects of independent variables (US equipment, age and sex, body mass index, radiologist) were considered. Comparison with MR was also performed.

RESULTS

The overall sensitivity and specificity were 0.88 (0.60-0.94) and 0.94 (0.86-0.98). PPV, pre-test probability, NPV, LH+, accuracy and post-P: 0.83/0.25/0.96/14.9/0.92/0.83. There were two false negative cases both graded as G3 and deeply located and three false positive US cases. Diagnostic accuracy was not dependent by US machine (p = 0.08), age and sex (p = 0.16), body mass index (p = 0.07) and radiologists (p = 0.07).

CONCLUSIONS

Diagnostic accuracy of ultrasound was relatively high. Negative US results excluded the presence of a local recurrence with acceptable accuracy.

KEY POINTS

• US accuracy is relatively high in sarcoma follow-up. • Negative US results exclude the presence of local recurrence with acceptable accuracy. • US may miss a small proportion of lesions. • False positive US cases are rare.