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.