| Sonographic finding | Malignant disease(n = 33) | Benign disease(n = 19) | p value (Fisherexact χ2) |
| Parietal pleural thickening | 16 | 5 | 0.090 |
| >1 cm | 14 | 1 | 0.004 |
| <1 cm | 2 | 4 | 0.175 |
| Nodular | 14 | 0 | 0.001 |
| Smooth | 2 | 5 | 0.085 |
| Visceral pleural thickening/nodularity | 5 | 0 | 0.145 |
| Diaphragmatic thickening | 19 | 4 | 0.019 |
| Nodular | 15 | 0 | <0.001 |
| Smooth | 4 | 4 | 0.443 |
| Diaphragmatic nodules | 10 | 0 | 0.009 |
| Size of effusion | |||
| Small | 9 | 6 | 0.541 |
| Moderate | 17 | 7 | 0.391 |
| Large | 7 | 6 | 0.510 |
| Nature of effusion | |||
| Anechoic/simple | 14 | 11 | 0.389 |
| Anechoic/septated | 14 | 8 | 1.000 |
| Echogenic | 5 | 0 | 0.145 |
| Liver metastases* | 2 | 0 | 0.527 |
| Overall TUS diagnostic rate† | 26/33 | 19/19 | N/A |
| Sensitivity 79% | Specificity 100% | ||
| NPV = 73% | PPV = 100% |
NPV, negative predictive value; PPV, positive predictive value; TUS, thoracic ultrasound.
*Liver metastases were the sole abnormality detected in one patient on TUS.
†Diagnostic rate of TUS based on the criteria mentioned in the Methods section (ie, diaphragmatic and parietal pleural nodule or nodules, pleural thickening >1 cm or hepatic metastasis).