Efficacy Of ultrasonography and computed tomography in differentiating transudate from exudate in patients with pleural effusion

Abstract

To evaluate USG and CT imaging findings in differentiating transudative and exudative pleural effusion. Materials and methods: A prospective observational study was performed over a period of eighteen months between January 2016 and June 2017. Eighty patients with pleural effusion were included and were evaluated with USG and CT along with diagnostic thoracocentesis. USG appearances and CT attenuation values along with additional findings like presence of pleural thickening, pleural nodules and loculation were evaluated. Results: 24 (30%) were transudates and 56 (70%) were exudates. Transudative were always anechoic. Exudates were complex septated (62.5%), echogenic (25%) or complex non-septated (8.9%) on USG with very few being anechoic (3.5%). Loculations were better appreciated on ultrasound while pleural thickening and nodules were better seen on CT. Mean attenuation values were significantly higher in exudates (14.65 ± 6.07; mean ± SD, range: 4.5 to 34) than transudates (4.66 ± 2.29; mean ± SD, range: 1.3 to 8.2) with a P value <0.01. Effusions can be considered as transudative if the CT attenuation value is <8, with a sensitivity of 91.6% and specificity of 82.7% with a significant P value <0.01. Pleural thickening, nodules and loculations were seen commonly in exudates than transudates with a high specificity (91.6 %, 95.8% and 100% respectively). Conclusion: USG is a helpful non-invasive and bedside tool in determining the nature of pleural effusion. CT attenuation values play a useful role in differentiating the nature of pleural effusion. Transudative effusions can be considered when HU values are <8.

Dual-energy CT quantitative parameters for the differentiation of benign from malignant lesions and the prediction of histopathological and molecular subtypes in breast cancer

“…Recently, DECT has attracted wide research interest for use in the differentiation of benign from malignant tumors, as well as histopathological and genotypic classification (12)(13)(14)(15)(16)(17). So far, only a few studies (18)(19)(20)(21) have evaluated breast lesion visibility by reconstructing images from DECT. A small-sample study (22) demonstrated that the iodine concentration was higher in invasive non-special carcinoma than in DCIS and benign tumors.…”

Diagnostic accuracy of CT Hounsfield unit in distinguishing Exudative and Transudative Pleural Effusion

“…Despite of numerous studies done across the globe to evaluate the utility of CT attenuation values in predicting the nature of pleural effusion, no consensus has been reached on a set threshold or numeric cut off value with good accuracy. [10][11][12][13][14] The present study revealed statistically significant difference was found between mean attenuation of transudative pleural effusion (2.97+2.69 HU) and the mean attenuation of exudative (5.9 + 6.48 HU) pleural effusion. Also, the exudative pleural effusion showed high levels of protein and LDH, consistent with Light's criteria with statistically significant results.…”

“…[13] Furthermore, Bandaru et al also found that mean attenuation in exudative effusion (14.65 + 6.07 HU) was significantly higher than that of transudative pleural effusion (4.66 + 2.29 HU). [14] Sekhon et al observed higher attenuation in exudative effusion (12.4 HU as compared to 9.6 HU in transudative effusion) but their finding was not statistically significant. [15] Small sample size of just twenty subjects may be the possible reason for such result.…”

“…[12] Bandaru et al also observed the higher association of pleural thickening, nodules and loculation in exudative effusion cases with specificity of 91.6 %, 95.8 % and 100 % respectively. [14] A comparison of key features of present study and previous literature has been illustrated in Table 4.…”

“…[12] Bandaru et al gave the cut off value of 8 HU in their study which had 91.6 % sensitivity and 82.7 % specificity in distinguishing the two types of pleural effusion. [14] Abramowitz et al noticed that with < 8.5 HU, surprisingly exudative effusion can be anticipated but with very poor sensitivity and specificity (55.1 % and 68.2 % respectively). [7] Apart from the mean attenuation values of pleural fluid, we also additionally read the CT images for presence of any pulmonary pathology like consolidation, pleural thickening, pulmonary nodules or any loculated fluid collection.…”