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Basis of Estimating Pleural Effusion Size on CT ScanEstimating Pleural Effusion Size on CT Scan: Reasonable Grouping of Volume Percentage FREE TO VIEW

Yijie Hu, MD, PhD; Qianjin Zhong, MD, PhD
Author and Funding Information

From the Department of Cardiovascular Surgery, Institute of Surgery Research, Daping Hospital, Third Military Medical University.

Correspondence to: Qianjin Zhong, MD, PhD, No. 10 Changjiang Zhi Rd, Yuzhong District, Chongqing 400042, China; e-mail: zhongqianjin@qq.com


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2013;143(6):1839. doi:10.1378/chest.13-0376
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To the Editor:

We read with great interest the article by Moy and colleagues1 in CHEST (April 2013) about estimating pleural effusion size on CT scan. The authors developed and validated a simple rule for quantitating pleural effusion size on CT scan with a three-point scale based the anteroposterior (AP) quartile and maximum AP depth: First AP quartile effusions are small, second AP quartile effusions are moderate, and third or fourth AP quartile effusions are large; in borderline cases, AP depth is measured with 3-cm and 10-cm thresholds for the upper limit of small and moderate, respectively. This newly developed classification rule can improve the interpretive consistency of all readers.

The study was based on assumptive grouping: Effusion percentage cutoffs were chosen at <20%, 20% to 40%, and >40% of the hemithorax for small, moderate, and large, respectively. Another study2 characterized pleural effusion occupying less than one-third, one-third to two-thirds, and greater than two-thirds of the hemithorax as small, moderate, and large, respectively, but the authors gave no explanation for choosing the assumptive grouping, which may affect the conclusion.

In fact, the total volume of hemithoracic cavity changed with the volume of pleural effusion. The pleural effusion percentage was elevated with the increase of effusion volume in a nonlinear pattern, as shown in Figure 1, which was drawn according to the mean effusion volume and corresponding percentage in the study.1 Based on the curve and its trend, the more reasonable cutoff would be set at <25%, 25% to 50%, and >50% of the hemithorax for small, moderate, and large, respectively. In addition, it was consistent with the broadly accepted classification on the chest radiograph, in which the volume of pleural effusion identified was quantitatively assessed and qualified as small (<500 mL), moderate (500-1,000 mL), or large (<1,000 mL).3-5 This will improve both interobserver agreement and the consistency of different imaging methods.

Figure Jump LinkFigure 1. Relationship between pleural effusion and effusion-to-hemithorax volume percentage.Grahic Jump Location

References

Moy MP, Levsky JM, Berko NS, Godelman A, Jain VR, Haramati LB. A new, simple method for estimating pleural effusion size on CT scans. Chest. 2013;143(4):1054-1059. [PubMed]
 
Mironov O, Ishill NM, Mironov S, et al. Pleural effusion detected at CT prior to primary cytoreduction for stage III or IV ovarian carcinoma: effect on survival. Radiology. 2011;258(3):776-784. [CrossRef] [PubMed]
 
Vignon P, Chastagner C, Berkane V, et al. Quantitative assessment of pleural effusion in critically ill patients by means of ultrasonography. Crit Care Med. 2005;33(8):1757-1763. [CrossRef] [PubMed]
 
Evans AL, Gleeson FV. Radiology in pleural disease: state of the art. Respirology. 2004;9(3):300-312. [CrossRef] [PubMed]
 
Blackmore CC, Black WC, Dallas RV, Crow HC. Pleural fluid volume estimation: a chest radiograph prediction rule. Acad Radiol. 1996;3(2):103-109. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1. Relationship between pleural effusion and effusion-to-hemithorax volume percentage.Grahic Jump Location

Tables

References

Moy MP, Levsky JM, Berko NS, Godelman A, Jain VR, Haramati LB. A new, simple method for estimating pleural effusion size on CT scans. Chest. 2013;143(4):1054-1059. [PubMed]
 
Mironov O, Ishill NM, Mironov S, et al. Pleural effusion detected at CT prior to primary cytoreduction for stage III or IV ovarian carcinoma: effect on survival. Radiology. 2011;258(3):776-784. [CrossRef] [PubMed]
 
Vignon P, Chastagner C, Berkane V, et al. Quantitative assessment of pleural effusion in critically ill patients by means of ultrasonography. Crit Care Med. 2005;33(8):1757-1763. [CrossRef] [PubMed]
 
Evans AL, Gleeson FV. Radiology in pleural disease: state of the art. Respirology. 2004;9(3):300-312. [CrossRef] [PubMed]
 
Blackmore CC, Black WC, Dallas RV, Crow HC. Pleural fluid volume estimation: a chest radiograph prediction rule. Acad Radiol. 1996;3(2):103-109. [CrossRef] [PubMed]
 
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