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Song, Lee, and Yoo: Differences in CT Findings According to Sputum Smear Results in Patients with Active Pulmonary Tuberculosis Having a Single Cavity
Original Article
Tuberculosis and Respiratory Diseases

Tuberculosis and Respiratory Diseases 2007; 62(6): 479-485.

Published online: 30 June 2007

DOI: https://doi.org/10.4046/trd.2007.62.6.479

Differences in CT Findings According to Sputum Smear Results in Patients with Active Pulmonary Tuberculosis Having a Single Cavity

In Sup Song, M.D.1, Hwa Yeon Lee, M.D.1, Seung Min Yoo, M.D.2

1Department of Diagnostic Radiology, Chung Ang University Hospital, Seoul, Korea.

2Department of Diagnostic Radiology, Guro Saint's Mary Hospital, Seoul, Korea.

Address for correspondence: Hwa Yeon Lee, M.D. Department of Diagnostic Radiology, Chung-Ang University College of Medicine, PO Box 65-207, 3-ga, Hangang-ro, Youngsan-gu, Seoul 140-757, Korea. Phone: 82-2-748-9775, Fax: 82-2-6299-1077, hynlee1@hanmail.net

Received 20 April 2007       Accepted 18 May 2007

Copyright © 2007 The Korean Academy of Tuberculosis and Respiratory Diseases

Abstract

Background

The purpose of this study was to evaluate the differences in CT findings according to sputum smear-positive or -negative results in patients with active pulmonary tuberculosis having a single cavity.

Methods

A total of 32 patients with active pulmonary tuberculosis having a single cavity on CT were classified into two groups: smear-positive (n=19) and smear-negative (n=13). The CT findings were reviewed retrospectively. The presence of consolidation, the number of lobes showing consolidation, ground-glass opacity, micronodules and nodule, the maximum diameter of the cavity, and the shape and maximum thickness of the cavity wall were assessed.

Results

The maximum diameter of the cavity was 33.84 ± 13.65 mm and 27.08 ± 9.04 mm in the smear-positive and -negative groups, respectively (p>0.05). The amount of consolidation and the number of lobes with consolidation were found to be 89.5% and 30.8% (p=0.01) and 1.37 ± 0.90 and 0.31 ± 0.48 (p=0.0002) in the smear-positive and -negative groups, respectively. Consolidations in two or more lobes were only noted in 31.6% of in the sputum smear- positive group (p< 0.05). There were no other significant differences between the two groups. The sensitivity, specificity, positive and negative predictive values for the presence of consolidation were 89.5%, 69.2%, 73.9%, and 81.8%, respectively.

Conclusion

While the absence of consolidation on CT may be associated with sputum smear-negative results in patients with active pulmonary tuberculosis having a single cavity, the presence of consolidation in two or more lobes on CT may be associated with spear-positive results in these patients.

Keywords: Computed tomography, Sputum smear, Pulmonary tuberculosis

Figures and Tables

Figure 1
CT images of a 30-year-old woman among the sputum smear-positive group in whom CT scan shows a cavity and consolidation. (A) CT scan at the level of both lower lobes bronchi shows a thin-walled cavity (52 × 43 mm in diameter) (arrowheads) in left lower lobe. Multiple centrilobular micronodules (arrows) are also demonstrated in the left lower lobe. (B) CT scan at the level of diaphragm shows a patch consolidation in left lower lobe (arrows).
trd-62-479-g001
Figure 2
A CT image of a 29-year-old man among the sputum smear-negative group in whom CT scan shows a cavity and no consolidation. CT scan at the level of bronchus intermedius shows a cavity (21 × 17 mm in diameter)(arrowheads) in right lower lobe. Multiple centrilobular micronodules (arrows) are also demonstrated in the right lower lobe. However, consolidations were not noted in this case through the entire CT images.
trd-62-479-g002
Table 1
Frequencies of CT findings in each group
trd-62-479-i001

Values in parentheses are percentages.

Positive and Negative mean smear-positive and -negative.

Table 2
Mean number of pulmonary lobes involving consolidation, ground-glass opacities, micronodules, and nodule in each group
trd-62-479-i002

Positive and Negative mean smear-positive and -negative.

Values are mean ± SD.

Table 3
Sensitivity, specificity, positive predictive value and negative predictive value of each CT finding
trd-62-479-i003

PPV: positive predictive value; NPV: negative predictive value.

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