Tuberc Respir Dis.
2020 Oct;83(4):283-288. 10.4046/trd.2020.0038.
Evolution of Interferon-Gamma Release Assay Results and Submillisievert Chest CT Findings among Close Contacts of Active Pulmonary Tuberculosis Patients
- Affiliations
-
- 1Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
- 2Seegene Medical Foundation, Seoul, Korea
- 3Department of Internal Medicine, Veterans Health Service Medical Center, Seoul, Korea
- 4Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
- KMID: 2506709
- DOI: http://doi.org/10.4046/trd.2020.0038
Abstract
- Background
Latent tuberculosis (TB) infection among TB contacts is diagnosed using plain chest radiography and interferon-gamma release assays (IGRAs). However, plain chest radiographs often miss active TB, and the results of IGRA could fluctuate over time. The purpose of this study was to elucidate changes in the results of the serial IGRAs and in the findings of the serial submillisievert chest computed tomography (CT) scans among the close contacts of active pulmonary TB patients.
Methods
Patients age 20 or older with active pulmonary TB and their close contacts were invited to participate in this study. Two types of IGRA (QuantiFERON-TB Gold In-Tube assay [QFT-GIT] and the T-SPOT.TB test [T-SPOT]) and submillisievert chest CT scanning were performed at baseline and at 3 and 12 months after enrollment.
Results
In total, 19 close contacts participated in this study. One was diagnosed with active pulmonary TB and was excluded from further analysis. At baseline, four of 18 contacts (22.2%) showed positive results for QFT-GIT and T-SPOT; there were no discordant results. During the follow-up, transient and permanent positive or negative conversions and discordant results between the two types of IGRAs were observed in some patients. Among the 17 contacts who underwent submillisievert chest CT scanning, calcified nodules were identified in seven (41.2%), noncalcified nodules in 14 (82.4%), and bronchiectasis in four (23.5%). Some nodules disappeared over time.
Conclusion
The results of the QFT-GIT and T-SPOT assays and the CT images may change during 1 year of observation of close contacts of the active TB patients.
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