J Korean Soc Radiol.  2013 Jun;68(6):463-472. 10.3348/jksr.2013.68.6.463.

Characteristics of Consolidation, Centrilobular Nodule and Bronchus as CT Findings for the Differentiation between Tuberculosis and Pneumonia

• Ko SY
• Chung MH
• Lim YS
• Lim HW
• Lee BY
• Sung MS
• Kahng J

• KMID: 2002897
• DOI: http://doi.org/10.3348/jksr.2013.68.6.463

Abstract

PURPOSE
To differentiate tuberculosis from pneumonia by computed tomography (CT) in cases difficult to diagnose clinically and radiologically.
MATERIALS AND METHODS
CT scans of 300 patients with tuberculosis and 234 patients with pneumonia were retrospectively analyzed. Parenchymal abnormalities, lymph nodes, pleural effusions and central bronchial narrowing were evaluated. The density of consolidation was measured by pre- and post-enhanced CT.
RESULTS
Centrilobular nodules, granulomas, cavitations in both nodules as well as consolidation, conglomerated nodules, and enlarged lymph nodes occurred with significantly greater frequency in patients with tuberculosis than in those with pneumonia. Centrilobular nodules were larger and denser in tuberculosis patients. In consolidation, decreases in lung lobe volume and a bronchial beaded appearance (irregular narrowing and dilatation) were more frequent in patients with tuberculosis. The tuberculous consolidation had significantly lower mean enhancement and net enhancement than that from pneumonia. When the diagnostic criteria for tuberculosis were set as well-demarcated larger centrilobular nodules and/or a lowerly enhancing consolidation with internal beaded bronchi, the diagnostic accuracy was found to be 82.0%.
CONCLUSION
Consolidation with a low level of enhancement, decreased lung lobe volume, and bronchi with irregular, beaded shape and denser and larger centrilobular nodules are helpful CT findings for the diagnosis of tuberculosis.

MeSH Terms

Bronchi
Granuloma
Humans
Lung
Lymph Nodes
Pleural Effusion
Pneumonia
Retrospective Studies
Tuberculosis

Figure

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  Fig. 1 CT imaging analysis. Centrilobular nodules were either smaller than 0.3 cm and ill-defined (A) or large and well demarcated (B). A granuloma was defined as a single nodule (C) or conglomeration of nodules (D) larger than 1.0 cm. The bronchial shape inside an area of consolidation was estimated as either a smooth air bronchogram (E) or a beaded air bronchograms characterized by alternate, irregular, narrowed, and dilated bronchi (F).

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  Fig. 2 Automatic densitometry of consolidation. Licensed 'lung parenchyma analysis' was used to apply a freehand region of interest (white areas) in consolidation. The internal enhancing vessels [about 130 Hounsfield units (HU)], the air in the bronchi, normal lung, and bones can be automatically eliminated because the evaluation limit was between 0 (lower limit) to 100 (upper limit) HU. The values were measured on pre- and post-enhanced CT scans (A, B, respectively) and the net enhancement was determined.

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  Fig. 3 A 45-year-old man without underlying disease. The more typical dense centrilobular nodules with consolidation that were less enhanced and had beaded air bronchograms were observed in this patient with tuberculosis.

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  Fig. 4 A 48-year-old man with diabetes mellitus, oligodendroglioma, and tuberculosis. Left lower lobar consolidation is typically less enhanced with cavities on enhanced CT scan (A). There were well-demarcated large centrilobular nodules in the left lung fields (B).

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  Fig. 5 Necrotizing pneumonia. Chest CT of a 76-year-old man showed heterogeneous enhancing consolidation (about 90 Hounsfield units) with smooth air bronchograms and cavities in the right upper lobe.

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  Fig. 6 Chest CT of a 35-year-old man with tuberculosis showed less enhancing consolidation with irregular beaded air bronchograms.

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