Tuberculosis CT

Pulmonary tuberculosis often presents with abnormal findings in a chest CT, which include micronodules, interlobular septal thickening, consolidation, and cavitation. CT scan is more sensitive than an X-ray to reveal lymphadenopathies.

• Abnormal findings on chest CT are seen in most patients with active pulmonary tuberculosis.
• CT findings include:^[1]

• Micronodules

• Often present in the subpleural region and peribronchovascular interstitium.
• CT scan is helpful for early and accurate detection of micronodules.

• Interlobular septal thickening
• Cavitation is the most common abnormal finding in secondary tuberculosis

• It has thick walls and irregular margins.
• It may be observed in almost 50% of patients.
• Usually observed in the upper lung.
• Cavities in the lower lung may be seen in HIV infection and diabetes.^[2][3]
• Despite being rare, superinfection of the cavities may occur and an air-fluid level is seen inside the cavity.
• Following the resolution the active infection, small cavities with may persist as a residual finding.

• Homogeneous and dense consolidation

• CT is more sensitive to detect hilar lymphadenopathy.
• The “tree-in-bud” sign is an abnormal characteristic finding on CT scan that may be observed in pulmonary tuberculosis due to mucus or pus impaction into the small airways which accentuates the branching course of peripheral airways.^[4]

• Pericardial thickening may be observed on a CT scan, particularly if it is more than 3 mm.^[5]
• Lymph node enlargement.^[5]
• Pericardial effusion is rare and is observed in less than 20% of patients.^[5]

CT findings of miliary tuberculosis are multiple pulmonary nodules with a diameter of 1-2mm, distributed randomly. pleural effusion may be present.

• Head CT findings in tuberculous meningitis are meningeal enhancement suggesting meningeal inflammation and choroidal calcifications.^[6]
• Areas of infarction and hemorrhage can be observed..
• Late complications can show hydrocephalus.

• CT findings in a pancreatic and spleen infection with tuberculosis can resemble a pancreatic cancer.^[7]
• Shown below is a CT scan of the pancreas showing a mass in the pancreatic tail with metastasis in the spleen.

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