Preliminary Diagnosis: Pulmonary Tuberculosis
I. What imaging technique is first-line for this diagnosis?
Chest radiograph (CXR) with posteroanterior (PA) and lateral views.
II. Describe the advantages and disadvantages of this technique for diagnosing pulmonary tuberculosis.
Advantages
-
Can be diagnostic of primary and post-primary tuberculosis (TB).
-
Often adequate to show the various findings of post-primary TB, including cavitation, apical distortion, and miliary disease.
-
Usually adequate to monitor response to treatment.
-
Widely available and inexpensive.
Disadvantages
-
Pulmonary findings of TB on CXR are often non-specific, requiring further imaging and tests for diagnosis.
-
Less sensitive than CT for signs of active pulmonary TB.
-
Exposes the patient to ionizing radiation.
III. What are the contraindications for the first-line imaging technique?
Chest radiography has no significant contraindication. Some institutions may require consent for pregnant patients.
IV. What alternative imaging techniques are available?
-
Computed tomography (CT) chest with contrast
-
CT chest without contrast
V. Describe the advantages and disadvantages of the alternative techniques for diagnosing pulmonary tuberculosis.
CT chest with contrast
Advantages
-
Optimal study for the evaluation and diagnosis of primary or post-primary TB
-
Shows the pulmonary parenchymal and mediastinal manifestations of primary and post-primary TB
-
Optimal examination for the diagnosis of many pulmonary diseases, including malignancy and infection
Disadvantages
-
Exposes the patient to more ionizing radiation than chest radiography.
-
The contrast dose administered may have to be reduced or withheld if the patient has decreased renal function.
-
Patients with known allergic reaction to iodinated contrast must undergo pre-treatment with steroids and anti-histamines for at least 13 hours prior to contrast dose, or have the contrast withheld.
CT chest without contrast
Advantages
-
More sensitive than CXR for the pulmonary parenchymal disease of TB.
-
Can be safely used in patients with renal disease or contrast allergy.
Disadvantages
-
Poorly evaluates the mediastinal and chest wall manifestations of pulmonary TB, including lymphadenopathy.
-
Exposes the patient to more ionizing radiation than chest radiography.
VI. What are the contraindications for the alternative imaging techniques?
CT chest with contrast
-
May be contraindicated in pregnant patients.
-
Relative contraindication in patients with renal failure.
-
Relative contraindication in patients with contrast allergy.
CT chest without contrast
-
Contraindicated in pregnant women, especially during the first and second trimesters.
Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved.
No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. The Licensed Content is the property of and copyrighted by DSM.