Preliminary Diagnosis: Toxic lung injury (Silo-Filler's disease)
I. What imaging technique is first-line for this diagnosis
-
Chest radiographs (CXR) with posteroanterior (PA) and lateral projections
II. Describe the advantages and disadvantages of this technique for diagnosis of toxic lung injury (Silo-Filler's disease).
Advantages
-
Diagnostic for the noncardiogenic edema seen with toxic lung injury (TLI)
-
Exposes the patient to less ionizing radiation than computed tomography (CT) of the chest
-
Serial chest radiographs are sufficient to follow the course of TLI
Disadvantages
-
Initial CXR can be negative as the noncardiogenic edema of TLI appears anytime from immediately to 48 hours after injury (usually by 6 hours)
-
Less sensitive for other types of thoracic disease, such as associated trauma
III. What are the contraindications for the first-line imaging technique?
-
CXR has no significant contraindication
IV. What alternative imaging techniques are available?
-
High resolution CT (HRCT) chest without contrast
-
CT chest with intravenous contrast
-
CT chest without contrast
-
Ventilation perfusion (V/Q) scan
V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of toxic lung injury (Silo-Filler's disease).
High resolution CT chest without contrast
Advantages
-
Diagnostic of TLI
-
Best alternative study in the scenario of unexplained chronic dyspnea and non-diagnostic chest radiography
-
Most capable study for diagnosis of any diffuse lung disease (i.e., hypersensitivity pneumonitis, interstitial lung disease, etc.)
-
HRCT with inspiratory and expiratory images can document air trapping, sometimes present in TLI
Disadvantages
-
HRCT performed without contrast is non-diagnostic for pulmonary thromboembolism (PTE)
-
More expensive and time-consuming, and exposes the patient to more ionizing radiation than chest radiography
CT chest with intravenous contrast
Advantages
-
Diagnostic of TLI
-
Best alternative study if there is also concern for traumatic thoracic injury
-
Appropriate alternative if infection or malignancy are other diagnostic considerations
Disadvantages
-
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 contrast withheld
-
Exposes the patient to ionizing radiation
CT chest without contrast
Advantages
-
Diagnostic of TLI
-
Can show other thoracic disease processes, including traumatic injury
Disadvantages
-
Exposes the patient to ionizing radiation
Ventilation perfusion (V/Q) scan
Advantages
-
V/Q scan can show air trapping or delayed radiotracer washout typical of TLI, even in the setting of negative CXR
-
V/Q scan can be diagnostic of PTE
Disadvantages
-
Less readily available and more time-consuming than CXR or CT
-
Exposes the patient to ionizing radiation
VI. What are the contraindications for the alternative imaging techniques?
High resolution CT chest without contrast
-
Patients unable to remain motionless and hold their breath for up to 25 seconds during the test will have images degraded by motion artifact
-
Contraindicated in pregnant women, especially in the first and second trimesters
CT chest with intravenous contrast
-
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 contrast withheld
-
Contraindicated in pregnant women, especially in the first and second trimesters
CT chest without contrast
-
Contraindicated in pregnant women, especially in the first and second trimesters
Ventilation perfusion (V/Q) scan
-
V/Q scan has no absolute contraindication
-
V/Q scan is not recommended for patients for whom there is high suspicion of massive PTE
-
Relative contraindications of V/Q scan include severe asthma, COPD, or cystic fibrosis
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.
