Preliminary Diagnosis: Drug-Induced Lung Injury

I. What imaging technique is first-line for this diagnosis?

High resolution computed tomography (HRCT) of the chest without contrast.

II. Describe the advantages and disadvantages of this technique for diagnosing drug-induced lung injury.

Advantages

  • Provides thin slice (1-2 mm) images of the entire chest with high spatial resolution.

  • Can provide an accurate and limited differential diagnosis for chronic dyspnea of any type, not just drug-induced lung injury, and often renders biopsy or further imaging unnecessary.

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  • Can reveal pulmonary disease, even in the setting of negative chest radiography.

  • Does not require administration of IV or PO contrast.

  • If histopathology is warranted, HRCT is the optimal tool for biopsy planning.

  • Relatively quick imaging examination and easily tolerated by most patients.

Disadvantages

  • Drug-induced lung injury is usually a diagnosis of exclusion and can be represented by all of the major disease patterns described by HRCT.

  • HRCT performed without contrast is non-diagnostic for pulmonary thromboembolism (PTE).

  • Exposure to ionizing radiation.

  • For pregnant women, the best alternative is to postpone HRCT until after pregnancy.

III. What are the contraindications for the first-line imaging technique?

  • Patients unable to remain motionless and hold their breath for up to 25 seconds during the test will have images degraded by motion artifacts.

  • HRCT is contraindicated in pregnant women, especially in the first and second trimesters.

IV. What alternative imaging techniques are available?

  • CT chest with contrast.

  • CT chest without contrast.

  • CT angiography (CTA) of the chest with contrast.

  • Chest radiograph with frontal and lateral images.

V. Describe the advantages and disadvantages of the alternative techniques for diagnosing drug-induced lung injury.

CT chest with contrast
Advantages

  • Can show the disease patterns associated with diffuse pulmonary diseases, such as drug-induced lung injury.

  • It is an appropriate alternative if infection or malignancy are other diagnostic considerations.

Disadvantages

  • Exposes the patient to ionizing radiation.

  • The contrast dose administered may have to be reduced or witheld 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.

CT chest without contrast
Advantages

  • Can show the disease patterns associated with diffuse pulmonary diseases, such as drug-induced lung injury.

  • CT chest without contrast is usually more available than HRCT.

  • CT chest without contrast can be safely used in patients with renal disease or contrast allergy.

Disadvantages

  • CT exposes the patient to ionizing radiation.

CTA chest with contrast
Advantages

  • Ideal if there is also high clinical suspicion for pulmonary embolism.

  • Can show the disease patterns associated with diffuse pulmonary diseases, such as drug-induced lung injury.

Disadvantages

  • CT exposes the patient to ionizing radiation.

  • 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.

Chest radiograph (CXR) with posteroanterior (PA) and lateral views
Advantages

  • Safe and inexpensive.

  • CXR is often adequate to monitor the course of drug-induced lung injury and response to treatment.

Disadvantages

  • CXR is mostly non-diagnostic and of limited use for initial imaging of diffuse pulmonary disease, like drug-induced lung injury.

  • Exposure to ionizing radiation.

VI. What are the contraindications for the alternative imaging techniques?

CT chest with 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

  • CT is contraindicated in pregnant women, especially in the first and second trimesters.

CTA chest with 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.

Chest radiograph

No significant contraindications.

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