Imaging

Non-Small Cell Lung Cancer

Preliminary Diagnosis: Non-Small Cell Lung Cancer

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

  • CT of the chest with intravenous contrast

II. Describe the advantages and disadvantages of this technique for diagnosis of non-small cell lung cancer.

Advantages

  • Can adequately assess the T stage of the tumor

  • Useful for identifying pleural nodules, pleural plaques, pleural/pericardial effusions, or metastasis

  • CT should include the upper abdomen to assess for adrenal metastasis

  • Easily accessible at most medical facilities

  • Better tolerated in obese or claustrophobic patients

Disadvantages

  • Low sensitivity (40-84%) and specificity (57-94%) for identifying mediastinal and lymph node involvement

  • Positive predictive value (PPV) of 50% and negative predictive value (NPV) of 85%

  • Limited in detecting chest wall or parietal pleural invasion

  • Limited in detecting extra-thoracic metastatic disease

  • Requires the use of IV contrast

  • Exposure to ionizing radiation

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

  • Contraindicated in pregnant patients, especially during the first and second trimester

  • Contraindicated in patients with iodine allergies

  • It should be used with caution in patients with acute renal insufficiency.

IV. What alternative imaging techniques are available?

  • PET/CT (commonly used as adjunct to chest CT for full staging)

  • MRI of chest

  • Chest X-ray

V. Describe the advantages and disadvantages of the alternative techniques for non-small cell lung cancer.

PET/CT

Advantages

  • Delineates anatomy and also determines metabolic activity of suspicious lesions

  • Improved sensitivity (98%) versus CT alone at identifying mediastinal invasion and lymph node metastases

  • Improved sensitivity and specificity for detecting extrathoracic metastatic disease versus CT alone

  • Can help determine locations for highest-yield biopsy, especially if considering invasive mediastinal lymph node staging

  • Helpful when planning definitive courses of radiation and determining disease response to treatment

  • Can drastically alter management by upstaging patients, making them inoperable, thus eliminating unnecessary surgery

Disadvantages

  • Expensive and not easily accessible at certain medical centers

  • High false positive rate (20%), which may require pathologic confirmation to rule out.

  • PET scans alone (without CT hybrid) are not as sensitive in detecting mediastinal or extrathoracic metastases and often more difficult to elucidate anatomy

MRI of chest/abdomen/brain with IV contrast

Advantages

  • Can help better assess extrathoracic and chest wall invasion

  • Does not expose patient to ionizing radiation

  • Can help delineate brain, adrenal, or spinal metastases

Disadvantages

  • Loss of signal from physiologic lung movement

  • Not as well tolerated in obese, claustrophobic, or patients with SOB or not able to hold breath

  • More time consuming than CT

Chest X-ray

Advantages

  • Cheap, easily accessible, easy to administer

  • Requires lower dose of radiation exposure

  • Helpful in comparing with previous films to determine if further workup is necessary

Disadvantages

  • Unable to determine full staging

  • Insufficient to assess mediastinal and lymph node metastases

  • Cannot determine extrathoracic metastases

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

PET/CT

  • Because CT is a component of this imaging technique, it is contraindicated in pregnant women.

MRI

  • Contraindicated in patients with pacemakers and other implantable, MRI-incompatible devices

  • Since contrast is administered, caution should be used in patients with renal insufficiency

CXR

  • There are no major contraindications for this imaging modality.

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