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.