Preliminary Diagnosis: Small Cell Lung Cancer
I. What imaging technique is first-line for this diagnosis?
CT of the chest with IV contrast.
II. Describe the advantages and disadvantages of this technique for diagnosing small cell lung cancer.
- Can adequately assess the T stage of the tumor.
- Useful for identifying pleural nodules, pleural plaques, pleural/ pericardial effusions, or metastasis.
- Higher sensitivity than PET/CT at visualizing brain metastases.
- CT of the chest should include upper abdomen to assess for adrenal metastasis.
- Easily accessible at most medical facilities.
- Better tolerated in obese or claustrophobic patients.
- Low sensitivity (40-84%) and specificity (57-94%) for identifying mediastinal and lymph node involvement.
- Limited in detecting chest wall or parietal pleural invasion.
- 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 trimesters.
- Relative contraindication in patients with iodine allergies.
- Relative contraindication in patients with renal failure.
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 diagnosing small cell lung cancer.
- Delineates anatomy and also determines metabolic activity of lesions.
- Improved sensitivity (98%) versus CT alone at identifying mediastinal invasion and lymph node metastases.
- Improved sensitivity and specificity versus CT alone for detecting extrathoracic metastatic disease.
- Can drastically alter management by correctly staging patients as limited or extensive stage, which ultimately dictates treatment course.
- Helps with radiation treatment planning and assessing disease response after definitive therapy.
- Expensive and not easily accessible at certain medical centers.
- Good positive predictive value, but poor negative predictive value.
- High false positive rate, which may require further pathologic confirmation.
- Sensitivity not as high in visualizing brain metastases.
MRI of chest/abdomen/brain with IV contrast
- Can help better assess extrathoracic and chest wall invasion.
- Does not expose patient to ionizing radiation.
- Can help delineate brain, adrenal, or spinal metastases.
- Higher sensitivity than PET/CT at visualizing brain metastases
- MRI of the brain with contrast should be obtained in all patients with suspected or confirmed diagnosis of small cell lung cancer prior to starting therapy
- Time consuming.
- Requires significant patient cooperation to minimize motion artifact.
- Loss of signal from physiologic lung movement.
- Not as well tolerated in patients that are obese, claustrophobic, or unable to hold their breath.
- Cheap, easily accessible, and easy to administer.
- Requires lower doses of radiation exposure.
- Is helpful to compare with previous films to determine if further workup is necessary.
- Unable to determine full staging of disease.
- Insufficient to assess mediastinal and lymph node metastases.
- Cannot determine extrathoracic metastases.
VI. What are the contraindications for the alternative imaging techniques?
- Contraindicated in pregnant women.
MRI chest/abdomen/brain with IV contrast
- Contraindicated in patients with pacemakers and other implantable, MRI-incompatible devices.
- Gadolinium contrast is contraindicated in patients with a GFR ≤ 30
- There are no major contraindications for this imaging modality. Some institutions may require consent for pregnant patients.
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- Preliminary Diagnosis: Small Cell Lung Cancer
- I. What imaging technique is first-line for this diagnosis?
- II. Describe the advantages and disadvantages of this technique for diagnosing small cell lung cancer.
- III. What are the contraindications for the first-line imaging technique?
- IV. What alternative imaging techniques are available?
- V. Describe the advantages and disadvantages of the alternative techniques for diagnosing small cell lung cancer.
- VI. What are the contraindications for the alternative imaging techniques?