What is the role of imaging studies in the workup of small cell lung cancer (SCLC)?

Updated: Sep 12, 2019
  • Author: Abid Irshad, MD; Chief Editor: Eugene C Lin, MD  more...
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Answer

The most common appearance of SCLC on imaging studies is a centrally located lung mass or mediastinal mass with hilar involvement. In two thirds of patients, tumor tissue encases mediastinal structures, including vessels, airways, and the esophagus. The usefulness of the various imaging examinations largely depends on the clinical findings at the time of presentation and on the stage of the disease. Many imaging modalities are used to further evaluate the findings seen on the previous imaging and to determine the stage of the disease. [20, 21, 22, 23]

Conventional radiography is not helpful in finding early disease. When the mass or mass effect is visible on a radiograph, the disease is almost invariably in an advanced stage. 

Chest CT is the modality of choice for initial evaluation of the SCLC. For patients with known or suspected SCLC, chest CT with IV contrast is recommended. If concurrent abdominal CT is not obtained, the adrenal glands should be covered. Chest CT without IV contrast may also be used. Chest CT with IV contrast can help identify tumor invasion in the chest wall, assess mediastinal invasion, evaluate other mediastinal and hilar lymph nodes, distinguish central obstructing tumor from surrounding atelectasis, and identify liver metastases. [15, 24, 10, 11, 25]

Brain MRI with IV contrast is recommended in all SCLC patients and has been shown to identify metastatic lesions in 10-15% of newly diagnosed SCLC patients without neurologic symptoms. Although most centers do not routinely use MRI to evaluate the primary lesion in the chest, it may provide useful information in problematic cases of mediastinal invasion. MRI does have a role in ruling out brain metastatic lesions and in differentiating questionable adrenal masses. In pregnant patients, MRI can also be used instead of CT scanning, to avoid the potential effects of ionizing radiation. [26]  MRI has a greater sensitivy than CT for intracranial metastases. [24, 10, 11, 25]

CT scanning is generally used to guide biopsy of suspicious lesions. It can be used to guide transbronchial biopsy by demonstrating the location of the lesions, or it can be used to direct CT scan–guided percutaneous transthoracic biopsy. Similarly, ultrasonography can also be used to guide biopsy of suspicious intra-abdominal or pelvic lesions.

FDG-PET or PET/CT is recommended in patients with clinical stage I or II LS-SCLC who are being considered for curative treatment. If ES-SCLC is established, FDG-PET or PET/CT is optional for further staging. [21, 22, 23]  It is less commonly used in patients with SCLC than in patients with NSCLC because most SCLC patients are not candidates for surgery. PET is also useful for evaluating cases in which recurrent disease is questionable. [27, 28, 29]

Technetium-99m bone scintigraphy may be used as an alternative imaging modality to evaluate for extrathoracic bone metastasis in SCLC patients if FDG-PET or PET/CT is not performed.

Bone scanning is routinely used to evaluate bony metastatic disease.


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