What is the role of CT scanning in the workup of secondary lung tumors?

Updated: Feb 08, 2019
  • Author: Daniel S Schwartz, MD, MBA, FACS; Chief Editor: John Geibel, MD, DSc, MSc, AGAF  more...
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Answer

Conventional CT of the chest from the level of the superior thoracic aperture to the adrenal glands is superior to plain chest radiography for the detection of pulmonary nodules and mediastinal lymph node involvement. Spiral (helical) CT further increases the odds of detecting pulmonary nodules.

Increased sensitivity comes at the cost of somewhat decreased specificity in comparison with standard chest radiography (posteroanterior and lateral) and conventional CT. However, the specificity of a test is strongly influenced by clinical circumstances. Thus, in highly selected patients (eg, those with osteogenic sarcoma or soft-tissue sarcoma, which are tumors that have a high propensity for metastasizing to the lungs), 95% of nodules on the CT scan have been shown to represent metastases.

Technetium-99m (99mTc)-labeled somatostatin analogue depreotide single-photon emission CT (SPECT) is used for evaluation of pulmonary nodules and staging of lung cancer, with reported sensitivity and specificity comparable to those of PET.

Indium-111 (111In)-labeled somatostatin analogue octreotide scanning is recommended for localization of carcinoid tumors. Whole-body iodine-131 (131I) scanning is recommended for the diagnosis of metastatic thyroid cancer.


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