Imaging in the diagnosis and treatment of non-small cell lung cancer

The available tools for diagnosing and staging lung cancer patients can be broadly categorized into non-invasive, minimally invasive and invasive (surgical) modalities. Non-invasive modalities include CT and PET. Minimally invasive modalities are endoscopic approaches, including endoscopic ultrasound, endobronchial ultrasound and transbronchial fine needle aspiration without ultrasound guidance. This review focuses on the non-invasive and minimally invasive techniques involving imaging. Application of Bayesian principles indicates that tests with a high sensitivity and specificity for detection of both systemic metastases and mediastinal nodal involvement are required for treatment selection and planning in patients with non-small cell lung cancer who would be considered for treatment with curative intent. Combined PET/CT using the glucose analogue fluorine-18 fluorodeoxyglucose currently provides the best diagnostic performance for this purpose and should now be considered the standard of care for staging non-small cell lung cancer. Endoscopic ultrasound and endobronchial ultrasound have important complementary roles to allow further evaluation of equivocal nodal abnormalities on PET or CT and to allow pathological samples to be obtained. Diagnostic CT has an important role in defining tumour relations for patients deemed suitable for surgical resection and as the initial investigation for patients with potential symptoms of lung cancer or proven lung cancer that would not be considered for curative treatment on medical grounds.