Pulmonary nodules are a common finding of chest radiography and computed tomography (CT) examinations not only in routine clinical practice but also in lung cancer screening with low-dose CT. Then, the main target for radiological examination for the detection of pulmonary nodules and lung cancer is differentiation of malignant from benign nodules and determination of accurate TNM staging based on morphological, metabolic, and relaxation time-dependent information obtained from CT and nuclear medicine studies including positron emission tomography (PET) or PET combined with CT (PET/CT) and magnetic resonance (MR) imaging. In addition, a limitation of the application of functional imaging has been its ability to prediction of postoperative lung function, and is therefore mainly used for perfusion scanning, perfusion single-photon emission tomography (SPECT) or SPECT/CT as well as CT, which is also used for prediction by means of the anatomical method, and is limited to non-small cell lung cancer (NSCLC) candidates for surgical resection. Moreover, some functional imaging methods have been suggested as having the capability for therapeutic effect prediction in advanced NSCLC patients. Therefore, pulmonary functional imaging is currently available for answering all abovementioned clinical questions and applicable in routine clinical practice. This chapter describes state-of-the-art pulmonary functional imaging with its clinical potentials for (1) prediction of postoperative lung function for lung cancer candidates for surgical treatment, (2) differentiation of malignant from benign lesions, and (3) prediction of treatment outcomes and recurrence for lung cancer patients treated with conservative therapy.