When lung cancer is suspected, CT scan of the chest should be preferred. Some people think that MRI is more expensive and better than CT, but it is not. Advantages of chest CT: 1. High resolution, small lesions can be detected. 2.It can clearly show the mass properties, such as location, size, shape, density, etc., and the adjacent tissues. 3, the current application of the CT machine scanning speed is extremely fast, a few seconds to complete the whole lung scan, even if the patient can not hold his breath can also be scanned. 4.It can show the masses that are not easy to show on X-ray chest film, such as the apical part of the lung, the paracardium or the posterior cardiac area, and the posterior rib diaphragm angle. 5.Enhanced CT scan can clearly show the mediastinum, hilar lymph nodes and pulmonary vessels. 6.CT-guided lung aspiration biopsy is feasible to further clarify the diagnosis. Magnetic resonance imaging (MRI) examination is the use of hydrogen protons in the human body resonate with each other in the magnetic field, through the computer to form images, can be scanned at any angle, the biggest advantage in doing cranial soft tissue, crista, spinal canal examination. In contrast, the lungs have more gas and fewer hydrogen protons, so the MRI signal is weak, and its display of lung lesions is mostly unclear, especially insensitive to calcification. In addition, to eliminate the artifacts caused by heartbeat and whistle need to be supplemented with cardiac gating and whistle gating during the scan, the scan time is prolonged, and the overall scan time is about 20 minutes or more, which is much longer than CT scan, and many patients cannot tolerate it, therefore, it is usually not recommended.