Editor-In-Chief: C. Michael Gibson, M.S., M.D.  Associate Editor(s)-in-Chief: Dildar Hussain, MBBS 
Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include, a solitary
pulmonary nodule, centrally located masses, mediastinal invasion
CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases: adrenal glands, liver, and brain. CT scans diagnose lung cancer by providing anatomical detail to locate the tumor, demonstrating proximity to nearby structures, and deciphering whether lymph nodes are enlarged in the mediastinum.
Chest CT scan is the modality of choice in the diagnosis of lung cancer. Findings on CT scan suggestive of lung cancer include:
Common radiological appearances of lung cancer. Centrally located mass with mediastinal invasion (arrow, A), peripherally situated mass abutting the pleura (arrow, B), mass with smooth, lobulated margins (arrow, C) and with spiculated, irregular margins (arrow, D), via < https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F1/> 
Lung cancers with atypical radiological pattern. Squamous cell cancer presenting as a cavitating mass (arrow, A). Adenocarcinoma presenting as dense consolidation (arrow, B). Bronchoalveolar carcinoma (adenocarcinoma in situ) presenting as ground-glass opacity (arrow, C) and mixed density, solid (arrow), and ground-glass nodules (arrowhead) in D via < https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F2/> 
Stage T1 and T2 tumors. Stage T1 tumor due to size <3 cm (arrow, A). Stage T2 endobronchial tumor (arrowhead) causing pneumonitis restricted to the upper lobe (arrow) in B. T2a tumor >3 cm but <5 cm (arrow, C). T2b tumor >5 cm but <7 cm (arrow in D) via < https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F3/> 
Stage T3 tumors. T3 tumor due to size >7 cm in size (arrow, A), eroding the ribs (arrow, B), infiltrating the mediastinal pleura but not the vessels (arrow, C), and causing atelectasis of the entire lung (arrowhead, D via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F4/>. 
Stage T4 tumors. T4 tumor due to invasion of pulmonary artery (arrow, A), descending aorta (arrow, B), vertebral body (arrow, C), superior vena cava with thrombus (arrow, D)via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F5/> 
Superior sulcus tumor. Axial (A) and coronal (B) CT scans show a large mass in the apex of the right lung causing destruction of the first and second ribs (arrows) with erosion of the right half of the vertebral body (arrowheads) suggestive of a superior sulcus tumor, via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F16/> 
Spiral CT perfusion imaging
Spiral CT perfusion study can be used as a diagnostic method for peripheral pulmonary nodules.
Spiral CT perfusion study provides non-invasive method of quantitative assessment about the blood flow patterns of peripheral pulmonary nodules.
Spiral CT perfusion imaging is analyzed and evaluated for:. ]]
 TDC (time density curve)
Perfusion parametric maps
The respective perfusion parameters.
Immunohistochemical findings of microvessel density (MVD) measurement
(A-H) Poorly differentiated adenocarcinoma found in the apicoposterior segment of superior lobe of the left lung of a 56 year-old male. (A) Time density curve. (B-F) (original image, BF, BV, MTT, PS) typeI parametric maps, PS value is higher (30.883). (G) CD34 staining shows many immature tumor microvessels (× 200). (H) VEGF expression is strong positive (× 400) via, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2474637/figure/F6/. 
(A-H) (A-H) Well differentiated squamous cell carcinoma found in the posterior basal segment of inferior lobe of the right lung of a 61-year-old male. (A) Time density curve. (B-F) (original image, BF, BV, MTT, PS) TypeII parametric maps, PS value is higher (27.051). (G) CD34 staining shows many immature tumor microvessels (× 200). (H) VEGF expression is strong positive (× 400). via, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2474637/figure/F3/. 
CT Findings of Metastatic disease
CT scans help stage the lung cancer. A CT scan of the abdomen and brain can help visualize the common sights of metastases: adrenal glands, liver, and brain.
The benefits of CT Scans in lung cancer patients are the following:
 Provides anatomical detail to locate the
tumor Demonstrates proximity to nearby structures
Deciphers whether lymph nodes are enlarged in the mediastinum
Metastatic disease. Bilateral pleural effusions-M1a (arrow, A), lung metastases-M1a (arrows, B), adrenal metastasis-M1b (arrow, C), vertebral metastasis-M1b (arrow, D), brain metastasis-M1b (arrow, E), liver metastases-M1b (arrows, F)via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F10/>This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 
Adrenal adenoma versus metastasis. Enhancing solid adrenal nodule on CT scan in a case of lung cancer (arrow, A) suggestive of metastatic deposit. Unenhanced CT scan shows fatty attenuation within the nodule with an HU value of 0 suggesting the possibility of an adenoma (arrow, B). FDG PET/CT shows no tracer concentration in the nodule, confirming the diagnosis of adenoma. Enhancing solid adrenal nodule on CT scan in another patient of lung cancer (arrow, D), which is indeterminate in nature. FDG PET/CT shows abnormal focal tracer concentration in the nodule (arrow, E) highly suggestive of a metastatic deposit via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F11/> 
Brain metastases in asymptomatic patient, CT scan versus MRI. MRI brain in a patient of lung cancer shows multiple tiny enhancing foci scattered in the parenchyma bilaterally (arrows in A and B) suggestive of metastatic lesions. Corresponding contrast CT scan sections of the brain show no obvious lesions (C and D). Note the beam hardening effects due to bone, leading to a loss of resolution on the CT images (C and D)via< https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4419420/figure/F12/> 
Unfortunately, research has shown that there are a number of false positives associated with CT scanning because a CT scan on its own cannot determine
malignancy. A positive result for a tumor using a CT scan is typically followed up with a biopsy for confirmation.
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Purandare, NilenduC; Rangarajan, Venkatesh (2015). "Imaging of lung cancer: Implications on staging and management". Indian Journal of Radiology and Imaging. 25 (2): 109. doi: 10.4103/0971-3026.155831. ISSN 0971-3026.
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Ma, Shu-Hua; Le, Hong-Bo; Jia, Bao-hui; Wang, Zhao-Xin; Xiao, Zhuang-Wei; Cheng, Xiao-Ling; Mei, Wei; Wu, Min; Hu, Zhi-Guo; Li, Yu-Guang (2008). "Peripheral pulmonary nodules: Relationship between multi-slice spiral CT perfusion imaging and tumor angiogenesis and VEGF expression". BMC Cancer. 8 (1). doi: 10.1186/1471-2407-8-186. ISSN 1471-2407.
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