title: Tumors in the tracheobronchial tree: CT and FDG PET features.
abstract: A variety of tumors, including primary malignant tumors, secondary malignant tumors, and benign tumors, can occur in the tracheobronchial tree. Primary malignant tumors commonly originate from the surface epithelium or the salivary glands, whereas most benign tumors arise from the mesenchymal tissue. At computed tomography (CT), primary malignant tumors manifest as a polypoid lesion, a focal sessile lesion, eccentric narrowing of the airway lumen, or circumferential wall thickening. At fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET), most squamous cell carcinomas show high uptake, whereas adenoid cystic carcinoma and mucoepidermoid carcinoma show variable uptake depending on the grade of differentiation. High-grade malignancies tend to show high and homogeneous uptake. Carcinoid tumors commonly show intense enhancement at contrast material-enhanced CT, which can be helpful in making the diagnosis, and usually have lower uptake at FDG PET than would be expected for a malignant tumor. Secondary malignant tumors occur as a result of either hematogenous metastasis or direct invasion by a malignancy from an adjacent structure. Their CT manifestations are similar to those of primary malignant tumors, with uptake at FDG PET depending primarily on the metabolic activity and degree of differentiation of the primary tumor. Among the benign tumors, hamartoma and lipoma can show characteristic CT findings such as "popcorn" calcification or internal fat. However, CT findings in most benign tumors are nonspecific. At FDG PET, benign tumors usually show little or no uptake and can be differentiated from malignant tumors. Knowledge of the characteristic CT and FDG PET findings of tracheobronchial tumors can aid in diagnosis and treatment planning.
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Institute of Radiation Medicine, Seoul National University Medical Research Center, 101 Daehangno, Jongno-gu, Seoul 110-744, Korea.
authors.forename: Chang Min
authors.initials: CM
authors.lastname: Park
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Goo
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Lee
authors.forename: Min A
authors.initials: MA
authors.lastname: Kim
authors.forename: Chang Hyun
authors.initials: CH
authors.lastname: Lee
authors.forename: Mi-Jin
authors.initials: MJ
authors.lastname: Kang
mesh_terms: D000328:Adult; D000368:Aged; D001984:Bronchial Neoplasms / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014134:Tracheal Neoplasms / Q000175:diagnosis*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18