title: Clinical significance of lung nodules reported on abdominal CT.
abstract: OBJECTIVE
  The objective of our study was to identify the significance of lung nodules reported on abdominal CT.
  
  
  METHODS
  Abdominal CT reports from a 1-year period were reviewed for the terms "nodule," "nodular," or "mass" in reference to the lung bases. Patients with prior chest or abdominal CT examinations were excluded; the study population included patients with an initial abdominal CT study and at least one follow-up chest or abdominal CT examination. Two thoracic radiologists characterized nodules in consensus. Radiology and clinical records were reviewed for nodule growth and clinical diagnoses.
  
  
  RESULTS
  The term "nodule," "nodular," or "mass" in reference to the lung bases was reported in 364 of 12,287 abdominal CT studies (3%). Of 125 patients with no prior CT examination, 42 had undergone follow-up chest CT, abdominal CT, or both. Common imaging indications included abdominal pain (13/42, 31%) and preexisting malignancy (n = 7, 16.7%). Regardless of the indication for imaging, 16 (38.1%) had malignancy that was known (n = 13) or newly diagnosed (n = 3) on the initial abdominal CT. Three of 42 patients (7.1%) had malignant nodules representing metastatic disease: Nodule growth was seen in one patient with preexisting colon cancer, one patient with newly diagnosed metastatic pancreatic cancer, and a third with known bladder cancer. The latter patient had suspected lung metastases that were confirmed on chest CT 1 day later. Three of the 16 patients (18.8%) with preexisting or newly diagnosed cancer had malignant nodules. No malignant nodules were identified without such history. Six patients (14.3%) had an infection.
  
  
  CONCLUSIONS
  Lung nodules incidentally detected on abdominal CT were rarely malignant and were seen only in the setting of an underlying abdominal malignancy. Knowledge of such history is of critical importance to both the clinician and the radiologist. Dedicated chest CT is most useful when assessing pulmonary nodules in patients with localized malignancy.
authors.affiliation: Department of Radiology, Thoracic Imaging Section, NYU Langone Medical Center, New York, 10016, USA. jbalpert@hotmail.com
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Alpert
authors.forename: John P
authors.initials: JP
authors.lastname: Fantauzzi
authors.forename: Kira
authors.initials: K
authors.lastname: Melamud
authors.forename: Heather
authors.initials: H
authors.lastname: Greenwood
authors.forename: David P
authors.initials: DP
authors.lastname: Naidich
authors.forename: Jane P
authors.initials: JP
authors.lastname: Ko
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003287:Contrast Media; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007472:Iohexol / Q000031:analogs & derivatives; D008175:Lung Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D011860:Radiography, Abdominal; D018570:Risk Assessment; D003074:Solitary Pulmonary Nodule / Q000150:complications / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide