title: Proposal to utilize simplified Swensen protocol in diagnosis of isolated pulmonary nodule.
abstract: BACKGROUND
  The problem of diagnosing whether a solitary pulmonary nodule is benign or malignant is even greater in developing countries due to a higher prevalence of infectious diseases. These infections generate a large number of patients who are generally asymptomatic and with a pulmonary nodule that cannot be accurately defined as having benign or malignant etiology.
  
  
  OBJECTIVE
  To verify the percentages of benign versus malignant non-calcified nodules, the length of time after contrast agent injection is spiral computed tomography (CT) most sensitive and specific, and whether three postcontrast phases are necessary.
  
  
  METHODS
  We studied 23 patients with solitary pulmonary nodules identified on chest radiographs or CT. Spiral scans were obtained with Swensen protocol, but at 3, 4, and 5 min after contrast injection onset. Nodules were classified as benign or malignant by histopathological examination or by an absence or presence of growth after 2 years of follow-up CT.
  
  
  RESULTS
  Of the 23 patients studied, 18 (78.2%) showed a final diagnosis of benign and five (21.7%) malignant nodules. Despite the small sample size, we obtained results similar to those of Swensen et al., with 80.0% sensitivity, 55.5% specificity, and 60.8% accuracy. Four minutes gave the greatest mean enhancement in both malignant and benign lesions.
  
  
  CONCLUSIONS
  Small non-calcified benign nodules were much more frequent than malignant nodules. The best time for dynamic contrast-enhanced CT density analysis was 4 min postcontrast. As well as saving time and money, this simplified Swensen protocol with only precontrast and 4 min postcontrast phases also reduces patient exposure to ionizing radiation.
authors.affiliation: Department of Tropical Diseases and Diagnostic Imaging, Botucatu Medical School, UNESP - Univ Estadual Paulista, Botucatu, Sao Paulo.
authors.forename: Sergio Marrone
authors.initials: SM
authors.lastname: Ribeiro
authors.forename: Raul Lopes
authors.initials: RL
authors.lastname: Ruiz
authors.forename: Hugo Hyung Bok
authors.initials: HH
authors.lastname: Yoo
authors.forename: Daniele Cristina
authors.initials: DC
authors.lastname: Cataneo
authors.forename: Antonio José Maria
authors.initials: AJ
authors.lastname: Cataneo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011857:Radiographic Image Interpretation, Computer-Assisted; D013902:Radiography, Thoracic; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging*; D018709:Statistics, Nonparametric; D036542:Tomography, Spiral Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Pulmonary nodule; diagnosis; lung CT; lung neoplasms