title: Tissue characterization of solitary pulmonary nodule: comparative study between helical dynamic CT and integrated PET/CT.
abstract: Recent advances in the technology of helical multidetector CT allow precise evaluations of nodule hemodynamics. In addition, the efficacy of tissue characterization has improved, and now sensitivity and specificity of >90% are achieved. Moreover, the efficacy of PET for the tissue characterization of solitary pulmonary nodules (SPNs) has also become of importance. The purpose of this study was to compare the diagnostic accuracy of helical dynamic (HD) CT (HDCT) and integrated PET/CT for pulmonary nodule characterization.
  
  
  METHODS
  One hundred nineteen patients with an SPN underwent both HDCT (unenhanced scans, followed by series of images at 30, 60, 90, 120 s and at 5 and 15 min after intravenous injection of contrast medium) and integrated PET/CT. On HDCT, a nodule was regarded as malignant with a net enhancement of > or =25 Hounsfield units (HU) and a washout of 5-31 HU. On integrated PET/CT, nodules were considered malignant with a > or =3.5 maximum standardized uptake value and an 18F-FDG uptake greater than that of mediastinal structures. The sensitivity, specificity, and accuracy of the 2 modalities for malignancy were compared using the McNemar test.
  
  
  RESULTS
  There were 79 malignant and 40 benign nodules. The sensitivity, specificity, and accuracy for malignancy on HDCT were 81% (64/79 nodules), 93% (37/40), and 85% (101/119), respectively, whereas those on integrated PET/CT were 96% (76/79), 88% (35/40), and 93% (111/119), respectively (P = 0.008, 0.727, and 0.011, respectively). All malignant nodules were interpreted correctly on either HDCT or PET/CT.
  
  
  CONCLUSIONS
  Integrated PET/CT is more sensitive and accurate than HDCT for the malignant nodule characterization; therefore, PET/CT may be performed as the first-line evaluation tool for SPN characterization. Because HDCT has high specificity and acceptable sensitivity and accuracy, it may be a reasonable alternative for nodule characterization when PET/CT is unavailable.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Chin A
authors.initials: CA
authors.lastname: Yi
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Lee
authors.forename: Byung-Tae
authors.initials: BT
authors.lastname: Kim
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Choi
authors.forename: O Jung
authors.initials: OJ
authors.lastname: Kwon
authors.forename: Hojoong
authors.initials: H
authors.lastname: Kim
authors.forename: Young Mog
authors.initials: YM
authors.lastname: Shim
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008175:Lung Neoplasms / Q000145:classification / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000145:classification / Q000000981:diagnostic imaging*; D013382:Subtraction Technique; D018511:Systems Integration; D036542:Tomography, Spiral Computed / Q000379:methods*