A Comparison of the Diagnostic Accuracy of 18F-FDG PET and CT in the Characterization of Solitary Pulmonary Nodules
James W. Fletcher 1*,
Steven M. Kymes 2,
Michael Gould 3,
Naomi Alazraki 4,
R. Edward Coleman 5,
Val J. Lowe 6,
Charles Marn 7,
George Segall 8,
Lyn A. Thet 9,
Kelvin Lee 10,
and for the VA SNAP Cooperative Studies Group
1 Department of Radiology, Indiana University School of Medicine, Indianapolis, Indiana
2 Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri
3 Department of Veterans Affairs Palo Alto Health Care System and the Department of Medicine, Stanford School of Medicine, Stanford, California
4 Department of Radiology, Emory University School of Medicine, Atlanta, Georgia
5 Department of Radiology, Duke University School of Medicine, Durham, North Carolina
6 Department of Radiology, Mayo Clinic, Rochester, Minnesota
7 Department of Radiology, University of Wisconsin School of Medicine, Madison, Wisconsin
8 Department of Veterans Affairs Palo Alto Health Care System and the Department of Radiology, Stanford School of Medicine, Stanford, California
9 Department of Medicine, University of Wisconsin School of Medicine, Madison, Wisconsin
10 Department of Radiology, Indiana University School of Medicine, Indianapolis, IndianaDepartment of Veterans Affairs Cooperative Studies Program Coordinating Center, Palo Alto, California
* To whom correspondence should be addressed. E-mail: jwfletch{at}iupui.edu.
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Abstract |
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CT and PET are widely used to characterize solitary pulmonary nodules (SPNs). However, most CT accuracy studies have been performed with outdated technology and methods, and previous PET studies have been limited by small sample sizes and incomplete masking. Our objective was to compare CT and PET accuracy in veterans with SPN. Methods: Between January 1999 and June 2001, we recruited 532 participants with SPNs newly diagnosed on radiography and untreated. The SPNs were 7–30 mm. All patients underwent 18F-FDG PET and CT. A masked panel of 3 PET and 3 CT experts rated the studies on a 5-point scale. SPN tissue diagnosis or 2-y follow-up established the final diagnosis. Results: A definitive diagnosis was established for 344 participants. The prevalence of malignancy was 53%. The average size was 16 mm. Likelihood ratios (LRs) for PET and CT results for combined ratings of either definitely benign (33% and 9% of patients, respectively) or probably benign (27% and 12%) were 0.10 and 0.11, respectively. LRs for PET and CT results for combined ratings of indeterminate (1% and 25%), probably malignant (21% and 39%), or definitely malignant (35% and 15%) were 5.18 and 1.61, respectively. Area under the receiver operating characteristic curve was 0.93 (95% confidence interval, 0.90–0.95) for PET and 0.82 (95% confidence interval, 0.77–0.86) for CT (P < 0.0001 for the difference). PET inter- and intraobserver reliability was superior to CT. Conclusion: Definitely and probably benign results on PET and CT strongly predict benign SPN. However, such results were 3 times more common with PET. Definitely malignant results on PET were much more predictive of malignancy than were these results on CT. A malignant final diagnosis was approximately 10 times more likely than a benign final diagnosis in participants with PET results rated definitely malignant.
Key Words:
oncology, PET, respiratory, CT, SPN, diagnosis
