Evaluation of pulmonary lesions with FDG-PET. Comparison of findings in patients with and without a history of prior malignancy.
OBJECTIVE
The purpose of this study was to evaluate the accuracy of positron emission tomography (PET) using F-18 fluorodeoxyglucose (FDG) in differentiating benign from malignant pulmonary lesions both in patients with and without a history of prior malignancy.


METHODS
Forty-eight consecutive patients with pulmonary lesions suspicious for malignancy underwent FDG-PET scanning. Group 1 included 27 patients without and group 2 included 21 patients with a history of malignancy. Pathologic proof of diagnosis was obtained for 32 patients and 16 patients were followed up clinically and radiographically for at least 6 month. The standard uptake ratio (SUR) and the lesion to background (L/B) ratio were determined in 45 patients.


METHODS
Vanderbilt University Medical Center.


RESULTS
In group 1, the average SUR and L/B ratio for malignant lesions (n=14) were 8.9 +/- 4.9 and 20.6 +/- 14.2, respectively. For benign lesions (n=12), the average SUR was 3.3 +/- 3.2 and L/B ratio was 5.2 +/- 5.5. In group 2, the average SUR and L/B ratio for malignant lesions were not significantly different from group 1. Using either a SUR greater than 2.5 or L/B ratio greater than 5 as an cutoff level to differentiate benign and malignant lesions, the sensitivity and negative predictive value in both groups were 100%. There were five false-positive studies in group 1 and one in group 2, including tuberculosis (n=2), a granulomatous lesion (n=1), an inflammatory lesion (n=1), a schwannoma (n=1), and a fibrous mesothelioma (n=1). The overall accuracy was 88%, 81% in group 1, and 95% in group 2.


CONCLUSIONS
FDG-PET can identify malignant pulmonary lesions both in patients without and with a history of prior malignancy with a high sensitivity and negative predictive value for lesions greater than 1 cm (100% in this study). High FDG uptake by some inflammatory processes and benign tumors may cause false-positive results. Semiquantitative evaluation using SUR or L/B ratio provides similar accuracy.
Knight
S B
SB
Department of Radiology, Vanderbilt University Medical Center, Nashville, Tenn., USA.
Delbeke
D
D
Stewart
J R
JR
Sandler
M P
MP
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003847:Deoxyglucose / Q000031:analogs & derivatives*; D005189:False Positive Reactions; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006099:Granuloma / Q000000981:diagnostic imaging; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008654:Mesothelioma / Q000000981:diagnostic imaging; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging; D011014:Pneumonia / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D011859:Radiography; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000000981:diagnostic imaging
D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose