Diagnostic accuracy of CT-guided automated needle biopsy of lung nodules

OBJECTIVE. The purpose of this study was to determine the factors influenci ng diagnostic accuracy in CT-guided automated needle biopsies of lung nodul es. SUBJECTS AND METHODS. One hundred thirty-eight consecutive CT-guided automa ted needle biopsy procedures were performed in 123 patients (124 pulmonary nodules). Factors for diagnostic accuracy were evaluated through analysis o f the procedures, which were classified into a success group (true-positive and true-negative) and a failure group (false-positive and false-negative) . RESULTS. Final diagnoses were 81 malignant lesions (91 biopsies) and 43 ben ign lesions (47 biopsies). More than two CT-guided biopsies were performed for 13 lesions. Seventy lesions were true-positive, 44 were true-negative, three were false-positive, and 21 were false-negative. The overall diagnost ic accuracy was 82.6%. The sensitivity for malignancy and specificity for b enign lesions were 76.9% and 93.6%, respectively. Positive and negative pre dictive values were 95.9% and 67.7%, respectively. Lesion size was a signif icant factor contributing to diagnostic: accuracy (p = 0.014), Mean diamete rs of lesions (+/-SD) in the success and failure groups were 24.1 +/- 12.4 mm and 17.6 +/- 7.8 mm, respectively. For lesions 6-10 mm in diameter, diag nostic accuracy was 66.7%; for lesions 11-20 mm in diameter, 78.9%; for les ions 21-30 mm in diameter, 86.7%; for lesions 31-50 mm in diameter, 93.3%; and for lesions 51-70 mm in diameter, 100%. CONCLUSION. Lesion size was a determining factor in diagnostic accuracy. Di agnostic accuracy decreased in proportion to the decrease in the lesion dia meter.