Simplified method of dynamic contrast-enhanced computed tomography in the evaluation of indeterminate pulmonary nodules.

BACKGROUND Dynamic contrast-enhanced computed tomography (CECT) is one of the methods used in the evaluation of lung nodules. OBJECTIVES The aim of the study was to evaluate the accuracy of the simplified method (based on only 2 postcontrast measurements) of dynamic CECT in determining the nature of pulmonary nodules. METHODS Forty nodules (solid, 10-40 mm in diameter, spherical, with no visible calcification or fatty tissue) in 40 patients were analyzed. In 30 patients, the nature of the nodule was confirmed by pathological examination. In 10 cases, the nodules were assumed to be benign, as no growth within 2 years was radiologically documented. All patients underwent CECT according to a simplified protocol (based on pre-enhancement and 2 postcontrast measurements at 30 s and 4 min after contrast injection). RESULTS Twenty-three (57.5%) nodules were proved to be malignant and 17 (42.5%) benign. The 7 benign and none of the malignant nodules showed an enhancement value of < or = 15 Hounsfield units. Thus, the sensitivity, specificity, positive and negative predictive value and diagnostic accuracy of shortened dynamic CECT were 100, 41, 70, 100 and 75%, respectively. CONCLUSIONS In CECT, contrast enhancement of a pulmonary nodule < or = 15 Hounsfield units is a reliable predictor of its benignity. Reduction in the number of postcontrast measurements in the simplified method of dynamic CECT does not influence its sensitivity.