Ct reconstruction algorithm selection in the evaluation of solitary pulmonary nodules

Objective: We have observed a significant CT artifact in the evaluation of lung nodules that occurred with the use of high-spatial-frequency reconstruction algorithms. We have seen this lead to a false-positive diagnosis of calcification in a small uncalcified lung nodule. Because of the seriousness of misinterpretation of benign calcification in an uncalcified nodule, we reviewed the various effects of several reconstruction algorithms on different scanners. Materials and Methods: Using high-spatial-frequency, smoothing, and intermediate reconstruction algorithms, we studied standardized cylinders in a CT reference phantom and lung nodules in eight patients. Algorithms on four CT scanners were analyzed. Results: We found peripheral edge enhancement artifact on some CT images of phantom cylinders and uncalcified lung nodules. The images with edge enhancement artifact were obtained from two scanners with the use of high-spatial-frequency algorithms (Picker 1200 SX and GE HiSpeed Advantage). Conclusion: Use of high-spatial-frequency reconstruction algorithms for the analysis of lung nodules with thin-section CT may lead to an erroneous diagnosis of calcification.