Multidetector Computed Tomography Findings in Pulmonary Hamartomas: A New Fat Detection Threshold.

Abstract

The aim of the study was to determine the accuracy of multidetector computed tomography in the evaluation of histologically confirmed pulmonary hamartomas (PHs), with a special focus on fat detection. Data from 55 patients who had received a histologically confirmed diagnosis of PH and had undergone 64-slice thoracic MDCT were retrospectively evaluated. PHs manifested predominantly as peripheral pulmonary nodules with lobulated margins. The average lesion diameter was 1.51 cm (SD 0.6 cm). Histologic analyses identified fat content in 43/55 (78.2%) surgical specimens. The accuracy, sensitivity, and specificity of fat detection at a density threshold of -40 HU were 83.7%, 100%, and 87.2%, respectively. A threshold of -33 HU yielded better results (95.3%, 100%, and 96.3%, respectively). Popcorn-like calcifications were found in only 12/55 (21.8%) PHs and were the only imaging feature suggestive of PH in 7.2% of cases. Most (66%) lesions with popcorn-like calcifications also contained fat. The adoption of a new threshold for fat content (<-33 HU) can lead to further improvements in the overall ability to detect PHs by CT.