Pulmonary nodules: experimental and clinical studies at low-dose CT

• Published in: Radiology Vol. 213; no. 1; p. 289
• Main Authors: Diederich, S, Lenzen, H, Windmann, R, Puskas, Z, Yelbuz, T M, Henneken, S, Klaiber, T, Eameri, M, Roos, N, Peters, P E
• Format: Journal Article
• Language: English
• Published: United States 01-10-1999
• Subjects: Adult; Aged; Autopsy; Female; Humans; Lung Diseases - diagnostic imaging; Lung Diseases - pathology; Lung Neoplasms - diagnostic imaging; Lung Neoplasms - pathology; Male; Middle Aged; Radiation Dosage; Tomography, X-Ray Computed
• ISSN: 0033-8419
• DOI: 10.1148/radiology.213.1.r99oc29289

To compare the number of pulmonary nodules detected at helical low- and standard-dose computed tomography (CT) and to investigate the diagnostic value of low-dose CT with a radiation exposure equivalent to that used at chest radiography.
Two radiologists recorded pulmonary nodules at standard-dose (250 or 100 mA, pitch of 1; 200 mA, pitch of 2) or low-dose CT (50 or 25 mA, pitch of 1 or 2) in five postmortem specimens and 75 patients. Nodules were assessed by size (5 mm or smaller, 6-10 mm, or larger than 10 mm) and by diagnostic confidence ("definite nodule," "definite lesion, not classic nodule," or "questionable lesion, possibly representing a vessel") with the Wilcoxon signed rank test. Artifacts depicted at low-dose CT were recorded.
There were no statistically significant differences in the number of nodules detected at standard- or low-dose CT except in nodules 5 mm or smaller that were assessed as definite nodules at standard- or low-dose CT (25 mA, pitch of 2) (472 vs 397, P < .05). Artifacts that possibly interfered with nodule detection were observed exclusively at CT with 25 mA and a pitch of 2.
Pulmonary nodules were detected reliably at CT with 50 mA and pitch of 2 or with 25 mA and a pitch of 1. However, further reduction of the dose to that used at chest radiography was associated with a significant decrease in the number of nodules 5 mm or smaller that were detected, possibly due to artifacts.