Evaluation of quantitative CT indexes in idiopathic interstitial pneumonitis using a low-dose technique.

Objective: To evaluate and compare histogram features (mean lung attenuation, skewness, kurtosis) of low-dose and standard-dose CT in a group of patients affected by idiopathic interstitial pneumonitis.

Methods: We analyzed 16 patients affected by idiopathic interstitial pneumonitis. Spiral whole lung thin-section CT acquisition at standard dose (100 mAs) and three additional low-dose (50 mAs) CT images were obtained. After obtained frequency histograms, mean lung attenuation (MLA), skewness and kurtosis and three range of density (-700/-200 HU; -700/-400 HU; -500/-200 HU) of the standard-and low-dose thin-section CT scans were analyzed and compared.

Results: The parameters obtained with low-dose and standard-dose spiral CT were correlated in a highly significant manner and were equivalent (p<0.01). The greatest correlation was found between standard-and low-dose kurtosis and standard and low-dose -700/-400 HU subrange of density (r=0.92; p<0.0001).

Conclusions: Our results prove that a quantitative CT objective evaluation in lung fibrosis can be successfully obtained with low-dose spiral CT, with reduced mA.