Purpose: The aim of this study was to assess the accuracy of high-resolution CT in the differential diagnosis between UIP and NSIP, and the correlations with histological and functional findings.
Materials and methods: Patients underwent thin-collimation spiral CT (1 mm), with 10-mm interval. Pulmonary function was assessed with a pneumotacograph and body plethysmograph connected with a computer for data analysis. Three pathologists, blinded to the clinical and functional data, provided a histological diagnosis based on established criteria reported in the literature. The study group only included patients with a histological diagnosis of either UIP or NSIP.
Results: We achieved a correct diagnosis of NSIP in 86.6% of cases (76.4% sensitivity; 84.6% specificity), whereas UIP was correctly diagnosed in 73.3% of cases (84.6% sensitivity; 76.5% specificity). An 80% agreement was achieved between the HRCT and histological findings in the whole case series (73% sensitivity, 87% specificity, p<0.01).
Conclusions: The most important finding of our study was that a ground glass appearance equal to or greater than 15% is highly suggestive of NSIP. Therefore, our results could be useful to confirm a suggested diagnosis of NSIP.