Progressive worsening of idiopathic pulmonary fibrosis. High resolution computed tomography (HRCT) study with functional correlations.

PURPOSE: To evaluate the usefulness of the high-resolution computed tomography (HRCT) visual score in idiopathic pulmonary fibrosis (IPF) and its correlation with respiratory function tests.

MATERIAL AND METHODS: We studied the pulmonary function tests and HRCT scans of 42 IPF patients, at presentation (T0) and follow-up (T1: mean 13.7 months post-diagnosis). Of the 42 patients, 21 had been treated with steroid and immunosuppresion therapy. The pulmonary function tests considered were vital capacity (VC), diffusion lung capacity for carbon monoxide (D(L)CO) and arterial blood oxygen partial pressure (PaO(2)). The main HRCT parameters were type of lesion, and site and extent, the latter calculated by means of the visual score.

RESULTS: Between T0 and T1, both mean HRCT score (from 43.57% to 50.64%) and lung function tests worsened (VC from 68.43% to 64.18%; D(L)CO from 36.31% to 28.97%; PaO(2) from 76.31 to 68.89 mmHg), without considerable differences between treated and untreated patients. At presentation (T0), the HRCT visual score had a significant correlation with lung function tests and these correlated with one another. Similar correlations were found at T1, but not for HRCT score and D(L)CO. In the interval between T0 and T1 the variations correlated significantly with each other, with two exceptions: HRCT score and D(L)CO, and D(L)CO and PaO(2).

DISCUSSION AND CONCLUSIONS: IPF exhibited a progressive deterioration both in HRCT extent of disease and lung function impairment. There is a significant correlation between HRCT visual score and lung function tests both at diagnosis and at follow-up. The HRCT study is able to identify and quantify anatomic IPF and also to evaluate the progression of the disease. In clinical practice, the HRCT visual score of disease extent can be used in association with function tests to monitor IPF evolution, and to evaluate prognosis and therapy. In the future, helical CT with 3D model construction will provide a more precise IPF quantification with automatic score.