SUV as an adjunct in evaluating disease activity in idiopathic pulmonary fibrosis - a pilot study

Objective We hypothesize that the standardized uptake value (SUV) from PET/computed tomography (CT) can act as an adjunct to forced vital capacity (FVC) in evaluating disease status in idiopathic pulmonary fibrosis (IPF). Methods Eight consecutive male patients diagnosed with IPF were prospectively recruited to undergo full pulmonary function tests, high-resolution computed tomography of the thorax and PET/CT. The corrected mean SUV (rSUVmean) and corrected maximum SUV (rSUVmax) against the mediastinal blood pool were correlated with clinical parameters. Examinations were repeated 6 months later in six patients (2/8 patients had died) and changes were evaluated. Correlation was assessed by Spearman's rank correlation, and statistical significance was considered when the P-value was less than 0.05. Results The rSUVmean in IPF was negatively correlated with FVC (r=-0.6, P=0.024) and diffusing capacity for carbon monoxide (r=-0.7, P=0.010). The decline in FVC was associated with an increment in rSUVmax (r=-0.9, P=0.019), but no similar observation was made with total CT score (r=-0.1, P=0.787). Conclusion Pulmonary metabolism, rSUVmean, contributes to the functional status of IPF patients, and changes in rSUVmax may serve as an adjunct surrogate marker to FVC in evaluating the disease status in IPF patients.