Initial clinical evaluation of stationary digital chest tomosynthesis in adult patients with cystic fibrosis

Abstract

Objective: The imaging evaluation of cystic fibrosis currently relies on chest radiography or computed tomography. Recently, digital chest tomosynthesis has been proposed as an alternative. We have developed a stationary digital chest tomosynthesis (s-DCT) system based on a carbon nanotube (CNT) linear x-ray source array. This system enables tomographic imaging without movement of the x-ray tube and allows for physiological gating. The goal of this study was to evaluate the feasibility of clinical CF imaging with the s-DCT system.

Materials and methods: CF patients undergoing clinically indicated chest radiography were recruited for the study and imaged on the s-DCT system. Three board-certified radiologists reviewed both the CXR and s-DCT images for image quality relevant to CF. CF disease severity was assessed by Brasfield score on CXR and chest tomosynthesis score on s-DCT. Disease severity measures were also evaluated against subject pulmonary function tests.

Results: Fourteen patients underwent s-DCT imaging within 72 h of their chest radiograph imaging. Readers scored the visualization of proximal bronchi, small airways and vascular pattern higher on s-DCT than CXR. Correlation between the averaged Brasfield score and averaged tomosynthesis disease severity score for CF was -0.73, p = 0.0033. The CF disease severity score system for tomosynthesis had high correlation with FEV1 (r = -0.685) and FEF 25-75% (r = -0.719) as well as good correlation with FVC (r = -0.582).

Conclusion: We demonstrate the potential of CNT x-ray-based s-DCT for use in the evaluation of cystic fibrosis disease status in the first clinical study of s-DCT.

Key points: • Carbon nanotube-based linear array x-ray tomosynthesis systems have the potential to provide diagnostically relevant information for patients with cystic fibrosis without the need for a moving gantry. • Despite the short angular span in this prototype system, lung features such as the proximal bronchi, small airways and pulmonary vasculature have improved visualization on s-DCT compared with CXR. Further improvements are anticipated with longer linear x-ray array tubes. • Evaluation of disease severity in CF patients is possible with s-DCT, yielding improved visualization of important lung features and high correlation with pulmonary function tests at a relatively low dose.

Keywords: Cystic fibrosis; Nanotubes, Carbon; Scoring methods; Tomography; X-rays.

FIGURE 1:. s-DCT SYSTEM

The stationary digital chest tomosynthesis system linear x-ray array is aligned with the patient imaging bed [stretcher]. The detector is integrated into the stretcher bed.

Figure 2:. Mild CF

Mild severity CF, corresponding to a 21 on Brasfield scoring system and 14 on tomosynthesis scoring system. A single image from the tomosynthesis exam [a] demonstrates improved visualization of bronchial wall thickening and mucous plugging compared to conventional radiograph [b].

Figure 3:. Severe CF

Severe CF, corresponding to a 15 on Brasfield scoring system and 33 on tomosynthesis scoring system. A single image from the tomosynthesis exam [a] demonstrates improved visualization of bronchial wall thickening, bronchiectasis, and mucous plugging compared to conventional radiograph [b].