Dark-field chest radiography visualizes the condition of the lungs’ alveolar structure by measuring the coherent ultra-small-angle scattering of X-rays. Here, we compare dark-field chest radiography with conventional radiography for the diagnosis and staging of pulmonary emphysema.

Subjects were included after a medically indicated CT scan of the thorax, showing either no lung impairments or different stages of emphysema. To establish a ground truth, all CTs were assessed separately by three radiologists assigning visual scores based on the Fleischner society classification scheme for emphysema severity (absent, trace, mild, moderate, confluent, advanced destructive).Participants were imaged at a commercial chest radiography device, yielding a conventional attenuation image, and at a clinical prototype for dark-field chest radiography, yielding both an attenuation and a dark-field image. Three independent blinded readers assessed the conventional attenuation image and both attenuation and dark-field image from the prototype for presence and severity of emphysema (no emphysema, mild emphysema, moderate emphysema, severe emphysema).Statistical analysis included evaluation of receiver-operator-characteristics and pair-wise comparison of adjacent Fleischner groups using an AUC-based z-test with a significance level of 0.05.

A total of 90 patients (56 males) were included, with a mean age of 65 ± 12 years.The dark-field images show a distinct decrease of signal strength with emphysema severity. Compared to conventional images (AUC = 0.74), readers were significantly better able to identify emphysema with images from the dark-field prototype (AUC = 0.85, p < 0.05). While ratings of adjacent emphysema severity groups with conventional radiographs were only different for trace and mild emphysema, ratings based on images from the dark-field prototype were different for trace and mild, mild and moderate, and moderate and confluent emphysema.

Compared to conventional chest radiography, dark-field chest radiography provideimproved capability for identification and staging of emphysema.

Dark-field chest radiography improves the detection of emphysematous changes in the lung, demonstrating its high diagnostic value for lung assessment.