Assessment of interstitial lung disease in a systemic sclerosis patient cohort using photon-counting detector CT with ultra-high resolution and a 1024-pixel image matrix.

Objective: This study assessed the potential of ultra-high resolution (UHR) and a 1024-matrix in photon-counting-detector CT (PCD-CT) for evaluating interstitial lung disease (ILD) in systemic sclerosis (SSc) patients.

Methods: Sixty-six SSc patients who underwent ILD-CT screening on a first-generation PCD-CT were retrospectively included. Scans were performed in UHR mode at 100 kVp with two different matrix sizes (512×512 and 1024x1024) and reconstructed at slice thicknesses of 1.5 and 0.2 mm. Image noise, subjective image quality, and ILD changes (ground glass opacities and reticulations) were evaluated on a 5-point Likert-scale by two independent readers.

Results: Interreader agreement for subjective image quality ranged from fair to almost perfect (Krippendorff-Alpha: 0.258-0.862). Overall image quality was highest for 1.5 mm/1024 matrix images [(reader 1: 4(4.4), reader 2: 5(4.5)]. Image sharpness was rated significantly better in 0.2 mm images (P < .001). Regarding ILD changes, 0.2 mm slice thickness outperformed 1.5 mm slice thickness significantly (P < .001), while there was no significant difference between the two matrix sizes. A 1024-matrix size demonstrated superiority in evaluating coarse reticulations compared to 512-matrix size.

Conclusion: UHR mode with a 0.2 mm slice thickness showed enhanced image sharpness and improved visibility of ILD changes compared to standard reconstructions. This has the potential to enable the early detection of subtle disease manifestations.

Advances in knowledge: With the invention of PCD-CT different reconstruction algorithms need to be evaluated for specific pathologies. In our study ILD UHR mode with 0.2 mm slice thickness showed to be beneficial in the detection of parenchymal changes in patients with scleroderma.