Ultra-high resolution CT imaging of interstitial lung disease: impact of photon-counting CT in 112 patients

ObjectivesTo compare lung parenchyma analysis on ultra-high resolution (UHR) images of a photon-counting CT (PCCT) scanner with that of high-resolution (HR) images of an energy-integrating detector CT (EID-CT).MethodsA total of 112 patients with stable interstitial lung disease (ILD) were investigated (a) at T0 with HRCT on a 3(rd)-generation dual-source CT scanner; (b) at T1 with UHR on a PCCT scanner; (c) with a comparison of 1-mm-thick lung images.ResultsDespite a higher level of objective noise at T1 (74.1 +/- 14.1 UH vs 38.1 +/- 8.7 UH; p < 0.0001), higher qualitative scores were observed at T1 with (a) visualization of more distal bronchial divisions (median order; Q1-Q3) (T1: 10(th) division [9-10]; T0: 9(th) division [8-9]; p < 0.0001); (b) greater scores of sharpness of bronchial walls (p < 0.0001) and right major fissure (p < 0.0001). The scores of visualization of CT features of ILD were significantly superior at T1 (micronodules: p = 0.03; linear opacities, intralobular reticulation, bronchiectasis, bronchiolectasis, and honeycombing: p < 0.0001), leading to the reclassification of 4 patients with non-fibrotic ILD at T0, recognized with fibrotic ILD at T1. At T1, the mean (+/- SD) radiation dose (CTDI (vol): 2.7 +/- 0.5 mGy; DLP: 88.5 +/- 21 mGy.cm) was significantly lower than that delivered at T0 (CTDI (vol): 3.6 +/- 0.9 mGy; DLP: 129.8 +/- 31.7 mGy.cm) (p < 0.0001), corresponding to a mean reduction of 27% and 32% for the CTDIvol and DLP, respectively.ConclusionsThe UHR scanning mode of PCCT allowed a more precise depiction of CT features of ILDs and reclassification of ILD patterns with significant radiation dose reduction.

Automated summary

This study compared the impact of the ultra-high resolution (UHR) images of a photon-counting CT (PCCT) scanner with the high-resolution (HR) images of an energy-integrating detector CT (EID-CT) on lung parenchyma analysis. It found that using the UHR scanning mode improved the visibility and identification of ILD features, leading to the reclassification of ILD patterns, all while reducing radiation dose.