Ultra-high resolution photon-counting CT of the lung after lung transplantation: should we go for optimal image quality or reduced radiation dose?

Objectives: As an often-young population with regular CT follow-up, lung transplant (LTX) patients could benefit from both high spatial resolution and lower radiation dose. We compared the image quality of ultra-high-resolution photon-counting CT (UHR-PCCT) with high-resolution energy-integrating-detector CT (HR-EIDCT) at both a normal (IQ100) and a reduced radiation dose (IQ40) in patients after LTX. Methods: Hundred patients post-LTX, with an UHR-PCCT (0.4 mm) between Dec-2021 and Aug-2022, and prior HR-EIDCT (1.0 mm) <14 months apart, were included. In 49 patients, PCCT-IQ100 images were compared with previous HR-EIDCT; in 51 patients, PCCT-IQ40 images were compared with previous HR-EIDCT. Image quality was scored using a 5-point Liker scale (-2 to +2) for 7 relevant entities (peripheral airways, micronodules, reticulations, pleural thickening, consolidation, ground glass opacities (GGO), and air-trapping) plus an overall quality impression score. Results: < 0.0001). Conclusions: A significant dose reduction was achieved using the PCCT-IQ40 protocol. Although image quality was best in PCCT-IQ100, image quality in PCCT-IQ40 was non-inferior to EIDCT. Therefore, a significant radiation dose reduction is feasible without compromising image quality. Clinical relevance statement: PCCT offers improved image quality while reducing radiation dose significantly.For lung transplant patients, who are often younger and require lifelong, regular follow-up with CT, both improved image quality and lowered radiation dose would be very beneficial. Key Points: - LTX patients require long-term follow-up with high-resolution imaging to detect often subtle abnormalities and would benefit from both improved image quality and radiation dose reduction.- Perceived image quality was significantly higher in IQ100-PCCT than EIDCT; a significant further radiation dose reduction was feasible (IQ40-PCCT) without compromising image quality compared to EIDCT.