Photon-Counting Computed Tomography (PC-CT) of the spine: impact on diagnostic confidence and radiation dose
Alexander Rau, Jakob Straehle, Thomas Stein, Thierno D. Diallo, Stephan Rau, Sebastian Faby, Konstantin Nikolaou, Stefan O. Schoenberg, Daniel Overhoff, Jürgen Beck, Horst Urbach, Jan‐Helge Klingler, Fabian Bamberg, Jakob Weiß
Abstract
Abstract Objectives Computed tomography (CT) is employed to evaluate surgical outcome after spinal interventions. Here, we investigate the potential of multispectral photon-counting computed tomography (PC-CT) on image quality, diagnostic confidence, and radiation dose compared to an energy-integrating CT (EID-CT). Methods In this prospective study, 32 patients underwent PC-CT of the spine. Data was reconstructed in two ways: (1) standard bone kernel with 65-keV (PC-CT std ) and (2) 130-keV monoenergetic images (PC-CT 130 keV ). Prior EID-CT was available for 17 patients; for the remaining 15, an age–, sex–, and body mass index–matched EID-CT cohort was identified. Image quality (5-point Likert scales on overall, sharpness, artifacts, noise, diagnostic confidence) of PC-CT std and EID-CT was assessed by four radiologists independently. If metallic implants were present ( n = 10), PC-CT std and PC-CT 130 keV images were again assessed by 5-point Likert scales by the same radiologists. Hounsfield units (HU) were measured within metallic artifact and compared between PC-CT std and PC-CT 130 keV . Finally, the radiation dose (CTDI vol ) was evaluated. Results Sharpness was rated significantly higher ( p = 0.009) and noise significantly lower ( p < 0.001) in PC-CTstd vs. EID-CT. In the subset of patients with metallic implants, reading scores for PC-CT 130 keV revealed superior ratings vs. PC-CT std for image quality, artifacts, noise, and diagnostic confidence (all p < 0.001) accompanied by a significant increase of HU values within the artifact ( p < 0.001). Radiation dose was significantly lower for PC-CT vs. EID-CT (mean CTDI vol : 8.83 vs. 15.7 mGy; p < 0.001). Conclusions PC-CT of the spine with high-kiloelectronvolt reconstructions provides sharper images, higher diagnostic confidence, and lower radiation dose in patients with metallic implants. Key Points • Compared to energy-integrating CT, photon-counting CT of the spine had significantly higher sharpness and lower image noise while radiation dose was reduced by 45%. • In patients with metallic implants, virtual monochromatic photon-counting images at 130 keV were superior to standard reconstruction at 65 keV in terms of image quality, artifacts, noise, and diagnostic confidence.