Eur Radiol (2011) 21:1390–1396 Fig. 2 St. Jude PHV in aortic position. The left image panel shows the excellent PHV visualization. The arrow head in the detailed right image panel indicates a PTFE pledget (component of the suture material) commonly used in PHV implantation purposes. Contrast agents (Ultravist ® −300 mg jopromide/ ml, Bayer Schering Pharma AG, Berlin, Germany or Imeron ® −400 mg iodine/ml, Bracco UK Limited, London, United Kingdom) were administered in all patients except in one patient with a Björk-Shiley PHV. Image quality scores The median image quality scores per PHV manufacturer type and PHV design type are shown in Tables 1 and 2. MDCT characteristics of different PHVs are illustrated in Figs. 2, 3, 4, 5 and 6. Comparing bileaflet PHVs with tilting disc PHVs demonstrated significant higher image quality scores for the bileaflet valves for all regions (p < 0.001). Nevertheless, the Medtronic Hall tilting disc demonstrated no significant differences in image quality scores for all regions compared with the bileaflet PHVs. The comparison of bileaflet PHVs versus biological PHVs resulted in no significant differ- ences in image quality per region, except for the valvular detail which was significantly higher for bileaflet valves (p < 0.001). The comparison of tilting disc PHVs versus biological PHVs resulted in significant (p < 0.001) higher image quality scores for the biological PHVs except for the valvular detail which did not differ significantly. In the tilting disc group, the image quality scores for all regions of the Medtronic Hall PHVs were significantly Fig. 3 C-E Perimount PHV in aortic position. In the left image panel (long axis view), the artefacts caused by the metallic components of the struts are visualised. In particular in the supravalvular region. In the right image panel (the short axis view), the valve leaflets are well visualised 1393 higher than for the Björk-Shiley PHVs and the Sorin monoleaflet PHVs (p = 0.001). In the biological and the bileaflet group, no significant differences in image quality scores were present for the different PHV manufacturers. No significant correlation between heart rate and the general image quality score was found (p=0.635). Further- more, the use of different CT systems showed no significant differences for general image quality scores (p= 0.889, 64 vs. 256-slice, 16-slice CT systems excluded from calculation because only 4 CT examinations available). Different CT protocols (aortic CTA vs dedicated cardiac CTA) demonstrat- ed no significant difference in general image quality score (p= 0.629). Interobserver variability The weighted kappa value for the image quality scores of both observers was 0.79 with a standard error of 0.10. This indicates a good interobserver agreement Discussion The principal results of this study are: (1) currently implanted PHVs and the periprosthetic region can be visualized with at least a good image quality by MDCT; (2) Björk-Shiley and Sorin monoleaflet tilting disc valves