Eur Radiol (2011) 21:1390–1396 additional diagnostic value to echocardiography and fluo- roscopy for the evaluation of PHV dysfunction, especially in detecting pannus tissue [3–6]. It is important to know which PHV types have a CT appearance that allows detection of PHV problems. However, little is currently known about the MDCT appearance of different valve types [3]. In our article titled “Multidetector-row computed tomography imaging characteristics of mechanical prosthetic valves” accepted for publication in Journal of Heart Valve Disease, we recently reported on imaging characteristics of five different PHV types in a controlled in-vitro model. The purpose of the current study was to assess the CT image quality of different PHV types in patients to determine which valves are suitable for CT evaluation. Materials and methods CT selection We reviewed all ECG-gated CT(A)s performed in the University Medical Centre Utrecht (UMCU) and Academic Medical Centre Amsterdam (AMC) between 2003 and April 2010 for the presence of PHVs based on the presence of a PHV and/or steel wires through the sternum (indicating an previous median sternotomy) on the surview images. If one or both criteria were met the CT images were reviewed for the presence and type of PHV. Patients with only a mitral or tricuspid annuloplasty ring or a stented valvegraft as used in percutaneous valve replacement were excluded. All other PHV types were included. CT data, as well as the reason for requesting the CT examination, were retrieved from the PACS archive of the Radiology department. CT data was sent to a workstation for image analysis. Heart rate during the examination was obtained from the CT data. Patient data on specific valve type and size were obtained from the patient medical files. The study was performed under a waiver from the local ethics committee. Image analysis Assessment of the CT examinations was performed on a dedicated workstation (Extended Brilliance Workstation, Philips Medical Systems, Philips, Best, the Netherlands). Three sets of images were reconstructed in three perpen- dicular imaging planes of each PHV: one set in plane with the valve, one set parallel and one set perpendicular to the valve leaflet(s). Reconstructions were made in both the diastolic and systolic phase of the cardiac cycle, if both phases were available. For each PHV, image quality of the supravalvular, peri- valvular, subvalvular and valvular region was scored on a four- point scale: 1= non-diagnostic, 2= moderate visualization, 1391 3= good visualization and 4=excellent visualization. The different regions are illustrated in Fig. 1. The criteria for the different scores per region were formulated as follows: for the supra-, sub- and perivalvular region: 1: no discernible supra-, sub-, or perivalvular detail widely beyond prosthesis; 2: no or limited details within 5 mm of prosthesis; 3: adequate details within 5 mm of prosthesis; 4: perfect details. For valvular detail: 1: no discernible leaflet; 2: leaflet discernible but no angle measurements possible; 3: leaflet angle measurement possible and 4: excellent leaflet detail. For the general score the image quality scores for all the regions were taken into account. Scoring was performed by two observers (PS and JH) independent of each other. The observers had three and 1 year experience with cardiac CT, respectively. Data analysis Data were analyzed using SPSS software (SPSS Statistics Version 15.0, SPSS Inc, Chicago, IL). The scores of the image quality scores per region of both observers was calculated and used for analysis. Data were presented as medians with minimum and maximum values because of a non-parametric data distribution. Image quality scores for different PHV types (bileaflet, tilting-disc and biological PHVs) and different manufacturers were compared with the Kruskal-Wallis test. If the Kruskal-Wallis test showed a significant result, the post-hoc Mann–Whitney U test was performed with Bonferroni correction. Interobserver variability was analyzed by weighted kappa statistics based on Cohen. Correlations between image quality scores and heart rate, were analyzed using the Spearman correlation. The influence of the CT protocol (aortic CTA/dedicated cardiac CTA) or type of CT system (16/64/256 slice) on the image quality scores were analyzed using the Fisher’s Exact Test. Statistical significance was defined as a p-value<0.05. Fig. 1 Different valvular regions for MDCT assessment (1=supravalvular, 2=perivalvular, 3=subvalvular, 4=valvular detail)