1282 Fig. 2 Distribution of non- diagnostic coronary segments in patients with prosthetic heart valves Eur Radiol (2012) 22:1278–1286 the different PHV types and PHV positions. These PHV- related artefacts are presented per coronary artery segment. Results Mean heart rate during the 82 CTA examinations was 73±18 beats per minute (bpm). In 15 of the 82 patients (18%), the heart rate during CT data acquisition was missing. Mean heart rates were 73±18 bpm and 72±19 bpm for the mechanical PHV group and biological PHV group, respectively. Sixty of 82 (73%) CT acquisitions were performed as a dedicated cardiac CTA including 51 retrospectively ECG-gated CTAs (120 kV, ≥600 mAs) and nine prospectively triggered CTAs (120 kV, 200–250 mAs); and 22/82 (27%) CTAs as a retro- spectively ECG-gated CTA of the thoraco-(abdominal) aorta with a lower tube current (200–400 mAs). Radiation dose information was available for 42/82 patients (51%). Mean radiation dose for retrospectively ECG-gated cardiac CTAs was 15.6±5.5 mSv, and for thoraco-abdominal aortic CTAs 17.6±4.2 mSv. Ninety-four PHVs and annuloplasty rings of 14 different PHV and annuloplasty ring types were present: 68 mechanical PHVs (72%), 21 biological PHVs (22%), and 5 annuloplasty rings (5%) (mitral n 0 4 and tricuspid n 01). PHVs and annuloplasty rings were positioned in the aortic (n0 73; 78%), mitral (n018; 19%), pulmonary (n01; 1%) and tricuspid (n02; 2%) positions (Table 1). PHV-related artefacts interfering with coronary artery assessment on MDCT In total 17/94 (18%) PHVs and annuloplasty rings induced artefacts prohibiting assessment of at least one coronary segment (Table 1). Valve-related artefacts per coronary seg- ment are shown in Tables 2 and 3. A theoretical total of 1394 coronary segments (82 patients × 17 segments) were available for analysis. Two hundred and thirty-four of the 1394 segments (17%) were scored absent. In total 1160 coronary segments were present for assessment. Three-hundred and six of 1160 coronary segments (26%) demonstrated a non-diagnostic image qual- ity, 538/1160 (46%) had acceptable image quality; and in Fig. 3 a Sorin tilting disc Prosthetic Heart Valve (PHV) in the aortic position, which causes PHV-related artefacts in RCA segment 1. b ON-X bileaflet Prosthetic Heart Valve (PHV) in the aortic position, which causes no PHV-related artefacts in RCA segment 1