title: Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve.
abstract: BACKGROUND
  Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation.
  
  
  OBJECTIVE
  To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range.
  
  
  METHODS
  Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale.
  
  
  RESULTS
  The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 ± 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves.
  
  
  CONCLUSIONS
  MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation.
authors.affiliation: Department of Diagnostic Radiology, Faculty of Medicine, Mansoura University, Egypt. m_bazeed@yahoo.com
authors.forename: Mohamed Fayez
authors.initials: MF
authors.lastname: Bazeed
authors.forename: Mohamed Saleh
authors.initials: MS
authors.lastname: Moselhy
authors.forename: Ahmad Ibrahim
authors.initials: AI
authors.lastname: Rezk
authors.forename: Mushabab Ayedh
authors.initials: MA
authors.lastname: Al-Murayeh
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017548:Echocardiography, Transesophageal; D005260:Female; D005471:Fluoroscopy; D006350:Heart Valve Prosthesis; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*