title: Cardiac magnetic resonance before and after percutaneous pulmonary valve implantation.
abstract: OBJECTIVE
  To measure the magnetic resonance (MR) artefact produced by a percutaneous pulmonary valve stent and to evaluate the changes in volumetric and functional right ventricle (RV) parameters due to percutaneous pulmonary valve implantation (PPVI).
  
  
  METHODS
  A Melody valve was studied in vitro using clinical cardiac MR (CMR) sequences. In vivo, we analysed the CMR examinations obtained before and after PPVI of 27 consecutive patients. The echocardiography pressure gradient (PG) and catheter PG were measured. The Wilcoxon test was used for comparisons.
  
  
  RESULTS
  In vitro, the least difference between artefact extent and actual valve size (0.1 mm) was obtained with a steady-state free precession (SSFP) sequence. In vivo, RV end-diastolic volume (ml/m(2)), end-systolic volume (ml/m(2)) and ejection fraction (%) were 79 ± 42, 43 ± 41 and 49 ± 13 before PPVI and 64 ± 21 (p = 0.054), 30 ± 14 (p = 0.021), and 54 ± 12 (p = 0.018) 6 months after PPVI, respectively. The PG and regurgitation fraction (RF) were 36 ± 15 mmHg and 14 ± 18 % before PPVI and 13 ± 15 mmHg (p < 0.001) and 2 ± 5 % (p = 0.013) after PPVI, respectively. No significant differences were found comparing the PG measured with CMR, echocardiography and catheter.
  
  
  CONCLUSIONS
  We showed in vitro that the SSFP sequence produced the most accurate valve measurement. After PPVI, CMR showed a strong decrease of PG and RF with a significant improvement of RV function.
authors.affiliation: Unità di Radiologia, IRCCS Policlinico San Donato, Piazza E. Malan, 20097, San Donato Milanese, Milan, Italy, francescosecchimd@gmail.com.
authors.forename: Francesco
authors.initials: F
authors.lastname: Secchi
authors.forename: Elda Chiara
authors.initials: EC
authors.lastname: Resta
authors.forename: Luciane
authors.initials: L
authors.lastname: Piazza
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Butera
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Leo
authors.forename: Mario
authors.initials: M
authors.lastname: Carminati
authors.forename: Francesco
authors.initials: F
authors.lastname: Sardanelli
mesh_terms: D000328:Adult; D016477:Artifacts; D006328:Cardiac Catheterization; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D004452:Echocardiography; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D011664:Pulmonary Valve / Q000601:surgery*; D012189:Retrospective Studies