title: BMI influence on the reproducibility of ECG-gated myocardial perfusion imaging phase analysis in comparison with novel echocardiographic dyssynchrony estimation methods.
abstract: OBJECTIVE
  Cardiac resynchronization therapy (CRT) is a treatment for patients with end-stage heart failure. However, two-thirds of the patients are nonresponders. Evaluation of left ventricular mechanical dyssynchrony may help in finding patients who will benefit from CRT. Dyssynchrony can be evaluated by the phase analysis method in myocardial perfusion imaging (MPI) or with cardiac ultrasound. The aim of this study was to investigate the reproducibility of phase analysis parameters in MPI and echocardiographic parameters in the evaluation of left ventricular mechanical dyssynchrony. In particular, the influence of BMI on reproducibility was studied.
  
  
  RESULTS
  Twenty-one patients underwent an ECG-gated MPI scan. Acquisition was repeated after the rest image. The patients were also studied twice with transthoracic echocardiography. Of MPI phase analysis parameters bandwidth, histogram SD and entropy% were highly reproducible in the pooled population: Cronbach's α 0.927-0.967 and intraclass correlation (ICC) 0.868-0.967, (P<0.001 for all). However, the reproducibility of bandwidth and SD was poorer in patients with BMI≥29 kg/m group (α 0.203 and -0.055; ICC 0.106 and -0.027, NS for both) than in those with BMI<29 kg/m (α 0.984 and 0.980; ICC 0.968 and 0.961, P<0.001 for both). In contrast, BMI had no obvious influence on the reproducibility of global longitudinal strain in echocardiography.
  
  
  CONCLUSIONS
  Parameters reflecting mechanical dyssynchrony were found to be well reproducible. However, this study indicates that phase analysis results may be less reproducible in patients with high BMI, whereas global longitudinal strain in echocardiography seems to be less critical for a patient's BMI.
authors.affiliation: aDepartment of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland bCancer Center cHeart Center, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Saara
authors.initials: S
authors.lastname: Sillanmäki
authors.forename: Tuomas
authors.initials: T
authors.lastname: Koivumäki
authors.forename: Tiina M
authors.initials: TM
authors.lastname: Laitinen
authors.forename: Mikko
authors.initials: M
authors.lastname: Hakulinen
authors.forename: Marja
authors.initials: M
authors.lastname: Hedman
authors.forename: Tomi
authors.initials: T
authors.lastname: Laitinen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D055426:Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography / Q000379:methods*; D003198:Computer Simulation; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D055420:Perfusion Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology*