title: Energy efficiency and pulmonary artery flow after balloon pulmonary angioplasty for inoperable, chronic thromboembolic pulmonary hypertension: Analysis by phase-contrast MRI.
abstract: OBJECTIVE
  The aims of this study were to propose a new quantitative method for pulmonary artery (PA) flow energetics using phase-contrast magnetic resonance imaging (PC-MRI), and to investigate how balloon pulmonary angioplasty (BPA) impacts energetics in chronic thromboembolic pulmonary hypertension (CTEPH).
  
  
  METHODS
  PC-MRI at 3-Teslar and with a flow sensitive gradient echo was used to examine energetics prior to and following BPA for 24 CTEPH patients. Stroke volume (m; ml) and mean velocity (V; mm/s) for the main pulmonary artery (PA), right PA, and left PA were calculated from a time-flow curve derived from PC-MRI. Based on the Bernoulli principle, PA energy was identified as 1/2mV2(μj/kg), and energy loss was defined as the following equation "energy loss=main PA energy-(rt. PA energy+lt. PA energy)".
  
  
  RESULTS
  Right PA energy was significantly greater post-BPA than pre-BPA (61±55 vs. 32±40μj/kg). There was no difference in main PA and left PA energies. Energy loss was significantly decreased post-BPA (18±97μj/kg) than pre-BPA (79±125μj/kg). An optimal cutoff of left PA energy of 45μj/kg pre-BPA can be used to predict patients with mPAP≥30mmHg after BPA, with an area under the curve of 0.91, 78% sensitivity, and 92% specificity.
  
  
  CONCLUSIONS
  Analysis of PA energetics using phase-contrast MRI demonstrates that BPA improves energy loss in CTEPH. In addition, BPA responses can be predicted by PA energy status pre-treatment.
authors.affiliation: Department of Diagnostic Imaging & Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan. Electronic address: nagao.michinobu@twmu.ac.jp.
authors.forename: Michinobu
authors.initials: M
authors.lastname: Nagao
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Yamasaki
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kohtaro
authors.initials: K
authors.lastname: Abe
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Hosokawa
authors.affiliation: Department of Molecular Imaging & Diagnosis, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawanami
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kamitani
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Torahiko
authors.initials: T
authors.lastname: Yamanouchi
authors.affiliation: Department of Medical Sciences, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hidetake
authors.initials: H
authors.lastname: Yabuuchi
authors.affiliation: Department of Diagnostic Imaging & Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukushima
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000800:Angioplasty, Balloon / Q000379:methods*; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011655:Pulmonary Embolism / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D016896:Treatment Outcome
keywords: Balloon pulmonary angioplasty; Chronic thromboembolic pulmonary hypertension; Energy efficiency; Phase-contrast MRI