title: Quantification of myocardial oxygenation in heart failure using blood-oxygen-level-dependent T2* magnetic resonance imaging: Comparison with cardiopulmonary exercise test.
abstract: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results.
  
  
  
  Thirty patients with refractory HF who underwent cardiac MRI and CPX test for heart transplantation, and 24 healthy, age-matched volunteers as controls were enrolled. M-T2* imaging was performed using a 3-Tesla and multi-echo gradient-echo sequence. M-T2* was calculated by fitting the signal intensity data for the mid-left ventricular septum to a decay curve. M-T2* was measured under room-air (T2*-air) and after inhalation of oxygen for 10min at a flow rate of 10L/min (T2*-oxy). MO was defined as the difference between the two values (ΔT2*). Changes in M-T2* at the two conditions and ΔT2* between the two groups were compared. Correlation between ΔT2* and CPX results was analyzed using the Pearson coefficient.
  
  
  
  T2*-oxy was significantly greater than T2*-air in patients with HF (29.9±7.3ms vs. 26.7±6.0ms, p<0.001), whereas no such difference was observed in controls (25.5±4.0ms vs. 25.4±4.4ms). ΔT2* was significantly greater for patients with HF than for controls (3.2±4.5ms vs. -0.1±1.3ms, p<0.001). A significant correlation between ΔT2* and CPX results (peak VO2, r=-0.46, p<0.05; O2pulse, r=-0.54, p<0.005) was observed.
  
  
  
  ΔT2* is increased T2*-oxy is greater in patients with HF, and is correlated with oxygen metabolism during exercise as measured by the CPX test. Hence, ΔT2* can be used as a surrogate marker of MO instead of CPX test.
authors.affiliation: Department of Diagnostic Imaging and 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: Molecular Imaging and 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: Koji
authors.initials: K
authors.lastname: Sagiyama
authors.affiliation: Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Taiki
authors.initials: T
authors.lastname: Higo
authors.affiliation: Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ide
authors.affiliation: Department of Marketing Division, Philips Healthcare Japan, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takemura
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Umiko
authors.initials: U
authors.lastname: Ishizaki
authors.affiliation: Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukushima
authors.affiliation: Molecular Imaging and Diagnosis, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Watanabe
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: D000328:Adult; D000368:Aged; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging*; D006333:Heart Failure / Q000000981:diagnostic imaging*; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology; D006454:Hemoglobins / Q000737:chemistry; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D010100:Oxygen / Q000097:blood* / Q000737:chemistry; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000737:chemistry; D012119:Respiration
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen
keywords: Bold; Heart failure; Oxygen metabolism; T2* magnetic resonance