title: Systolic MOLLI T1 mapping with heart-rate-dependent pulse sequence sampling scheme is feasible in patients with atrial fibrillation.
abstract: BACKGROUND
  T1 mapping enables assessment of myocardial characteristics. As the most common type of arrhythmia, atrial fibrillation (AF) is often accompanied by a variety of cardiac pathologies, whereby the irregular and usually rapid ventricle rate of AF may cause inaccurate T1 estimation due to mis-triggering and inadequate magnetization recovery. We hypothesized that systolic T1 mapping with a heart-rate-dependent (HRD) pulse sequence scheme may overcome this issue.
  
  
  METHODS
  30 patients with AF and 13 healthy volunteers were enrolled and underwent cardiovascular magnetic resonance (CMR) at 3 T. CMR was repeated for 3 patients after electric cardioversion and for 2 volunteers after lowering heart rate (HR). A Modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired before and 15 min after administration of 0.1 mmol/kg gadopentetate dimeglumine. For AF patients, both the fixed 5(3)3/4(1)3(1)2 and the HRD sampling scheme were performed at diastole and systole, respectively. The HRD pulse sequence sampling scheme was 5(n)3/4(n)3(n)2, where n was determined by the heart rate to ensure adequate magnetization recovery. Image quality of T1 maps was assessed. T1 times were measured in myocardium and blood. Extracellular volume fraction (ECV) was calculated.
  
  
  RESULTS
  In volunteers with repeated T1 mapping, the myocardial native T1 and ECV generated from the 1st fixed sampling scheme were smaller than from the 1st HRD and 2nd fixed sampling scheme. In healthy volunteers, the overall native T1 times and ECV of the left ventricle (LV) in diastolic T1 maps were greater than in systolic T1 maps (P < 0.01, P < 0.05). In the 3 AF patients that had received electrical cardioversion therapy, the myocardial native T1 times and ECV generated from the fixed sampling scheme were smaller than in the 1st and 2nd HRD sampling scheme (all P < 0.05). In patients with AF (HR: 88 ± 20 bpm, HR fluctuation: 12 ± 9 bpm), more T1 maps with artifact were found in diastole than in systole (P < 0.01). The overall native T1 times and ECV of the left ventricle (LV) in diastolic T1 maps were greater than systolic T1 maps, either with fixed or HRD sampling scheme (all P < 0.05).
  
  
  CONCLUSIONS
  Systolic MOLLI T1 mapping with heart-rate-dependent pulse sequence scheme can improve image quality and avoid T1 underestimation. It is feasible and with further validation may extend clinical applicability of T1 mapping to patients with atrial fibrillation.
authors.affiliation: Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029, Beijing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
authors.forename: Songnan
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029, Beijing, China.
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Ma
authors.affiliation: Siemens Healthcare, Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.affiliation: MR Collaborations NE Asia, Siemens Healthcare, Beijing, China.
authors.forename: Tianjing
authors.initials: T
authors.lastname: Zhang
authors.affiliation: MR Collaborations NE Asia, Siemens Healthcare, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: An
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Bai
authors.affiliation: Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
authors.forename: Jianzeng
authors.initials: J
authors.lastname: Dong
authors.affiliation: Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029, Beijing, China. fanzm120@126.com.
authors.forename: Zhanming
authors.initials: Z
authors.lastname: Fan
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D055424:Cardiac-Gated Imaging Techniques; D016022:Case-Control Studies; D003287:Contrast Media; D004554:Electric Countershock; D005240:Feasibility Studies; D005260:Female; D019786:Gadolinium DTPA; D006339:Heart Rate; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: Atrial fibrillation; Cardiovascular magnetic resonance; Extracellular volume fraction; Modified Look-Locker inversion recovery; T1 mapping