title: Pulmonary artery pulsatility and effect on vessel diameter assessment in magnetic resonance imaging.
abstract: BACKGROUND
  Information about thoracic vascular sizes can crucially affect clinical decision-making in cardiovascular disease. A variety of imaging techniques such as catheter angiography, contrast enhanced computed tomography (CT) and cardiac magnetic resonance imaging (CMR) are routinely used to measure vascular diameters. Traditionally, CMR black blood sequences were the main anatomical tool for visualization of vascular anatomy and still are in many centers. More recently, the vessel diameters are measured on multiplanar reconstructions derived from static magnetic resonance angiography (MRA). This study was performed to investigate the variation of vessel diameter measurements on different CMR techniques with respect to their data acquisition scheme.
  
  
  METHODS
  We recruited two groups of patients for this prospective study. One group included patients with repaired tetralogy of Fallot (TOF), with at least moderate pulmonary insufficiency and another group of patients who underwent CMR as part of a diagnostic work-up for arrhythmogenic right ventricular cardiomyopathy (ARVC). Additional images of the right pulmonary artery (RPA) were acquired in the double inversion recovery (DIR) black blood, cine steady state free precession (SSFP) and MRA. All images were reviewed by two CMR trained readers using the electronic caliper provided within the picture archiving and communication system package. The maximum diameter of each artery was recorded in millimeters with up to one decimal point. Paired t-tests and Bland-Altman plots were used for comparison of measurements between different sequences.
  
  
  RESULTS
  A total of 52 patients were recruited for this study, 26 patients in the TOF group (15 males, age 12.55±2.9) and 26 patients in the ARVC group (15 males, age 15.6±2.3). In both groups, the RPA sizes were not significantly different between the DIR images and diastolic cine SSFP (p>0.05). Measurements on DIR were significantly smaller than those made on systolic cine SSFP or MRA in both groups (p<0.0001). Vessel diameters measured on systolic SSFP were significantly larger than measurements made on diastolic SSFP (p<0.0001). There was no significant difference between vessel measurements on MRA and measurements on systolic cine SSFP (p=0.44 for the TOF group and p=0.79 for ARVC group). Measurements on the MRA datasets were significantly larger than those on diastolic SSFP images (p<0.0001).
  
  
  CONCLUSIONS
  Black blood, white blood and MRA sequences are all reproducible CMR methods for the assessment of arterial diameters in children and adolescents. Measurements from systolic phase SSFP images are comparable to those from contrast-enhanced MRA. Therefore, the administration of contrast medium is not necessary in every case. Cine SSFP images offer the additional advantage over the other methods in such that both the largest and the smallest diameter of the vessel during the cardiac cycle can be assessed using this technique. This is even more relevant in highly pulsatile circulations, such as patients with repaired TOF and significant pulmonary insufficiency.
authors.affiliation: Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada; Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: masoudshariat@gmail.com.
authors.forename: Masoud
authors.initials: M
authors.lastname: Shariat
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: daryl.schantz@gmail.com.
authors.forename: Daryl
authors.initials: D
authors.lastname: Schantz
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: shi-joon.yoo@sickkids.ca.
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
authors.affiliation: Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada. Electronic address: bernd.wintersperger@uhn.ca.
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Wintersperger
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: mike.seed@sickkids.ca.
authors.forename: Mike
authors.initials: M
authors.lastname: Seed
authors.affiliation: Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario, Canada. Electronic address: bahiyah.alnafisi@uhn.ca.
authors.forename: Bahiyah
authors.initials: B
authors.lastname: Alnafisi
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: leysia_99@yahoo.com.
authors.forename: Leysia
authors.initials: L
authors.lastname: Chu
authors.affiliation: Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: christopher.macgowan@sickkids.ca.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Macgowan
authors.affiliation: Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: Joshu.vanamerom@sickkids.ca.
authors.forename: Joshua
authors.initials: J
authors.lastname: van Amerom
authors.affiliation: Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada; Department of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: lars.grosse-wortmann@sickkids.ca.
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
mesh_terms: D000293:Adolescent; D001783:Blood Flow Velocity; D002648:Child; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D011651:Pulmonary Artery / Q000473:pathology* / Q000503:physiopathology*; D011652:Pulmonary Circulation; D011666:Pulmonary Valve Stenosis / Q000473:pathology* / Q000503:physiopathology*; D011673:Pulsatile Flow; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Cardiac MRI; Congenital heart disease; Vessel diameter