title: Influence of age and sex on the longitudinal relaxation time, T1, of the lung in healthy never-smokers.
abstract: BACKGROUND
  As several studies have provided evidence that lung disease affects the T1 of the human lung, our purpose was to investigate the effect of age on the T1-relaxation time in the lungs of healthy never-smokers, including group difference between sexes.
  
  
  METHODS
  The Snapshot FLASH pulse sequence (inversion recovery with multiple gradient echo read-outs) was used to quantify lung T1 in 30 healthy never-smoking volunteers at 1.5 Tesla. Measurements were performed under breathhold of a tidal inspiration. Additionally, subjects underwent clinical MRI and pulmonary function tests. A linear regression model of T1 as a function of age and sex was tested.
  
  
  RESULTS
  The slope of lung T1 at tidal end-inspiration as a function of age was statistically different between males and females (P < 0.001). In a linear regression model of T1 as a function of age and sex, females have slope of -4.1 ms/year (95% confidence interval [CI], [-5.2, -3.0]) at P < 0.001, and males -0.064 ms/year (95% CI, [-1.2, 1.1]) at P = 0.9, with a whole model R(2)  = 0.83.
  
  
  CONCLUSIONS
  The observed dependencies of lung T1 on age and sex are here attributed to a previously reported difference in blood T1 between sexes, and a previously reported decrease of pulmonary blood volume with increasing age. This may have implications for the interpretation of lung T1 measurements in both healthy individuals and patients.
authors.affiliation: Medical Radiation Physics, Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Simon S I
authors.initials: SS
authors.lastname: Kindvall
authors.affiliation: Medical Radiology, Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Sandra
authors.initials: S
authors.lastname: Diaz
authors.affiliation: Medical imaging and physiology, Skane University Hospital, Lund, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Svensson
authors.affiliation: Clinical Physiology, Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Wollmer
authors.affiliation: Medical Radiology, Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Slusarczyk
authors.affiliation: Medical Radiation Physics, Translational Medicine, Lund University, Malmö, Sweden.
authors.forename: Lars E
authors.initials: LE
authors.lastname: Olsson
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001810:Blood Volume; D062485:Breath Holding; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012737:Sex Factors; D012907:Smoking; D055815:Young Adult
keywords: age factors; lung; magnetic resonance imaging; sex factors; spirometry