title: Ultrashort TE MR imaging of bovine cortical bone: the effect of water loss on the T1 and T2* relaxation times.
abstract: The effects of water loss on the T1 and T2* of bovine cortical bone were investigated using ultrashort echo time sequences with signals excited either by a short hard pulse or by two longer half pulses. Nine bovine femur samples were prepared and sequentially air- and oven-dried. On average 3.42% of bone by weight was lost after air-drying for 3 days, with another 5.98% of bone weight loss after oven-drying at 100°C for 24 h. T1 and T2* were measured after every 1% decrease in weight, with 9-10% bone weight loss at the termination of the drying process. After both forms of drying, the overall T1 decreased 33% from 153±18 ms to 102±17 ms when measured using the hard pulse and from 186±25 ms to 122±23 ms when using the half pulses. T2* decreased by 45-50% from 368±29 μs to 201±19 μs using the hard pulse and from 379±35 μs to 191±17 μs using the half pulses. A steady decrease of 26-31% was observed in both T1 and T2* with the first 3-4% bone water loss after air-drying. Oven-drying at 100°C for 24 h resulted on an additional 4% T1 reduction but 25% T2* reduction.
authors.affiliation: Department of Radiology, University of California, San Diego, California 92103-8226, USA.
authors.forename: Nima
authors.initials: N
authors.lastname: Kokabi
authors.forename: Won
authors.initials: W
authors.lastname: Bae
authors.forename: Eric
authors.initials: E
authors.lastname: Diaz
authors.forename: Christine B
authors.initials: CB
authors.lastname: Chung
authors.forename: Graeme M
authors.initials: GM
authors.lastname: Bydder
authors.forename: Jiang
authors.initials: J
authors.lastname: Du
mesh_terms: D000465:Algorithms; D000818:Animals; D001834:Body Water / Q000737:chemistry*; D002417:Cattle; D005269:Femur / Q000737:chemistry* / Q000502:physiology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity