title: Magnetization transfer ratio in the brain of preterm subjects: age-related changes during the first 2 years of life.
abstract: To study the progress of myelination in preterm-born subjects by measuring the MT ratio (MTR) from birth, up to 24 months of corrected age. One hundred twenty-five preterm subjects (64 males and 61 females of gestational age 33+/-2.4 weeks with chronologic and corrected age of 9.3+/-5.1 and 7.7+/-5.1 months, respectively) with normal brain MR using classic sequences were further evaluated for MTR by using a three-dimensional gradient-echo sequence (TR=32/TE=8/flip angle=6 degrees 4 mm/2 mm overlapping sections) with and without magnetization transfer prepulse. The magnetization transfer ratio was calculated as: MTR=(SIo-SIm)/SIox100%, where SIm refers to signal intensity from an image acquired with a MT prepulse and SIo the signal intensity from the image acquired without a MT prepulse. MTR increased asymptotically in the genu (R2=0.85) and splenium (R2=0.85) of the corpus callosum, the white matter of the frontal lobe (R2=0.91) and occipital lobe (R2=0.82), thalamus (R2=0.86), caudate nucleus (R2=0.67) and putamen (R2=0.71), reaching the 95% of the final value at the corrected age 18.7, 17.7, 15.6, 12.9, 10.4, 9.2 and 6.4 months, respectively. This study shows age-related changes of the brain MTR and provides data that may be useful to assess disturbances in the progress of myelination.
authors.affiliation: Department of Radiology, Medical School, University of Ioannina, Ioannina, Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Xydis
authors.forename: Loukas
authors.initials: L
authors.lastname: Astrakas
authors.forename: Anastasia
authors.initials: A
authors.lastname: Zikou
authors.forename: Kostandina
authors.initials: K
authors.lastname: Pantou
authors.forename: Styliani
authors.initials: S
authors.lastname: Andronikou
authors.forename: Maria I
authors.initials: MI
authors.lastname: Argyropoulou
mesh_terms: D000367:Age Factors; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology; D002675:Child, Preschool; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D011247:Pregnancy; D047928:Premature Birth