Yang Zheng1, Xiaoming Wang2, and Xuna Zhao3
1Shengjing Hospital of China Medical University, shenyang, People's Republic of China, 2Shengjing Hospital of China Medical University, People's Republic of China, 3Philips Healthcare, People's Republic of China
Synopsis
The environment of the brain
dynamically changes with neonatal brain development, and the topic of whether
the application of magnetic resonance imaging (MRI) can reflect these brain
environment changes is a recent one. In recent years, a new magnetic resonance
contrast technology called amide proton transfer (APT) imaging has emerged
which can detect protein and peptides through the signal from water (1),
reflecting in vivo pH and protein concentration at the cellular and molecular
level. The so-called amide proton mainly refers to the amide proton from the
free protein and the polypeptide backbones.
Abstract
PURPOSE: To evaluate
neonatal brain injury at the internal environmental level with the application
of amide proton transfer (APT) imaging by measuring the APT values of the
brain.
METHODS: A total of 51
neonatal patients with gestational ages from 27 to 41 weeks who underwent MR
examination were enrolled in the study. Using conventional MR, 38 newborns were
found to have no abnormalities in the nervous system (the control group) and
there were 13 newborns with different degrees of brain injury (the case group).
The diagnoses were jointly made by two or more experienced radiologists. After
obtaining informed consent and the clinicians’ permissions to assess the
neonatal status, APT imaging was performed immediately followed by conventional
MR. Thirty
minutes before the examination,
all
newborns were given 5% chloral hydrate (50 mg/kg) via the intestinal tract, and
provided with warmth and comfort.
APT acquisition: All newborns were
positioned at the basal ganglia level with axial T1WI and the case
group increase the lesions location. In this study, an off-resonance continuous-wave
RF saturation pulse with a duration of 500 ms was
used for APT imaging. This
study used a multi-offset and multi-acquisition APT imaging protocol, in which
the APT scan and z-spectrum scan were combined. In this process, the protocol
(31 offsets = 0, ±0.25, ±0.5, ±0.75, ±1, ±1.5, ±2, ±2.5, ±3 (2), ±3.25(4), ±3.5
(8), ±3.75 (4), ±4 (2), ±4.5, ±5, ±6 ppm; the numbers in parentheses were
acquisitions (1 if not specified); an unsaturated image was acquired for the
signal normalization) which can provide B0 inhomogeneity corrected
APT images with sufficient signal-to-noise ratios within a clinically relevant
time frame, which was 4 mi n 16 sec. The APT parameters were: TR=4000 ms;
TE=8.1 ms; matrix=108×71,
FOV=170×145 mm; thickness=5 mm. All data were processed using programs
written in interactive data language (IDL; Research Systems, Inc., Boulder, CO,
USA) to analyze and reconstruct a pseudo color. First, the raw image data were
organized into the Z-spectrum voxel by voxel (the normalized signal
intensities, Ssat/S0as a function of 31 offsets, where Ssat and S0
are the signal intensities with and without radiofrequency irradiation).
Regions of interest (ROIs) were carefully chosen by two experienced radiologists,
selecting bilateral frontal subcortical white matter, basal ganglia and
occipital subcortical white matter (Figure.
1). The case group had increased lesions area for ROIs, with the
contralateral area as control. In the control group, the ROIs diameters were
about 1.5 cm, whereas in the case group the ROIs should be selected within the
range of disease, and no more than the edge of the lesions. Keep away from the
skull and cerebrospinal fluid and the ventricles.
First,
in the control group, analysis was conducted of APT values in each of the parts
of the bilateral frontal subcortical white matter, basal ganglia and occipital
subcortical white matter, to determine whether there were any differences. If
there were no differences between the two sides, bilateral APT values were
assigned to each group by parts respectively. The APT values of lesions and the
contralateral area were compared with each other, and significant differences
between lesions and contralateral relatively normal area were analyzed.
Meanwhile, the APT values of bilateral frontal subcortical white matter, basal
ganglia and occipital subcortical white matter of the case group and control
group with the same gestational age (gestational age difference ± 1 day) were
applied, to analyze the statistical differences.
RESULTS: In the
control group, bilateral frontal subcortical white matter, basal ganglia and
occipital subcortical white matter had no significant difference in APT value (P>0.05). Between the different parts of the brain, APT
values of preterm were lower than full-term infants (P = 0.01, P = 0.028, P = 0.003), Figure. 2. In the case group, there were significant differences in
APT values between the lesion side and contralateral area, being significantly
lower in lesion side than the contralateral side (P=0.000), Figure. 3. In
the case group, the APT values of different parts of the brain were lower than
the control group with the same gestational age (P = 0.000, P = 0.008, P = 0.01).
DISCUSSION:
In
conclusion, utilizing endogenous protein and pH (2, 3), APT noninvasively
evaluates neonatal brain injury, helping understand the mechanisms of brain injury.
Furthermore, APT can be applied across the wide age-range of brain development,
and this preliminary study also confirms this is achievable.
CONCLUSION: From
changes in the pH level in the neonatal brain, APT imaging can help
understand neonatal brain injury.synopsis
The environment of the brain
dynamically changes with neonatal brain development, and the topic of whether
the application of magnetic resonance imaging (MRI) can reflect these brain
environment changes is a recent one. In recent years, a new magnetic resonance
contrast technology called amide proton transfer (APT) imaging has emerged
which can detect protein and peptides through the signal from water (1),
reflecting in vivo pH and protein concentration at the cellular and molecular
level. The so-called amide proton mainly refers to the amide proton from the
free protein and the polypeptide backbones.Acknowledgements
This study was supported by National Natural Science
Foundation of China (NO. 30570541, 30770632, 81271631).
Acknowledge the NIH grant
P41 EB015909.References
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