Supplemental Digital Content
Changes in brain tissue oxygenation after treatment of
diffuse traumatic brain injury by erythropoietin
Pierre BOUZAT
Anne MILLET
Yvonnick BOUE
Karin PERNET-GALLAY
Thibaut TROUVE-BUISSON
Lucie GAIDE-CHEVRONNAY
Emmanuel L. BARBIER
Jean-Francois PAYEN
Supplemental Digital Content 1. MRI imaging
The protocol for MRI acquisition included successive sequences to assess brain edema
using diffusion-weighted imaging, local brain oxygen saturation using a multiparametric
quantitative blood oxygenation level-dependent (BOLD) approach (1), cerebral perfusion
using a dynamic susceptibility approach allowing the determination of mean transit time
(MTT) of an intravenously injected contrast agent (2), and blood volume fraction (BVf) using
a steady-state approach (3).
Anatomical T2-weighted images were acquired using a 2D spin-echo sequence and the
following parameters: repetition time (TR) /echo time (TE) = 4000/33 ms; one average; 13
sections with 30x30 mm2 field of view (FOV); matrix = 256x256; voxel size = 117x117x1000
μm3. Acquisition duration was 2 min 8 sec.
The apparent diffusion coefficient (ADC) of water was mapped before and 2 h after
the trauma using 2D diffusion-weighted, spin-echo, single-shot echo-planar imaging (EPI):
TR/TE = 2500/30 ms; FOV = 30x30 mm2; matrix = 64x64; 8 averages; voxel size
468x468x1000 µm3. This sequence was applied four times, once without diffusion weighting
(b~0 s.mm-2) and three times with diffusion weighting (b = 800 s.mm-2) in three orthogonal
directions, in order to map the ADC. Acquisition duration lasted about 5 min.
T2 was mapped using a 2D multiple spin-echo sequence: TR/TE = 1500/15 ms; 20
spin echoes; TE = 12 ms; one average; FOV = 30x30 mm2, matrix = 64x64 and voxel size =
468x468x1000 μm3). Acquisition duration was 1 min 36 sec.
B0 was mapped using a 3D multiple gradient-echo sequence: TR/TE = 100/4 ms; 15
gradient echoes; TE = 4.5 ms; one average; FOV = 30x30x6 mm3; matrix = 96x128x30;
voxel size = 234x234x200 μm3. Acquisition duration was 4 min 48 sec.
T2* was mapped before and after an intravenous administration of ultrasmall
superparamagnetic particles of iron oxide (USPIO): TR/TE = 6000/4 ms; 15 gradient echoes;
TE = 4 ms; one average; FOV = 30x30 mm2; matrix = 64x64; voxel size = 468x468x1000
μm3. Acquisition duration was 38 sec. A dynamic 2D-echo-planar imaging (EPI) gradient
echo sequence was also acquired: TR/TE = 250/12 ms; two segments; two sections; one
average; FOV = 30x30 mm2; matrix = 64x64; voxel size = 468x468x1000 μm3. Acquisition
of one image lasted 0.5 sec and the EPI sequence was repeated 120 times (total duration 1
min). After image acquisition during a 10-sec baseline, USPIO was intravenously injected
(100 µmol of iron per kg of body weight; P904, Guerbet, Roissy, France). At the end of the
EPI sequence, a second dose of USPIO (100 µmol/kg) was intravenously injected to permit
the acquisition of the second T2* map in the static dephasing regime (total dose of USPIO:
200 µmol/kg) (4).
References
1.
Christen T, Lemasson B, Pannetier N, et al: Evaluation of a quantitative blood
oxygenation level-dependent (qBOLD) approach to map local blood oxygen saturation. NMR
Biomed 2011; 24:393-403
2.
Barbier EL, Lamalle L, Decorps M: Methodology of brain perfusion imaging. J Magn
Reson Imaging 2001; 13:496-520.
3.
Tropres I, Grimault S, Vaeth A, et al: Vessel size imaging. Magn Reson Med 2001;
45:397-408.
4.
Valable S, Lemasson B, Farion R, et al: Assessment of blood volume, vessel size, and
the expression of angiogenic factors in two rat glioma models: a longitudinal in vivo and ex
vivo study. NMR Biomed 2008; 21:1043-1056