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Published online before print October 25, 2006, 10.1148/radiol.2413051168
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Placental Perfusion and Permeability: Simultaneous Assessment with Dual-Echo Contrast-enhanced MR Imaging in Mice1

Fabienne Taillieu, MD, Laurent J. Salomon, MD, PhD, Nathalie Siauve, MD, PhD, Olivier Clément, MD, PhD, Nathalie Faye, MD, Daniel Balvay, PhD, Catherine Vayssettes, PhD, Guy Frija, MD, Yves Ville, MD and Charles A. Cuenod, MD, PhD

1 From the Université Paris Descartes, Faculté de Médecine, INSERM U494, Laboratory of Research in Imaging, site Necker, 156 rue de Vaugirard, 75015 Paris, France (F.T., L.J.S., N.S., O.C., N.F., D.B., C.V., G.F., C.A.C.); and Gynecologic-Obstetric Service, Centre Hospitalier Intercommunal de Poissy-St Germain, Poissy, France (L.J.S., Y.V.). Received July 12, 2005; revision requested September 19; revision received October 17; accepted October 26; final version accepted February 17, 2006. Address correspondence to F.T. (e-mail: fab.taillieu{at}noos.fr).


Figure 1
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  		Figure 1: Three-compartment model of placenta, consisting of maternal vascular compartment (Vpm) and fetal vascular compartment (Vpf) between which contrast medium may be exchanged. Maternal compartment is supplied by arterial input and drained by venous output. Fetal vascular compartment may exchange contrast agent with the fetus (Vf) itself through the umbilical cord. Exchanges between compartments are described by using transfer constants k(i,j). Because the initial gadolinium concentration in the fetus is zero and might increase only slowly during the experiment, the transfer constant k(3,4) from fetus to placenta was not considered. q = Quantity of contrast medium.

 

Figure 2
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  		Figure 2: Coronal spoiled gradient-echo MR images (19.5/3.9; flip angle, 60°; bandwidth, 31.25 kHz; matrix, 256 x 224; zero-filling interpolation, 512; field of view, 14 x 7 cm; section thickness, 3 mm; one section). Images 1–5 were obtained successively, 3.1 seconds apart. Before injection of contrast agent (image 1), the maternal left ventricle (arrow) was identified, but placental and fetal areas were not distinguishable. After injection (images 2–5), maternal left ventricle exhibited strong and rapid enhancement, whereas placentas (arrowheads) showed slower enhancement and it was not possible to see any enhancement of fetuses (dotted lines). One FPU (at bottom right of the mouse) was not analyzed because it was too small.

 

Figure 3
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  		Figure 3: Example of SI curves in maternal left ventricle with monophasic protocol before and during first 100 seconds after injection of contrast medium at first echo (TE1) (echo time, 3.9 msec) and with T2* effect suppression. At first echo, SI during bolus injection showed a small increase followed by slow decline. There was no peak because of marked T2* effect, which decreased SI of the images. T2* effect suppression allowed us to obtain an SI that depended only on the T1 effect and showed a peak during the bolus. Rapidly after the bolus, both curves were superimposable; calculation of SIT1 was not necessary thereafter.

 

Figure 4
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  		Figure 4a: Examples of maternal left ventricle SIT1 after conventional gadolinium chelate injection with (a) monophasic protocol and (b) biphasic protocol. First-pass peak was marked with both protocols, and SI declined slowly thereafter. Biphasic protocol resulted in a second lower peak followed by slowly declining SI.

 

Figure 4
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  		Figure 4b: Examples of maternal left ventricle SIT1 after conventional gadolinium chelate injection with (a) monophasic protocol and (b) biphasic protocol. First-pass peak was marked with both protocols, and SI declined slowly thereafter. Biphasic protocol resulted in a second lower peak followed by slowly declining SI.

 

Figure 5
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  		Figure 5a: Examples of FPU gadolinium concentration curves after (a) monophasic and (b) biphasic injection of contrast agent in two mice. Placental tissue concentration indicates gradual uptake of contrast agent followed by gradual decline, whereas fetus shows slow gradual uptake of contrast agent. With the biphasic injection protocol, biphasic uptake of gadolinium was seen in placenta.

 

Figure 5
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  		Figure 5b: Examples of FPU gadolinium concentration curves after (a) monophasic and (b) biphasic injection of contrast agent in two mice. Placental tissue concentration indicates gradual uptake of contrast agent followed by gradual decline, whereas fetus shows slow gradual uptake of contrast agent. With the biphasic injection protocol, biphasic uptake of gadolinium was seen in placenta.

 

Figure 6
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  		Figure 6: Typical fit and modelization of placental concentration kinetic curve with compartmental analysis. Experimental placental concentration kinetic curve of gadolinium chelate ({square}) is fitted by upper dotted line and is modeled as the sum of the curves of two components. Solid line = effect of gadolinium contained in maternal vascular compartment of the placenta, lower dotted line = effect of gadolinium contained within fetal vascular compartment of the placenta. The quantity of gadolinium in the maternal vascular compartment of the placenta first increased rapidly and then declined parallel to the arterial concentration. The gadolinium chelate then diffused slowly into the fetal vascular compartment of the placenta through the placental membrane.

 




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