HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Salomon, L. J. Articles by Clément, O. Search for Related Content PubMed PubMed Citation Articles by Salomon, L. J. Articles by Clément, O.

Placental Perfusion MR Imaging with Contrast Agents in a Mouse Model¹

¹ From the Laboratoire de Recherche en Imagerie, INSERM U494, Faculté de Médecine Necker, Université Paris 5, 156 rue de Vaugirard, 75015 Paris, France (L.J.S., N.S., D.B., C.A.C., C.V., A.L., G.F., O.C.); and Service de Gynécologie-Obstétrique, Centre Hospitalier Intercommunal de Poissy-St Germain, Poissy, France (L.J.S., Y.V.). Received February 1, 2004; revision requested April 12; revision received May 6; accepted June 2. Address correspondence to O.C. (e-mail: clement@necker.fr).

View larger version (26K): [in a new window]   Figure 1. Diagram shows three-compartment model. Software was used to calculate the transfer constant k(i,j) on the basis of enhancement kinetics. Placenta consists of a maternal vascular compartment (Vpm) and a fetal vascular compartment (Vpf), between which contrast media may exchange. Maternal compartment is supplied by an arterial input and drained by a venous output. Fetal vascular compartment may exchange contrast agent with the fetus itself (Vf) through the umbilical cord. Because the initial gadolinium concentration in the fetus is zero and might only slowly increase during the experiment, the transfer constant k(3,4) from the fetus to the placenta was neglected. q = quantity of contrast agent.

View larger version (91K): [in a new window]   Figure 2a. MR imaging-anatomic comparison. (a) Two uterine tubes containing multiple fetoplacental units are well visualized on a T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left). Anatomy is illustrated on right. (b) T2-weighted transverse MR image (3000/95; field of view, 6 x 6 cm) shows placenta (large arrow) with a signal intensity comparable to that of muscle, together with umbilical cord (small arrow). (c) Fetal sagittal shape is well recognized on this T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left) correlating to anatomic image (right).

View larger version (92K): [in a new window]   Figure 2b. MR imaging-anatomic comparison. (a) Two uterine tubes containing multiple fetoplacental units are well visualized on a T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left). Anatomy is illustrated on right. (b) T2-weighted transverse MR image (3000/95; field of view, 6 x 6 cm) shows placenta (large arrow) with a signal intensity comparable to that of muscle, together with umbilical cord (small arrow). (c) Fetal sagittal shape is well recognized on this T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left) correlating to anatomic image (right).

View larger version (95K): [in a new window]   Figure 2c. MR imaging-anatomic comparison. (a) Two uterine tubes containing multiple fetoplacental units are well visualized on a T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left). Anatomy is illustrated on right. (b) T2-weighted transverse MR image (3000/95; field of view, 6 x 6 cm) shows placenta (large arrow) with a signal intensity comparable to that of muscle, together with umbilical cord (small arrow). (c) Fetal sagittal shape is well recognized on this T1-weighted coronal MR image (500/2.2; field of view, 6 x 6 cm) (left) correlating to anatomic image (right).

View larger version (88K): [in a new window]   Figure 3. Typical pattern of placental enhancement after gadoterate meglumine injection on magnified spoiled gradient-echo coronal dynamic MR images (15/2.2; flip angle, 60°; bandwidth, 31.25 kHz; matrix, 256 x 128; field of view, 7 x 3 cm; section thickness, 5 mm; one section acquired); one image was acquired every 2.2 seconds (images 1 to 5). Before injection (image 1), placenta could not be visualized. It started to enhance a few seconds after injection, with maternal blood flow bouncing back to placental base (images 2 and 3). Thereafter, the entire area enhanced gradually (images 4 and 5). Image 6: placental area (gray) and fetal area (black) are represented schematically.

View larger version (119K): [in a new window]   Figure 4. Example of coronal images obtained during spoiled gradient-echo MR sequences (15/2.2; flip angle, 60°; bandwidth, 31.25 kHz; matrix, 256 x 128; field of view, 7 x 3 cm; section thickness, 5 mm; one section acquired). On left image, acquired before injection, left ventricle and placental and fetal areas cannot be identified. On right image, after conventional gadolinium chelate injection, enhancement of left ventricle (), placental area (arrows), and fetal area () can be measured.

View larger version (100K): [in a new window]   Figure 5a. Parametric map analysis obtained from series of images shown in Figure 3. Note central arterial canal (arrow) on time-to-peak intensity map. (a) Pixels that reach peak intensity early are represented in red; scale is in seconds. On peak-intensity map, maximum is reached in center of placenta, corresponding to labyrinth region that contains only blood. (b) Red represents pixels that reach highest intensity; scale is in signal intensity.

View larger version (91K): [in a new window]   Figure 5b. Parametric map analysis obtained from series of images shown in Figure 3. Note central arterial canal (arrow) on time-to-peak intensity map. (a) Pixels that reach peak intensity early are represented in red; scale is in seconds. On peak-intensity map, maximum is reached in center of placenta, corresponding to labyrinth region that contains only blood. (b) Red represents pixels that reach highest intensity; scale is in signal intensity.

View larger version (28K): [in a new window]   Figure 6a. Examples of enhancement curves obtained after contrast agent injection in two fetuses in two mice (a) Conventional gadolinium chelate. (b) Macromolecular gadolinium chelate. For left ventricle kinetics, first-pass peak is highlighted, and contrast agent tissue concentration decreases slowly thereafter. Placental tissue concentration shows gradual uptake of contrast agent, followed by gradual decay; no enhancement is seen in the fetus.

View larger version (27K): [in a new window]   Figure 6b. Examples of enhancement curves obtained after contrast agent injection in two fetuses in two mice (a) Conventional gadolinium chelate. (b) Macromolecular gadolinium chelate. For left ventricle kinetics, first-pass peak is highlighted, and contrast agent tissue concentration decreases slowly thereafter. Placental tissue concentration shows gradual uptake of contrast agent, followed by gradual decay; no enhancement is seen in the fetus.