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Maternal–Foetal Medicine
Contrast Imaging and 3D Ultrasound
Anna Maria Marconi
1
and Antonino F Barbera
2
1. Associate Professor and Head, Unit of Obstetrics and Gynaecology, Department of Medicine, Surgery and Dentistry, San Paolo Hospital Medical School,
University of Milan; 2. Labour and Delivery Research Co-ordinator, Department of Obstetrics and Gynecology, Denver Health Medical Center
Abstract
The use of contrast media and 3D ultrasound represents the most recent innovation in ultrasonography in obstetrics and gynaecology.
They can be used by themselves or together. In gynaecology, the use of contrast media has been extensively applied to the diagnosis of
endometrial abnormalities and tubal patency, while a promising area of research in gynaecological oncology is represented by the study
of neoangiogenesis of malignant tumours. In contrast, the use of contrast media in obstetrics is still anecdotal, with very few reports and
no clinical indications at the moment. Conversely, 3D ultrasound has been extensively used in the detection of foetal anomalies,
especially of the true mid-line sagittal plane of the foetal face. Its main advantage is that data can be stored and, subsequently, rescued,
analysed and manipulated.
Keywords
Contrast media, 3D ultrasound, hysterocontrastosonography (HyCoSy), foetal abnormalities
Disclosure: The authors have no conflicts of interest to declare.
Received: 21 February 2009 Accepted: 23 March 2009
Correspondence: Anna Maria Marconi, Unit of Obstetrics and Gynaecology, Department of Medicine, Surgery and Dentistry (DMSD), San Paolo Hospital Medical School,
University of Milan, Via A di Rudinì 8, 20142 Milan, Italy. E:
annamaria.marconi@unimi.it
Continuous advances in medical biotechnology have always been an application are encapsulated microbubbles, and are all <10µm in
important stimulus in the improvement of patient care in clinical diameter. Microbubbles within a vascular contrast agent have been
settings. 2D ultrasound (US) has been an indispensable tool in obstetrics reduced to 2–5µm in size. Furthermore, to stabilise and increase the
and gynaecology (OG) since its first appearance in the late 1950s,
1
and longevity of small microbubbles in the systemic circulation, additional
frequent innovations in its application are supported by its relative ease material at the gas–liquid interface has been added to stabilise against
of use, immediate availability of results, non-invasiveness, low cost dissolution and coalescence. The main mechanisms for signal
compared with other imaging modalities and safety record. The two enhancement are backscattering, bubble resonance and bubble
modalities that appeared a few years ago that may influence the future rupture. US contrast media can be classified as aqueous solutions, liquid
of OG practice are US contrast media and 3D US. droplets in emulsions, suspension of free gas bubbles or solid particles
or gas bubbles encapsulated in various media.
6,7
Contrast Media
Discrimination of different tissue by US is based on the intensity of Gas microbubble contrast media are classified in the following way: first-
backscattering echo where there is a change in acoustic impedance generation – non-transpulmonary, vascular, free microbubbles,
between the different interfaces: the bigger the change, the more US is Echovist
®
(SHU 454); second-generation – transpulmonary, vascular,
reflected.
2
The use of contrast agents introduced orally, vascularly or in short half-life (<5 minutes), Albunex
®
, Levovist
®
(SHU 508 A); third-
a body cavity allows significant improvements of the image quality of generation – transpulmonary, vascular, longer half-life (>5 minutes),
the sonography either by decreasing the reflectivity of the undesired Aerosomes (Definity
®
, MRX 115, DMP 115), Echogen (QW 3600), Optison
tissue interfaces (if taken by mouth) or by increasing the backscattered (FSO 69), PESDA, Quantison, QW 437, Imavist (Imagent, AFO 150),
echoes from the desired region (when introduced vascularly).
3
Sonovue (BR 1); and fourth-generation – transpulmonary with organ-
specific phase (liver, spleen), Levovist (SHU 508 A), Sonovist (SHU 563 A),
The first contrast medium was agitated saline, used in 1960 by Joyner to Sonazoid (NC 100100). As all US images depend on the echoes produced
identify mitral valve echo; this utilisation was reported in 1968 in the first when a specific structure is insonated (acoustic backscatter), the
article on the use of US contrast media.
4
However, the free air injection of an echo-producing substance such as US contrast media in
microbubbles produced by agitation were both large and unstable, the insonated area will produce more echoes, which when properly
diffusing into solution in less than 30 seconds. In 1970, Feigenbaum processed will provide additional information on that specific structure.
reported his success with the use of indocyanine green
5
in the This is extremely important when dealing with blood vessels whose size
identification of left ventricular echoes by its intracardiac injection. Since is beyond the resolution of greyscale US, colour imaging or power
then, much progress has been made in both the size and the stability of Doppler. Using a contrast agent 3–5µm in diameter, its subsequent
the new media. Today, all commercial US contrast media for human passing through the smallest capillaries will increase the echoes
54 © TOUCH BRIEFINGS 2009
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