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Contrast Imaging and 3D Ultrasound
originating from blood vessels that contain it by two different Figure 1: Sagittal View of Uterine Cavity Filled with
mechanisms: first, by improving the signal-to-noise ratio and
Normal Saline During Hysterocontrastosonography
subsequently the spectral/colour/power Doppler signal, and second, by
selective uptake in particular tissues such as Kupffer cells of the
reticuloendothelial system. US contrast media are clinically used in
many specialties. In adult echocardiography they are utilised to study
cardiac cavities and valves, to visualise coronary circulation and to
provide an assessment of myocardial perfusion.
8
Hepatic and renal
vascular beds are other areas that have benefited from the use of US
contrast media.
9
One peculiarity of malignant tumours is the creation of
abnormal blood vessels whose visualisation is not possible with US only.
The intravascular utilisation of contrast media has allowed the
construction of time–intensity curves demonstrating that tumours have
steeper rises and slower wash-outs secondary to neoangiogenesis.
10
Ultrasonographic studies of the upper gastrointestinal (GI) tract are
limited by gas-filled bowels, which produce many artefacts. The use of
oral US contrast agents designed to adsorb and displace stomach and Two endometrial polyps are clearly filling the uterine cavity, originating from the posterior wall.
bowel gas has been approved by the US Food and Drug Administration
Courtesy of William W Brown III, MD.
(FDA) for clinical use (SonoRX, Bracco). The major concern about the use
Figure 2: Sagittal View of Uterine Cavity Filled with
of US contrast media is their safety. As a whole they have a good safety
Normal Saline During Hysterocontrastosonography
record, but many potential risks need to be kept in mind: gases can cause
embolic phenomena, haemolysis of red blood cells (which are probably
enhanced by their presence) by the process of cavitation,
11
accelerated
thrombolysis induced by US,
12
transient effects such as back pain,
trembling, fever, increased liver enzymes and mild allergic symptoms.
13,14
Obstetrics
The use of US contrast media in obstetrics is limited by the potential
damage to the developing foetus. The mechanism of damage could be
a direct teratogenic effect via transplacental passage, ischaemic
damage secondary to embolism of the small foetal and/or placental
vessels or the cavitation phenomenon, which may occur due to the
presence of gas bubbles in insonated fluid.
Two contrast media (Albunex and IDE [iodipamide ethyl ester]) have
been used in experimental models using human placentas maintained
The uterine cavity is distorted by one endometrial polyp originating from the posterior
under double (maternal- and foetal-site) perfusion.
15
Neither of these two
uterine wall and by a submucosal fibroid (type I, more than 50% in the uterine cavity)
media was found to cross the placenta or cause clear morphological or
located in the anterior wall. Courtesy of William W Brown III, MD.
functional placental damage. This information, if confirmed by further underwent diagnostic antenatal amnioinfusion found that the overall
studies on media safety, could eventually be used to assess placental rate of adequate visualisation of foetal anatomy improved from 51 to
function in pregnancies complicated by foetal growth restriction, with 77% after amnioinfusion.
18
A case report of unclear chorionicity in a
the goal of identifying the quality of placental circulation able to twin pregnancy was studied with an injection of Levovist into the
distribute vasoactive medication potentially used to improve placental circulation of one foetus. The injected medium was observed to appear
circulation. Levovist has also been used to enhance slow flow velocities in the other twin, confirming the diagnosis of monochorionicity.
19
in differentiating ectopic pregnancies from other less vascularised Currently, there are no clinical indications in which the use of US
adnexal masses.
16
This may be helpful when the results obtained from contrast media is accepted in obstetrics practice.
colour flow imaging are ambiguous or typical ultrasonographic signs of
peritrophoblastic ring cannot be clearly recognised in the adnexal mass. Gynaecology
Conversely, in gynaecology there are no concerns of foetal
Of particular scientific interest is the investigation of the first-trimester teratogenicity, and consequently the use of contrast media has been
placental slow-velocity blood-flow circulation. The possibility of investigated more extensively. The uterine cavity is a virtual cavity
injecting contrast media in the maternal circulation in the first unless occupied by a foetus or blood, and because of this structure
trimester may demonstrate or deny the presence of slow flow in the many endometrial pathologies cannot be diagnosed unless a contrast
placental vasculature, which is hypothesised to happen in the first 12 between the endometrial wall and the uterine cavity can be created.
weeks of gestation.
17
This was first obtained by introducing into the uterine cavity 10–20ml
of sterile normal saline through a small catheter, a procedure known
Intra-amniotic infusion of normal saline may be used in cases of severe as: contrast hysterosalpingography, hysterocontrastosonography
oligoanhydramnios to help sonographic foetal imaging. A review of (HyCoSy), hysterosonography, sonohysterography, chohysterosalping-
patients with unexplained mid-trimester oligoanhydramnios who ography and hydrogynecography.
EUROPEAN OBSTETRICS & GYNAECOLOGY 55
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