Imaging and assessment of placental function (original) (raw)
In utero imaging of the placenta: importance for diseases of pregnancy
Placenta, 2007
Maurice Panigel demonstrated by X-rays, almost 40 years ago, placental maternal blood jets in non-human primates. Although to researchers the importance of the placenta is evident, in clinical obstetrical imaging, the fetus takes precedence. The placenta is imaged almost as an after thought and mostly to determine its location in the uterus. In animal species, the placenta was imaged with techniques which would be considered too invasive (or too costly for routine use) in humans, many pioneered by Panigel: radioangiography, radioisotopes scintigraphy, thermography, magnetic resonance imaging (MRI) and spectroscopy, positive emission tomography (PET) and single photon emission computed tomography (SPECT). Ultrasound allows for detailed, and, as far as is known, safe analyses of not only placental structure in the human but also its function. Earlier, only 2-dimensional grey-scale was available and more than 20 years ago, placental grading was popular. Later, colour imaging and spectral Doppler analysis of blood velocity both in the umbilical artery and within the placenta as well as the uterus and fetal vessels became essential and, more recently, the use of ultrasound contrast agents has been described, albeit not yet in a clinical setting. Threedimensional ultrasound permits evaluation of the placenta in several planes, more precise depiction of internal vasculature as well as more accurate volume assessment. Several medical disorders of the pregnant woman or her fetus begin or end in the placenta, and ultrasound is the optimal investigation method. Obvious examples include pre-eclampsia and other forms of hypertension in pregnancy, less than optimal fetal growth (i.e. intrauterine growth restriction), triploidy (and its placental manifestation: partial mole), non-immune hydrops as well as several infectious processes. Ultrasound is also particularly suited to evaluate specific placental conditions, such as abnormal placentation (placenta previa and accreta for instance), gestational trophoblastic disease and placental tumors (e.g. chorioangioma).
Placenta, 2016
Introduction: To investigate a simple visual assessment method of placental function using half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance imaging (MRI). Methods: The institutional review board approved this retrospective study of fetal MRI in 48 singleton pregnant women for whom placentas had undergone clinical pathological examinations. Two readers independently assessed the placentas using the HASTE scoring system, particularly emphasizing the visualization of the regular two-tone pattern inside and signal intensity (SI) of placental parenchyma referring to SI of the fetal kidney and liver. After categorization using the HASTE scoring system, the associations between the scores and the presence of pathologically proven placental insufficiency or of low birth weight less than the tenth percentile were examined using chi-square tests. The associations between the HASTE scores and the MRI findings previously reported to suggest placental insufficiency, such as placental thickness and placenta to amniotic fluid SI ratio, were also examined using Student ttests. Results: The HASTE scores were associated significantly with the presence of pathologically proven placental insufficiency (P ¼ .003 for reader 1; P ¼ .04 reader 2) and birth weight less than the tenth percentile (P ¼ .005 for reader 1; P ¼ .003 for reader 2). The HASTE scores were associated significantly with the placenta thickness (P < .0001 for both readers) and the placenta to the amniotic fluid SI ratio (P < .0001 for both readers). Discussion: The HASTE scoring system is feasible for use in clinical assessment of placental function and for diagnosing placental insufficiency.
Structured evaluation and reporting in imaging of placenta and umbilical cord
Acta Radiologica, 2019
The human placenta plays a pivotal role in development and growth of the fetus. Disorder of this multifunctional organ is central to various fetal disorders. Doppler sonography and MRI provide excellent diagnostic evaluation of the placental morphology and umbilical cord. Decades of experience in obstetric imaging have highlighted the need of careful prenatal assessment of placenta. However, in most of the routine obstetric scans, the evaluation and reporting of the placental examination is limited to the location and grade of the placenta. The purpose of this article is to review the existing literature and facilitate step-by-step evaluation of the placenta and umbilical cord by the radiologists.
Ultrasound of the Placenta: A Systematic Approach. Part II: Functional Assessment (Doppler)
Placenta, 2008
Diagnostic ultrasound has been in use in clinical obstetrics for close to half-a-century. However, in the literature, examination of the placenta appears to be treated with less attention than the fetus or the pregnant uterus. This is somewhat unexpected, given the obvious major functions this organ performs during the entire pregnancy. Examination of the placenta plays a foremost role in the assessment of normal and abnormal pregnancies. A methodical sonographic evaluation of the placenta should include: location, visual estimation of the size (and, if appearing abnormal, measurement of thickness and/or volume), implantation, morphology, anatomy, as well as a search for anomalies, such as additional lobes and tumors. Additional assessment for multiple gestations consists of examining the intervening membranes (if present). The current review considers the various placental characteristics, as they can be evaluated by ultrasound, and the clinical significance of abnormalities of these features. Numerous and varied pathologies of the placenta can be detected by routine ultrasound. It is incumbent on the clinician performing obstetrical ultrasound to examine the placenta in details and in a methodical fashion because of the far reaching clinical significance and potentially avoidable severe consequences of many of these abnormalities.
An anatomic basis for ultrasound images of the human placenta
American journal of obstetrics and gynecology, 1985
Placentas after uneventful pregnancies were perfused under physiologic pressure in the fetal vessels, expanded to their predelivery volume, fixated with 4% formaldehyde, and compared to their ultrasound images in pregnancy. The placentas showed a side arrangement of the fetal cotyledons in contact with the basal plate. The centers of the cotyledons showed an empty space in which the spiral arteries ended. These spaces in the placenta corresponded with transsonic areas of ultrasound. The central spaces were surrounded by a relatively dense shell of villi containing the more or less fibrotic stem villi. This explained the areas of increased echo-density, as seen by ultrasound during the last trimester of pregnancy. The fetal cotyledons, composed of a central cavity and a dense villous shell, were separated by a reticular area. The veins ended at the basal plate in these intercotyledonary areas.
MRI evaluation of invasive placenta: “Cool” answers to radiologists’ “hot” questions
2017
During the last decades, the incidence of invasive placenta has risen significantly, probably due to the increased rate of caesarian delivery. Invasive placenta may cause massive intra-or postpartum hemorrhage; therefore, prenatal diagnosis of the presence and extent of myometrial invasion or extrauterine placental spread is critical for optimal management. Sonography is the imaging modality of choice for the evaluation of abnormal placenta; MRI performs equally well and can be used as a reliable alternative in cases of equivocal sonographic findings. Indications for MRI include evaluation of a posteriorly located placenta and the need for precise delineation of placenta percreta for pre-delivery planning. Suspicious MRI findings for abnormal placentation include, marked placental heterogeneity, low T2 signal intraplacental bands, extensive intraplacental vascularity, focal uterine bulge, myometrial thinning or disruption with loss of utero-placental interface, bladder ‘tenting’ and...
Magnetic resonance imaging of the placenta and gravid uterus: a pictorial essay
Abdominal Imaging, 2018
The placenta is commonly overlooked on magnetic resonance imaging of the pregnant patient, which is frequently performed for alternative reasons such as to characterize fetal or uterine anomalies or to investigate the etiology of acute pelvic pain in pregnancy. Placental disorders have potential for significant maternal and fetal morbidity and peripartum complications if not recognized and treated in a timely manner. The radiologist must be familiar with normal placental variants and the spectrum of benign to life-threatening conditions affecting the placenta so that the Obstetrician can be promptly notified and patient management altered, if necessary. In this pictorial essay, we will describe our MR protocol for placental imaging, provide an image rich review of the normal placenta, placental variants, and a variety of pathological conditions affecting the placenta and gravid uterus.