The atrium is the point of confluence between the occipital horn, inferior horn, and the body of the lateral ventricle and is the largest, most easily identifiable portion of the lateral ventricle. 1.46). 1.36). After 11 weeks gestation, the calvarium should be ossified and is seen as an echogenic ring around the intracranial structures (see Fig. In the 11th week of gestation, the fetus begins to flex and extend its body to a degree that may significantly affect CRL; therefore, CRL measurements need to be carefully standardized from this point on (Fig. When using Doppler during the 11 to 13+6 week scan, power indices should be reduced to a minimum, and the region of interest should be interrogated for the minimum time necessary. In this view, an upper lip seen extending beyond the tip of the nose raises the possibility of cleft lip and palate. 1 synonym for dolichocephaly: dolichocephalism. 1.21 and 1.22). 8 . The effect of 3D/4D . Most of all, know that you are not alone, and you will get through this. Has anyone experienced this, this early. 2. 1.44). Scaphocephaly, results from premature closure of the sagittal suture, so that lateral growth of the skull is prevented whilst anteroposterior growth continues, producing a narrow and elongated cranium. FIGURE 1.16: Left longitudinal view of the abdomen at 12 weeks gestation demonstrating the left lung (Lu), intact diaphragm (arrow), left lobe of the liver (L), stomach (s), and small bowel (sb). The vertebrae have three ossification centers visible prenatally: Vertebral body anteriorly and one in each of the vertebral arches (laminae) posteriorly. It can change according to various situations such as, The usual range is variable depending on various sources and different demographic groups. Usually, this misshapen look is minimal and resolves on its own. By Wendy Wisner In addition to describing the basic components of an obstetrical ultrasound examination in this chapter, we also present extended views that improve the quality of the examination and the detection of pregnancy-related problems. s, stomach; L, liver; arrow, portal sinus. FIGURE 1.28: Right parasagittal section of a fetus at 12 to 13 weeks gestation with color and pulsed Doppler. /Filter /FlateDecode Assessment of the central nervous system is not complete without detailed examination of the fetal spine. 1.23). They are linear in shape and form a roof over the spinal canal (Fig. Bethesda, MD: National Council on Radiation Protection and Measurements; 2002. FIGURE 1.33: Posterior coronal view of the brain at 24 weeks gestation. This sacral upswing may be absent in the presence of an open spine defect and in the presence of caudal regression syndrome. The transvaginal approach should be used in all circumstances where a viable intrauterine pregnancy is not obvious on transabdominal assessment. EARLY FIRST TRIMESTER SCAN (5 TO 10 WEEKS GESTATION). FIGURE 1.35: Axial view of a fetal head at 32 weeks. CI nh hn 75. The exam was . I only noticed this when . Isolated enlargement of the fourth ventricle is unlikely to occur and is of limited clinical significance. Early fusing of the joints (sutures) between the bony plates that form an infant's skull keeps the brain . This involves evaluation of the vertebrae and the contents of the spinal canal. Ultrasound is a noninvasive imaging test that shows structures inside your body using high-intensity sound waves. Prenatally ultrasound can reveal clinical features of arthrogryposis multiplex congenita/fetal akinesia . Scaphocephaly accounts for approximately 50% of all cases of craniosynostosisand has a male predilection with an M:F ratio of 3:1. Babys heads are made of several soft plates that havent fully fused together at birththis flexibility helps babies pass more easily through the birth canal, and makes the rapid brain growth that happens during your babys first 12 months possible. B: Axial view of the same fetus. What Does It Mean to Have a Frank Breech Baby? 4,f~Z]\1aHZ9Lx40!?-v*oTf+*i;/F@l#C5b[4I.uf B,\ux+~G39EzF^}gsR8v.jnS$6p-,b$1F3{o V W'4C8)3j|jO 7w&p5=Rj [BD,11X1vHd+/H3$S)`"A 1@"2FIcD]9Rt52D[ The index is calculated from measurement of the diameters of the skull. aawamy 21/02/15. . 1 0 obj 1. The shape of the cerebellar hemispheres becomes somewhat flattened on its anterior surface. Another marker for aneuploidy, the fetal nasal bone, can be examined in the same section. The sagittal suture usually begins closing later in life, at around 2130 years of age. 5B\HSnv/iW]7qhfb[7+VFAa\javI*>POzyK{=Dc9Y0V{ns#/i^">\aPJ/m]_ m|38&B. This is a normal variant and is part of the leptomeningeal space between the roof of the third ventricle and the body of the fornices. zW1}>P 1 The normal range for CI is 0.74 to 0.83. 1.48). Fusion of all sutures produces a tall pointed skull known as acro- or oxy-cephaly. Its common for babies heads to look slightly misshapen after birth and even in the first few weeks that follow. 1.2). All stated gestational ages are according to last menstrual period dating. A finding that is commonly seen in the early first trimester and that deserves special mention is physiologic herniation of the midgut into the root of the abdominal cord insertion (Fig. /AIS false Mosby Inc. (2009) ISBN:0323031250. In contrast to other craniosynostoses, there is near normal IQ and no hydrocephalus. Note the sacral upswing (notched arrow). << "They are purely cosmetic, and the majority do not require surgery. FIGURE 1.24: Fetal foot (arrow) with all five toes visible (12 to 13 weeks gestation). As operculization progresses, the depression is roofed over by the temporal lobe. FIGURE 1.12: Transverse view of the chest at 12 to 13 weeks gestation containing a four-chamber heart view. Antonyms for dolichocephaly. Dolichocephaly - understanding 'breech head' molding | The midwife, the mother and the breech 31/07/2015 19:13 1.7). This is true for more severe cases of sagittal craniosynostosis. Conclusion. Brachycephaly as dened by a BPD/OFD ratio > 0.85 was diagnosed in one case. Dolichocephaly. The paired laminar ossification centers are slightly offset from the midline. On this page: Article: Epidemiology Pathology Unable to process the form. Dolichocephaly most commonly occurs in preterm infants in the NICU: so-called NICUcephaly. Thank you, {{form.email}}, for signing up. Asterisks, corpus callosum; open arrow, cavum septi pellucidi; chevron, cavum septi vergae; solid arrow, fourth ventricle; c, cerebellum; cm, cisterna magna. FIGURE 1.46: Coronal views of the vertebral column. Systematic evaluation is needed to accurately distinguish between a viable intrauterine pregnancy, a miscarriage, or an ectopic pregnancy. The accuracy of CRL measurement decreases with gestational age. 1.38). Appointments & Locations. 1.12 to 1.14). It is a structure that is usually very easy to visualize, and if absent, the possibility of a severe structural defect such as alobar holoprosencephaly should be entertained. anyone dealt with this? Confirm that the fetal heart is beating. The routine calculation of CI can be performed at antenatal scanning, and a value outside the normal range, or a . The sacral portion of the spine usually has a more persistent curvature, with the tip of the spine pointing posteriorly (Fig. Absence of normal operculization raises the possibility of a neuronal migration defect such as lissencephaly. Synonyms for dolichocephaly in Free Thesaurus. /ColorSpace /DeviceGray The vertebral column should be evaluated in at least two of the three planes: coronal, axial, and longitudinal (midsagittal). The images can provide valuable information for diagnosing and directing treatment for a variety of diseases and conditions. Cortical maturation continues throughout pregnancy, as the brain develops gyri and loses its smooth appearance (Fig. h, fetal head. /CA 1.0 This is something your doctor will discuss with you, as the need for these interventions is case-by-case. It checks on the physical development of the fetus and can detect certain congenital disorders as well as major anatomical abnormalities. Open arrow, vertebral body ossification center; solid arrow, vertebral arch ossification center. The cephalic index or cranial index, the ratio of the maximum width ( biparietal diameter or BPD, side to side) of the head of an organism multiplied by 100 and then divided by their maximum length ( occipitofrontal diameter or OFD, front to back). The posterior fossa anomalies are one area where a fetal MRI may be especially helpful in arriving at the correct diagnosis. In the early first trimester, the transvaginal approach is ideal to detect any adnexal pathology or free fluid. 1.30 to 1.33). cp, choroid plexus; arrow, third ventricle. Note that this is a neonatal image to show the anatomy in its entirety. Group 2 Fifteen patients were referred with suspected fetal dolichocephaly as dened by a biparietal diameter (BPD)/occipitofrontal diameter (OFD) ratio < 0.7. Most ultrasound machines can produce this calculation automatically at any obstetric scan with minimal programming. Calipers, CRL measurement. If you are concerned that your baby may have a severe case of dolichocephaly that may result in any developmental, health, or psychological issues, you should speak to your pediatrician. Willis S, Hsiao R, Holland RA, Lee K, Pitetti K. Measuring for nonsynostotic head deformities in preterm infants during NICU management: A pilot study. Thin solid arrows, bodies of the lateral ventricles; thick solid arrow, corpus callosum; open arrows, location of the foramina of Monro; notched arrow, third ventricle; asterisk, operculization of the insula; c, cavum septi pellucidi. Employing the transvaginal route to image a fetus that is cephalic in presentation can facilitate a detailed examination of the intracranial anatomy. Note that this is a neonatal image to show the anatomy in its entirety. A CI, which is below 0.74, connotes a relatively flat head (dolichocephaly), while a CI above 0.83 describes a relatively round head (brachycephaly).83 Dolichocephaly is not uncommon and is often seen in fetuses that are in a persistently breech presentation or in association with chronic oligohydramnios. Notched arrow, falx cerebri. At the time the article was last revised Daniel J Bell had no recorded disclosures. HC=90th percentile, . Prior to the completion of the 7th gestational week, the anatomy of the embryonic pole is difficult to clearly delineate. The whole length of the vertebral column can be seen in both a coronal and in a sagittal section, and the ossification centers should be spaced evenly in these views. . The sagittal suture permits growth in the width of the skull; premature closure results in a cranium that is high, long, and narrow (dolichocephaly). A complete examination of the uterine contents in pregnancy includes much more than evaluation of the fetal anatomy; the remaining issues will be discussed in later chapters. W'#2@mMTh)X\]meY :@p_W Qv,&jg-"Q+-]20J-Ede@mr3zMKx0ogi`]r/oF5>W*9`ai[-B)cKonUEZ`O Dolichocephaly can develop in an otherwise normal developing skull when a baby spends too much time in certain positions. The four-chamber view and outflow tracts can be assessed using both grayscale and color Doppler imaging (Figs. B: Slightly more caudal section of the same fetus demonstrating the course of the middle cerebral artery (solid arrow) to the base of the insula (open arrow) with color Doppler. 22 week US baby head was oval and stated possible dolichocephaly&nbsp; but needed repeat scan at 24 weeks. Kyutoku S, Inagaki T. Review of past reports and current concepts of surgical management for craniosynostosis. /SMask 6 0 R In longitudinal section, the line of ossification of vertebral bodies is seen anteriorly and, if there is a slight oblique cut, one set of posterior ossification sites will be visualized. The posterior fossa undergoes rapid change during the late first trimester, and by 13 to 14 weeks the cerebellum begins to assume a shape resembling that seen in the mid-second trimester (Fig. However, unlike the CSP, a thin echogenic line can be seen between the two fornices, which helps to differentiate between the two entities (Fig. These are generally located in the occipital portion of the calvarium, but can be seen less frequently in the area of the nasal root anteriorly or parietally. The body and the anterior horn of the lateral ventricle radiate anteriorly, superiorly, and laterally from the atrium. Abnormalities such as frontal bossing, which are part of a number of skeletal dysplasias or a sloping forehead present in conditions such as microcephaly, are best visualized in this fashion. Has anyone else had any experience with this? Virchow correlated head shape with the fusion of specific sutures and introduced some definitions that are still in general usage such as dolichocephaly for sagittal synostosis, trigonocephaly for metopic synostosis, and plagiocephaly for unilateral coronal synostosis. 1.40). And will have appointment with my private Obstertric , he will do ultrasound to check head . During Pregnancy During pregnancy, microcephaly can sometimes be diagnosed with an ultrasound test (which creates pictures of the body). At this point, the pregnant uterus is out of the pelvis and is located well within the maternal abdomen. >> The kidneys are generally difficult to see owing to their small size and echogenicity, which is similar to that of the small bowel. The midsagittal section of the fetus is very important, as this allows accurate measurement of CRL and, when adequately magnified, nuchal translucency (Fig. The sagittal section offers the best view of the fetal forehead. Estimating fetal age: effect of head shape on BPD. s^Xmj{4BM+o2Lo_Y0 1.45).106,107 In the presence of an open spine defect, this arrangement is disrupted, and the laminar ossification centers are displaced laterally, forming the shape of the letter U or V in the axial view of the spine. Her work has been published in medical journals in the field of surgery, and she has received numerous awards for publication in education. 1.42). . The lateral ventricles are essentially filled by choroid plexi, which are seen as paired echogenic structures, one within each hemisphere (butterfly view). << You can find out more about our use, change your default settings, and withdraw your consent at any time with effect for the future by visiting Cookies Settings, which can also be found in the footer of the site. This represents the choroid plexus. Understanding Vaginal Tears During Labor and Delivery. This is due to ossification of the skull, which casts an acoustic shadow over the proximal portion of the fetal brain. Care must be taken so that the cerebellar hemispheres are symmetrical, and the measurement is done at a point where the distance between the lateral edges of the two hemispheres is the greatest.101,102. The spinal cord can be delineated within the spinal canal using ultrasound on most exams (Fig. Gestational age is 20 weeks, 1 day, with EDD of 09/01/2023 by the clinical dates given. Remember that any concerns you may have are valid. The occipital horns project posteriorly. Since the vermis is not fully developed until mid-gestation, vermian defects, especially small ones, are difficult to diagnose prior to 18 to 20 weeks gestation. 1 2 . Neurologia Medico-Chirurgica. /Height 60 Often the mean value is taken ~78 (range 74-83 3). Immediately after starting the scan, the fetal heart is checked, establishing viability and providing some reassurance to the mother. 3. Increased BMI can significantly compromise the ultrasound examination and may require a change in the usual strategy. It represents a space between the two septi pellucidi, which is filled with cerebrospinal fluid (CSF). This is because babies heads are meant to be moldable to accommodate the many changes that happen during gestation, birth, and the first year of life. The embryonic stage, ending at 10 weeks gestation, is a time of very rapid change in the small, developing conceptus.45 Ultrasound before 11 weeks gestation is not typically regarded as a routine part of pregnancy assessment. Because sutures are fluid, they allow the brain to grow and develop. Septations within the CM are a common finding and occasionally they can simulate a small cyst. Asterisk, heart; chevron, aorta; open arrows, ductus venosus and its corresponding waveform; solid arrows, hepatic artery and its corresponding waveform; uv, umbilical vein; ua, umbilical artery; fa, femoral artery. Craniosynostosis is a birth defect in which the bones of the baby's skull fuse together prematurely before the brain has fully developed. Cookies collect information about your preferences and your devices and are used to make the site work as you expect it to, to understand how you interact with the site, and to show advertisements that are targeted to your interests. The fetus is in a neutral position and occupies the majority of the image. It has an incidence of 1 in every 4,200 babies." - Does this mean it ex Continue Reading More answers below Is ABVS ultrasound better at detecting abnormal tissues in breasts than conventional ultrasound? It is bounded by the corpus callosum anteriorly and superiorly, the fornix posteriorly, and the anterior commissure inferiorly. /Filter /FlateDecode c, cerebellar hemispheres. CVA is the difference between 2 diagonal measurements (frontozygomaticus to opposite eurion). Routine examination of the posterior fossa is critical to detect not only anomalies that originate in the posterior fossa but also changes that are indicative of problems in the spine. Marley Hall is a writer and fact-checker who is certified in clinical and translational research. /BitsPerComponent 8 FIGURE 1.18: Transverse view of the abdomen at the level of the kidneys (arrows) at 12 weeks gestation (A) and at 13 weeks gestation (B). 1.49). The atrium is located medially. v, ventricles; a, atria. If a cerebellar defect or ventriculomegaly is suspected, the fourth ventricle should be evaluated. Please note the difference in the texture of the surface of the cortex, with absent sulci and gyri at 22 weeks gestation (A) and well-developed pattern of sulci and gyri at term (B). 4 0 obj Cephalic index: a gestational age-dependent biometric parameter. Dolichocephaly, variant of normal. She has worked with breastfeeding parents for over a decade, and is a mom to two boys. In these conditions, the skull is also easily compressible, which can be demonstrated by applying gentle pressure with the ultrasound transducer. Each lateral ventricle is divided into five parts: The frontal horn, the body of the lateral ventricle, the occipital horn, the inferior (temporal) horn, and the atrium (trigone). FIGURE 1.32: Midcoronal view of the brain at 24 weeks gestation. FIGURE 1.5: Sagittal view of a 12- to 13-week fetus. C: Arrow, cisterna magna. Typical facial characteristics include dolichocephaly, downslanting palpebral fissures, enophthalmos, retrognathia, and malar hypoplasia. The Ultrasound Care specialist doctors and sonographers can use the Morphology scan for the following insights into your pregnancy and your baby. ", However, some severe cases of dolichocephaly can be more serious and may affect your babys health and development. Head ultrasound was normal except marked dolicocephaly, head circumference between -1 and -2 SD, and suspected delay of sulcation. The general symmetry of the fetal brain is first assessed using standard axial views. The inferior (temporal) horns run through the area of the temporal lobe and are difficult to identify unless they are enlarged. However, many experts in the field advocate the use of additional views to improve diagnostic performance. Notched arrow, falx cerebri; cp, choroid plexus. << In utero death occurs in more than 95% of fetuses with this chromosome anomaly. FIGURE 1.34: Sagittal view of the fetal head at 24 weeks gestation. Unilateral or bilateral CPCs are a common finding affecting 1% to 4% of euploid fetuses but have also been associated with aneuploidy, particularly trisomy 18. 7) Finally, the suboccipitobregmatic view is also used as a standardized view for nuchal fold measurement. 1.34). Absence of an ossified calvarium in association with abnormal intracranial anatomy is consistent with exencephaly/anencephaly sequence. Even though normal CM diameter is below 10 mm, isolated CM enlargement (mega-cisterna magna) is considered to be a normal variant. With the exception of the above-described Chiari Type II malformation, most defects affecting the posterior fossa are cystic in nature (DandyWalker malformation, Blakes pouch, arachnoid cysts, and dysgenesis of the cerebellar vermis). In this section, the intracranial anatomy essentially consists of the lateral ventricles and a very thin layer of brain parenchyma. So worried 1.6). Vi s pht trin qu mc sm ca ng khu sagittal (bao hot dch sagittal), tt u dolichocephaly pht trin, trong hp s tng ln theo hng trc sau v gim kch thc theo chiu ngang. /BitsPerComponent 8 Dolichocephaly = CI <76%; 5. 2019;131:56-62. doi:10.1016/j.earlhumdev.2019.03.002. [ 5] An exception to this is the preterm. According to the American Academy of Pediatrics (AAP), misshapen heads and skull deformities occur about 20% of the time during childbirth or as a result of a babys position in the womb. A cystic midline structure that is occasionally seen located posteriorly and inferiorly to the CSV is the cavum veli interpositi (Fig. /Creator ( w k h t m l t o p d f 0 . There is a tendency of the ankles to turn inward, making the diagnosis of clubfoot in the first trimester challenging. In this rare case, surgery is very successful after birth to correct the problem. At my 20w anatomy scan, the ultrasound tech made a note of "possible Dolichocephaly". 1.18 and 1.19). Color Doppler is used to demonstrate the renal arteries (solid arrows) in A, which can become nondetectable with only a slight adjustment of the transducer, as in B. At this point, the CRL is defined as measurement between the top of the fetal head and the fetal rump along its longitudinal axis (Fig. cp, choroid plexus; solid arrow, falx cerebri; open arrow, ossified portion of calvarium. A skeletal survey is best performed by utilizing both axial and transverse sections. 1.28).8 Doppler examination involves higher power levels and consequently should generally be avoided during the embryonic period (10 weeks menstrual gestational age) unless the benefits clearly outweigh the risks. http://carta.anthropogeny.org/moca/topics/age-closure-fontanelles-sutures. Some critically ill infants may be positioned supine with the head. Often, axial views are best for assessing the integrity of the skin. Brachycephaly may also be a normal variant but has been described in association with trisomy 21. Images Scaphocephaly: The head has a short laterolateral and a long anteroposterior diameter. /Length 9 0 R At the time the article was created Yuranga Weerakkody had no recorded disclosures. xYr6z9 >$II4 R_? IQP]HU>aJ[iJ*UFeuVk~T. Y\4r$9I 3^nvlZ6|=!ss2%+u*W'Z9 The exact timing of the examination may also depend on maternal habitus. In humans, the anterior-posterior diameter (length) of the dolichocephaly head is more than the transverse diameter (width). Just in case the CI is significantly lower, that suggests dolichocephaly (long head), where the sutures have closed too early. Dolichocephaly is a term used to describe a tall, narrow head. no financial relationships to ineligible companies to disclose. FP Hadlock, RL Deter, RJ Carpenter, SK Park. (2005) ISBN:1588901475. ADVERTISEMENT: Supporters see fewer/no ads. The calvarium will be completely absent in anencephaly. ICD 10 code for Maternal care for other (suspected) fetal abnormality and damage, not applicable or unspecified. Note the relatively prominent adrenal glands (a), which need to be kept in mind in order not to mistake them for the kidneys. Every attempt should be made to visualize both cerebellar hemispheres to allow a comparison of their size and echotexture. According to the AAP, there are three main interventions for misshapen skulls and positions skull deformities: physical therapy, helmet therapy, and surgery. Even though operculization of the insula begins at approximately 14 weeks gestation, on ultrasound, this process does not become evident until approximately 19 weeks gestation. It is commonly, though not exclusively, a result of an extended stay in neonatal intensive care unit (NICU). Summary Epidemiology Incidence is estimated at between 1/6000 and 1/8000 births. The genital tubercle (open arrow) up from the fetal longitudinal axis (>30). The CSP and its posterior extension, the cavum septi vergae (CSV), are seen as a continuous hypoechoic structure located in the midline. The bladder should be visible in all cases from 12 weeks onward. There is no direct communication between the ventricular system and CSPV; it is diffusion across the thin septi pellucidi that allows CSF to enter this space. 1.47). << Other causes may include: Craniosynostosis (kray-nee-o-sin-os-TOE-sis). Centers for Disease Control and Prevention. J Ultrasound Med. Cephalic index less than 76%. In the anteroposterior axis, the spine is curved, being convex in the thoracic region and concave in the lumbosacral region. Nuchal translucency assessment is easier to perform and more sensitive at an earlier gestation (11 to 12 weeks), whereas anatomy is best assessed at a slightly later gestation (12 to 13 weeks).8 The examination may be performed transabdominally, and if necessary transvaginally, but a combination of the two approaches often yields the best results. 137 (1): 83-5. FIGURE 1.36: A: Sagittal section of a fetal head at 22 weeks gestation with a cavum veli interpositi (notched arrow) located posteriorly and inferiorly to CSPV (asterisk). The calvarium should be systematically examined to ensure that it is intact. Note that CVA will be symmetric in symmetric brachy-, and dolichocephaly. Most examinations at this stage are performed for a specific clinical indication such as pain or vaginal bleeding associated with a positive pregnancy test. 1.20).56,57. A standardized longitudinal measurement of the bladder in the first trimester should be performed in this view if it appears to be enlarged.58 The same section provides information regarding fetal gender by qualitative evaluation or measurement of the angle between the genital tubercle and the fetal longitudinal axis. Healthcare providers use ultrasound exams for several purposes, including during pregnancy, for diagnosing conditions and for image guidance during certain procedures. Selected Safety Recommendations for Diagnostic Ultrasound, Ultrasound exposures that elevate fetal temperature by 4C above normal for 5 min or more have the potential to induce severe developmental defects, Apply the ALARA principle if the tissues to be exposed contain stabilized gas bodies (lung) and the MI exceeds 0.4, There is no epidemiologic support for a causal relationship between diagnostic ultrasound during pregnancy and adverse biologic effects to the fetus observed for outputs under a spatial-peak temporal-average intensity of 94 mW/cm2, The temperature of the fetus should not safely rise more than 0.5C above its normal temperature, When MI is above 0.5 or the TI is above 1.0, the NCRP recommends that the risks of ultrasound be weighed against the benefits. "Positional skull deformities do not affect brain growth or intellectual development," writes the AAP. Sagittal views of the posterior fossa are also very informative. /CreationDate (D:20180611143312+03'00') ic d-li-k-s-fa-lik : having a relatively long head with cephalic index of less than 75 dolichocephaly d-li-k-se-f-l noun Word History Etymology New Latin dolichocephalus long-headed, from Greek dolichos long + -kephalos, from kephal head more at cephalic First Known Use Solid arrow, medulla oblongata; open arrow, pons; asterisk, cisterna magna; c, cerebellum. Note the differences in their appearance depending on the level. 7 0 obj Calipers, transcerebellar diameter; cp, cerebral peduncles; t, thalami; open arrow, insula; asterisk, cavum septi pellucidi; chevron, falx cerebri. 1.39). American Institute of Ultrasound in Medicine consensus report on potential bioeffects of diagnostic ultrasound. Early Hum Dev. Dolichocephaly has two primary causes: craniosynostosis or positioning.