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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5805_Библиотеки_им_академика_М_И_Перельмана.pdf
ab
5.4 Frontal Space Distance
33
A
A
**
M
M
MM
c
A
Fig. 5.3 Normal and abnormal appearance of retronasal
triangle. (TAS) (a) Normal retronasal triangle arrows
point to intact base of triangle, apex (A), mandible (M).
(b) Midline defect (* denotes defect seen on either side of
M
M
vomer) in the base of the triangle in a case of bilateral
CLP. (c) Lateralized defect (arrows) in the base of the tri-
angle in a case of unilateral cleft palate
from the midsagittal section in a case of isolated
cleft palate at 14weeks.
5.4 Frontal Space Distance
The Frontal Space (FS) distance is the distance
between the forehead and an extended line intersecting the most anterior portions of the mandible and the maxilla (MM line) (Fig. 5.5). In
facial clefts, due to protrusion of the maxilla,
there is an alteration in the normal position of
the maxilla in relation to the mandible, thus
modifying the FS distance. Hence FS distance
can be used as a screening marker to evaluate
facial clefts [10].
Cases with bilateral CLP (Fig.5.6) and retrognathia (Fig.5.7) have a highly abnormal FS distance, and this suggests that it may be useful in
identifying a broad spectrum of anomalies. It is
important to remember that different types of
abnormalities have different effects on the FS
distance. In cases of bilateral CLP and in retrognathia, measurements are increased, whereas in
cases of median cleft, the FS distance is
decreased.
34
ab
5 Signs andMarkers in theDetection ofFirst-Trimester Palatine Clefts
0.65 cm
Fig. 5.4 Appearance of the normal and shortened maxillary line. (TAS) (a) Midsagittal section illustrating normal
maxillary line. (b) 3D sagittal section slightly off the midline demonstrating shortened maxillary line in isolated
NB
FS
CP. (Note that the maxillary line posterior to the premaxilla is absent (arrows point to the defect), premaxilla
(dashed arrow). (Video 5.2)
with a palatine cleft, and sonographic visualization of this junction aids in their detection.
In normal fetuses, the posterior aspect of the
ML
M
maxillary line appears bid in midsagittal section. The shorter cranial line is the vomer bone
which is seen superior to and superimposed on a
longer, more caudal line which is the hard secondary palate. Both the vomer and secondary palate
comprise the maxillary line in the posterior aspect.
The superimposed line can be imaged by gently tilting the probe from one side to the other of
the fetal nose focusing on the maxillary line using
the same technique as to image the nasal bone.
This line is better visualized in real-time imaging
Fig. 5.5 Normal frontal space distance. Midsagittal section of the fetal face showing measurement of FS distance.
MM line (dotted line) connects the anterior protuberance
of mandible and maxilla, extended superiorly. FS distance
(solid line) is measured perpendicularly between the fetal
forehead to the MM line. Nasal bone (NB), maxillary line
(ML), mandible (M)
with the fetal neck in the neutral position or slight
exion, as illustrated in Video 5.3.
The sign is based on the simple anatomical
fact that the maxillary line appears single in an
isolated cleft palate as the secondary palate is
absent and only the vomer contributes to the
maxillary line. The application of this sign also
5.5 Superimposed Line Sign
enables interpretation of cleft extension into the
secondary palate, as shown in line diagram
The “superimposed line sign” (SLS) is a novel
sonographic sign based on 2D imaging of the
vomero-maxillary junction in the midsagittal
view [11]. We proposed this sign for early diagnosis of the cleft of the secondary palate. The
vomero-maxillary junction is abnormal in fetuses
(Fig.5.8) [11]. Note that the posterior aspect of
the maxillary line appears single in clefts involving secondary palate (Fig.5.8 d, f, g and h).
Figure 5.9 is an illustration of the normal
(Fig. 5.9a) superimposed line sign and the
absence of superimposed line sign in bilateral
0.35 cm
5.5 Superimposed Line Sign
35
ba
NB
ML
Fig. 5.6 FS distance in bilateral CLP. (a) Midsagittal sec-
tion illustrating premaxillary protrusion (arrowhead),
maxillary gap (arrow), nasal bone (NB), maxillary line
(ML), mandible (M). (b) The premaxillary protrusion in
NB
ML
M
M
bilateral CLP causes the MM line (dotted line) to be displaced anteriorly, thus increasing the FS distance (solid
line)
ba
Fig. 5.7 FS distance in retrognathia. (a) Midsagittal sec-
tion illustrating receding chin, nasal bone (NB), maxillary
line (ML), mandible (M). (b) The receding chin causes the
(Fig.5.9b), median (Fig.5.9c), and isolated cleft
palate (Fig.5.9d). Figure5.9a depicts the normal
bid appearance of the posterior aspect of the
maxillary line. Figure5.9b is a case of complete
bilateral CLP with absent SLS. Note that the
maxillary line in Fig.5.9b, d appears single in the
posterior aspect. Here the maxillary line is
formed only by the premaxilla and vomer.
In the rst trimester, the maxillary gap used
along with PMD serves as an efcient marker to
MM line (dotted line) to be anteriorly displaced, thus
increasing the FS distance (solid line)
detect isolated CP [6, 10]. The retronasal triangle
does not serve to identify isolated cleft of secondary
palate and clefts conned to the premaxilla alone.
The strength of the superimposed line sign is
that it gives the initial clue to suspect cleft of the
secondary palate in cases where the routine,
conventional signs are not present. This sign can
easily be incorporated into routine practice as we
are familiar with the anatomical landmarks in
midsagittal prole view.
36
a
b
cd
ef
5 Signs andMarkers in theDetection ofFirst-Trimester Palatine Clefts
NB
VB
M
P
PM
VB
PMP
VB
P
g
VB VB
PMP
h
PMP
VB
Fig. 5.8 Line diagram illustrating SLS in various types
of palatine clefts. Illustration of superimposed line sign in
various types of palatine clefts. NB—Nasal Bone, VB—
Vomer Bone, PMP—Premaxillary protrusion, PM—
Premaxilla, M—Mandible, P—Palate. (a) Normal Palate
(b) Unilateral CLP involving premaxilla (c) Unilateral
CLP involving secondary palate (d) Unilateral CLP with
midline extension into secondary palate (e) Bilateral CLP
with intact secondary palate (f) Bilateral CLP involving
secondary palate (g) Median CLP (h) Isolated cleft of the
secondary palate
PMP
PM
5.6 Overview ofMarkers
The measurement of the frontomaxillary facial
(FMF) angle and maxilla nasion mandible
(MNM) angle are the other proposed markers for
the detection of cleft palate [12, 13]. However,
the clinical utility of these signs is yet to be estab-
lished in routine practice. The intact alveolar arch
seen in the axial view is another important marker
in rst-trimester evaluation of palate (see Chap.
4, Fig. 4.7) [14].
Figure 5.10 depicts the various signs and markers described for rst-trimester evaluation of the
palate in the sagittal, axial, and coronal planes.
ab
cd
5.6 Overview ofMarkers
37
ML
V
P
PM
V
V
V
PM
Fig. 5.9 Appearance of superimposed line sign in normal
and abnormal cases. Midsagittal section - (a) Superimposed line sign, the vomer bone (V) is seen superimposed
on the posterior two-thirds of maxillary line (ML), (Video
5.3) (b) Absent superimposed line sign in a case of bilat-
* Maxillary gap sign
* Frontal space distance
* Palatino-maxillary diameter
* Super imposed line sign
* MNM angle
* FMF angle
eral CLP premaxillary protrusion (arrow), (c) Median
CLP with absent superimposed line sign, note the absence
of premaxillary portion (arrow), (d) Absent superimposed line sign in isolated CP. Palate (P), premaxilla
(PM), vomer (V)
Signs and markers
Axial
*Intact alveolar arch
Coronal Sagittal
* Retronasal triangle
Fig. 5.10 Flow chart depicting the various signs and markers in the sagittal, axial and coronal planes
38
5 Signs andMarkers in theDetection ofFirst-Trimester Palatine Clefts
References
1. Syngelaki A, Chelemen T, Dagklis T, Allan L,
Nicolaides KH. Challenges in the diagnosis of fetal
non-chromosomal abnormalities at 11–13 weeks.
Prenat Diagn. 2011 Jan;31(1):90–102.
2. Becker R, Wegner RD. Detailed screening for fetal
anomalies and cardiac defects at the 11–13-week scan.
Ultrasound Obstet Gynecol. 2006 Jun;27(6):613–8.
3. Salomon LJ, Alrevic Z, Raine-Fenning NJ, TimorTritsch I, Seshadri S. ISUOG practice guidelines:
performance of rst-trimester fetal ultrasound scan.
Ultrasound Obstet Gynecol. 2013;41(1):102–13.
4. Syngelaki A, Hammami A, Bower S, Zidere V,
Akolekar R, Nicolaides KH.Diagnosis of fetal nonchromosomal abnormalities on routine ultrasound
examination at 11–13 weeks’ gestation. Ultrasound
Obstet Gynecol. 2019 Oct;54(4):468–76.
5. Chaoui R, Orosz G, Heling KS, Sarut-Lopez A,
Nicolaides KH.Maxillary gap at 11–13 weeks’ gestation: marker of cleft lip and palate. Ultrasound Obstet
Gynecol. 2015 Dec;46(6):665–9.
6. Sepulveda W, Wong AE, Martinez-Ten P, PerezPedregosa J. Retronasal triangle: a sonographic
landmark for the screening of cleft palate in the
rst trimester. Ultrasound Obstet Gynecol. 2010
Jan;35(1):7–13.
7. Sepulveda W, Wong AE, Vinals F, Andreeva E,
Adzehova N, Martinez-Ten P.Absent mandibular gap
in the retronasal triangle view: a clue to the diagno-
sis of micrognathia in the rst trimester. Ultrasound
Obstet Gynecol. 2012 Feb;39(2):152–6.
8. Suresh S, Vijayalakshmi R, Indrani S, Devaki G,
Bhavani K. The premaxillary triangle: clue to the
diagnosis of cleft lip and palate. J Ultrasound Med.
2006 Feb;25(2):237–42.
9. Lachmann R, Schilling U, Brückmann D, Weichert A,
Brückmann A.Isolated cleft lip and palate: maxillary
gap sign and palatino-maxillary diameter at 11–13
weeks. Fetal Diagn Ther. 2018;44(4):241–6.
10. Hoopmann M, Sonek J, Esser T, Bilardo CM,
Wagner P, Abele H, Kagan KO. Frontal space distance in facial clefts and retrognathia at 11–13
weeks’ gestation. Ultrasound Obstet Gynecol. 2016
Aug;48(2):171–6.
11. Lakshmy SR, Rose N, Masilamani P, Umapathy
S, Ziyaulla T. Absent ‘superimposed-line’sign:
novel marker in early diagnosis of cleft of fetal secondary palate. Ultrasound Obstet Gynecol. 2020
Dec;56(6):906–15.
12. Pan M, Chen M, Sahota DS, Lao TT, Lau TK, Leung
TY.Can we use the frontomaxillary facial angle in
the rst trimester to predict facial cleft? Prenat Diagn.
2012 May;32(5):491–3.
13. de Jong-Pleij EA, Ribbert LS, Manten GT, Tromp E,
Bilardo CM.Maxilla–nasion–mandible angle: a new
method to assess prole anomalies in pregnancy.
Ultrasound Obstet Gynecol. 2011 May;37(5):562–9.
14. Lakshmy SR, Deepa S, Rose N, Mookan S, Agnees
J. First-trimester sonographic evaluation of palatine
clefts: a novel diagnostic approach. J Ultrasound
Med. 2017 Jul;36(7):1397–414.
3D Techniques toEvaluate Palate
at 11–14Weeks
6
It has been observed that it is very easy to visualize the entire primary and secondary palate in
the axial plane at 11–14weeks using multiplanar
imaging. One of the probable explanations for
this would be that the secondary palate in the
rst trimester is at and not arched as it appears
in later gestation. The other is the lack of ossication of all facial structures surrounding the
palate at this period of gestation. Therefore there
is minimal shadowing from surrounding facial
bones, which favors the study in multiplanar
mode display.
Acoustic shadowing is always a signicant
problem in the second and third trimesters, which
hinders visualization of the palate [1, 2]. Indeed,
Campbell considers that in the rst trimester, the
absence of acoustic shadowing from the maxilla is
an advantage for an early examination of the secondary palate [3]. Further, the secondary palate is
larger in the lateral than in the anteroposterior
dimension, favoring its examination in the axial
plane [1] This chapter deals with the ofine analysis of 3D datasets in evaluating the palate. Most
cases of orofacial clefts can be accurately
detected and characterized at this gestational age
by analyzing the 3D datasets [4, 5].
Supplementary Information The online version of this
chapter (https://doi.org/10.1007/978- 981- 16- 4613- 3_6)
contains supplementary material, which is available to
authorized users.
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
L. R. Selvaraj, T. Ziyaullah, First and Mid Trimester Ultrasound Diagnosis of Orofacial Clefts,
https://doi.org/10.1007/978-981-16-4613-3_6
6.1 Multiplanar Imaging
For evaluating the palate a volume acquisition is
done in the midsagittal view of the fetal face after
adequate magnication. 3D data sets are obtained
using a 40-degree sweep from one side of the face
to the other using optimized sonographic settings.
Ofine analysis of the stored 3D data sets is used
to assess the sectional anatomy of the palate.
The essential markers to evaluate the palate
are an intact maxillary line in the sagittal view,
continuity of the alveolar arch of the maxilla in
the axial view and intact base of the retronasal
triangle in the coronal view. All the abovemen-
tioned 2D markers in the three orthogonal planes
can be visualized simultaneously by multiplanar
imaging (Fig. 6.1). Video 6.1 illustrates the
simultaneous visualization of the maxillary line
in the sagittal view and the palate in the axial
view in multiplanar imaging.
Multiplanar imaging helps to identify the
anatomic structure in the three orthogonal
planes simultaneously with the use of a reference dot. The anatomy of the retronasal triangle
is illustrated in Fig.6.2. The reference dot, when
placed at the apex of the triangle as in Fig.6.2a
shows the nasal bone. The reference dot, when
placed at the base of the triangle as in Fig.6.2b
shows the palate. Video 6.2 illustrates the anatomy of the retronasal triangle in multiplanar
imaging using the reference dot.
Figure 6.3 is an illustration of the anatomy of
vomero-maxillary junction with reference dot
39
40
6 3D Techniques toEvaluate Palate at 11–14Weeks
a
P
Fig. 6.1 Multiplanar imaging of palate in orthogonal
planes. (a) 14weeks (TVS) representation of base of the
retronasal triangle in orthogonal planes (note that the reference dot is placed at the base of the RNT in plane A, the
maxillary line (ML), and palate (P) is visualized in B and
A
ML
C
B
a
A
NB
b
ML
C planes respectively. (b) 14weeks (TAS) representation
of the palate in orthogonal planes (note that the reference
dot is placed on the maxillary line in plane A, the palate is
visualized in axial and coronal planes in B and C planes,
respectively.(Video 6.1)
A
P
C
B
b
B
P
Fig. 6.2 Multiplanar imaging illustrating anatomical
landmarks of the retronasal triangle (14 weeks TVS).
(a) The reference dot placed at the apex (A) of the tri-
placed on the caudal and cranial lines. The refer-
ence dot, when placed on the cranial line
highlights, the vomer (Fig. 6.3a) and when
placed on the caudal line depicts the secondary
palate (Fig. 6.3b).
Figure 6.4 is an illustration of the vomer
bone in multiplanar imaging. Note that the
vomer fuses with the posterior two-thirds of the
palate as shown in plane C (see line diagram
Chap. 2, Fig. 2.5).
angle shows the nasal bone (NB). (b) The reference dot
placed at the base (B) of the triangle shows the palate
(P) (Video 6.2)
6.2 Volume Contrast Imaging
Volume contrast imaging (VCI) is a technique
that projects a 1–10mm slice of a volume dataset onto a two-dimensional (2D) screen. As a
result of adding the tissue information from adjacent layers, there is an enhancement of tissue
demarcation leading to better visualization of
structures. Figure6.5 illustrates the utility of VCI
in imaging the fetal face.
6.3 Omni View Technique
41
a
V
V
P
Fig. 6.3 Multiplanar imaging of the vomer and palate. (a) Reference dot placed on cranial line corresponds to the
vomer (V) in axial view. (b) Reference dot placed on caudal line corresponds to the palate (P) in axial view
A
b
V
P
P
C
O
V
NB
V
O
Fig. 6.4 Multiplanar imaging of the vomer (14weeks TVS) Plane A axial section through the nasal cavity, the reference dot placed on the vomer (V) illustrates its appearance in the sagittal section in plane C.Orbits (O), nasal bone (NB)
6.3 Omni View Technique
Omni view technique is a exible technique that
allows the operator to draw lines in any direction
or angle to visualize the area of interest in the
volume dataset. This technique is an excellent
tool in evaluating the palate, especially in mid
trimester to assess the curved anatomy of the
palate. The entire secondary palate can be visual-
ized as an echogenic plate of bone caudal to the
alveolar arch as demonstrated by omni view in
Fig.6.6 [6]. The utility of the omni view line in
42
6 3D Techniques toEvaluate Palate at 11–14Weeks
a
a1
b
b1
Fig. 6.5 Utility of VCI in evaluating fetal face. Midsagittal section of the face without VCI, (a, b) and their correspond-
ing images with VCI (a1, b1)
evaluating the retronasal triangle is shown in
Chap. 4, Fig. 4.6.
6.4 Rendered View
oftheIntraoral Surface
ofthePalate
Rendering of the palate can be done by using the
ipped face technique described by Platt et al.
[7]. After the usual volume acquisition in the sagittal plane (Fig.6.7a), the acquired volume was
rotated to obtain a facial image, as shown in
Fig.6.7b. The render box is placed on the maxillary line with the green dotted line facing the
intraoral surface of the palate as shown in
Fig.6.7c. By this technique, the axial view of the
palate is seen in the rendered view.
Various rendering modes can be used to depict
the palate, like surface and maximum mode rendering Fig.6.8a and HD live mode Fig.6.8b. The
anatomic landmarks of the fetal palate can be
well appreciated in the rendered image, as shown
in Fig.6.8e [8].
Examination of the palate can be done very
quickly by using only the surface rendering mode