Virtual Bronchoscopy for Evaluating Cervical Tumors of the Fetus
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Transcript of Virtual Bronchoscopy for Evaluating Cervical Tumors of the Fetus
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Copyright 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Virtual Bronchoscopy for Evaluating Cervical Tumors of the Fetus
Heron Werner 1,3, Jorge R. Lopes dos Santos 2,5, Ricardo Fontes 2,5, Simone
Belmonte 2, Pedro Daltro 1,3,4, Emerson Gasparetto 1,3, Edson Marchiori 3,
Stuart Campbell
6
1. Clnica de Diagnstico por Imagem (CDPI), Rio de Janeiro, Brazil.2. Instituto Nacional de Tecnologia (INT), Rio de Janeiro, Brazil.3. Department of Radiology, Universidade Federal do Rio de Janeiro (UFRJ),Rio de Janeiro, Brazil.4. Instituto Fernandes Figueira (IFF), Rio de Janeiro, Brazil.5. Pontificia Universidade Catlica do Rio de Janeiro, Brazil.
6. Create Health Clinic, London, UK.*Correspondence.(e-mail: [email protected])Abstract
We report four cases of cervical tumors (three lymphangiomas and oneteratoma) evaluated by ultrasound and magnetic resonance imaging (MRI)
between 26 and 37 weeks gestation. The aim was to investigate the use of
Virtual Bronchoscopy (VB) to evaluate fetal airway patency on each case. A 3D
file of the airway was created by overlapping layers generated by MRI. The 3D
files were converted into an OBJ extension using the 3D modeling software
MAYA (Autodesk, USA). This allowed the virtual positioning of observation
cameras while working with multiple windows. Using the indoor and outdoor
lighting features, 3D simulation movies were generated for analysis of a virtual
path. In all fetuses, fetal airway patency was clearly demonstrated by VB. MRI
This article has been accepted for publication and undergone full scientific peer review but has not
been through the copyediting, typesetting, pagination and proofreading process which may lead to
differences between this version and the Version of Record. Please cite this article as an Accepted
Article, doi: 10.1002/uog.11162.
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with VB could become a useful tool for studying fetal airway patency in cases of
cervical tumor.
Keywords: fetus, cervical tumors, ultrasound, magnetic resonance imaging,
virtual bronchoscopy
Case Reports
Four fetuses with a cervical tumor (three lymphangiomas and one
teratoma) were evaluated in our Tertiary Imaging Center (Clnica de
Diagnstico por Imagem) in Rio de Janeiro between September 2010 and
March 2011 by ultrasound (US) and magnetic resonance imaging (MRI) (Table
1). All cases were examined first by US on the same day of MRI. The ethical
issues associated with this work were considered and approved by our research
ethics committee (CEPIFF: 0012/10).
The main outcome of this study was the creation of 3D virtual airway
paths from fetuses with cervical tumors, and performing Virtual Bronchoscopy
(VB) based on those images. The median gestational age of the fetuses with
cervical tumors diagnosed by US in this study was 24.7 weeks (range 22-27
weeks). MRI was performed between 26 and 37 weeks. In case 2, MRI was
performed twice, at 26 and 37 weeks. The mean tumor diameters observed by
US and MRI are recorded in Table 2. Polyhydramnios was detected only in
case 2. In all cases, VB was successful, showing the absence of tumor invasion
or tracheal distortion or compression (Figures 1-4;videos1-4)). The mean time
to perform a VB after MRI was 2 hours. In two cases (2 and 3), postnatal
surgery to remove the tumor was performed. In cases 1 and 4, treatment with
OK 432 was performed, with successful results to date. All fetuses had normal
karyotypes. Babies were delivered by cesarean section after 36 weeks
gestation. EXIT and tracheostomy were not necessary. All neonates had good
outcomes (Table 3).
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US scans included 3D imaging and were performed transabdominally
using a high-resolution US probe with harmonic imaging for all examinations (4-
8 MHz transducer, Voluson 730 Pro/Expert system, General Electric,
Kretztechnik, Zipf, Austria).
MRI examination was performed using a 1.5-T scanner (Siemens,
Erlangen, Germany). The protocol used was a T2-weighted sequence in the
three planes of the fetal body (HASTE; repetition time, shortest; echo time, 140
ms; field of view, 300200 mm; 256 256 matrix; slice thickness, 4 mm;
acquisition time, 17 s; 40 slices) 1. A T1-weighted sequence was taken for three
planes of the fetal body (repetition time, shortest; echo time, 140 ms; field of
view, 300200 mm; 256 256 matrix; slice thickness, 4 mm; acquisition time,
17 s; 40 slices). Additionally, a three-dimensional (3D) T2-weighted truefispsequence in the sagittal plane (trufi, TR/TE = 3.02/1.34, voxel size 1.6 x 1.6 x
1.6 mm3, FA = 70, PAT 2, acquisition time = 0.26 s) was applied. The entire
examination time did not exceed 40 min 1,2.
A 3D file of the airway, using overlapping image layers from the MRI, was
created by using the software Mimics (Materialize, Leuven, Belgium). To
separate by contrast differences, output 3D files were generated of areas of
interest, exported as standard triangular language (STL) files, and convertedinto OBJ extensions using the 3D modeling software MAYA (Autodesk, USA) 2.
Discussion
Although the incidence of fetal congenital cervical tumors is low, US is
effective for identifying such tumors3. They tend to be large and can encircle
essential structures such as the esophagus, thyroid, and trachea, making it
impossible for a newborn to breath after birth. Estimation of the degree of
tracheal compression or distortion allows multidisciplinary planning for delivery
and neonatal resuscitation4,5.
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Lymphangioma is a benign congenital malformation of the lymphatic
system that has the potential to infiltrate surrounding structures. It constitutes
approximately 5% to 6% of all benign lesions in childhood and adolescence 5. It
occurs most frequently in the head, neck or axilla 6. The prognosis depends on
the presence of other associated features such as skin edema, hydrops and
polyhydramnios, abnormal karyotype, location and extent of the lesion 5.
Cervical teratoma is a rare congenital tumor that tends to be large, and is
usually solid/cystic. It has an incidence of 1 in 20,00040,000 live births,
accounting for about 6% of all fetal teratomas. Airway obstruction in the
newborn as determined by tracheal compression or occlusion is reported to be
the reason for an 80100% mortality rate in the neonatal period4,5.
Recently, the ability to diagnose fetal tumors in the prenatal period has
improved greatly because of technical advances in imaging7. Early diagnosis
and determination of tumors may affect prognosis, making it possible for babies
with fetal tumors to be saved. US is the method of choice for fetal evaluation
because of its low cost, real-time capability, and non-invasiveness. Cervical
tumors are usually diagnosed in the second and third trimesters of gestation,
and identified as multiseptated, thin-walled cystic masses in the fetal neck. MRI
is a valuable complementary method to US for diagnosing fetal malformations
8
.Technical developments in this imaging modality have greatly improved fetal
imaging, with increasingly rapid sequencing and reduction of fetal motion
artifacts1,7.
The initial stage of cervical tumor treatment involves careful monitoring of
the mother and fetus, with the development of a surgical plan4,5. Ideally the
treatment will be by a multidisciplinary team of medical professionals including a
radiologist, a perinatologist, and a pediatric surgeon. In some cases, surgery isperformed immediately after the baby is delivered by Cesarean section followed
by an EXIT procedure. This gives the surgeon time to perform multiple
procedures to secure the babys airway while preserving the blood flow and gas
exchange that normally occurs between the fetus and the placenta5,9.
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VB is based on MRI archives providing net images of the fetal airway2. It
generates representations of the bronchial tree and surrounding structures from
spatial information derived from imaging sources rather than the bronchoscope
itself10,11. Several software options generate accurate and realistic renderings of
the bronchial tree that can confirm previous MRI findings12
.To perform a VB, a 3D file of the airway is created from overlapping MRI
image layers, which allows separation by contrast difference and by area of
interest. This generates 3D files that are exported as STL files and converted
into OBJ extensions using the 3D modeling software MAYA (Autodesk, USA).
This program allows the virtual positioning of observation cameras while
working with multiple windows. Controlling the indoor and outdoor lighting
features allows the production of 3D simulation movies for analysis of a virtualpath 2.
In the cases in this study, US was used to monitor amniotic fluid volume,
tumor size, and overall fetal well being. MRI provided good information about
both the anatomy and extension of the tumors and helped in the evaluation of
encircled structures and in the study of fetal airway patency by means ofVB.
These examples show that MRI with VB in the third trimester of pregnancy can
be an important tool for planning the mode of delivery and for studying fetalairway patency for fetuses with a cervical mass. In the four cases described
here the outcome was anticipated to be favorable because VB demonstrated an
unobstructed airway. Further studies will demonstrate whether VB is useful in
optimizing outcome when the fetal airway is compromised.
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References
1. Werner H, Dos Santos JRL; Fontes R, Daltro P, Gasparetto E, MarchioriE, Campbell S. Additive manufacturing models of fetuses built fromthree-dimensional ultrasound, magnetic resonance imaging andcomputed tomography scan data. Ultrasound Obstet Gynecol 2010; 36:
355361.2. Werner H, Dos Santos JRL; Fontes R, Daltro P, Gasparetto E, Marchiori
E, Campbell S. Virtual bronchoscopy in the fetus. Ultrasound ObstetGynecol 2011; 37: 113-115.
3. Frates M, Kumar AJ, Benson CB, Ward VL, Tempany CM. Fetalanomalies: comparison of MR imaging and US for diagnosis. Radiology2004; 232: 398-404.
4. Azizkhan RG, Haase GM, Applebaum H, Dillon PW, Coran AG, King PA,King DR, Hodge DS. Diagnosis, management, and outcome ofcervicofacial teratomas in neonates: a childrens cancer group study. JPediatr Surg 1995; 30: 312316.
5. Woodward PJ, Sohaey R, Kennedy A, Koeller K. A comprehensivereview of fetal tumors with pathologic correlation. Radiographics. 2005;25: 215242.
6. Sanlialp I, Karnak I, Tanyel FC, Senocak ME, Buyukpamukcu N.Sclerotherapy for lymphangioma in children. Int J PediatrOtorhinolaryngol. 2003; 67(7): 795-800.
7. Prayer D, Brugger PC, Prayer L. Fetal MRI: techniques and protocols.Pediatr Radiol 2004; 34: 685693.
8. Kathary N, Bulas DI, Newman KD, Schonberg RL. MR imaging of fetalneck masses with airway compromise: utility in delivery planning. PediatrRadiol 2001; 31: 727-731.
9. Luzzatto C, Lo Piccolo R, Leon FF, Zanon GF, Toffolutti T, Tregnaghi A.
Further experience with OK-432 for limphangiomas. Pediatr Surg Int.2005; 21: 969-972.10. Ferguson JS, McLennan G. Virtual bronchoscopy. Proc Am Thorac Soc.
2005; 2: 488491.11. Lam WW, Tam PKH, Chan FL, Chan K, Cheng W. Esophageal atresia
and tracheal stenosis: Use of three-dimensional CT and virtualbronchoscopy in neonates, infants, and children. AJR 2000; 174: 10091012.
12. Merritt SA, Gibbs JD, Yu KC, Patel V, Rai L, Cornish DC, Bascom R,Higgin WE. Image-guided bronchoscopy for peripheral lung lesions.Chest 2008; 134: 10171026.
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Table 1.
Cases Maternal age
(years)
Gestational age
(weeks) US
diagnosis
Gestational age
(weeks) MRI +
VB
Gestational age
at delivery
(weeks)
1 27 27 27 36
2 31 24 26/37 38
3 35 22 36 38
4 27 26 31 39
Case 2: 2 MRI (26 and 37 weeks).
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Table 2.
Cases Tumor US: Mean
tumor
diameter
(mm)
MRI: Mean
tumor
diameter
(mm)
Invasion Development of
polyhydramnios
1 Lymphangioma 63 70 No No
2 Teratoma 60/94 62/91 No/No Yes/Yes
3 Lymphangioma 64 58 No No
4 Lymphangioma 35 50 No No
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Table 3.
Cases Weight
(g)
Apgar Sex Tracheostomy EXIT Pregnancy
outcome
Post
natal
surgery
1 2850 7 / 9 Female No No Live birth No
2 3210 6 / 8 Male No No Live birth Yes
3 2910 7 / 9 Female No No Live birth Yes
4 3150 9 / 9 Female No No Live birth No
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Figures
Figure 1: Lymphangioma (case 1). Facial profile illustrated by ultrasound and
MRI (a). Three dimensional (3D) view of the fetal airway and lungs obtained by
MRI (b). Neonate (c).
Figure 2: Cervical teratoma (case 2). Sagittal view of the fetus by MRI and 3D
MRI (a). 3D view of the airway path and a still image from virtual bronchoscopy
showing the airway patency (b). 3D model of the fetus obtained by MRI and the
neonate (c).
Figure 3: 3D view of the lymphangioma (case 3) obtained by ultrasound and
coronal MRI T2 view of the fetus (a). 3D view obtained by MRI showing the
tumor close to the unobstructed airway path and the neonate.
Figure 4: Coronal T2 view (case 4), 3D airway path reconstruction and neonate.
Video 1: Virtual bronchoscopy (VB) (case 1).
Video 2: Virtual bronchoscopy (VB) (case 2).
Video 3: Virtual bronchoscopy (VB) (case 3).
Video 4a,b: Virtual bronchoscopy (VB) (case 4). In video 4a, look at the camera
going into the airways of the fetus.
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Acknowledgments
We would like to thank Drs. Romeu Domingues, Maene Marcondes, Mrcio
Bernardes da Silva and Fernando Maia Peixoto for their assistance.
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Figure 1a
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Figure 1b
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Figure 1c
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Figure 2a
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Figure 2b
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Figure 2c
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Figure 3a
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Figure 3b
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Figure 4