Virtual bronchoscopy through the fetal airways in a case of cervical teratoma using magnetic resonance imaging data

摘要

Cervical teratomas are rare congenital tumors, usually solid or cystic (3-5% of all teratomas), with an incidence of 1:20 000 to 1:40 000 among live births (Nascimento et al. 2007). This malformation is usually diagnosed during the prenatal period by ultrasound exam in the second and third trimesters. Knowledge about the degree of compression of the fetal airways during the prenatal period is important for the obstetrician/neonatology team to plan the correct management strategy during delivery (Azizkhan et al. 1995). A 28-year-old primiparous pregnant woman was referred to our service with a diagnosis of fetal neck mass at 21 weeks during the second trimester ultrasound exam. Another ultrasound exam showed a large solid/cystic mass measuring 41 × 24 mm in the fetal cervical region, and no other fetal abnormalities were observed. Subsequent follow-up ultrasound exams showed a normal amniotic fluid index. We decided to perform a three-dimensional ultrasound (3DUS) and magnetic resonance imaging (MRI) at 36 weeks for a better assessment of the fetal airways to plan the delivery (Fig. S1). The ultrasound exam was performed using a Voluson E8 apparatus (General Electric Medical System, Zipf, Austria) equipped with a convex probe (RAB 4-8L). The 3D images were shown on the screen in multiplanar (three orthogonal planes-axial, sagittal, and coronal) and rendering modes. The MRI exam was performed using a 1.5-T scanner (Siemens, Erlangen, Germany). The protocol involved a T2-weighted sequence in the three planes of the fetal body (HASTE; repetition time (TR), shortest; echo time (TE), 140 ms; field of view, 300-200 mm; matrix, 256 × 256; slice thickness, 4 mm; acquisition time, 17 s; 40 slices). In addition, we applied 3D T2-weighted true fast imaging with a steady-state precession (true fisp) sequence in the sagittal plane (TR, 3.02 ms; TE, 1.34 ms; voxel size, 1.6 × 1.6 × 1.6 mm~3; FA, 70; PAT, 2; acquisition time, 0.26 s). The entire examination time did not exceed 30 min (Fig. S2).