Published onIn Utero Insights
At the Center for Fetal Diagnosis and Treatment, we believe one of the most important elements of care is careful diagnostic testing and interpretation of results, both prenatally and postnatally. At their first visit with us, women with a suspected lung lesion undergo a day of testing using the most advanced diagnostic equipment to evaluate the fetal chest. The expertise of our imaging team frequently leads to additional findings and may significantly alter the initial diagnosis.
A sonographer and a radiologist, both highly specialized in diagnosing fetal anomalies, use state-of-the-art ultrasound machines and high-frequency probes, as well as 3-D and 4-D techniques if needed, to visualize a baby’s condition. The examination is held in a private room with a TV screen overhead so the family can watch the ultrasound in real time. Our team thoroughly examines the fetus from head to toe, including fine details such as the ears, corpus callosum and the conus medullaris. We have developed specific ultrasound protocols for each suspected anomaly and typically devote up to 1½ hours or more for each initial scan.
Fetal ultrasound imaging protocol
- The highest frequency transducer possible (9-12 MHz) to show the most detailed resolution
- Identification of the size and type of lesion with volumetric measurements
- Localization and assessment of lobar involvement based on the lesion location
- Color and spectral Doppler views of the blood vessels supplying and draining the lesion
- Measurement of the largest macrocysts, if applicable
- Calculation of the CVR (CCAM volume ratio), if applicable
- Evaluation for evidence of a dilated bronchus or fluid-filled trachea, if applicable
- Identification of ipsilateral and contralateral uninvolved normal lung parenchyma
- Subjective determination of the degree of mediastinal shift as mild, moderate or severe, with mild representing cardiac displacement just past the midline and severe representing cardiac displacement to the contralateral chest wall
- Evaluation of the fetus for signs of hydrops, including scalp/skin edema, polyhydramnios, ascites, pleural effusions, pericardial effusions, placental thickening or Doppler changes
Fetal magnetic resonance imaging (MRI) provides excellent soft tissue resolution and proportionate anatomic detail of the anomaly, and often provides important information about the patency, caliber and position of the fetal airway. This information is critical in counseling and management decisions.
Fetal MRI imaging protocol
- Performed on 1.5 or 3 Tesla magnet systems
- Patient positioned in supine or decubitus position with coil overlying the abdomen
- No sedation or contrast material used
- 30 to 40 minutes average imaging time
- Localization and characterization of the lung lesion and the central airway to complement ultrasound evaluation
- Volumetric assessment of normal lung and lesion
- Evaluation for additional fetal or maternal abnormalities
Postnatal computed tomography angiography (CTA) within the first two months of life provides information essential for diagnostic confirmation and surgical planning. This technique allows multiplanar reconstructions of the airway, lung parenchyma and vasculature. CT images are compared with prenatal studies. Studies performed at CHOP also allow for additional imaging post processing that provides important information in some cases.
The CHOP nursing and sedation staff is highly attuned to the unique imaging and sedation needs of pediatric patients. Our experienced pediatric radiologists perform CTA adhering to ALARA (As Low As Reasonably Achievable) principles for radiation exposure. CTA protocols have been designed with attention to radiosensitivity, low body weight index, faster heart rates, smaller cardiovascular structures and increased patient motion. The administration of intravenous iodinated contrast material helps to define vascular anatomy.
Types of anomalies in the fetal chest we evaluate
- CCAM (congenital cystic adenomatoid malformation)
- BPS (bronchopulmonary sequestration)
- Hybrid lung lesion
- Bronchial atresia
- Foregut duplication cyst
- Pulmonary agenesis
Complex referred cases made clear by our imaging team
- Hybrid lesion misconstrued as a simple CCAM
- CCAM misidentified as a CDH or CDH mistaken for CCAM because of a herniated gallbladder
- Extralobar BPS in the abdomen thought to represent an adrenal mass
- Bronchogenic cysts mistaken for bronchial atresia or CCAM
- Bronchial atresia misconstrued as a CCAM or BPS
- Pulmonary agenesis referred as a CCAM or CDH
- CHAOS referred as a bilateral CCAM
(A) Transverse view of the chest demonstrating a dilated fluid-filled bronchus in a case of bronchial atresia that was referred as a CCAM. (B) Sagittal view of a hybrid lesion, demonstrating a systemic feeding vessel from the celiac axis below the diaphragm. (C) Transverse view of the same hybrid lesion, demonstrating the pulmonary draining vein.