ABSTRACT
Objective The medical and emotional impact of three-dimensional imaging will be reviewed in the context of perinatal consultation.
Methods A literature review on three-dimensional (3D) imaging is compared to our experience with consecutive patients referred for perinatal consultation. High-resolution two-dimensional (2D) scanning and concurrent volume-mode imaging (Aloka 1700) were available for all patients. Informed consent for three-dimensional use was obtained to document patient acceptance. Patients with superficial defects underwent typical surface rendering, with images obtained by mechanical sweep in less than 4 s. Patients with defects requiring internal rendering underwent imaging with a new sectional technique similar to ‘tomogram’ slices. This rapidly produces volume-rendered images in a single plane with unique three-dimensional characteristics. No post-image processing was required, allowing immediate patient feedback. All patients were followed to delivery. Post-delivery neonatal images were obtained when possible. A follow-up patient survey is reported.
Results Of 1639 consecutive patients, 2.9% were preconceptual, leaving 1591 available for high-resolution 2D scanning and concurrent volume-mode imaging (Aloka 1700). Abnormal ultrasound findings (positive examinations) were found in 537 of the 1591 ultrasound patients (33.7%). The percentage of positive scans ranged from 2% (1/50) for patients referred only for ‘3D’ to 67.2% for patients referred for a previous suspected abnormality on screening ultrasound (236/351). There were 386 patients with structural fetal abnormalities potentially amenable to volume rendering (24.2%). Consistently improved counselling occurred for major abnormalities such as chromosomal defects (14/14), abdominal wall defect (11/11), neural tube defect (11/11), cystic hygroma/lymphangioma (9/9), skeletal dysplasia (5/5), hydrops (7/7), ovarian mass (6/6), myoma (11/14) and fetal chest mass (5/5). Moderate image concordance was seen for nuchal thickness (4/8), renal dysgenesis and dilatation (37/76), and placental mass or separation (28/49). Lowest concordance was seen for ‘soft’ findings such as echogenic bowel (0/15), isolated single umbilical artery (0/9) and isolated choroid plexus cysts (4/34). If we include all ultrasound patients, 3D imaging had added counselling value in 10.5% of consultative visits. In a post-delivery follow-up interview, patient acceptance was high (no refusals) and up to 87% of patients felt the 3D imaging was ‘successful’. Despite this high acceptance, only 61 % thought 3D imaging should be used in routine obstetric ultrasound. The highest stated concern for routine use would be the potential added charges of the examination.
Conclusion Volume-mode imaging of fetal abnormalities can provide powerful visual concordance for discussing normal and abnormal fetal development. Complex syndromes with superficial and deep architecture are accessible with a simple volume-mode planar scanning technique. Care must be taken to consider this tool as advanced practice sonography as the potential emotional and financial impact of routinely adding three-dimensional imaging is not yet understood.