Summary

Background:

Sonographic evaluation of congenital skeletal dysplasias is often challenging. Ultrasound may be limited in demonstrating the skeleton and may overlook specific signs of skeletal abnormality. Computed tomography (CT) with 3D reconstruction was proposed as an aid in the diagnosis of skeletal dysplasias.

Objectives:

To describe our experience with 3D-CT imaging for the evaluation of suspected skeletal dysplasias.

Methods:

The study group comprised 20 pregnant women carrying 22 fetuses, referred for further evaluation by CT following sonographic suspicion of fetal skeletal dysplasia at 17–39 weeks of gestation. Examinations were performed using various CT protocols. Radiation exposure was decreased during the study period, with eventual lowering of the dose to 1–3 mSv. Meticulous review of the skeleton and long bone measurements were performed on 3D reconstructions. For cases of pregnancy termination, the postmortem diagnosis was compared retrospectively with the CT findings.

Results:

Very low dose CT protocols provided excellent diagnostic images. Of 22 fetuses suspected of having skeletal dysplasia on ultrasound, 8 were found by CT to be dysplastic and in 7 the pregnancy was terminated. Postmortem findings, when available, concurred with the CT diagnosis. The remaining 14 fetuses within this cohort were found to be normal according to CT and were carried to term.

Conclusions:

3D-CT may be a valuable complimentary imaging tool to ultrasound for the diagnosis of skeletal dysplasias. Using low dose protocols makes this examination relatively safe, and in the appropriate clinical context may assist in making difficult decisions prenatally.