Prenatal diagnosis of osteogenesis imperfecta type II by three-dimensional computed tomography: the current state of fetal computed tomography

Osteogenesis Imperfecta type II with the variant c.4237G>A (p.Asp1413Asn) in COL1A1 in a dichorionic, diamniotic twin pregnancy

We present the case of a 34-year-old woman with a prenatally diagnosed osteogenesis imperfecta type II of one fetus of a diamniotic-dichorionic twin pregnancy at 28 weeks and 2 days of gestation. The diagnosis was suspected after a routine ultrasound examination, specified by 3D-ultrasound and confirmed with moleculargenetic analyses of COL1A1 with DNA of fetal cells obtained after amniotic drainage. Since a premature rupture of membranes occurred a cesarean section was performed at 36 weeks of gestation. Both newborns received primary medical care by neonatologists. The affected child received further treatment initially stationary, later as an ambulant patient. Even though ultrasound is a powerful tool to identify clinical features of osteogenesis imperfecta, the condition can finally only be confirmed by collagen or DNA analyses. We discuss the possibilities and limits of prenatal diagnosis, treatment options as well as issues that are relevant for genetic counseling.

Stem cell transplantation before birth - a realistic option for treatment of osteogenesis imperfecta?

Osteogenesis imperfecta (OI) is characterized by severe bone deformities, growth retardation and bones that break easily, often from little or no apparent cause. OI is a genetic disorder primarily with defective type I collagen with a wide spectrum of clinical expression. In the more severe cases, it can be diagnosed before birth. Transplantation of mesenchymal stem cells (MSC) has the potential to improve the bone structure and stability, growth and fracture healing. Prenatal and postnatal cell transplantation has been investigated in preclinical and clinical studies of OI and suggests that this procedure is safe and has positive effects. Cell transplantation resulted in improved linear growth, mobility and reduced fracture incidence. However, the effect is transient and for this reason re-transplantation may be needed. So far there is limited experience in this area, and proper studies are required to accurately determine if MSC transplantation is of clinical benefit in the treatment of OI. In this review, we summarize what is currently known in this field.

Radiation dose reduction at MDCT with iterative reconstruction for prenatal diagnosis of skeletal dysplasia: preliminary study using normal fetal specimens

OBJECTIVE

The purpose of this study was to investigate to what degree the radiation dose can be reduced without affecting the ability to evaluate normal fetal bones at MDCT with iterative reconstruction.

MATERIALS AND METHODS

Fifteen normal fetal specimens immersed in containers (30- and 35-cm diameter) were scanned with a 64-MDCT scanner, with tube voltage of 100 kVp and tube current of 600, 300, 150, 100, and 50 mA. Images were subjected to adaptive statistical iterative reconstruction (ASIR). The fetal dose was measured using glass dosimeters. We calculated the relative ratio of the dose at 600 mA. Image quality was evaluated on maximum-intensity-projection and volume-rendering images. Two radiologists recorded the visualization scores of five regions. Images at 600 mA were considered to be standard.

RESULTS

With the 30-cm-diameter container, the fetal dose was 10.15 mGy (relative ratio, 100%) at a tube current of 600, 51% at 300, 25% at 150, 17% at 100, and 9% at 50 mA. With the 35-cm-diameter container the fetal dose was 10.01 mGy (relative ratio, 100%) at 600, 47% at 300, 24% at 150, 17% at 100, and 8% at 50 mA. Visual evaluation showed that in both containers, with ASIR 90%, there was a statistically significant difference between 50-and 600-mA images (p<0.01) but not between 600-mA images and those acquired at 100, 150, and 300 mA (p=0.08-1.00).

CONCLUSION

The fetal radiation dose for the evaluation of normal fetal bones can be reduced by 83% with ASIR 90%.