Cerebral calcifications are an unusual sonographic finding in the fetus. They are thought to occur late in gestation and result from localized neuronal-cell death. Intracranial calcifications are most commonly associated with the in utero infections due to the TORCH (toxoplasmosis, other agents, rubella, cytomegalovirus, herpes virus) agents (Ghidini et al., 1989). This chapter covers three types of fetal cerebral calcifications: (1) focal, punctate parenchymal calcifications, (2) periventricular echogenicity, and (3) echogenic blood vessels demonstrated in the thalami and basal ganglia (Estroff et al., 1992).

Fetal intracranial calcifications are rare. Although congenital cytomegalovirus is common [affecting 30,000 to 40,000 infants each year in United States (Ross and Boppana, 2004)], most cases of congenital cytomegalovirus are not associated with cerebral calcifications. One study found fetal brain abnormalities, including intracranial calcifications, in 10 of 39 (20%) of fetuses who were infected congenitally and had prenatal sonographic studies (Enders et al., 2001).

Much of the information regarding the differential diagnosis and outcome for infants with intracranial calcifications derives from the postnatal pediatric radiographic literature. The use of postnatal cranial sonography as an effective means of visualizing intracranial calcifications in newborn infants with congenital infections was first described by Dykes et al. in 1982. She and her colleagues demonstrated the presence of multifocal, high-intensity echoes in infants with infection. What was unusual about this sonographic finding was that there was no acoustical shadowing from these echoes. Subsequently, Teele et al. (1988) noted the unique sonographic finding of bright, branching vessels in the thalami and basal ganglia of 12 newborn infants. This finding was strongly associated with the presence of congenital infection. In this group of 12 infants, 5 had congenital cytomegalovirus (CMV), 2 had congenital rubella, 1 had congenital syphilis, and 3 had trisomy 13 with no known evidence of infection. These findings later were extended by other investigators, including Ben-Ami et al. (1990), who studied 11 infants noted to have bright echogenic stripes in the thalami and basal ganglia. By using duplex sonography, these investigators demonstrated that the stripes derived from the lenticulostriate arteries in the basal ganglia (Figure 9-1). In their study group, 8 of 11 cases were infected in utero, and 1 additional patient had trisomy 13. In a retrospective review of 2320 neonatal cranial sonograms, 25 newborns were identified with these linear areas of echogenicity in the basal ganglia (Hughes et al., 1991). Three of the 25 newborns were shown to have abnormal chromosomes (2 had trisomy 21 and 1 had trisomy 13). An additional four patients had CMV, and eight had clinical evidence of either anoxia or other metabolic brain injury (Hughes et al., 1991).

Relatively few cases of fetal intracranial calcifications have been described in the literature on prenatal diagnosis (Ghidini et al., 1989). Fakhry and Khoury (1991) reported two cases of fetal intracranial calcifications associated with CMV. In one case, at 32 weeks of gestation, the fetus was also noted to have microcephaly (Figure 9-2). In the other case, the fetus had a completely normal sonographic examination at 17 weeks, but by 22 weeks was noted to have mild hydrocephalus and hyperechoic foci in the periventricular areas. The pattern of bilateral periventricular calcifications may be a specific finding for intrauterine CMV infection (Figure 9-3) (Tassin et al., 1991). A different fetal manifestation of congenital CMV infection has also been reported by Estroff et al. (1992). This included a hyperechoic rim in the periphery of the fetal cerebral cortex, with branching linear areas of echogenicity seen in the fetal thalami, which is likely to be the fetal equivalent of the lenticulostriate artery echogenicity demonstrated postnatally in several studies (Teele et al., 1988; Ben-Ami et al., 1990; Hughes et al., 1991).