1Nicolaides DH, Gabba SG, Campbell S, et al. Ultrasound screening for spina bifida cranial and cerebellar signs [J]. Lancet,1986,1:72-74.
2Goldstein RB, Podrasky AE, Filly RA, et al. Effacement of the fetal cisterna magna in association with myelomeningocele [J]. Radiology, 1989,172:409-413.
3Platt LD, Carlson DE, Medearis AL, et al. Fatal choroid plexus cysts in the second trimester of pregnancy:a cause for concern [J]. Am J Obstet Gynecol, 1991,164:1652-1656.
5Roy AF, Jimmy DC, Ruth B, et al. Detection of fetal central nervous system anomalies:a practical level of effort for a routine sonogram [J]. Genitourin Radiol, 1989,172:403-408.