Dose and image quality optimization in neonatal radiography.

In a special care baby unit, neonates, mainly premature, encounter serious to life-threatening diseases, the timely diagnosis and treatment of which may require a large number of radiographs. Increased neonatal radiosensitivity and longer life expectancy increase the risk of radiation-induced cancer, which emphasizes the importance of minimizing dose while maintaining clinically satisfactory image quality. An optimization study on radiation dose and image quality in neonatal radiography is presented. Neonates were categorized into four groups depending on birthweight. For a total of 378 chest and chest-abdomen radiographs, exposure parameters were recorded. Entrance surface dose (ESD) was estimated and dose-area product (DAP) was measured. Image quality evaluation was performed by two observers and was based on the visibility of certain anatomical features and catheters placed during treatment using a five-grade scale. ESD values increased with neonatal weight and demonstrated wide variation (16.4-76.9 microGy, mean 38.2 microGy). A wide variation was also observed in DAP values (1.2-15.0 mGycm2, mean 7.2 mGycm2). Image quality evaluation revealed the feasibility of achieving a diagnostically satisfactory image (score >70%) using both low and high tube voltage techniques, with the latter resulting in reduced ESDs. The majority of estimated ESDs are in accordance with the reference level of 50 microGy recommended by the National Radiological Protection Board for neonatal radiography. The results suggest that the use of high tube voltage techniques could result in further reductions in neonatal dose, without image quality degradation, underlying the requirement for establishing standard examination protocols for neonatal radiography with respect to neonatal weight.

Isolated non-compaction of the ventricular myocardium: prenatal diagnosis and natural history.

Isolated non-compaction of the ventricular myocardium (NCVM) is a rare cardiomyopathy characterized by the persistence of numerous marked ventricular trabeculations and deep intertrabecular recesses with direct vascular supply by the ventricular cavities. We report two cases diagnosed by fetal echocardiography at 27 and 30 weeks' gestation, respectively. Postnatal echocardiography verified the presence of the NCVM seen prenatally. Diagnosis was confirmed at postmortem following neonatal demise in the first case. Surgical intervention for exomphalos and extrahepatic biliary atresia was required in the second case, but there is no clinical abnormality of the cardiovascular system a year after delivery. The uncertainty of prognosis and the familial recurrence described elsewhere indicate the difficulty of counseling and the value of prenatal diagnosis, which is feasible using currently available ultrasonographic equipment.

Influence of twin-twin transfusion syndrome on fetal cardiovascular structure and function: prospective case-control study of 136 monochorionic twin pregnancies.

OBJECTIVE: To test the hypothesis that identical twins show no inter-twin differences in cardiovascular structure or physiology in fetal life unless there has been twin-twin transfusion syndrome. DESIGN: Unselected prospective case-control observational study of fetoplacental haemodynamics including echocardiography at a median of 24 (16.7 to 32.3) weeks, with postnatal confirmation of congenital heart disease or normality. SETTING: Fetal medicine unit. PATIENTS: 136 women with monochorionic diamniotic twin pregnancies, of which 47 fetal twin pairs (35%) had twin-twin transfusion syndrome. RESULTS: There were no haemodynamic differences between the bigger fetus (twin 1) and the smaller co-twin (twin 2) in uncomplicated monochorionic diamniotic pairs. In twin-twin transfusion syndrome, recipient fetuses had increased aortic and pulmonary velocities compared with their donor co-twins (mean (SD): 0.73 (0.23) m/s and 0.63 (0.14) m/s), respectively, v 0.53 (0.16) m/s and 0.48 (0.10) m/s in donor twins; p = 0.003 (aortic) and < 0.0001 (pulmonary)), and also in comparison with twin 1 and twin 2. The overall prevalence of congenital heart disease was increased above that in singletons (3.8% v 0.56%; 6.9% in twin-twin transfusion v 2.3% in uncomplicated monochorionic diamniotic twins), with inter-twin discordance for defects. The prevalence in recipient twins was 11.9% (p = 0.014 v uncomplicated control twins). CONCLUSIONS: Fetuses with an identical genome but no circulatory imbalance have similar cardiovascular physiology but discordant phenotypic expression of congenital heart disease. The high prevalence of congenital heart disease in monochorionic diamniotic twins merits detailed fetal echocardiography.