The contribution of colour Doppler flow imaging to the study of cerebral haemodynamics in the neonate

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

A Preliminary Study of Neonatal Cranial Venous System by Color Doppler

Aim

To present anatomic data in the ultrasound planes for the identification of the major veins and the venous sinuses in cerebrum and to establish the sonographic normal reference values for the visualization of vein vessels and vein sinuses and blood flow velocities.

Methods

This study involved 55 healthy full-term neonates for transfontanellar color Doppler sonography. The imaging included both sagittal and coronal planes with LA332E probe, supplemented with PA240 probe as necessary. As low as reasonably achievable (ALARA) principle was obeyed, limiting Doppler exposure time and maximizing signal intensity by increasing gain rather than outputting transducer power settings. The output power was kept at a minimum level consistent with recording an adequate signal. Keeping the newborns in calm state, the total examination time which every neonate required was less than 5 min. All images were stored also in a workstation for further analysis. The description statistics and t-test for statistical analysis were used.

Result

In all studied cases (100% cases), subependymal veins (SV), internal cerebral veins (ICV), Galen vein (GV), straight sinus (SS), superior sagittal sinus (SSS), and transverse sinuses (TS) were visualized. The visualization percentages of inferior sagittal sinus (ISS) or basal veins/Rosenthal veins (BV/RV) were lower than 100%. Based on vessel visualization percentage from high to low, the vessels were ordered as follows: SV, ICV, BV, SS, TS, ISS, and SSS. In SSS and TS, the pulsation percentage was 100%. The descending percentages of vessel pulsation were noted in SS, BV, ICV, and SV. On the basis of the mean of maximum velocities of the vessels from low to high, the vessels were ordered as follows: ISS, BV-L, BV-R, ICV-R, ICV-L, SV-L, SV-R, SSS, TS-L, TS-R, and SS.

Conclusion

The measurements percent of visualization of cerebral deep veins was higher than the percent of cerebral venous sinuses. The pulsation percent of measurement and the velocities of cerebral venous sinuses were absolutely higher than the cerebral deep venous system. The pairs of vascular blood flow velocities were nonsignificantly different from one another.

Doppler-assessed cerebral blood flow velocity in the neonate as estimator of global cerebral blood volume flow measured using phase-contrast magnetic resonance angiography

BACKGROUND

We hypothesized that color Doppler-measured cerebral blood flow velocity (CD-CBFV) as measured in the three feeding arteries of the brain can be used as an estimator of global cerebral blood flow.

PATIENTS AND METHODS

CD-CBFV was determined as soon as possible after determination of phase-contrast magnetic resonance angiography-measured blood volume flow (PC-MRA BVF) by adding up angle-corrected time-averaged mean flow velocities of both internal carotid arteries and basilar artery. 30 newborns (gestational age ranging from 25 to 42 weeks; actual weight ranging from 1,050 to 5,858 g; postconceptional age ranging from 225 to 369 days) were investigated.

RESULTS

Doppler-determined CBFV ranged from 37 to 131 cm/s with a median of 69 cm/s. CD-CBFV showed a positive correlation with actual weight (r = 0.56, p < 0.01) and postconceptional age (r = 0.53, p < 0.01). CD-CBFV correlated positively with PC-MRA-measured BVF (r = 0.51, p < 0.01). Gestational age at birth, mechanical ventilation or gender did not influence this relationship. The limits of agreement, however, are wide, especially at higher CD-CBFV- and PC-MRA-measured BVF.

CONCLUSION

CD-CBFV may be used as a non-invasive trend-monitoring tool to detect gross changes in global cerebral blood flow in the unstable and sick neonate.

Assessment of fetal cerebral arterial and venous blood flow before and after vaginal delivery or Cesarean section

OBJECTIVES

To compare perinatal intracranial arterial and venous blood velocity changes between healthy term neonates delivered vaginally or by Cesarean section and to correlate these changes with cord blood gases and pH values at birth.

METHODS

The study involved 43 healthy term neonates who were delivered vaginally (n = 20) or by Cesarean section (n = 23). All fetuses/neonates were examined by Doppler ultrasound to obtain middle cerebral artery (MCA) and cerebral transverse sinus (Tsin) Doppler waveforms on three occasions (before delivery, and 1 h and 24 h after birth). Pulsatility index (PI) and peak systolic velocity (PSV) for MCA and Tsin were measured and compared between neonates who were delivered vaginally or by Cesarean section. Umbilical cord blood samples were analyzed for umbilical artery and vein pH, pO(2) and pCO(2) and values were correlated with MCA and Tsin Doppler indices.

RESULTS

MCA-PI increased and MCA-PSV decreased at 1 h after birth, and Doppler measurements returned to predelivery values at 24 h after birth. Tsin Doppler measurements remained unchanged at 1 h and 24 h when compared to predelivery values in both the Cesarean and vaginal delivery groups. There was a negative correlation between Tsin-PI before birth and umbilical venous pH. There was a positive correlation between Tsin-PSV at 1 h after birth and umbilical vein pCO(2).

CONCLUSIONS

Cerebral arterial blood velocity decreases immediately after birth and increases within 24 h, probably as part of neonatal adaptation. Cerebral venous blood velocity remains constant during the perinatal period and is likely to be regulated in a different and more complex manner than that of arterial blood velocity. Mode of delivery does not affect cerebral blood velocity.

Selection of babies for intervention after birth asphyxia

Based on animal experiments, the therapeutic window for neonates with signs of perinatal hypoxia-ischaemia is probably less than 6 h, and early selection of patients is of utmost importance. In term neonates, fetal heart rate and blood flow patterns, the Apgar score, and other clinical scoring systems are insufficient to select patients for intervention, whereas umbilical artery pH<7.0 combined with umbilical arteriovenous differences in PCO(2), lactate/pyruvate ratios in cord blood, and CSF interleukin-1beta have a better predictive value. At present, neurophysiological methods such as (amplitude-integrated) EEG and evoked potentials have the best predictive value. In preterm neonates, lactate/pyruvate and uric acid measurements in cord blood, as well as neurophysiology appear to be helpful to predict brain injury, and might be used to select patients for intervention.

Doppler sonographic study of the effect of indomethacin on cardiac and pulmonary hemodynamics of the preterm infant

OBJECTIVE

Indomethacin (INDO) causes an increase in systemic vascular resistance and decrease in perfusion of important organ systems in preterm infants treated for patent ductus arteriosus (PDA). Information on the effect of INDO on cardiac and pulmonary hemodynamics of these babies is scarce.

METHODS

The left ventricular output (LVO), resistance in the ascending aorta (R(Ao)), determined mean cerebral blood velocity (cerebral-mv), ductal-peak and mean blood velocity (ductal-pv and -mv) and pulmonary artery peak and mean blood velocity (pulmonary pv and -mv) were measured, before, and up to 12 h after 0.1 mg/kg of INDO in 20 preterm infants with PDA using Doppler echocardiography.

RESULTS

LVO was abnormally high (mean+/-S.E.M.: 354+/-50 ml/min/kg) before INDO treatment, and an important left-to-right shunt through the ductus was detectable in all infants. At 1 h after INDO treatment, R(Ao) had significantly increased with a significant decrease in LVO and cerebral-mv. Ductal patency and pulmonary vascular resistance seemed not to be affected at this early stage, as indicated by unchanged ductal and pulmonary arterial blood velocities. At 4 h post-INDO, ductal-pv and -mv, and to a lesser extent pulmonary-pv and -mv, were transiently lower as compared to pre-INDO, 1 and 12 h post-INDO values. This coincided with a transient absence of clinical signs of PDA at 4 h post-INDO in a substantial number of infants. R(Ao) steadily decreased and LVO steadily increased, whereas cerebral-mv normalized from 4 h post-INDO onward.

CONCLUSIONS

no important action of INDO was detected on pulmonary arterial blood velocity or pulmonary function.

[Superior sagittal sinus thrombosis in children during the first year of life: clinical aspects, imaging and development]

BACKGROUND

Thrombosis of the intracranial sinuses and veins may be septic or aseptic, and in the latter case are often due to alteration in hemodynamics. It may also be seen in young babies without known predisposing factors.

PATIENTS

From 1988 to 1994, 11 children had cerebral venous thrombosis (longitudinal sinus) in the first year of their life. Their ages ranged from two days to 11 months. Transient seizures, lethargy, pseudo tumor cerebri were the first clinical symptoms. The presence of longitudinal sinus thrombosis was suggested by unenhanced CT scan, confirmed by colour doppler flow imaging and magnetic resonance angiography, with absence of blood flow in the longitudinal sinus. Repeated doppler flow imaging showed thrombus resolution within 3 weeks. Thrombosis was associated with predisposing factors in seven cases and appeared idiopathic in the four others.

CONCLUSION

Diagnosis of longitudinal sinus thrombosis can be made more accurately and noninvasively by colour doppler flow and angio-MRI. Treatment with anticoagulants appears unnecessary and dangerous in idiopathic forms.

New pattern of hyperechogenicity in thalamus and basal ganglia studied by color Doppler flow imaging

Thirty-seven infants whose cerebral real-time B-mode ultrasound (CUS) documented hyperechogenic areas in the thalamus and basal ganglia (HTBG) either of linear or fine punctate pattern, were studied prospectively by color Doppler imaging (CDI). This study aimed to establish a relationship between these areas and the regional vasculature, to analyze associated disorders to establish pathogenesis, and to determine clinical significance. HTBG were diagnosed in the first 4 days of life in all but 7 infants. Different patterns of HTBG were observed: punctate in 11 infants, linear in 12, and mixed in 14. The basal ganglia were affected in all patients, 9 also had involvement of the thalamus. CDI confirmed that HTBG were allocated along the gangliothalamic vessels. Blood flow velocity waves were obtained at this level in all patients. Real-time spectral analyses were performed in 35 patients and compared with a control group of 20 healthy neonates. Differences were not significant. Computed tomography and magnetic resonance imaging failed to indicate this abnormality. Necropsy revealed basophilic deposits in the walls of involved arteries. Congenital infections manifested in 5 patients, chromosomal abnormality in 1, dysmorphic syndromes in 9 (3 unidentified), isolated congenital defects in 5, and diverse congenital disorders in 3. In the remaining 14, no congenital disorders nor infections were found. This CDI study demonstrates the vascular location of these HTBG. Supported by early CUS diagnosis, it is speculated that vascular injury in that region has a prenatal origin. This abnormality does not appear to alter regional blood flow. HTBG are associated with very heterogeneous disorders and in most patients the etiology and pathogenesis remain unclear.