Age dependence of flow velocities in basal cerebral arteries.

Bode, Harald; Wais, U

doi:10.1136/adc.63.6.606

Cited by 182 publications

(127 citation statements)

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“…the time it takes blood to flow from the labeling slab to the imaging slices. Previous studies (29,30) have shown that flow velocities in the basal cerebral arteries and carotid arteries are lower in neonates than in adults. It is therefore reasonable to assume that a TI 1 of 700 ms, which was optimized in adults, fulfills the abovementioned first condition in neonates as well.…”

Section: Discussionmentioning

confidence: 99%

Noninvasive Measurements of Regional Cerebral Perfusion in Preterm and Term Neonates by Magnetic Resonance Arterial Spin Labeling

2006

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Magnetic resonance arterial spin labeling (ASL) at 3 Tesla has been investigated as a quantitative technique for measuring regional cerebral perfusion (RCP) in newborn infants. RCP values were measured in 49 healthy neonates: 32 preterm infants born before 34 wk of gestation and 17 term-born neonates. Examinations were performed on unsedated infants at postmenstrual age of 39 -40 wk in both groups. Due to motion, reliable data were obtained from 23 preterm and 6 term infants. Perfusion in the basal ganglia (39 and 30 mL/100 g/min for preterm and term neonates, respectively) was significantly higher (p Ͻ 0.0001) than in cortical gray matter (19 and 16 mL/100 g/min) and white matter (15 and 10 mL/100 g/min), both in preterm neonates at term-equivalent age and in term neonates. Perfusion was significantly higher (p ϭ 0.01) in the preterm group than in the term infants, indicating that RCP may be influenced by developmental and postnatal ages. This study demonstrates, for the first time, that noninvasive ASL at 3T may be used to measure RCP in healthy unsedated preterm and term neonates. ASL is, therefore, a viable tool that will allow serial studies of RCP in high-risk neonates. H igh-risk neonates, either infants born prematurely or asphyxiated infants born at term, have a vulnerable cerebral circulation (1). Impaired autoregulation of the CBF and thus cerebral perfusion contributes to some extent to the development of brain damage in those infants (2-4). Other mechanisms, as inflammation-mediated perfusion disturbances might also be implicated in brain damage development (5), however, this point has not yet been demonstrated.Studies of the cerebral circulation have previously been performed using different invasive methods as xenon clearance (1,6), positron emission tomography (PET) (7,8), and SPECT (9). Noninvasive approaches for estimating global CBF, e.g. Doppler ultrasonography and NIRS (10) have been used achieving only a limited use (11). NIRS as a cot-side method for measuring CBF was described in the late 1980s (12) but has not yet become a routine application, probably because methodological limitations are a problem in quantitative NIRS perfusion measurements. However, quantitative measurements of CBF in neonates have recently been performed with sonographic flowmetry of carotid and vertebral arteries (13)(14)(15)(16). From these studies, it is known that global CBF increases with PMA; however, quantitative regional brain perfusion data and the influence of postnatal age beyond the first 2 wk of life (16) are not yet available on healthy neonates.In recent years, a noninvasive magnetic resonance (MR) method for accurately measuring regional brain perfusion has been developed (17). MR-Atrial spin labeling (ASL) is a completely noninvasive MR technique that enables accurate maps of RCP to be acquired in a few minutes. As this MR method is noninvasive and safe, even in very young infants, the measurements may be repeated, e.g. for monitoring changes in perfusion or response to treatment.The basic...

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Section: Discussionmentioning

confidence: 99%

Noninvasive Measurements of Regional Cerebral Perfusion in Preterm and Term Neonates by Magnetic Resonance Arterial Spin Labeling

2006

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“…Vários estudos sobre a dopplerfl uxometria pela ultra-sonografi a transfontanela em recém-nascidos têm sido realizados, demonstrando um declínio fi siológico progressivo do IR com a idade cronológica 16 , e alterações dos valores de IR em condições patológicas, como por exemplo na hipóxia [17][18][19][20][21][22][23][24][25] . Porém este pare- Em estudos correlatos utilizando o Doppler transfontanela para a avaliação da EHI em RN a termo, não foram excluídos RN com alterações morfológi-cas detectadas pela USTF [17][18][19][20][21][22][23] .…”

Section: Discussionunclassified

Relação entre índice de resistência obtido pela ultra-sonografia Doppler transfortanela e o neurodesenvolvimento até o primeiro ano de vida em recém-nascidos a termo com encefalopatia hipóxico-isquêmica leve e moderada

arcia

Monteiro

Freire

2007

Arq. Neuro-Psiquiatr.

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RESUMO -Objetivo: Avaliar a relação do índice de resistência (IR) obtido pela ultra-sonografia Doppler transfontanela com o neurodesenvolvimento até um ano de idade, em recém-nascidos (RN) a termo com encefalopatia hipóxica-isquêmica (EHI) leve a moderada, secundária à asfixia intra-parto. Método: Estudo prospectivo em 20 RN com EHI leve a moderada, IR elevado no primeiro exame de Doppler, e sem doenças associadas ou anormalidades morfológicas cerebrais. Foram realizados exames seriados bimensais de Doppler transfontanela a partir do sétimo dia de vida, e avaliações clínicas mensais do neurodesenvolvimento no primeiro ano de vida. Resultados: Houve normalização progressiva dos valores de IR até o último exame realizado. Cinco pacientes apresentaram normalização clínico-neurológica no período neonatal, após o primeiro exame de Doppler. Quinze lactentes apresentaram alterações neurológicas com resolução a partir do segundo trimestre de vida. Conclusão: Houve relação entre os períodos em que ocorreu a normalização dos valores de IR e a melhora clínica-neurológica. PALAVRAS-CHAVE: encefalopatia hipóxica-isquêmica, ultra-sonografia Doppler, recém-nascido, neurodesenvolvimento.Relation between the resistance index obtained by the transfontanellar Doppler ultrasonography and the neurological development until the first year of life in term infants with mild or moderate hypoxic-ischaemic encephalopathy ABSTRACT -Objective: To evaluate the relation between the resistance index (RI) obtained by transfontanellar Doppler ultrasonography, and the neurodevelopment until one year of life, at term newborns with mild or moderate hypoxic-ischaemic encephalopathy due to intrapartum asphyxia. Method: 20 term newborns, with mild or moderate hypoxic-ischemic encephalopathy, high values of resistance index in the first exam, and without cerebral morfologic abnormalities or other diseases. They were submitted to serial bimonthly transfontanellar Doppler ultrasonography, from the seventh day of life on, and monthly clinical neurodevelopment assessment until one year of life. Results: There was a progressive normalization of RI values until the last examination. In five cases there were clinical neurologic normalization in the neonatal period after the first Doppler exam. Fifteen infants presented neurologic abnormalities, with normalization after the second trimester of life. Conclusion: There was a relation between the normal RI values with the normalization of the clinical assessment.

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“…Normal RI values are typically higher in premature infants (< 33 weeks' gestational age: 0.77 ± 0.09; > 34 weeks: 0.70 ± 0.07) and gradually decrease to a mean value of 0.50 during the first 1 to 2 years of life. 9,30 Our available study and control populations differ in median age, and this may have introduced bias into our study results, especially in the cutoff points between normal and abnormal RI values as determined by our ROC analysis. Nonetheless, we believe our results accurately reflect the mix of diagnoses and age groups that can be encountered in daily clinical practice in that ventriculomegaly is more likely to be associated with elevated ICP in younger than in older children, in whom loss of brain parenchyma due to neonatal insult has become more manifest.…”

Section: Discussionmentioning

confidence: 99%

Transcranial Doppler ultrasonography to evaluate need for cerebrospinal fluid drainage in hydrocephalic children.

Westra

Lazareff

Curran

et al. 1998

Journal of Ultrasound in Medicine

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levation of ICP in infants, resulting from hydrocephalus, cerebral edema, and intracranial hemorrhage, may lead to brain damage through diastolic hypoperfusion. 1-5 TCD ultrasonography is an accepted noninvasive method to quantify perfusion of intracranial arteries in adults 6,7 and children. [8][9][10][11][12][13][14][15][16][17] The peak S and end D flow velocities are measured, and the RI is calculated as (S -D)/S. Several authors have described the use of RI to study the relationship between cerebral perfusion pressure and ICP, 1,15-18 to investigate ICP-volume relationships (compliance [19][20][21][22] ), and to examine the effects of treatments aimed at decreasing ICP and improving brain perfusion in infants with the previously mentioned clinical conditions. 1,15,16,18,20,21 These treatments include transfontanellar tapping and shunting procedures for hydrocephalus and subdural fluid collections and hyperventilation, diuretics, and blood pressure manipulations for cerebral edema.The purpose of our study was to prospectively determine whether RI measurements obtained with TCD ultrasonography predict the need for treatment in hydrocephalic children. The aim of this study was to determine whether the resistive index in the anterior cerebral artery, as measured by transcranial Doppler ultrasonography without and with pressure provocation, predicts the need for cerebrospinal fluid drainage in hydrocephalic children. Both without and with pressure provocation, the resistive index was significantly higher (P > 0.05) in patients with raised intracranial pressure compared with control group patients and dropped significantly after drainage. With receiver operating characteristic analysis, the optimal cutoff point between normal and abnormal resistive index values was determined at 0.71 without pressure provocation and at 0.90 with pressure provocation. The addition of the pressure provocation test improved accuracy from 81 to 91%, mainly by improving specificity. In conclusion, transcranial Doppler ultrasonography with pressure provocation accurately identifies hydrocephalic children who require cerebrospinal fluid drainage procedures. KEY WORDS: Doppler ultrasonography; Ultrasonography, infants and children; Skull, surgery; Cerebral blood vessels; Hydrocephalus; Brain, ultrasonography; Brain, blood flow.

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Age dependence of flow velocities in basal cerebral arteries.

Abstract: SUMMARY Flow velocities in the basal cerebral arteries were studied by transcranial Doppler sonography. A longitudinal study was undertaken on 25 healthy newborn babies during the first 20 days of life, and a cross sectional study was

Cited by 182 publications

References 17 publications

Noninvasive Measurements of Regional Cerebral Perfusion in Preterm and Term Neonates by Magnetic Resonance Arterial Spin Labeling

Noninvasive Measurements of Regional Cerebral Perfusion in Preterm and Term Neonates by Magnetic Resonance Arterial Spin Labeling

Relação entre índice de resistência obtido pela ultra-sonografia Doppler transfortanela e o neurodesenvolvimento até o primeiro ano de vida em recém-nascidos a termo com encefalopatia hipóxico-isquêmica leve e moderada

Transcranial Doppler ultrasonography to evaluate need for cerebrospinal fluid drainage in hydrocephalic children.

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