Determining the relationship between three‐dimensional power Doppler data and true blood flow characteristics: an in‐vitro flow phantom experiment

Abstract

Objectives

A longitudinal study of three-dimensional ultrasonographic assessment of the placenta in uncomplicated pregnancies

“…We are still uncertain whether 3D power Doppler measurements truly reflect the vascularization and blood flow of the targeted region. Recent in vitro studies using a flow phantom experiment have explored this issue [11][12][13]. These studies have shown how VI, FI, and VFI indices are not equally related to the number of vessels and volume flow.…”

“…This suggestion is supported by our finding that increased placental blood flow as determined by FI has positive influence on fetal growth under the pre-established 3D power Doppler settings. It was also known that variability of the vascular indices is significantly affected by the 3D power Doppler settings [12], therefore, Alcázar [14] recommended that the constant instrumental settings should be described in upcoming publications. With regard to the reproducibility of 3D power Doppler measurements of the placenta, several investigators [4,15,16] have found that most PV and vascular indices showed good reproducibility through correlation and limits of agreement analyses.…”

Re: Three‐dimensional power Doppler: validity and reliability

“…The same problem occurs in other areas of gynecology and obstetrics, be it different thicknesses (1-5 mm) in the evaluation of subendometrial blood flow in infertility 15,16 or different sampling methods of the placenta (as a whole or by representative samples) 17,18 . Additionally, we should not forget about the effect of attenuation 4,19 , which can be avoided by normalizing the intensity of signals during 2D evaluation. Another way to compensate for the effect of attenuation and machine settings would be to determine indices that relate maximum, average and minimum VI, FI and VFI observed during a cardiac cycle, in a similar way that pulsatility index relates blood flow velocities assessed by spectral Doppler (unpubl.…”

Avaliação da vascularização renal fetal em gestações de fetos com restrição de crescimento fetal

“…66,136 De fato, a análise de correlações deste estudo evidenciou correlação negativa significativa da profundidade média dos rins direito e esquerdo com todos os três índices de vascularização (IV, IF e IVF), achados similares aos de Bernardes et al 25,26 quando analisaram a vascularização renal para predizer a função renal pós-natal em fetos com suspeita de obstrução urinária e avaliaram a profundidade entre o probe e o córtex renal fetal.…”

“…Como o tecido celular subcutâneo varia de paciente para paciente, e os fetos apresentam movimentação, o estudo da influência da profundidade é fundamental para a avaliação da vascularização dos órgãos fetais. Chang et al 46 questionaram a influência da atenuação dos tecidos maternos sobre os índices de vascula- 6 DISCUSSÃO 69 rização de órgãos fetais, e, para responder a esse questionamento, Raine-Fenning et al 136 realizaram estudo experimental com a USG3D, utilizando fluxo artificial para avaliar o impacto da atenuação nos índices de vascularização, e todos os três se mostraram significativamente afetados pela atenuação em formas diferentes.…”