Three-Dimensional Volumetric Spatially Angle-Corrected Pixelwise Fetal Flow Volume Measurement

Abstract

Purpose: Early attempts to calculate fetal global perfusion used 2 D images. The results were not sufficiently reliable. That‘s why RI measurements are still in use despite the fact that they do not reflect the amount of blood passing through the fetus. We present a novel three-dimensional approach to overcome these limitations.

Materials and Methods: In 124 singleton pregnancies between the 23^rd and 4^st gestational week, a three-dimensional color Doppler sonographic record of the umbilical cord was made, resulting in 281 volume data sets. With dedicated software (PixelFlux) the spatial angle of the umbilical vein was calculated and the true global fetal perfusion was calculated from its horizontal transection as the product of the area of all pixels and the spatial angle-corrected velocity. To validate the PixelFlux technique, phantom flow measurements were carried out.

Results: Phantom flow measurements revealed a highly significant correlation of actual flow volumes and those measured by the PixelFlux technique (p < 0.001; rPearson = 0.987 – 0.991) with an even higher interobserver correlation (p < 0.001; rPearson = 0.997). We found a significant correlation of fetal volume flow to gestational age and weight (r = 0.529 at spatial angles below 30° to r = 0.724 at spatial angles below 5°) and a significant influence of the spatial angle on this correlation (p = 0.003; r = – 0.865).

Conclusion: Spatial angle-corrected global fetal perfusion measurement improves existing approaches to fetal perfusion evaluation, and is feasible, simple and fast. Thus, it can be recommended to explore the relationship of fetal perfusion and disturbances of fetal development.

Zusammenfassung

Ziel: Frühere Versuche, mithilfe von zweidimensionalen Sonogrammen die fetale Gesamtperfusion zu berechnen, scheiterten an methodischen Grenzen. Daher wird zur fetalen Beurteilung noch heute die Bestimmung des Resistance-Indexes der Nabelarterie benutzt, wenngleich dessen methodische Basis unzureichend ist. Wir entwickelten daher ein neuartiges Verfahren der Flussvolumenkalkulation aus dreidimensionalen Farbdoppler-Bildern der Nabelschnur, welches hier vorgestellt wird.

Material und Methoden: Aus 281 dreidimensionalen Farbdoppler-Bildern der Nabelschnur von 124 Einlingen in der 23. – 41. Schwangerschaftswoche wurden mit der PixelFlux-Software der Raumwinkel der Nabelvene und deren horizontale Querschnittsfläche pixelweise bestimmt. Daraus wurde der Volumenfluss errechnet. Zur Evaluierung der PixelFlux-Methode wurden Phantomflussmessungen vorgenommen.

Ergebnisse: Die Phantomflussmessungen erbrachten eine hochsignifikante Korrelation der tatsächlichen und der mit der PixelFlux-Methode ermittelten Flussvolumina (p < 0,001; rPearson = 0,987 – 0,991) bei einer exzellenten Interobserver-Korrelation (p < 0,001; rPearson = 0,997). Wir konnten einen signifikanten Zusammenhang der raumwinkelkorrigierten fetalen Globalperfusion mit dem Fetalgewicht (r = 0,529 bei Raumwinkeln kleiner 30° bis zu r = 0,724 bei Raumwinkeln kleiner 5°) und der Schwangerschaftsdauer nachweisen, einen signifikanten Einfluss des Raumwinkels auf diesen Zusammenhang (p = 0,003; r = – 0,865) sowie den Effekt der maximal darstellbaren Flussgeschwindigkeit auf die Messungen beschreiben.

Schlussfolgerung: Die neuartige Methode der raumwinkelkorrigierten fetalen globalen Perfusionsmessung überwindet methodische Schwächen herkömmlicher Verfahren der fetalen Perfusionsbeurteilung, ist schnell und einfach durchführbar. Sie kann für weitergehende Untersuchungen von Feten, deren Entwicklung und Erkrankungen empfohlen werden.

Key words

3 D ultrasound - fetal volume perfusion - umbilical vein - PixelFlux - spatial angle correction

• References

• 1 Hoskins PR, Haddad NG, Johnstone FD et al. The choice of index for umbilical artery Doppler waveforms. Ultrasound Med Biol 1989; 15: 107-111
• 2 van Huisseling H, Hasaart TH, Muijsers GJ et al. Umbilical artery pulsatility index and placental vascular resistance during acute hypoxemia in fetal lambs. Gynecol Obstet Invest 1991; 31: 61-66
• 3 Al-Gazali W, Chapman MG, Chita SK et al. Doppler assessment of umbilical artery blood flow for the prediction of outcome in fetal cardiac abnormality. Br J Obstet Gynaecol 1987; 94: 742-745
• 4 Woo JS, Liang ST, Lo RL. Significance of an absent or reversed end diastolic flow in Doppler umbilical artery waveforms. J Ultrasound Med 1987; 6: 291-297
• 5 Scholbach T, Girelli E, Scholbach J. Tissue pulsatility index: a new parameter to evaluate renal transplant perfusion. Transplantation 2006; 81: 751-755
• 6 Scholbach TM. Changes of renal flow volume in the hemolytic-uremic syndrome--color Doppler sonographic investigations. Pediatr Nephrol 2001; 16: 644-647
• 7 Gill RW, Trudinger BJ, Garrett WJ et al. Fetal umbilical venous flow measured in utero by pulsed Doppler and B-mode ultrasound. I. Normal pregnancies.. Am J Obstet Gynecol 1981; 139: 720-725
• 8 Eik-Nes SH, Marsal K, Brubakk AO et al. Ultrasonic measurement of human fetal blood flow. J Biomed Eng 1982; 4: 28-36
• 9 Sauders JB, Wright N, Lewis KO. Measurement of human fetal blood flow. Br Med J 1980; 280: 283-284
• 10 Erskine RL, Ritchie JW. Quantitative measurement of fetal blood flow using Doppler ultrasound. Br J Obstet Gynaecol 1985; 92: 600-604
• 11 Scholbach T, Dimos I, Scholbach J. A new method of color Doppler perfusion measurement via dynamic sonographic signal quantification in renal parenchyma. Nephron Physiol 2004; 96: 99-104
• 12 Scholbach T, Herrero I, Scholbach J. Dynamic color Doppler sonography of intestinal wall in patients with Crohn disease compared with healthy subjects. J Pediatr Gastroenterol Nutr 2004; 39: 524-528
• 13 Scholbach T, Hormann J, Scholbach J. Dynamic tissue perfusion measurement of the intestinal wall – correlation to histology in ulcerative colitis. Journal of Medical Ultrasound 2010; 18: 62-70
• 14 Chameleon-Software. PixelFlux; 2009 www.chameleon-software.de
• 15 Link G, Clark KE, Lang U. Umbilical blood flow during pregnancy: evidence for decreasing placental perfusion. Am J Obstet Gynecol 2007; 196: e489-e487
• 16 Rizzo G, Capponi A, Pietrolucci ME et al. Umbilical vein blood flow at 11 + 0 to 13 + 6 weeks of gestation. J Matern Fetal Neonatal Med 2010; 23: 315-319
• 17 Sutton MS, Theard MA, Bhatia SJ et al. Changes in placental blood flow in the normal human fetus with gestational age. Pediatr Res 1990; 28: 383-387
• 18 Favre R, Ditesheim PJ. Value of Doppler velocimetry of the umbilical artery, aorta, cerebral artery, and uterine artery in pathological pregnancies. J Gynecol Obstet Biol Reprod 1991; 20: 253-259
• 19 Gasser B, Ditesheim PJ, Willemetz JC. Measuring fetal ischemia using multichannel pulsed Doppler sonography of the aorta and umbilical vein. Preliminary results in normal pregnancy. Gynakol Rundsch 1989; 29: 22-31
• 20 Tchirikov M, Rybakowski C, Huneke B et al. Umbilical vein blood volume flow rate and umbilical artery pulsatility as “venous-arterial index” in the prediction of neonatal compromise. Ultrasound Obstet Gynecol 2002; 20: 580-585
• 21 Chen HY, Chang FM, Huang HC et al. Antenatal fetal blood flow in the descending aorta and in the umbilical vein and their ratio in normal pregnancy. Ultrasound Med Biol 1988; 14: 263-268
• 22 Tchirikov M, Strohner M, Forster D et al. A combination of umbilical artery PI and normalized blood flow volume in the umbilical vein: venous-arterial index for the prediction of fetal outcome. Eur J Obstet Gynecol Reprod Biol 2009; 142: 129-133