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F51Development of power Doppler as a quantifiable tool for assessing fetal perfusion: fractional renal vascular volume
Author(s) -
Welsh A.W.,
Eckersley R.,
Blomley M.,
Cosgrove D.,
Fisk N.M.
Publication year - 2000
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1046/j.1469-0705.2000.00015-1-51.x
Subject(s) - medicine , perfusion , fetus , power doppler , blood flow , reproducibility , doppler effect , blood volume , cardiology , radiology , ultrasound , pregnancy , mathematics , physics , statistics , genetics , astronomy , biology
Background Power Doppler allows the display dynamic range to be increased by up to 10–25dB by coding the amplitude rather than the velocity component of the Doppler frequency shift. Though this means an improvement in image quality, the real advantage of the additional information coded within this signal lies in the potential for quantification of flow (as vascular volume). Method Isolated measurements of amplitude do not have meaning unless they can be standardised to remove the effects of machine settings and attenuation. Two important functions are necessary for this: 1. Correction of the nonlinearities of the energy scale bar (purpose‐designed software ‐CQ Analysis, Kinetic Imaging Ltd, Liverpool). 2. Standardisation to a local area of 100% blood flow (the fetal aorta) to define a fractional regional vascular volume. Multiple clips of fetal renal perfusion were stored to mo disk using the Acuson Sequoia TM for offline computer analysis. Results 150 fetuses were examined (24–40 weeks). Fetal vascular branching could be seen throughout the renal parenchyma in > 80% of fetuses, with clear fluctuations in the fetal cardiac cycle and statistically significant energy values to the aorta and renal parenchyma. Standardising the peripheral volume flow to the aorta gives a fractional vascular volume of approximately 10–20%. Conclusions Further work is underway to improve reproducibility of this technique, to develop an accurate index of fetal renal perfusion. Acknowledgements Alec Welsh is supported by a Research Training Fellowship from RCOG/WellBeing.