Contrast sonography, video densitometry and intervillous blood flow: a pilot project.
OBJECTIVE
To examine the feasibility of constructing time-intensity (TI) curves from the intervillous space with an intravascular ultrasound contrast agent and computer assisted video densitometry.


METHODS
We sedated nine pregnant baboons, optimized the grey scale and color Doppler images of their placentas, and then fixed the transducers in place. For each injection of contrast, we recorded images on videotape without changing the ultrasound image processing functions. Video images were captured using a Macintosh personal computer equipped with a video-capture board using image analysis software (Image 1.4, W Rasband, NIH). For each injection, we sampled digitized images of a fixed region of interest at regular intervals. After computing the mean video density of each image, we used the sampling frequency to construct TI curves depicting any change over time as the contrast agents washed into and out of the intervillous space.


RESULTS
Three of four agents tested produced changes in the video density of the placenta. TI curves were established using both grey scale and color Doppler signal augmentation. As expected, intra-arterial agents produced rapid accumulation and decay. Intravenous agents produced more protracted effects secondary to bolus dilution and transit through the right heart and pulmonary vascular bed.


CONCLUSIONS
TI curves may be generated from the intervillous space with the use of a transpulmonary ultrasound contrast agent and video densitometry. If validated by further study, this may allow investigators to apply ultrasound and indicator-dilution theory to intervillous blood flow.
Barth
W H
WH
Vincent Memorial Hospital, Women's Care Division of the Massachusetts General Hospital, Boston, MA 02114, USA. wbarthjr@partners.org
McCurnin
D C
DC
Dee Carey
K
K
Hankins
G D V
GD
D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology / Q000662:veterinary; D002824:Chorionic Villi / Q000098:blood supply* / Q000502:physiology; D003287:Contrast Media / Q000008:administration & dosage* / Q000145:classification; D003720:Densitometry / Q000379:methods / Q000662:veterinary*; D005240:Feasibility Studies; D007089:Image Enhancement / Q000379:methods; D023421:Models, Animal; D048548:Papio cynocephalus / Q000502:physiology*; D010865:Pilot Projects; D018615:Ultrasonography, Doppler, Color / Q000379:methods / Q000662:veterinary*; D016216:Ultrasonography, Prenatal / Q000379:methods / Q000662:veterinary*; D014741:Video Recording / Q000379:methods
D003287:Contrast Media