fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net
fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net home contcat us downloads fetalultrasoundsafety.net
fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net
fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net fetalultrasoundsafety.net
The Skim Milk Study

Video clips of skim milk study, using the high-frequency (at 14 MHz) high-resolution matrix probe with the Toshiba Aplio.  I noted the effects originally when doing scrotal ultrasound when fluid was present around the testicle and showed marked dose-dependant motion and turbulence, leading to this small “experiment”.  The skim milk was decanted carefully from a container which had not been shaken and was allowed to stand for a couple of hours. 

B-mode (standard two-dimensional) imaging: The power setting on the machine was turned down for the initial image then progressively turned up.  Note increasing flow with increasing intensities, shown by MI values in the upper right side of the screen, which illustrates the known process of acoustic streaming. Also, with higher MI values there is the appearance of bright spots (echogenic foci), especially in the near field – the image looks like a snowfall.  I cannot give an explanation for the echogenic foci, and have been unable to see anything visually using a glass container, dilution of the skim milk, transillumination and a magnifying glass.  The thoughts that cross my mind are some sort of transient condensation of skim milk particles, air brought out of solution and cavitation.  It would be interesting for real scientists to examine this, especially with a degassed fluid sample.  I have checked this experiment briefly with the corresponding probe for the GE Logiq 9 and similar effects are demonstrable at similar MI values; this provides some reassurance that output data from different companies are comparable.  Requirements of the FDA document of reference 9 indicate that manufacturers’ measurements should be reasonably standardized.

Note for Internet Explorer users:  To view videos you must first click on the video, then use the player controls to play.


Pulsed wave (PW) Doppler used for flow measurements:  Apologies for the interference signal.  Increased flow is demonstrated along the thin PW path shown by the dotted line, with Bernoulli effect (?) pulling in adjacent fluid.  Note that, despite the increased flow with PW Doppler, it appears that echogenic foci are not so much generated by it but are drawn in from adjacent fluid.  This may be related to the lower peak pulse intensities in PW Doppler than in conventional imaging ultrasound, even though the energy intensity along the narrow beam path is greater than in the surrounding image.  Note the Doppler tracing across the bottom of the image, with flow rate away from the probe of about 4cm/sec; the tracing shows “bumps” when there is an echogenic focus in the PW stream.  In this case ultrasound is both causing fluid motion and measuring it.

Color Doppler (used for visual demonstration of flow):  Note the increased flow rate compared to the B-mode imaging.  Color Doppler, as I understand it, is generated by using pulses similar to those in imaging but with higher repetition rates along each line of the color image.  Moving reflecting particles or bubbles cause phase shifts in the returning echoes; this information is used to determine flow rates which are then displayed with color.  Using pulses similar to B-mode may explain why color imaging produces not only increased flow rates but may also be adding echogenic foci as well.  Note that adjacent fluid is also pulled into the increased flow in color the color box.  Flow rates with PW and color Doppler can be altered by changing power settings – these video clips were taken on the default (maximum) setting.

This experiment was done with a high-frequency high-resolution probe that is not used in transabdominal fetal ultrasound, but should help illustrate that acoustic intensity as measured by onscreen MI values can have ramifications with respect to whatever is being exposed.  It also helps to document the particular influences of the use of PW and color Doppler.  I cannot demonstrate the effect with the lower frequency probe we use for transabdominal fetal ultrasound, but this has nowhere near the resolution although MI values are similar.  CORRECTION - see Miscellaneous Items: Update July 2008 #1 - this can actually be demonstrated. Effects can be demonstrated on transvaginal ultrasound, where fluid motion produced by PW or color Doppler can help characterize pelvic cysts as being fundamentally fluid even when they have internal echoes suggesting a solid nature; I have seen motion in a cyst on transvaginal B-mode without color.  This might raise some questions when the same probe is used for fetal studies.  The ultrasound frequency of transvaginal probes is intermediate between high-frequency high-resolution and conventional transabdominal imaging probes.