Philips probes meaning of blood-volume numbers

Philips Ultrasound should have its ultrasound blood-quantificationproduct, CVI-Q, on the market by the third quarter of this year.While there is general expectation that CVI-Q will provide newand valuable diagnostic information, a successful launch requiresthat clinical utility be demonstrated in specific applications,said Larry Czapla, national sales manager.

To obtain that certificate of usefulness, Philips will placethe blood volume measurement package at clinical research sitesrepresenting five specialities: general radiology, peripheralvascular surgery, neurosurgery, perinatology and interventionalradiology, Czapla said.

The Santa Ana, CA, ultrasound vendor established a clinicalresearch board last year to facilitate development of standardsand normal case files for CVI-Q. Philips has installed its quantificationtechnology at two clinical sites and will place CVI-Q in the fiveadditional facilities early this year, he said.

CVI-Q is based on Philips' non-Doppler color velocity imagingtechnique for measuring blood flow, introduced in 1990 (SCAN 2/14/90).CVI tracks particular groups of blood cells over minute distances,measures time and distance traveled and computes flow velocitydirectly, using these measurements. Doppler, on the other hand,measures changes in the frequency of ultrasound echoes in orderto determine blood-flow velocity.

Blood volume quantification takes this computer-intensive technologya step further. Tracking blood pulsing through a vessel, CVI-Qprovides a velocity profile along an m-mode strip. M-mode displayschanges over time at one point in a vessel.

Blood volume numbers are obtained by matching the velocityprofile with variations in vessel diameter, again measured directlyusing the CVI algorithms, said Thomas DiGiacinto, marketing director.

CVI-Q displays average blood volume--in milliliters per minute--flowingpast a point in the vessel during a complete cardiac cycle. Italso shows the change in systolic/diastolic volume and providesrelated ratios, he said.

PHYSICIANS HAVE WANTED blood volume numbers for some time, butthey don't know quite what to do with them. At first glance, thediagnostic opportunities are considerable. Obstetricians and perinatologistsmight wish to look at the volume of umbilical blood flow to measurefetal development. Neurologists could probe the volume of bloodflowing to the brain and its relation to physiological conditions,Czapla said.

"Standards will be developed over the next couple of years,enabling clinicians to make quick (volume) measurements and determinetheir implications," he said.

Philips developed customized computer chips last year thatallowed the vendor to integrate CVI-Q into its ultrasound scanners.The package was run previously on an independent Sun Microsystemsworkstation. It is now integrated into both the premium Platinumsystem and a new mid-tier Philips scanner called the P700.

CVI-Q differs from the cardiac acoustic quantification featureintroduced by Hewlett-Packard last year. HP's AQ product usesultrasound wave analysis to determine the border between bloodand tissue in the heart and then computes heart chamber area.Variations in heart contraction can indicate cardiac function(SCAN 7/31/91).

Eventually, HP hopes its AQ quantification technology willalso provide a measure of blood-flow volume. Philips, on the otherhand, could use CVI-Q for cardiac analysis in the future.

"The time may come (for applications of CVI-Q) in thenext few years in cardiology, but that is not our short-term goal,"Czapla said.

Apart from developing the volume quantification product, Philipshas worked to improve Platinum's gray-scale images, so that thecomplete scanner package will be up to premium standards, DiGiacintosaid.

"Our emphasis since the introduction of CVI has been toimprove the gray scale. Everybody has been calibrated to Acusonand ATL images. Even though our color is better, users still expectour gray scale to be as good as the market leaders," he said.