HP separates blood from myocardium

Hewlett-Packard introduced a high-end cardiovascular ultrasoundsystem last month that is the first implementation of the tissuecharacterization technology HP has had under development for 10years.

Acoustic Quantification is not tissue characterization perse, but is based on the same underlying technology, said CynthiaP. Danaher, marketing manager.

The AQ package on HP's Sonos 1500 scanner analyzes differencesin acoustic waves reflected from blood and heart tissue. It thenidentifies the border between the blood and tissue and computesthe chamber area in each image frame.

The raw ultrasound signals are analyzed before they are processedinto video data for display. This results in a real-time displayof the heart chamber area on screen and a numerical measurementof the area, which can be used for comparison over time, Danahersaid.

When the system identifies a change in the wave pattern asit sweeps along a scan line, it determines that the reflectingsurface represented in the line has shifted from blood to myocardium.It then takes note of the image pixel in which the shift occurredand flags it as a point on the chamber border.

Sonos 1500 displays cyclic changes in the cardiac chamber areaas a dynamic waveform. Clinicians can use the waveform to observecontractile function throughout every cardiac cycle for as longas the system is operating, said cardiologist John Gorcsan, whodirects the echocardiography laboratory at Montefiore Hospitalin Pittsburgh.

One useful application of this ability to track beat-to-beatvariations in contraction might be continuous monitoring of theeffects of major surgery on cardiac function, he said.

The traditional method of measuring cardiac chamber area involvesoff-line manipulation of freeze-framed ultrasound images and time-consumingmanual tracing of the borders between blood and the heart wall.This process may take about eight minutes to obtain left ventriclearea values for a typical span of three cardiac cycles, Gorcsansaid.

Sonos 1500 should improve HP's already dominant position inthe cardiac ultrasound market by appealing to cardiologists whoare quantitatively inclined, Danaher said. The AQ feature providesadditional information to the clinician without increasing thenumber of tests required, she said.

The American Society of Echocardiography has indicated thatsuch measurements should be part of a comprehensive cardiac exam.Taking measurements off line can reduce throughput, which is animportant issue for most cardiac labs, she said.

While current applications of AQ provide an area measurementthat helps tell the cardiologist how well the ventricle is functioning,a more distant objective of the technology is to provide a measurementof blood volume, Danaher said.

"Volume (measurements) would give you the entire amountof blood that is in the ventricle, which indicates ventricularfunction--or how well that heart muscle is pumping blood to therest of the body. This is a strong indicator of how well a patientwith cardiac disease will do," Danaher said.

Ultimately, the quantitative capabilities of ultrasound maycause the imaging modality to replace some nuclear cardiologystudies, she said.

AQ also has potential in the operating room, where anesthesiologistsmust monitor how well the heart is pumping under the stress ofsurgery, and in vascular imaging. The vendor is in the early stagesof evaluating the technique for use in differentiating plaquewithin an artery, she said.

Sonos 1500 has been added to the top of HP's ultrasound lineand will not replace the existing high-end Sonos 1000. The 1500sells for about $200,000, compared to $165,000 to $175,000 forthe 1000, Danaher said.